Patent Publication Number: US-2021170149-A1

Title: Systems, Kits and Methods for Inducing Negative Pressure to Increase Renal Function

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/879,770, filed Jan. 25, 2018, which is a continuation-in-part of U.S. patent application Ser. No. 15/687,064 filed Aug. 25, 2017, now issued as U.S. Pat. No. 10,765,834, which is a continuation-in-part of U.S. patent application Ser. No. 15/411,884 filed Jan. 20, 2017, now issued as U.S. Pat. No. 10,512,713, which is a continuation-in-part of U.S. patent application Ser. No. 15/214,955 filed Jul. 20, 2016, now issued as U.S. Pat. No. 10,307,564, which claims the benefit of U.S. Provisional Application No. 62/300,025 filed Feb. 25, 2016, U.S. Provisional Application No. 62/278,721, filed Jan. 14, 2016, U.S. Provisional Application No. 62/260,966 filed Nov. 30, 2015, and U.S. Provisional Application No. 62/194,585, filed Jul. 20, 2015, each of which is incorporated by reference herein in its entirety. 
     Also, U.S. patent application Ser. No. 15/879,770 is a continuation-in-part of U.S. patent application Ser. No. 15/745,823 filed Jan. 18, 2018, which is the U.S. national phase of PCT/US2016/043101, filed Jul. 20, 2016, which claims the benefit of U.S. Provisional Application No. 62/300,025 filed Feb. 25, 2016, U.S. Provisional Application No. 62/278,721, filed Jan. 14, 2016, U.S. Provisional Application No. 62/260,966 filed Nov. 30, 2015, and U.S. Provisional Application No. 62/194,585, filed Jul. 20, 2015, each of which is incorporated by reference herein in its entirety. 
     Also, U.S. patent application Ser. No. 15/879,770 claims the benefit of U.S. Provisional Application No. 62/489,789 filed Apr. 25, 2017 and U.S. Provisional Application No. 62/489,831 filed Apr. 25, 2017. 
     Also, U.S. patent application Ser. No. 15/879,770, is a continuation-in-part of U.S. patent application Ser. No. 15/687,083 filed Aug. 25, 2017, which is a continuation-in-part of U.S. patent application Ser. No. 15/411,884 filed Jan. 20, 2017, now issued as U.S. Pat. No. 10,512,713, which is a continuation-in-part of U.S. patent application Ser. No. 15/214,955 filed Jul. 20, 2016, now issued as U.S. Pat. No. 10,307,564, which claims the benefit of U.S. Provisional Application No. 62/300,025 filed Feb. 25, 2016, U.S. Provisional Application No. 62/278,721, filed Jan. 14, 2016, U.S. Provisional Application No. 62/260,966 filed Nov. 30, 2015, and U.S. Provisional Application No. 62/194,585, filed Jul. 20, 2015, each of which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     Technical Field 
     The present disclosure relates to methods and devices for treating impaired renal function across a variety of disease states and, in particular, to methods for removing fluid (e.g., urine) from a patient by using, for example, a combination of ureteral stent(s) and/or ureteral catheter(s) and a bladder catheter by applying negative pressure through the bladder catheter. 
     Background 
     The renal or urinary system includes a pair of kidneys, each kidney being connected by a ureter to the bladder, and a urethra for draining fluid or urine produced by the kidneys from the bladder. The kidneys perform several vital functions for the human body including, for example, filtering the blood to eliminate waste in the form of urine. The kidneys also regulate electrolytes (e.g., sodium, potassium and calcium) and metabolites, blood volume, blood pressure, blood pH, fluid volume, production of red blood cells, and bone metabolism. Adequate understanding of the anatomy and physiology of the kidneys is useful for understanding the impact that altered hemodynamics other fluid overload conditions have on their function. 
     In normal anatomy, the two kidneys are located retroperitoneally in the abdominal cavity. The kidneys are bean-shaped encapsulated organs. Urine is formed by nephrons, the functional unit of the kidney, and then flows through a system of converging tubules called collecting ducts. The collecting ducts join together to form minor calyces, then major calyces, which ultimately join near the concave portion of the kidney (renal pelvis). A major function of the renal pelvis is to direct urine flow to the ureter. Urine flows from the renal pelvis into the ureter, a tube-like structure that carries the urine from the kidneys into the bladder. The outer layer of the kidney is called the cortex, and is a rigid fibrous encapsulation. The interior of the kidney is called the medulla. The medulla structures are arranged in pyramids. 
     Each kidney is made up of approximately one million nephrons. Each nephron includes the glomerulus, Bowman&#39;s capsule, and tubules. The tubules include the proximal convoluted tubule, the loop of Henle, the distal convoluted tubule, and the collecting duct. The nephrons contained in the cortex layer of the kidney are distinct from the anatomy of those contained in the medulla. The principal difference is the length of the loop of Henle. Medullary nephrons contain a longer loop of Henle, which, under normal circumstances, allows greater regulation of water and sodium reabsorption than in the cortex nephrons. 
     The glomerulus is the beginning of the nephron, and is responsible for the initial filtration of blood. Afferent arterioles pass blood into the glomerular capillaries, where hydrostatic pressure pushes water and solutes into Bowman&#39;s capsule. Net filtration pressure is expressed as the hydrostatic pressure in the afferent arteriole minus the hydrostatic pressure in Bowman&#39;s space minus the osmotic pressure in the efferent arteriole. 
       Net Filtration Pressure=Hydrostatic Pressure(Afferent Arteriole)−Hydrostatic Pressure(Bowman&#39;s Space)−Osmotic Pressure(Efferent Arteriole)  (Equation 1)
 
     The magnitude of this net filtration pressure defined by Equation 1 determines how much ultra-filtrate is formed in Bowman&#39;s space and delivered to the tubules. The remaining blood exits the glomerulus via the efferent arteriole. Normal glomerular filtration, or delivery of ultra-filtrate into the tubules, is about 90 ml/min/1.73 m 2 . 
     The glomerulus has a three-layer filtration structure, which includes the vascular endothelium, a glomerular basement membrane, and podocytes. Normally, large proteins such as albumin and red blood cells, are not filtered into Bowman&#39;s space. However, elevated glomerular pressures and mesangial expansion create surface area changes on the basement membrane and larger fenestrations between the podocytes allowing larger proteins to pass into Bowman&#39;s space. 
     Ultra-filtrate collected in Bowman&#39;s space is delivered first to the proximal convoluted tubule. Re-absorption and secretion of water and solutes in the tubules is performed by a mix of active transport channels and passive pressure gradients. The proximal convoluted tubules normally reabsorb a majority of the sodium chloride and water, and nearly all glucose and amino acids that were filtered by the glomerulus. The loop of Henle has two components that are designed to concentrate wastes in the urine. The descending limb is highly water permeable and reabsorbs most of the remaining water. The ascending limb reabsorbs 25% of the remaining sodium chloride, creating a concentrated urine, for example, in terms of urea and creatinine. The distal convoluted tubule normally reabsorbs a small proportion of sodium chloride, and the osmotic gradient creates conditions for the water to follow. 
     Under normal conditions, there is a net filtration of approximately 14 mmHg. The impact of venous congestion can be a significant decrease in net filtration, down to approximately 4 mmHg. See Jessup M.,  The cardiorenal syndrome: Do we need a change of strategy or a change of tactics?, JACC  53(7):597-600, 2009 (hereinafter “Jessup”). The second filtration stage occurs at the proximal tubules. Most of the secretion and absorption from urine occurs in tubules in the medullary nephrons. Active transport of sodium from the tubule into the interstitial space initiates this process. However, the hydrostatic forces dominate the net exchange of solutes and water. Under normal circumstances, it is believed that 75% of the sodium is reabsorbed back into lymphatic or venous circulation. However, because the kidney is encapsulated, it is sensitive to changes in hydrostatic pressures from both venous and lymphatic congestion. During venous congestion the retention of sodium and water can exceed 85%, further perpetuating the renal congestion. See Verbrugge et al.,  The kidney in congestive heart failure: Are natriuresis, sodium, and diruetucs really the good, the bad and the ugly? European Journal of Heart Failure  2014:16, 133-42 (hereinafter “Verbrugge”). 
     Venous congestion can lead to a prerenal form of acute kidney injury (AKI). Prerenal AKI is due to a loss of perfusion (or loss of blood flow) through the kidney. Many clinicians focus on the lack of flow into the kidney due to shock. However, there is also evidence that a lack of blood flow out of the organ due to venous congestion can be a clinically important sustaining injury. See Damman K,  Importance of venous congestion for worsening renal function in advanced decompensated heart failure , JACC 17:589-96, 2009 (hereinafter “Damman”). 
     Prerenal AKI occurs across a wide variety of diagnoses requiring critical care admissions. The most prominent admissions are for sepsis and Acute Decompensated Heart Failure (ADHF). Additional admissions include cardiovascular surgery, general surgery, cirrhosis, trauma, burns, and pancreatitis. While there is wide clinical variability in the presentation of these disease states, a common denominator is an elevated central venous pressure. In the case of ADHF, the elevated central venous pressure caused by heart failure leads to pulmonary edema, and, subsequently, dyspnea in turn precipitating the admission. In the case of sepsis, the elevated central venous pressure is largely a result of aggressive fluid resuscitation. Whether the primary insult was low perfusion due to hypovolemia or sodium and fluid retention, the sustaining injury is the venous congestion resulting in inadequate perfusion. 
     Hypertension is another widely recognized state that creates perturbations within the active and passive transport systems of the kidney(s). Hypertension directly impacts afferent arteriole pressure and results in a proportional increase in net filtration pressure within the glomerulus. The increased filtration fraction also elevates the peritubular capillary pressure, which stimulates sodium and water re-absorption. See Verbrugge. 
     Because the kidney is an encapsulated organ, it is sensitive to pressure changes in the medullary pyramids. The elevated renal venous pressure creates congestion that leads to a rise in the interstitial pressures. The elevated interstitial pressures exert forces upon both the glomerulus and tubules. See Verbrugge. In the glomerulus, the elevated interstitial pressures directly oppose filtration. The increased pressures increase the interstitial fluid, thereby increasing the hydrostatic pressures in the interstitial fluid and peritubular capillaries in the medulla of the kidney. In both instances, hypoxia can ensue leading to cellular injury and further loss of perfusion. The net result is a further exacerbation of the sodium and water re-absorption creating a negative feedback. See Verbrugge, 133-42. Fluid overload, particularly in the abdominal cavity is associated with many diseases and conditions, including elevated intra-abdominal pressure, abdominal compartment syndrome, and acute renal failure. Fluid overload can be addressed through renal replacement therapy. See Peters, C. D.,  Short and Long - Term Effects of the Angiotensin II Receptor Blocker Irbesartanon Intradialytic Central Hemodynamics: A Randomized Double - Blind Placebo - Controlled One - Year Intervention Trial  ( the SAFIR Study ), PLoS ONE (2015) 10(6): e0126882. doi:10.1371/journal.pone.0126882 (hereinafter “Peters”). However, such a clinical strategy provides no improvement in renal function for patients with the cardiorenal syndrome. See Bart B,  Ultrafiltration in decompensated heart failure with cardiorenal syndrome, NEJM  2012; 367:2296-2304 (hereinafter “Bart”). 
     In view of such problematic effects of fluid retention, systems and methods for improving removal of fluid such as urine from the patient and, specifically for increasing quantity and quality of fluid output from the kidneys, are needed. 
     SUMMARY 
     In some examples, a method for removing fluid (e.g., urine) from a patient is provided, the method comprising: deploying a ureteral stent or ureteral catheter into a ureter of a patient to maintain patency of fluid flow between a kidney and a bladder of the patient; deploying a bladder catheter into the bladder of the patient, wherein the bladder catheter comprises a distal end configured to be positioned in a patient&#39;s bladder, a drainage lumen portion having a proximal end, and a sidewall extending therebetween; and applying negative pressure to the proximal end of the bladder catheter to induce negative pressure in a portion of the urinary tract of the patient to remove fluid from the patient. 
     In some examples, a system for removing fluid from a patient is provided, comprising: a ureteral stent or ureteral catheter for maintaining patency of fluid flow between at least one of a kidney and a bladder of the patient; a bladder catheter comprising a drainage lumen for draining fluid from the bladder of the patient; and a pump in fluid communication with a distal end of the drainage lumen, the pump comprising a controller configured to actuate the pump to apply negative pressure to the proximal end of the catheter to induce negative pressure in a portion of the urinary tract of the patient to remove fluid from the patient. 
     In some examples, a kit for removing fluid from a patient is provided, the kit comprising: a ureteral stent or ureteral catheter comprising a drainage channel for facilitating flow of fluid from the ureter and/or kidney through the drainage channel of the ureteral stent towards the bladder of the patient; and a pump comprising a controller configured to induce a negative pressure in at least one of the ureter, kidney or bladder of the patient to draw urine through a drainage lumen of a catheter deployed in the patient&#39;s bladder. 
     In some examples, a kit is provided comprising: a plurality of disposable bladder catheters, each bladder catheter comprising a drainage lumen portion having a proximal end, a distal end configured to be positioned in a patient&#39;s bladder, and a sidewall extending therebetween; and a retention portion extending radially outward from a portion of the distal end of the drainage lumen portion, and being configured to be extended into a deployed position in which a diameter of the retention portion is greater than a diameter of the drainage lumen portion; instructions for deploying the bladder catheter; and instructions for connecting the proximal end of the bladder catheter to a pump and for operating the pump to draw urine through the drainage lumen of the bladder catheter. 
     In some examples, a method for preserving renal function by application of negative pressure to decrease interstitial pressure within tubules of the medullar region to facilitate urine output and to prevent venous congestion-induced nephron hypoxia in the medulla of the kidney, the method comprising: deploying a ureteral stent or ureteral catheter into a ureter of a patient to maintain patency of fluid flow between a kidney and a bladder of the patient; deploying a bladder catheter into the bladder of the patient, wherein the bladder catheter comprises a distal end configured to be positioned in a patient&#39;s bladder, a drainage lumen portion having a proximal end, and a sidewall extending therebetween; and applying negative pressure to the proximal end of the bladder catheter to induce negative pressure in a portion of the urinary tract of the patient for a predetermined period of time to remove fluid from the patient. 
     Non-limiting examples, aspects or embodiments of the present invention will now be described in the following numbered clauses: 
     Clause 1. A method for removing fluid from a patient, the method comprising: deploying a ureteral stent or ureteral catheter into a ureter of a patient to maintain patency of fluid flow between a kidney and a bladder of the patient; deploying a bladder catheter into the bladder of the patient, wherein the bladder catheter comprises a distal end configured to be positioned in a patient&#39;s bladder, a drainage lumen portion having a proximal end, and a sidewall extending therebetween; and applying negative pressure to the proximal end of the bladder catheter to induce negative pressure in a portion of the urinary tract of the patient to remove fluid from the patient. 
     Clause 2. The method of clause 1, further comprising deploying a second ureteral stent or second ureteral catheter into a second ureter of the patient to maintain patency of fluid flow between a second kidney and the bladder of the patient. 
     Clause 3. The method of any of clauses 1 or 2, wherein the ureteral catheter comprises a drainage lumen portion having a proximal end, a distal end configured to be positioned in at least one of the patient&#39;s ureter, renal pelvis or kidney, and a sidewall extending therebetween; and a retention portion extending radially outward from a portion of the distal end of the drainage lumen portion, and being configured to be extended into a deployed position in which a diameter of the retention portion is greater than a diameter of the drainage lumen portion. 
     Clause 4. The method of any of clauses 1 or 2, wherein the ureteral catheter comprises a tube defining a drainage lumen and comprising a helical retention portion comprising a helical arrangement with multiple coils when deployed and a plurality of drainage ports. 
     Clause 5. The method of clause 4, wherein deploying the ureteral catheter comprises expanding the helical retention portion at a fluid collection position in at least one of the patient&#39;s ureter, renal pelvis or kidney for receiving urine or fluid from the kidney. 
     Clause 6. The method of any of clauses 1 or 2, wherein the ureteral catheter comprises: a drainage lumen comprising a proximal portion and a distal portion configured to be positioned in at least one of a portion of a patient&#39;s ureter adjacent to the renal pelvis, renal pelvis or kidney, the distal portion comprising a coiled retention portion, the coiled retention portion comprising: at least a first coil having a first diameter; at least a second coil having a second diameter, the first diameter being less than the second diameter; and one or more perforations on a sidewall of the coiled retention portion of the distal portion of the drainage lumen for permitting fluid flow into the drainage lumen, wherein the proximal portion of the drainage lumen is essentially free of or free of perforations. In some embodiments, the second coil is closer to an end of the distal portion of the drainage lumen than is the first coil. In some embodiments, the second coil is closer to an end of the proximal portion of the drainage lumen than is the first coil. 
     Clause 7. The method of any of clauses 1 or 2, wherein the ureteral stent comprises an elongated body comprising a proximal end, a distal end, a longitudinal axis, and at least one drainage channel that extends along the longitudinal axis from the proximal end to the distal end to maintain patency of fluid flow between a kidney and a bladder of the patient. 
     Clause 8. The method of clause 7 wherein the ureteral stent further comprises a pigtail coil or loop(s) on at least one of the proximal end or the distal end. 
     Clause 9. The method of clause 7 wherein the body of the ureteral stent further comprises at least one perforation on a sidewall thereof. 
     Clause 10. The method of clause 7 wherein the body of the ureteral stent is essentially free of or free of perforation(s) on a sidewall thereof. 
     Clause 11. The method of clause 7, wherein the at least one drainage channel is partially open along at least a longitudinal portion thereof. 
     Clause 12. The method of clause 7, wherein the at least one drainage channel is closed along at least a longitudinal portion thereof. 
     Clause 13. The method of clause 7, wherein the at least one drainage channel is closed along the longitudinal length thereof. 
     Clause 14. The method of clause 7, wherein the ureteral stent is radially compressible. 
     Clause 15. The method of clause 7, wherein the ureteral stent is radially compressible to narrow the at least one drainage channel. 
     Clause 16. The method of clause 7, wherein the elongated body comprises at least one external fin along the longitudinal axis of the elongated body. 
     Clause 17. The method of claim  7 , wherein the elongated body comprises one to four drainage channels. 
     Clause 18. The method of any of clauses 1 or 2, wherein the ureteral stent comprises: an elongated body comprising a proximal end, a distal end, a longitudinal axis, an outer surface, and an inner surface, wherein the inner surface defines a transformable bore that extends along the longitudinal axis from the proximal end to the distal end; wherein the transformable bore comprises: (a) a default orientation comprising an open bore defining a longitudinally open channel; and (b) a second orientation comprising an at least essentially closed bore or closed bore defining a longitudinally essentially closed drainage channel along the longitudinal axis of the elongated body, wherein the transformable bore is moveable from the default orientation to the second orientation upon radial compression forces being applied to at least a portion of the outer surface of the body. In some examples, at least two fins project radially away from the outer surface of the body. 
     Clause 19. The method of clause 18, wherein the drainage channel of the ureteral stent has a diameter which is reduced upon the transformable bore moving from the default orientation to the second orientation, wherein the diameter is reducible up to the point above where urine flow through the transformable bore would be reduced. 
     Clause 20. The method of clause 19, wherein the diameter is reduced by up to about 40% upon the transformable bore moving from the default orientation to the second orientation. 
     Clause 21. The method of clause 18, wherein the elongated body further comprises at least two fins comprise a flexible material that is soft to medium soft based on the Shore hardness scale, and wherein the body comprises a flexible material that is medium hard to hard based on the Shore hardness scale. 
     Clause 22. The method of clause 21, wherein the at least two fins have a durometer between about 15 A to about 40 A and the body has a durometer between about 80 A to about 90 A. 
     Clause 23. The method of clause 18, wherein the the elongated body further comprises at least two fins and the body comprises a flexible material that is medium soft to medium hard based on the Shore hardness scale. 
     Clause 24. The method of clause 23, wherein the at least two fins and the body have a durometer between about 40 A to about 70 A. 
     Clause 25. The method of clause 18, wherein the elongated body further comprises at least two fins and the body comprises a flexible material that is medium hard to hard based on the Shore hardness scale. 
     Clause 26. The method of clause 25, wherein the at least two fins and the body have a durometer between about 85 A to about 90 A. 
     Clause 27. The method of any of clauses 18 to 26, wherein the default orientation and the second orientation support fluid flow around the outer surface of the stent in addition to through the transformable bore. 
     Clause 28. The method of clause 18, wherein the at least two fins extend longitudinally from the proximal end to the distal end. 
     Clause 29. The method of any of clauses 18 to 28, wherein the outer surface of the body has a diameter of about 0.036 inches. 
     Clause 30. The method of any of clauses 18 to 29, wherein the inner surface of the body has a diameter of about 0.024 inches. 
     Clause 31. The method of clause 21, wherein each of the at least two fins has a tip that is about 0.040 inches from the longitudinal axis. 
     Clause 32. The method of any of clauses 18 to 31, wherein the radial compression forces are provided by at least one of normal ureter physiology, abnormal ureter physiology, or application of any external force. 
     Clause 33. The method of clause 21, wherein the number of fins is two or three. 
     Clause 34. The method of clause 1, wherein the ureteral stent purposefully adapts to a dynamic ureteral environment, the ureteral stent comprising: an elongated body comprising a proximal end, a distal end, a longitudinal axis, an outer surface, and an inner surface, wherein the inner surface defines a transformable bore that extends along the longitudinal axis from the proximal end to the distal end; wherein the transformable bore comprises: (a) a default orientation comprising an open bore defining a longitudinally open channel; and (b) a second orientation comprising an at least essentially closed bore defining a longitudinally essentially closed channel, wherein the transformable bore is moveable from the default orientation to the second orientation upon radial compression forces being applied to at least a portion of the outer surface of the body, wherein the inner surface of the body has a diameter which is reduced upon the transformable bore moving from the default orientation to the second orientation, wherein the diameter is reducible up to the point above where urine flow through the transformable bore would be reduced. 
     Clause 35. The method of clause 34, wherein the diameter is reduced by up to about 40% upon the transformable bore moving from the default orientation to the second orientation. 
     Clause 36 The method of any of clauses 34 or 35, wherein the body comprises a flexible material that is medium hard to hard based on the Shore hardness scale. 
     Clause 37. The method of clause 36, wherein the body has a durometer between about 80 A to about 90 A. 
     Clause 38. The method of clause 36, wherein the body has a durometer between about 85 A to about 90 A. 
     Clause 39. The method of any of clauses 34 or 36, wherein the body comprises a flexible material that is medium soft to medium hard based on the Shore hardness scale. 
     Clause 40. The method of clause 39, wherein body has a durometer between about 40 A to about 70 A. 
     Clause 41. The method of clause 34, wherein the default orientation and the second orientation support fluid flow around the outer surface of the stent in addition to through the transformable bore. 
     Clause 42. The method of any of clauses 1 to 41, wherein the bladder catheter comprises a drainage lumen portion having a proximal end, a distal end configured to be positioned in a patient&#39;s bladder, and a sidewall extending therebetween; and a retention portion extending radially outward from a portion of the distal end of the drainage lumen portion, and being configured to be extended into a deployed position in which a diameter of the retention portion is greater than a diameter of the drainage lumen portion. 
     Clause 43. The method of any of clauses 1 to 42, wherein the bladder catheter comprises a tube defining a drainage lumen and comprising a helical retention portion comprising a helical arrangement with multiple coils when deployed and a plurality of drainage ports. 
     Clause 44. The method of clause 43, wherein deploying the bladder catheter comprises expanding the helical retention portion at a fluid collection position in the patient&#39;s bladder for receiving urine which passes through the ureter and/or ureteral stent and enters the bladder. 
     Clause 45. The method of any of clauses 1 to 44, wherein the ureteral stent or ureteral catheter is deployed and remains in the patient&#39;s body for at least 24 hours. 
     Clause 46. The method of any of clauses 1 to 45, wherein the ureteral stent or ureteral catheter is deployed and remains in the patient&#39;s body for at least 30 days or longer. 
     Clause 47. The method of any of clauses 1 to 46, wherein the bladder catheter is replaced more often that the ureteral stent or ureteral catheter. 
     Clause 48. The method of any of clauses 1 to 47, wherein multiple bladder catheters are sequentially placed and removed during the indwell time for a single ureteral stent or ureteral catheter. 
     Clause 49. The method of clause 2, wherein multiple bladder catheters are placed and removed during the indwell time for a single set of ureteral stents or ureteral catheters. 
     Clause 50. The method of any of clauses 1 to 49, wherein an urologist or other physician places the ureteral stent(s) or ureteral catheter(s) in the patient. 
     Clause 51. The method of any of clauses 1 to 49, wherein a physician, nurse, caregiver or patient places the bladder catheter(s) in the patient at home or in any healthcare setting. 
     Clause 52. The method of any of clauses 1 to 51, wherein negative pressure is applied each evening for a predetermined number of evenings, and optionally the bladder catheter is replaced each evening before application of negative pressure. 
     Clause 53. The method of any of clauses 1 to 52, wherein removing excess fluid from the patient is provided as one of a treatment for systemic fluid volume management associated with chronic edematous, hypertension, chronic kidney disease and/or acute heart failure. 
     Clause 54. The method of clause 53, further comprising: periodically measuring the patient&#39;s weight; and if the measured weight is less than a predetermined threshold value, ceasing the application of the negative pressure to the urinary tract. 
     Clause 55. The method of clause 54, wherein the predetermined threshold value is a dry weight of the patient. 
     Clause 56. A system for removing fluid from a patient is provided, comprising: a ureteral stent or ureteral catheter for maintaining patency of fluid flow between at least one of a kidney and a bladder of the patient; a bladder catheter comprising a drainage lumen for draining fluid from the bladder of the patient; and a pump in fluid communication with a distal end of the drainage lumen, the pump comprising a controller configured to actuate the pump to apply negative pressure to the proximal end of the catheter to induce negative pressure in at least a portion of the urinary tract of the patient to remove fluid from the patient 
     Clause 57. The system of clause 56, further comprising one or more physiological sensors associated with the patient, the physiological sensors being configured to provide information representative of at least one physical parameter to the controller. 
     Clause 58. The system of clause 57, wherein the one or more physiological sensors comprise an analyte and/or capacitance sensor associated with an extracorporeal blood system associated with the patient. 
     Clause 59. The system of clause 56, wherein, prior to ceasing application of the negative pressure, the controller is further configured to adjust an operating parameter of the pump based, at least in part, on measured value(s) of the at least one physical parameter. 
     Clause 60. The system of clause 59, wherein adjusting an operating parameter of the pump based on the measured value(s) the at least one physical parameter comprises reducing applied negative pressure when a downward trend in value(s) the at least one physical parameter is identified. 
     Clause 61. The system of any of clauses 56 to 60, wherein the pump provides a sensitivity of about 10 mmHg or less. 
     Clause 62. The system of any of clauses 56 to 61, wherein the controller is configured to cause the pump to alternate between providing negative pressure and providing positive pressure. 
     Clause 63. The system of clause 62, wherein the negative pressure is provided within a range of about 0.1 mmHg to about 150 mmHg, and wherein the positive pressure is provided within a range of about 5 mmHg to about 20 mmHg. 
     Clause 64. The system of clause 56, wherein excess fluid is provided to the patient during a fluid resuscitation procedure. 
     Clause 65. A kit for removing fluid from a patient, the kit comprising: a ureteral stent or ureteral catheter comprising a drainage channel for facilitating flow of fluid from the ureter and/or kidney through the drainage channel of the ureteral stent or ureteral catheter towards the bladder of the patient; and a pump comprising a controller configured to induce a negative pressure in at least one of the ureter, kidney or bladder of the patient to draw fluid through a drainage lumen of a catheter deployed in the patient&#39;s bladder. 
     Clause 66. The kit according to clause 65, further comprising a bladder catheter. 
     Clause 67. The kit according to clause 66, further comprising instructions for inserting a ureteral stent, a bladder catheter, and operating the pump to draw urine through a drainage lumen of a catheter deployed the patient&#39;s bladder. 
     Clause 68. A kit comprising: a plurality of disposable bladder catheters, each bladder catheter comprising a drainage lumen portion having a proximal end, a distal end configured to be positioned in a patient&#39;s bladder, and a sidewall extending therebetween; and a retention portion extending radially outward from a portion of the distal end of the drainage lumen portion, and being configured to be extended into a deployed position in which a diameter of the retention portion is greater than a diameter of the drainage lumen portion; instructions for deploying the bladder catheter; and instructions for connecting the proximal end of the bladder catheter to a pump and for operating the pump to draw fluid through the drainage lumen of the bladder catheter. 
     Clause 69. A method for preserving renal function by application of negative pressure to decrease interstitial pressure within tubules of the medullar region to facilitate urine output and to prevent venous congestion-induced nephron hypoxia in the medulla of the kidney, the method comprising: deploying a ureteral stent or ureteral catheter into a ureter or kidney of a patient to maintain patency of fluid flow between a kidney and a bladder of the patient; deploying a bladder catheter into the bladder of the patient, wherein the bladder catheter comprises a distal end configured to be positioned in a patient&#39;s bladder, a drainage lumen portion having a proximal end, and a sidewall extending therebetween; and applying negative pressure to the proximal end of the bladder catheter to induce negative pressure in a portion of the urinary tract of the patient for a predetermined period of time to remove fluid from the urinary tract of the patient. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and characteristics of the present disclosure, as well as the methods of operation and functions of the related elements of structures and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended clauses with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limit of the invention. 
       Further features and other examples and advantages will become apparent from the following detailed description made with reference to the drawings in which: 
         FIG. 1  is a schematic drawing of an indwelling portion of a system comprising a ureteral stent and a bladder catheter deployed in a urinary tract of a patient, according to an example of the present invention; 
         FIG. 2  is a schematic drawing of an indwelling portion of a system comprising a ureteral catheter and a bladder catheter deployed in a urinary tract of a patient, according to an example of the present invention; 
         FIG. 3  is a dimetric view of an example of a prior art transformable ureteral stent according to FIG. 1 of PCT Patent Application Publication WO 2017/019974, wherein the image on the left represents the uncompressed state of the stent and the image on the right represents the compressed state of the stent; 
         FIG. 4  is a perspective view of an example of a prior art ureteral stent according to FIG. 4 of US Patent Application Publication No. 2002/0183853 A1; 
         FIG. 5  is a perspective view of an example of a prior art ureteral stent according to FIG. 5 of US Patent Application Publication No. 2002/0183853 A1; and 
         FIG. 6  is a perspective view of an example of a prior art ureteral stent according to FIG. 7 of US Patent Application Publication No. 2002/0183853 A1. 
         FIG. 7  is a schematic drawing of another example of an indwelling portion of a system comprising a ureteral catheter and a bladder catheter deployed in a urinary tract of a patient, according to an example of the present invention; 
         FIG. 7A  is a schematic drawing of a system for inducing negative pressure to the urinary tract of a patient according to an example of the present invention; 
         FIG. 8A  is a perspective view of an exemplary catheter according to an example of the present invention; 
         FIG. 8B  is a front view of the catheter of  FIG. 8A ; 
         FIG. 9A  is a schematic drawing of an example of a retention portion for a catheter according to an example of the present invention; 
         FIG. 9B  is a schematic drawing of another example of a retention portion for a catheter according to an example of the present invention; 
         FIG. 9C  is a schematic drawing of another example of a retention portion for a catheter according to an example of the present invention; 
         FIG. 9D  is a schematic drawing of another example of a retention portion for a catheter according to an example of the present invention; 
         FIG. 9E  is a schematic drawing of another example of a retention portion for a catheter according to an example of the present invention; 
         FIG. 10  is a front view of another example of a catheter according to an example of the present invention; 
         FIG. 10A  is a perspective view of the retention portion of the catheter of  FIG. 10  enclosed by circle  10 A according to an example of the present invention; 
         FIG. 10B  is a front view of the retention portion of  FIG. 10A  according to an example of the present invention; 
         FIG. 10C  is a rear view of the retention portion of  FIG. 10A  according to an example of the present invention; 
         FIG. 10D  is a top view of the retention portion of  FIG. 10A  according to an example of the present invention; 
         FIG. 10E  is a cross sectional view of the retention portion of  FIG. 10A  taken along line  30 E- 30 E according to an example of the present invention; 
         FIG. 11  is a schematic drawing of a retention portion of a catheter in a constrained or linear position according to an example of the disclosure; 
         FIG. 12  is a schematic drawing of another example of a retention portion of a catheter in a constrained or linear position according to an example of the disclosure; 
         FIG. 13  is a schematic drawing of another example of a retention portion of a ureteral catheter in a constrained or linear position according to an example of the disclosure; 
         FIG. 14  is a schematic drawing of another example of a retention portion of a catheter in a constrained or linear position according to an example of the disclosure; 
         FIG. 15A  is a graph showing a percentage of fluid flow through openings of an exemplary catheter as a function of position according to an example of the disclosure; 
         FIG. 15B  is a graph showing a percentage of fluid flow through openings of another exemplary catheter as a function of position according to an example of the disclosure; 
         FIG. 15C  is a graph showing a percentage of fluid flow through openings of another exemplary catheter as a function of position according to an example of the disclosure; 
         FIG. 16  is a schematic drawing of a retention portion of a catheter showing stations for calculating fluid flow coefficients for a mass transfer balance evaluation according to an example of the present disclosure; 
         FIG. 17  is a schematic drawing of an indwelling portion of a system deployed in a urinary tract of a patient, according to another example of the present invention; 
         FIG. 18A  is side elevational view of a retention portion of a catheter according to an example of the present disclosure; 
         FIG. 18B  is cross-sectional view of the retention portion of the catheter of  FIG. 18A  taken along lines B-B of  FIG. 18A ; 
         FIG. 18C  is a top plan view of the retention portion of the catheter of  FIG. 18A  taken along lines C-C of  FIG. 18A ; 
         FIG. 19  is a side elevational view of a retention portion of another catheter according to an example of the present disclosure; 
         FIG. 20  is a side elevational view of a retention portion of another catheter according to an example of the present disclosure; 
         FIG. 21  is a side elevational view of a retention portion of another catheter according to an example of the present disclosure; 
         FIG. 22A  is a perspective view of a retention portion of another ureteral catheter according to an example of the present disclosure; 
         FIG. 22B  is a top plan view of the retention portion of the catheter of  FIG. 22A  taken along lines B-B of  FIG. 22A ; 
         FIG. 23A  is a perspective view of a retention portion of another catheter according to an example of the present disclosure; 
         FIG. 23B  is a top plan view of the retention portion of the catheter of  FIG. 23A  taken along lines B-B of  FIG. 23A ; 
         FIG. 24  is a perspective view of a retention portion of another catheter according to an example of the present disclosure; 
         FIG. 25  is a side elevational view of a retention portion of another catheter according to an example of the present disclosure; 
         FIG. 26  is a side elevational view of a retention portion of another catheter according to an example of the present disclosure; 
         FIG. 27  is a cross-sectional side view of a retention portion of another catheter according to an example of the present disclosure; 
         FIG. 28A  is a perspective view of a retention portion of another catheter according to an example of the present disclosure; 
         FIG. 28B  is a top plan view of the retention portion of the catheter of  FIG. 28A ; 
         FIG. 29A  is a perspective view of a retention portion of another catheter according to an example of the present disclosure; 
         FIG. 29B  is a top plan view of the retention portion of the catheter of  FIG. 29A ; 
         FIG. 30  is a perspective view of a retention portion of another catheter according to an example of the present disclosure; 
         FIG. 31  is a top plan view of the retention portion of the catheter of  FIG. 30 ; 
         FIG. 32A  is a perspective view of a retention portion of another catheter according to an example of the present disclosure; 
         FIG. 32B  is a top plan view of the retention portion of the catheter of  FIG. 32A ; 
         FIG. 33  is a cross-sectional side elevational view of a retention portion of another catheter according to an example of the present disclosure; 
         FIG. 34  is a cross-sectional side elevational view of a retention portion of another catheter according to an example of the present disclosure; 
         FIG. 35A  is a perspective view of a retention portion of another catheter according to an example of the present disclosure; 
         FIG. 35B  is a cross-sectional side elevational view of the retention portion of the catheter of  FIG. 35A  taken along lines B-B of  FIG. 35A ; 
         FIG. 36  is a side elevational view showing a cut away cross-sectional view of the sheath surrounding a catheter according to an example of the present disclosure in a contracted configuration for insertion into a patient&#39;s ureter 
         FIG. 37A  is a schematic drawing of another example of a retention portion for a catheter according to an example of the present invention; 
         FIG. 37B  is a schematic drawing of a cross-sectional view of a portion of the retention portion of  FIG. 37A , taken along lines B-B of  FIG. 37A ; 
         FIG. 38A  is a schematic drawing of another example of a retention portion for a catheter according to an example of the present invention; 
         FIG. 38B  is a schematic drawing of a portion of a cross-sectional view of the retention portion of  FIG. 5A , taken along lines B-B of  FIG. 38A ; 
         FIG. 39  is a schematic drawing of another example of a retention portion for a catheter according to an example of the present invention; 
         FIG. 40  is a schematic drawing of a cross section of another example of a retention portion for a catheter according to an example of the present invention; 
         FIG. 41  is a schematic drawing of another example of a retention portion for a catheter according to an example of the present invention; 
         FIG. 42A  is a flow chart illustrating a process for insertion and deployment of a system according to an example of the present invention; 
         FIG. 42B  is a flow chart illustrating a process for applying negative pressure using a system according to an example of the present invention; 
         FIG. 43  is a schematic drawing of a nephron and surrounding vasculature showing a position of the capillary bed and convoluted tubules. 
         FIG. 44  is a schematic drawing of a system for inducing negative pressure to the urinary tract of a patient according to an example of the present invention; 
         FIG. 45A  is a plan view of a pump for use with the system of  FIG. 44  according to an example of the present invention; 
         FIG. 45B  is a side elevation view of the pump of  FIG. 45A ; 
         FIG. 46  is a schematic drawing of an experimental set-up for evaluating negative pressure therapy in a swine model; 
         FIG. 47  is a graph of creatinine clearance rates for tests conducted using the experimental set-up shown in  FIG. 21 ; 
         FIG. 48A  is a low magnification photomicrograph of kidney tissue from a congested kidney treated with negative pressure therapy; 
         FIG. 48B  is a high magnification photomicrograph of the kidney tissue shown in  FIG. 48A ; 
         FIG. 48C  is a low magnification photomicrograph of kidney tissue from a congested and untreated (e.g., control) kidney; 
         FIG. 48D  is a high magnification photomicrograph of the kidney tissue shown in  FIG. 23C   
         FIG. 49  is a flow chart illustrating a process for reducing creatinine and/or protein levels of a patient according to an example of the disclosure; 
         FIG. 50  is a flow chart illustrating a process for treating a patient undergoing fluid resuscitation according to an example of the disclosure; and 
         FIG. 51  is a graph of serum albumin relative to baseline for tests conduct on swine using the experimental method described herein. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As used herein, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly states otherwise. 
     As used herein, the terms “right”, “left”, “top”, and derivatives thereof shall relate to the invention as it is oriented in the drawing figures. The term “proximal” refers to the portion of the catheter device that is manipulated or contacted by a user and/or to a portion of an indwelling catheter nearest to the urinary tract access site. The term “distal” refers to the opposite end of the catheter device that is configured to be inserted into a patient and/or to the portion of the device that is inserted farthest into the patient&#39;s urinary tract. However, it is to be understood that the invention can assume various alternative orientations and, accordingly, such terms are not to be considered as limiting. Also, it is to be understood that the invention can assume various alternative variations and stage sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are examples. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as limiting. 
     For the purposes of this specification, unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, dimensions, physical characteristics, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present invention. 
     Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. 
     Also, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” is intended to include any and all sub-ranges between and including the recited minimum value of 1 and the recited maximum value of 10, that is, all subranges beginning with a minimum value equal to or greater than 1 and ending with a maximum value equal to or less than 10, and all subranges in between, e.g., 1 to 6.3, or 5.5 to 10, or 2.7 to 6.1. 
     As used herein, the terms “communication” and “communicate” refer to the receipt or transfer of one or more signals, messages, commands, or other type of data. For one unit or component to be in communication with another unit or component means that the one unit or component is able to directly or indirectly receive data from and/or transmit data to the other unit or component. This can refer to a direct or indirect connection that can be wired and/or wireless in nature. Additionally, two units or components can be in communication with each other even though the data transmitted can be modified, processed, routed, and the like, between the first and second unit or component. For example, a first unit can be in communication with a second unit even though the first unit passively receives data, and does not actively transmit data to the second unit. As another example, a first unit can be in communication with a second unit if an intermediary unit processes data from one unit and transmits processed data to the second unit. It will be appreciated that numerous other arrangements are possible. 
     As used herein, “maintain patency of fluid flow between a kidney and a bladder of the patient” means establishing, increasing or maintaining flow of fluid, such as urine, from the kidneys through the ureter(s), ureteral stent(s) and/or ureteral catheter(s) to the bladder. As used herein, “fluid” means urine and any other fluid from the urinary tract. 
     Fluid retention and venous congestion are central problems in the progression to advanced renal disease. Excess sodium ingestion coupled with relative decreases in excretion leads to isotonic volume expansion and secondary compartment involvement. In some examples, the present invention is generally directed to devices and methods for facilitating drainage of urine or waste from the bladder, ureter, and/or kidney(s) of a patient. In some examples, the present invention is generally directed to systems and methods for inducing a negative pressure in the bladder, ureter, and/or kidney(s) of a patient. While not intending to be bound by any theory, it is believed that applying a negative pressure to the bladder, ureter, and/or kidney(s) can offset the medullary nephron tubule re-absorption of sodium and water in some situations. Offsetting re-absorption of sodium and water can increase urine production, decrease total body sodium, and improve erythrocyte production. Since the intra-medullary pressures are driven by sodium and, therefore, volume overload, the targeted removal of excess sodium enables maintenance of volume loss. Removal of volume restores medullary hemostasis. Normal urine production is 1.48-1.96 L/day (or 1-1.4 ml/min). 
     Fluid retention and venous congestion are also central problems in the progression of prerenal Acute Kidney Injury (AKI). Specifically, AKI can be related to loss of perfusion or blood flow through the kidney(s). Accordingly, in some examples, the present invention facilitates improved renal hemodynamics and increases urine output for the purpose of relieving or reducing venous congestion. Further, it is anticipated that treatment and/or inhibition of AKI positively impacts and/or reduces the occurrence of other conditions, for example, reduction or inhibition of worsening renal function in patients with NYHA Class III and/or Class IV heart failure. Classification of different levels of heart failure are described in  The Criteria Committee of the New York Heart Association , (1994),  Nomenclature and Criteria for Diagnosis of Diseases of the Heart and Great Vessels , (9th ed.), Boston: Little, Brown &amp; Co. pp. 253-256, the disclosure of which is incorporated by reference herein in its entirety. Reduction or inhibition of episodes of AKI and/or chronically decreased perfusion may also be a treatment for Stage 4 and/or Stage 5 chronic kidney disease. Chronic kidney disease progression is described in National Kidney Foundation, K/DOQI  Clinical Practice Guidelines for Chronic Kidney Disease: Evaluation, Classification and Stratification . Am. J. Kidney Dis. 39:S1-S266, 2002 (Suppl. 1), the disclosure of which is incorporated by reference herein in its entirety. 
     With reference to  FIGS. 1, 2, 7, 17, 27 and 44 , the urinary tract comprises a patient&#39;s right kidney  2  and left kidney  4 . As discussed above, the kidneys  2 ,  4  are responsible for blood filtration and clearance of waste compounds from the body through urine. Urine produced by the right kidney  2  and the left kidney  4  is drained into a patient&#39;s bladder  10  through tubules, namely a right ureter  6  and a left ureter  8 . For example, urine may be conducted through the ureters  6 ,  8  by peristalsis of the ureter walls, as well as by gravity. The ureters  6 ,  8  enter the bladder  10  through a ureter orifice or opening  16 . The bladder  10  is a flexible and substantially hollow structure adapted to collect urine until the urine is excreted from the body. The bladder  10  is transitionable from an empty position (signified by reference line E) to a full position (signified by reference line F). When the bladder is in the empty position E, the bladder superior wall  70  can be positioned adjacent to and/or conform to the periphery  72  of the distal end  136  of the bladder catheter  56 ,  116 . Normally, when the bladder  10  reaches a substantially full state, urine is permitted to drain from the bladder  10  to a urethra  12  through a urethral sphincter or opening  18  located at a lower portion of the bladder  10 . Contraction of the bladder  10  can be responsive to stresses and pressure exerted on a trigone region  14  of the bladder  10 , which is the triangular region extending between the ureteral openings  16  and the urethral opening  18 . The trigone region  14  is sensitive to stress and pressure, such that as the bladder  10  begins to fill, pressure on the trigone region  14  increases. When a threshold pressure on the trigone region  14  is exceeded, the bladder  10  begins to contract to expel collected urine through the urethra  12 . 
     In some examples, methods and systems  50 ,  100 , as shown for example in  FIGS. 1, 2, 7, 17, 27 and 44 , are provided for removing fluid (such as urine) from a patient, the method comprising: deploying a ureteral stent  52 ,  54  (shown in  FIG. 1 ) or ureteral catheter  112 ,  114  (shown in  FIGS. 2, 7, 17, 27 and 44 ) into a ureter  6 ,  8  of a patient to maintain patency of fluid flow between a kidney  2 ,  4  and a bladder  10  of the patient; deploying a bladder catheter  56 ,  116  into the bladder  10  of the patient, wherein the bladder catheter  56 ,  116  comprises a distal end  136  configured to be positioned in a patient&#39;s bladder  10 , a drainage lumen portion  140  having a proximal end  117 , and a sidewall  119  extending therebetween; and applying negative pressure to the proximal end  117  of the bladder catheter  56 ,  116  to induce negative pressure in a portion of the urinary tract of the patient to remove fluid from the patient. In some examples, the method further comprises deploying a second ureteral stent or second ureteral catheter into a second ureter or kidney of the patient to maintain patency of fluid flow between a second kidney and the bladder of the patient. Specific characteristics of exemplary ureteral stents or ureteral catheters of the present invention are described in detail herein. 
     Delivering negative pressure into the kidney area of a patient has a number of anatomical challenges for at least three reasons. First, the urinary system is composed of highly pliable tissues that are easily deformed. Medical textbooks often depict the bladder as a thick muscular structure that can remain in a fixed shape regardless of the volume of urine contained within the bladder. However, in reality, the bladder is a soft deformable structure. The bladder shrinks to conform to the volume of urine contained in the bladder. An empty bladder more closely resembles a deflated latex balloon than a ball. In addition, the mucosal lining on the interior of the bladder is soft and susceptible to irritation and damage. It is desirable to avoid drawing the urinary system tissue into the orifices of the catheter to maintain adequate fluid flow therethrough and avoid injury to the surrounding tissue. 
     Second, the ureters are small tube-like structures that can expand and contract to transport urine from the renal pelvis to the bladder. This transport occurs in two ways: peristaltic activity and by a pressure gradient in an open system. In the peristaltic activity, a urine portion is pushed ahead of a contractile wave, which almost completely obliterates the lumen. The wave pattern initiates in the renal pelvis area, propagates along the ureter, and terminates in the bladder. Such a complete occlusion interrupts the fluid flow and can prevent negative pressure delivered in the bladder from reaching the renal pelvis without assistance. The second type of transport, by pressure gradient through a wide-open ureter, may be present during large urine flow. The pressure head in the renal pelvis is not caused by contraction of the smooth muscles of the upper urinary tract, but rather is generated by the flow of urine, and therefore reflects arterial blood pressure. Kiil F., “Urinary Flow and Ureteral Peristalsis” in: Lutzeyer W., Melchior H. (eds) Urodynamics. Springer, Berlin, Heidelberg (pp. 57-70) ( 1973 ). 
     Third, the renal pelvis is at least as pliable as the bladder. The thin wall of the renal pelvis can expand to accommodate multiple times the normal volume, for example as occurs in patients having hydronephrosis. 
     While not intending to be bound by any theory, it is believed that the tissues of the renal pelvis and bladder may be flexible enough to be drawn inwardly during delivery of negative pressure to somewhat conform to the shape and volume of the tool being used to deliver negative pressure. As such, a three dimensional shape that maintains a three dimensional void volume that can transmit the negative pressure to at least one calyx is believed to be helpful to delivery negative pressure to the nephrons. In addition, given the flexibility of the tissues, the protection of these tissues from the openings that lead to the lumen of the tool is desirable. The catheters discussed herein can be useful for delivering negative pressure, positive pressure, or can be used at ambient pressure, or any combination thereof. 
     Exemplary Ureteral Catheters: 
     As shown in  FIGS. 2, 7, 17, 27 and 44 , examples of systems  100  including ureteral catheters  112 ,  114  configured to be positioned within the urinary tract of a patient are illustrated. For example, distal ends  120 ,  121  of the ureteral catheters  112 ,  114  can be configured to be deployed in at least one of the patient&#39;s ureters  2 ,  4 ; renal pelvis  20 ,  21  area of the kidneys  6 ,  8 ; or the kidneys  6 ,  8 . 
     In some examples, suitable ureteral catheters are disclosed in U.S. Pat. No. 9,744,331, US Patent Application Publication No. US 2017/0021128 A1, U.S. patent application Ser. No. 15/687,064, and U.S. patent application Ser. No. 15/687,083, each of which is incorporated by reference herein. 
     In some examples, the system  100  can comprise two separate ureteral catheters, such as a first catheter  112  disposed in or adjacent to the renal pelvis  20  of the right kidney  2  and a second catheter  114  disposed in or adjacent to the renal pelvis  21  of the left kidney  4 . The catheters  112 ,  114  can be separate for their entire lengths, or can be held in proximity to one another by a clip, ring, clamp, or other type of connection mechanism (e.g., connector) to facilitate placement or removal of the catheters  112 ,  114 . As shown in  FIGS. 2, 7, 17, 27 and 44 , the proximal end  113 ,  115  of each catheter  112 ,  114  is positioned within the bladder  10 , or at the proximal end of the ureter near the bladder  10 , such that the fluid or urine drains into the bladder. In some examples, catheters  112 ,  114  can merge or be connected together within the bladder to form a single drainage lumen that is drains into the bladder  10 . 
     In other examples, the catheters  112 ,  114  can be inserted through or enclosed within another catheter, tube, or sheath along portions or segments thereof to facilitate insertion and retraction of the catheters  112 ,  114  from the patient&#39;s body. For example, a bladder catheter  116  can be inserted over and/or along the same guidewire as the ureteral catheters  112 ,  114 . 
     With reference to  FIGS. 2, 7, 8A, and 8B , an exemplary ureteral catheter  112  can comprise at least one elongated body or tube  122 , the interior of which defines or comprises one or more drainage channel(s) or lumen(s), such as drainage lumen  124 . The tube  122  size can range from about 1 Fr to about 9 Fr (French catheter scale). In some examples, the tube  122  can have an external diameter ranging from about 0.33 to about 3 mm, and an internal diameter ranging from about 0.165 to about 2.39 mm. In one example, the tube  122  is 6 Fr and has an outer diameter of 2.0±0.1 mm. The length of the tube  122  can range from about 30 cm to about 120 cm depending on the age (e.g., pediatric or adult) and gender of the patient. 
     The tube  122  can be formed from a flexible and/or deformable material to facilitate advancing and/or positioning the tube  122  in the bladder  10  and ureters  6 ,  8  (shown in  FIGS. 2 and 7 ). The catheter material should be flexible and soft enough to avoid or reduce irritation of the renal pelvis and ureter, but should be rigid enough that the tube  122  does not collapse when the renal pelvis or other portions of the urinary tract exert pressure on the exterior of the tube  122 , or when the renal pelvis and/or ureter are drawn against the tube  122  during inducement of negative pressure. For example, the tube  122  or drainage lumen can be formed, at least in part, from one or more materials including copper, silver, gold, nickel-titanium alloy, stainless steel, titanium, and/or polymer such as biocompatible polymer(s), polyurethane, polyvinyl chloride, polytetrafluoroethylene (PTFE), latex, silicon coated latex, silicon, silicone, polyglycolide or poly(glycolic acid) (PGA), Polylactide (PLA), Poly(lactide-co-glycolide), Polyhydroxyalkanoates. Polycaprolactone and/or Poly(propylene fumarate). In one example, the tube  122  is formed from a thermoplastic polyurethane. The tube  1222  can also include or be impregnated with one or more of copper, silver, gold, nickel-titanium alloy, stainless steel, and titanium. In some examples, the tube  1222  is impregnated with or formed from a material viewable by fluoroscopic imaging. For example, the biocompatible polymer which forms the tube  1222  can be impregnated with barium sulfate or a similar radiopaque material. As such, the structure and position of the tube  1222  is visible to fluoroscopy. 
     At least a portion or all of the catheter  112 , such as the tube  122 , can be coated with a hydrophilic coating to facilitate insertion and/or removal, and/or to enhance comfort. In some examples, the coating is a hydrophobic and/or lubricious coating. For example, suitable coatings can comprise ComfortCoat® hydrophilic coating which is available from Koninklijke DSM N.V. or hydrophilic coatings comprising polyelectrolyte(s) such as are disclosed in U.S. Pat. No. 8,512,795, which is incorporated herein by reference. 
     In some examples, as shown in  FIG. 8B , for example, the tube  122  can comprise: a distal portion  118  (e.g., a portion of the tube  122  configured to be positioned in the ureter  6 ,  8  and renal pelvis  20 ,  21 ); a middle portion  126  (e.g., a portion of the tube  122  configured to extend from the distal portion through the ureteral openings  16  into the patient&#39;s bladder  10  and urethra  12 ); and a proximal portion  128  (e.g., a portion of the tube  122  extending into the bladder). In one example, the combined length of the proximal portion  128  and the middle portion  126  of the tube  122  is about 54±2 cm. In some examples, the tube  122  terminates in the bladder  110 . In that case, fluid drains from the proximal end of the ureteral catheter  112 ,  114  and is directed from the body through the additional indwelling bladder catheter. 
     Exemplary Ureteral Retention Portions: 
     Any of the retention portions disclosed herein can be formed from the same material as the drainage lumen discussed above, and can be unitary with the drainage lumen, or the retention portion can be formed from a different material, such as those that are discussed above for the drainage lumen, and connected thereto. For example, the retention portion can be formed from any of the aforementioned materials, for example a polymer such as polyurethane, flexible polyvinyl chloride, polytetrafluoroethylene (PTFE), latex, silicone, silicon, polyglycolide or poly(glycolic acid) (PGA), Polylactide (PLA), Poly(lactide-co-glycolide), Polyhydroxyalkanoates. Polycaprolactone and/or Poly(propylene fumarate). 
     With continued reference to  FIGS. 2, 8A, and 8B , the distal portion  118  of the ureteral catheter  112  comprises a retention portion  130  for maintaining the distal end  120  of the catheter  112  at a desired fluid collection position proximate to or within the renal pelvis  20 ,  21  of the kidney  2 ,  4 . In some examples, the retention portion  130  is configured to be flexible and bendable to permit positioning of the retention portion  130  in the ureter and/or renal pelvis. The retention portion  130  is desirably sufficiently bendable to absorb forces exerted on the catheter  112  and to prevent such forces from being translated to the ureters. For example, if the retention portion  130  is pulled in the proximal direction P (shown in  FIG. 9A ) toward the patient&#39;s bladder, the retention portion  130  can be sufficiently flexible to begin to unwind or be straightened so that it can be drawn through the ureter. Similarly, when the retention portion  130  can be reinserted into the renal pelvis or other suitable region within the ureter, it can be biased to return to its deployed configuration. 
     In some examples, the retention portion  130  is integral with the tube  122 . In that case, the retention portion  130  can be formed by imparting a bend or curl to the catheter body  122  that is sized and shaped to retain the catheter at a desired fluid collection location. Suitable bends or coils can include a pigtail coil, corkscrew coil, and/or helical coil. For example, the retention portion  130  can comprise one or more radially and longitudinally extending helical coils configured to contact and passively retain the catheter  112  within the ureter  6 ,  8  proximate to or within the renal pelvis  20 ,  21 . In other examples, the retention portion  130  is formed from a radially flared or tapered portion of the catheter body  122 . For example, the retention portion  130  can further comprise a fluid collecting portion, as shown in  FIGS. 4A and 4B , such as a tapered or funnel-shaped inner surface  186 . In other examples, the retention portion  130  can comprise a separate element connected to and extending from the catheter body or tube  122 . 
     The retention portion  130  can further comprise one or more perforated sections, such as drainage holes or ports  132  (shown, for example, in  FIGS. 9A-9E, 10A and 10E ). A drainage port can be located, for example, at the open distal end  120 ,  121  of the tube  122 . In other examples, perforated sections and/or drainage ports  132  are disposed along the sidewall of the distal portion  118  of the catheter tube  122 . The drainage ports or holes can be used for assisting in fluid collection. In other examples, the retention portion  130  is solely a retention structure and fluid collection and/or imparting negative pressure is provided by structures at other locations on the catheter tube  122 . In some examples, the drainage holes, ports or perforations are positioned such that tissue from the bladder does not directly contact the holes, ports or perforations. 
     Referring now to  FIGS. 8A, 8B, and 9A-9E , exemplary retention portions  130  comprising a plurality of helical coils, such as one or more full coils  184  and one or more half or partial coils  183 , are illustrated. The retention portion  130  is capable of moving between a contracted position and the deployed position with the plurality of helical coils. For example, a substantially straight guidewire can be inserted through the retention portion  130  to maintain the retention portion  130  in a substantially straight contracted position. When the guidewire is removed, the retention portion  130  can transition to its coiled configuration. In some examples, the coils  183 ,  184  extend radially and longitudinally from the distal portion  118  of the tube  122 . With specific reference to  FIGS. 8A and 8B , in an exemplary embodiment, the retention portion  130  comprises two full coils  184  and one half coil  183 . The outer diameter of the full coils  184 , shown by line D 1 , can be about 18±2 mm. The half coil  183  diameter D 2  can be about 14 mm. The coiled retention portion  130  has a height H of about 16±2 mm. 
     The retention portion  130  can further comprise the one or more drainage holes  132  (shown in  FIGS. 9A-9E, 10A and 10E , for example) configured to draw fluid into an interior of the catheter tube  122 . In some examples, the retention portion  130  can comprise six drainage holes, plus an additional hole at the distal tip  120  of the retention portion. The diameter of each of the drainage holes  132  (shown in  FIGS. 9A-9E, 10A and 10E , for example) can range from about 0.7 mm to 0.9 mm and, preferably, is about 0.83±0.01 mm. The distance between adjacent drainage holes  132 , specifically the linear distance between drainage holes  132  when the coils are straightened, can be about 22.5±2.5 mm. 
     As shown in  FIGS. 9A-9E , in another exemplary embodiment, the distal portion  118  of the drainage lumen proximal to the retention portion  130  defines a straight or curvilinear central axis L. In some examples, at least a half or first coil  183  and a full or second coil  184  of the retention portion  130  extend about an axis A of the retention portion  130 . The first coil  183  initiates or begins at a point where the tube  122  is bent at an angle α ranging from about 15 degrees to about 75 degrees from the central axis L, as indicated by angle α, and preferably about 45 degrees. As shown in  FIGS. 9A and 9B , prior to insertion in the body, the axis A can be coextensive with the longitudinal central axis L. In other examples, as shown in  FIGS. 9C-9E , prior to insertion in the body, the axis A extends from and is curved or angled, for example at angle β, relative to the central longitudinal axis L. 
     In some examples, multiple coils  184  can have the same inner and/or outer diameter D and height H 2 . In that case, the outer diameter D 1  of the coils  184  may range between 10 mm and 30 mm. The height H 2  between coils  184  may be about 3 mm to 10 mm. 
     In other examples, the retention portion  130  is configured to be inserted in the tapered portion of the renal pelvis. For example, the outer diameter D 1  of the coils  184  can increase toward the distal end  120  of the tube  122 , resulting in a helical structure having a tapered or partially tapered configuration. For example, the distal or maximum outer diameter D 1  of the tapered helical portion ranges from about 10 mm to about 30 mm, which corresponds to the dimensions of the renal pelvis. The height H 2  of the retention portion  130  ranges from about 10 mm to about 30 mm. 
     In some examples, the outer diameter D 1  and/or height H 2  of the coils  184  can vary in a regular or irregular fashion. For example, the outer diameter D 1  of coils or height H 2  between coils can increase or decrease by a regular amount (e.g., about 10% to about 25% between adjacent coils  184 ). For example, for a retention portion  130  having three coils (as shown, for example, in  FIGS. 9A and 9B ) an outer diameter D 3  of a proximal-most coil or first coil  183  can be about 6 mm to 18 mm, an outer diameter D 2  of a middle coil or second coil  185  can be about 8 mm to about 24 mm, and an outer diameter D 1  of a distal-most or third coil  187  can be between about 10 mm and about 30 mm. 
     The retention portion  130  can further comprise the drainage ports  132  or holes disposed on or through the sidewall of the catheter tube  122  on or adjacent to the retention portion  130  to permit urine waste to flow from the outside of the catheter tube  122  to the inside of the catheter tube  122 . The position and size of the drainage ports  132  can vary depending upon the desired flow rate and configuration of the retention portion. The diameter of the drainage ports  132  can range from about 0.005 mm to about 1.0 mm. The spacing between the drainage ports  132  can range from about 1.5 mm to about 5 mm. The drainage ports  132  can be spaced in any arrangement, for example, linear or offset. In some examples, the drainage ports  132  can be non-circular, and can have a surface area of about 0.00002 to 0.79 mm 2 . 
     In some examples, as shown in  FIG. 9A , the drainage ports  132  are located around the entire periphery of the sidewall of the catheter tube  122  to increase an amount of fluid that can be drawn into the drainage lumen  124  (shown in  FIGS. 2, 9A, and 9B ). In other examples, as shown in  FIGS. 9B-9E , the drainage ports  132  can be disposed essentially only or only on the radially inwardly facing side of the coils  184  to prevent occlusion or blockage of the drainage ports  132 , and the outwardly facing side of the coils may be essentially free of drainage ports  132  or free of drainage ports  132 . For example, when negative pressure is induced in the ureter and/or renal pelvis, mucosal tissue of the ureter and/or kidney may be drawn against the retention portion  130  and may occlude some drainage ports  132  on the outer periphery of the retention portion  130 . Drainage ports  132  located on the radially inward side of the retention structure would not be appreciably occluded when such tissues contact the outer periphery of the retention portion  130 . Further, risk of injury to the tissues from pinching or contact with the drainage ports  132  can be reduced or ameliorated. 
     With reference to  FIGS. 9C and 9D , other examples of ureteral catheters  112  having a retention portion  130  comprising a plurality of coils are illustrated. As shown in  FIG. 9C , the retention portion  130  comprises three coils  184  extending about the axis A. The axis A is a curved arc extending from the central longitudinal axis L of the portion of the drainage lumen  181  proximal to the retention portion  130 . The curvature imparted to the retention portion  130  can be selected to correspond to the curvature of the renal pelvis, which comprises a cornucopia-shaped cavity. 
     As shown in  FIG. 9D , in another exemplary embodiment, the retention portion  130  can comprise two coils  184  extending about an angled axis A. The angled axis A extends at an angle from a central longitudinal axis L, and is angled, as shown by angle β, relative to an axis generally perpendicular to the central axis L of the portion of the drainage lumen. The angle β can range from about 15 to about 75 degrees (e.g., about 105 to about 165 degrees relative to the central longitudinal axis L of the drainage lumen portion of the catheter  112 ). 
       FIG. 9E  shows another example of a ureteral catheter  112 . The retention portion comprises three helical coils  184  extending about an axis A. The axis A is angled, as shown by angle β, relative to the horizontal. As in the previously-described examples, the angle β can range from about 15 to about 75 degrees (e.g., about 105 to about 165 degrees relative to the central longitudinal axis L of the drainage lumen portion of the catheter  112 ). 
     In some examples shown in  FIGS. 10-10E , the retention portion  1230  is integral with the tube  1222 . In other examples, the retention portion  1230  can comprise a separate tubular member connected to and extending from the tube or drainage lumen  1224 . 
     In some examples, the retention portion comprises a plurality of radially extending coils. The coils are configured in the shape of a funnel, and thereby form a funnel support. Some examples of coil funnel supports are shown in  FIGS. 2, 7, and 8A-10E . 
     In some examples, the at least one sidewall of the funnel support comprises at least a first coil having a first diameter and a second coil having a second diameter, the first diameter being less than the second diameter, wherein the maximum distance between a portion of a sidewall of the first coil and a portion of an adjacent sidewall of the second coil ranges from about 0 mm to about 10 mm. In some examples, the first diameter of the first coil ranges from about 1 mm to about 10 mm and the second diameter of the second coil ranges from about 5 mm to about 25 mm. In some examples, the diameter of the coils increases toward a distal end of the drainage lumen, resulting in a helical structure having a tapered or partially tapered configuration. In some embodiments, the second coil is closer to an end of the distal portion of the drainage lumen than is the first coil. In some embodiments, the second coil is closer to an end of the proximal portion of the drainage lumen than is the first coil. 
     In some examples, the at least one sidewall of the funnel support comprises an inwardly facing side and an outwardly facing side, the inwardly facing side comprising at least one opening for permitting fluid flow into the drainage lumen, the outwardly facing side being essentially free of or free of openings, as discussed below. In some examples, the at least one opening has an area ranging from about 0.002 mm 2  to about 100 mm 2 . 
     In some examples, the first coil comprises a sidewall comprising a radially inwardly facing side and a radially outwardly facing side, the radially inwardly facing side of the first coil comprising at least one opening for permitting fluid flow into the drainage lumen. 
     In some examples, the first coil comprises a sidewall comprising a radially inwardly facing side and a radially outwardly facing side, the radially inwardly facing side of the first coil comprising at least two openings for permitting fluid flow into the drainage lumen. 
     In some examples, the first coil comprises a sidewall comprising a radially inwardly facing side and a radially outwardly facing side, the radially outwardly facing side of the first coil being essentially free of or free of one or more openings. 
     In some examples, the first coil comprises a sidewall comprising a radially inwardly facing side and a radially outwardly facing side, the radially inwardly facing side of the first coil comprising at least one opening for permitting fluid flow into the drainage lumen and the radially outwardly facing side being essentially free of or free of one or more openings. 
     Referring now to  FIGS. 10-10E , in some examples, the distal portion  1218  comprises an open distal end  1220  for drawing fluid into the drainage lumen  1224 . The distal portion  1218  of the ureteral catheter  1212  further comprises a retention portion  1230  for maintaining the distal portion  1218  of the drainage lumen or tube  1222  in the ureter and/or kidney. In some examples, the retention portion comprises a plurality of radially extending coils  1280 ,  1282 ,  1284 . The retention portion  1230  can be a flexible and bendable to permit positioning of the retention portion  1230  in the ureter, renal pelvis, and/or kidney. For example, the retention portion  1230  is desirably sufficiently bendable to absorb forces exerted on the catheter  1212  and to prevent such forces from being translated to the ureters. Further, if the retention portion  1230  is pulled in the proximal direction P (shown in  FIGS. 9A-9E ) toward the patient&#39;s bladder  10 , the retention portion  1230  can be sufficiently flexible to begin to unwind or be straightened so that it can be drawn through the ureter  6 ,  8 . In some examples, the retention portion  1230  is integral with the tube  1222 . In other examples, the retention portion  1230  can comprise a separate tubular member connected to and extending from the tube or drainage lumen  1224 . In some examples, the catheter  1212  comprises a radiopaque band  1234  (shown in  FIG. 29 ) positioned on the tube  1222  at a proximal end of the retention portion  1230 . The radiopaque band  1234  is visible by fluoroscopic imaging during deployment of the catheter  1212 . In particular, a user can monitor advancement of the band  1234  through the urinary tract by fluoroscopy to determine when the retention portion  1230  is in the renal pelvis and ready for deployment. 
     In some examples, the retention portion  1230  comprises perforations, drainage ports, or openings  1232  in a sidewall of the tube  1222 . As described herein, a position and size of the openings  1232  can vary depending upon a desired volumetric flow rate for each opening and size constraints of the retention portion  1230 . In some examples, a diameter of the openings  1232  ranges from about 0.05 mm to about 2.5 mm and having an area of about 0.002 mm 2  to 5.00 mm 2 . Openings  1232  can be positioned extending along on a sidewall of the tube  1222  in any direction desired, such as longitudinal and/or axial. In some examples, spacing between the openings  1232  can range from about 1.5 mm to about 15 mm. Fluid passes through one or more of the perforations, drainage ports, or openings  1232  and into the drainage lumen  1234 . Desirably, the openings  1232  are positioned so that they are not occluded by tissues of the ureters  6 ,  8  or kidney when negative pressure is applied to the drainage lumen  1224 . For example, as described herein, openings  1234  can be positioned on interior portions of coils or other structures of the retention portion  1230  to avoid occlusion of the openings  1232 . In some examples, the middle portion  1226  and proximal portion  1228  of the tube  1222  can be essentially free of or free from perforations, ports, openings or openings to avoid occlusion of openings along those portions of the tube  1222 . In some examples, a portion  1226 ,  1228  which is essentially free from perforations or openings includes substantially fewer openings than other portions of the tube  1222 . For example, a total area of openings  1232  of the distal portion  1218  may be greater than or substantially greater than a total area of openings of the proximal portion  1226  and/or the distal portion  1228  of the tube  1222 . 
     In some examples, the openings  1232  are sized and spaced to improve fluid flow through the retention portion  1230 . In particular, the present inventors have discovered that when a negative pressure is applied to the drainage lumen  1224  of the catheter  1212  a majority of fluid is drawn into the drainage lumen  1224  through proximal-most perforations or openings  1232 . In order to improve flow dynamics so that fluid is also received through more distal openings and/or through the open distal end  1220  of the tube  1222 , larger size or a greater number of openings can be provided towards the distal end of the retention portion  1230 . For example, a total area of openings  1232  on a length of tube  1222  near a proximal end of the retention portion  1230  may be less than a total area of openings  1232  of a similar sized length of the tube  1222  located near the open distal end  1220  of the tube  1222 . In particular, it may be desirable to produce a flow distribution through the drainage lumen  1224  in which less than 90%, preferably less than 70%, and, more preferably, less than 55% of fluid flow is drawn into the drainage lumen  1224  through a single opening  1232  or a small number of openings  1232  positioned near the proximal end of the retention portion  1230 . 
     In many examples, the openings  1232  are generally a circular shape, through triangular, elliptical, square-shaped, diamond shaped, and any other opening shapes may also be used. Further, as will be appreciated by one of ordinary skill in the art, a shape of the openings  1232  may change as the tube  1222  transitions between an uncoiled or elongated position and a coiled or deployed position. It is noted that while the shape of the openings  1232  may change (e.g., the orifices may be circular in one position and slightly elongated in the other position), the area of the openings  1232  is substantially similar in the elongated or uncoiled position compared to the deployed or coiled position. 
     In some examples, the drainage lumen  1224  defined by tube  1222  comprises: a distal portion  1218  (e.g., a portion of the tube  1222  configured to be positioned in the ureter  6 ,  8  and renal pelvis  20 ,  21  (shown in  FIGS. 7 and 7A )); a middle portion  1226  (e.g., a portion of the tube  1222  configured to extend from the distal portion through ureteral openings  16  into the patient&#39;s bladder  10  and urethra  12  (shown in  FIGS. 7 and 7A )); and a proximal portion  1228  (e.g., a portion of the tube  1222  extending from the urethra  12  to an external fluid collection container and/or pump  2000 ). In one example, the combined length of the proximal portion  1228  and the middle portion  1226  of the tube  1222  is about 54±2 cm. In some examples, the middle portion  1226  and proximal portion  1228  of the tube  1222  includes distance markings  1236  (shown in  FIG. 10 ) on a sidewall of the tube  1222  which can be used, during deployment of the catheter  1212 , to determine how far the tube  1222  is inserted into the urinary tract of the patient. 
     As shown in  FIGS. 7 and 10-14 , an exemplary ureteral catheter  1212  comprises at least one elongated body or tube  1222 , the interior of which defines or comprises one or more drainage channel(s) or lumen(s), such as drainage lumen  1224 . The tube  1222  size can range from about 1 Fr to about 9 Fr (French catheter scale). In some examples, the tube  1222  can have an external diameter ranging from about 0.33 to about 3.0 mm, and an internal diameter ranging from about 0.165 to about 2.39 mm. In one example, the tube  1222  is 6 Fr and has an outer diameter of 2.0±0.1 mm. The length of the tube  1222  can range from about 30 cm to about 120 cm depending on the age (e.g., pediatric or adult) and gender of the patient. 
     The tube  1222  can be formed from a flexible and/or deformable material to facilitate advancing and/or positioning the tube  1222  in the bladder  10  and ureters  6 ,  8  (shown in  FIG. 7 ). For example, the tube  1222  can be formed from materials including biocompatible polymers, polyvinyl chloride, polytetrafluoroethylene (PTFE) such as Teflon®, silicon coated latex, or silicon. In one example, the tube  1222  is formed from a thermoplastic polyurethane. 
     Helical Coil Retention Portion 
     Referring now to  FIGS. 10A-10E , an exemplary retention portion  1230  comprises helical coils  1280 ,  1282 ,  1284 . In some examples, the retention portion  1230  comprises a first or half coil  1280  and two full coils, such as a second coil  1282  and a third coil  1284 . As shown in  FIGS. 10A-10D , in some examples, the first coil comprises a half coil extending from 0 degrees to 180 degrees around a curvilinear central axis A of the retention portion  1230 . In some examples, as shown the curvilinear central axis A is substantially straight and co-extensive with a curvilinear central axis of the tube  1222 . In other examples, the curvilinear central axis A of the retention portion  1230  can be curved giving the retention portion  1230  a cornucopia shape. The first coil  1280  can have a diameter D 1  of about 1 mm to 20 mm and preferably about 8 mm to 10 mm. The second coil  1282  can be a full coil extending from 180 degrees to 540 degrees along the retention portion  1230  having a diameter D 2  of about 5 mm to 50 mm, preferably about 10 mm to 20 mm, and more preferably about 14 mm±2 mm. The third coil  1284  can be a full coil extending between 540 degrees and 900 degrees and having a diameter D 3  of between 5 mm and 60 mm, preferably about 10 mm to 30 mm, and more preferably about 18 mm±2 mm. In other examples, multiple coils  1282 ,  1284  can have the same inner and/or outer diameter. For example, an outer diameter of the full coils  1282 ,  1284 , can each be about 18±2 mm. 
     In some examples, an overall height H 1  of the retention portion  1230  ranges from about 10 mm to about 30 mm and, preferably about 18±2 mm. A height H 2  of a gap between coils  1284 , namely between the sidewall of the tube  1222  of the first coil  1280  and the adjacent sidewall of the tube  122  of the second coil  1282  is less than 3.0 mm, preferably between about 0.25 mm and 2.5 mm, and more preferably between about 0.5 mm and 2.0 mm. 
     The retention portion  1230  can further comprise a distal-most curved portion  1290 . For example, the distal most portion  1290  of the retention portion  1230 , which includes the open distal end  1220  of the tube  1222 , can be bent inwardly relative to a curvature of the third coil  1284 . For example, a curvilinear central axis X 1  (shown in  FIG. 10D ) of the distal-most portion  1290  can extend from the distal end  1220  of the tube  1222  towards the curvilinear central axis A of the retention portion  1230 . 
     The retention portion  1230  is capable of moving between a contracted position, in which the retention portion  1230  is straight for insertion into the patient&#39;s urinary tract, and the deployed position, in which the retention portion  1230  comprises the helical coils  1280 ,  1282 ,  1284 . Generally, the tube  1222  is naturally biased toward the coiled configuration. For example, an uncoiled or substantially straight guidewire can be inserted through the retention portion  1230  to maintain the retention portion  1230  in its straight contracted position, as shown for example in  FIGS. 11-14 . When the guidewire is removed, the retention portion  1230  naturally transitions to its coiled position. 
     In some examples, the openings  1232  are disposed essentially only or only on a radially inwardly facing side  1286  of the coils  1280 ,  1282 ,  1284  to prevent occlusion or blockage of the openings  1232 . A radially outwardly facing side  1288  of the coils  1280 ,  1282 ,  1284  may be essentially free of the openings  1232 . In similar examples, a total area of openings  1232  on the inwardly facing side  1286  of the retention portion  1230  can be substantially greater than a total area of openings  1232  on the radially outwardly facing side  1288  of the retention portion  1230 . Accordingly, when negative pressure is induced in the ureter and/or renal pelvis, mucosal tissue of the ureter and/or kidney may be drawn against the retention portion  1230  and may occlude some openings  1232  on the outer periphery of the retention portion  1230 . However, openings  1232  located on the radially inward side  1286  of the retention portion  1230  are not appreciably occluded when such tissues contacts the outer periphery of the retention portion  1230 . Therefore, risk of injury to the tissues from pinching or contact with the drainage openings  1232  can be reduced or eliminated. 
     Hole or Opening Distribution Examples 
     In some examples, the first coil  1280  can be free or essentially free from openings. For example, a total area of openings on the first coil  1280  can be less than or substantially less than a total area of openings of the full coils  1282 ,  1284 . Examples of various arrangements of openings or openings  1332 , which could be used for a coiled retention portion (such as coiled retention portion  1230  shown in  FIGS. 10A-10E ), are illustrated in  FIGS. 11-14 . As shown in  FIGS. 11-14 , a retention portion is depicted in its uncoiled or straight position, as occurs when a guidewire is inserted through the drainage lumen. 
     An exemplary retention portion  1330  is illustrated in  FIG. 11 . In order to more clearly describe positioning of openings of the retention portion  1330 , the retention portion  1330  is referred to herein as being divided into a plurality of sections or perforated sections, such as a proximal-most or first section  1310 , a second section  1312 , a third, section  1314 , a fourth section  1316 , a fifth section  1318 , and a distal-most or sixth section  1320 . One of ordinary skill in the art would understand that additional sections can be included, if desired. As used herein, “section” refers to a discrete length of the tube  1322  within the retention portion  1330 . In some examples, sections are equal in length. In other examples, some sections can have the same length, and other sections can have a different length. In other examples, each section has a different length. For example, sections can have a length L 1 -L 6  of between about 5 mm and about 35 mm, and preferably between about 5 mm and 15 mm. 
     In some examples, each section comprises one or more openings. In some examples, each section each comprises a single opening  1332 . In other examples, the first section  1310  includes a single opening  1332  and other sections comprise multiple openings  1332 . In other examples, different sections comprise one or more openings  1332 , each of the opening(s) having a different shape or different total area. 
     In some examples, such as the retention portion  1230  shown in  FIGS. 10A-10E , the first or half coil  1280 , which extends from 0 to about 180 degrees of the retention portion  1230  can be free from or essentially free from openings. The second coil  1282  can include the first section  1310  extending between about 180 and 360 degrees. The second coil  1282  can also include the second and third sections  1312 ,  1314  positioned between about 360 degrees and 540 degrees of the retention portion  1230 . The third coil  1284  can include the fourth and fifth sections  1316 ,  1318  positioned between about 540 degrees and 900 degrees of the retention portion  1230 . 
     In some examples, the openings  1332  can be sized such that a total area of openings of the first section  1310  is less than a total area of openings of the adjacent second section  1312 . In a similar manner, if the retention portion  1330  further comprises a third section  1314 , then openings of a third section  1314  can have a total area that is greater than the total area of the openings of the first section  1310  or the second section  1312 . Openings of the forth  1316 , fifth  1318 , and sixth  1320  sections may also have a gradually increasing total area and/or number of openings to improve fluid flow through the tube  1222 . 
     As shown in  FIG. 11 , the retention portion  1230  of the tube includes five sections  1310 ,  1312 ,  1314 ,  1316 , each of which includes a single opening  1332 ,  1334 ,  1336 ,  1338 ,  1340 . The retention portion  1230  also includes a sixth section  1320  which includes the open distal end  1220  of the tube  1222 . In this example, the opening  1232  of the first section  1310  has the smallest total area. For example, a total area of the opening  1332  of the first section can be between about 0.002 mm 2  and about 2.5 mm 2 , or between about 0.01 mm 2  and 1.0 mm 2 , or between about 0.1 mm 2  and 0.5 mm 2 . In one example, the opening  1332  is about 55 mm from the distal end  1220  of the catheter, has a diameter of 0.48 mm, and an area of 0.18 mm 2 . In this example, a total area of an openings  1334  of the second section  1312  is greater than the total area of openings  1232  of the first section  1310  and can range in size from about 0.01 mm 2  and 1.0 mm 2 . The third  1336 , fourth  1338 , and fifth  1350  openings can also range in size from about 0.01 mm 2  and 1.0 mm 2 . In one example, the second opening  1334  is about 45 mm from the distal end of the catheter  1220 , has a diameter of about 0.58 mm, and an area of about 0.27 mm 2 . The third opening  1336  can be about 35 mm from the distal end of the catheter  1220  and have a diameter of about 0.66 mm. The fourth opening  1338  can be about 25 mm from the distal end  1220  and have a diameter of about 0.76 mm. The fifth opening  1340  can be about 15 mm from the distal end  1220  of the catheter and have a diameter of about 0.889 mm. In some examples, the open distal end  1220  of the tube  1222  has the largest opening having an area of between about 0.5 mm 2  to about 5.0 mm 2  or more. In one example, the open distal end  1220  has a diameter of about 0.97 mm and an area of about 0.74 mm 2 . 
     As described herein, openings  1332   1334 ,  1336 ,  1338 ,  1340  can be positioned and sized so that a volumetric flow rate of fluid passing through the first opening  1332  more closely corresponds to a volumetric flow rate of openings of more distal sections, when negative pressure is applied to the drainage lumen  1224  of the catheter  1212 . As described above, if each opening were the same area, then, when negative pressure is applied to the drainage lumen  1224 , the volumetric flow rate of fluid passing through the proximal-most of first opening  1332  would be substantially greater than a volumetric flow rate of fluid passing through openings  1334  closer to the distal end  1220  of the retention portion  1330 . While not intending to be bound by any theory, it is believed that when negative pressure is applied, the pressure differential between the interior of the drainage lumen  1224  and external to the drainage lumen  1224  is greater in the region of the proximal-most opening and decreases at each opening moving towards the distal end of the tube. For example, sizes and positions of the openings  1332   1334 ,  1336 ,  1338 ,  1340  can be selected so that a volumetric flow rate for fluid which flows into openings  1334  of the second section  1312  is at least about 30% of a volumetric flow rate of fluid which flows into the opening(s)  1332  of the first section  1310 . In other examples, a volumetric flow rate for fluid flowing into the proximal-most or first section  1310  is less than about 60% of a total volumetric flow rate for fluid flowing through the proximal portion of the drainage lumen  1224 . In other examples, a volumetric flow rate for fluid flowing into openings  1332 ,  1334  of the two proximal-most sections (e.g., the first section  1310  and the second section  1312 ) is can be less than about 90% of a volumetric flow rate of fluid flowing through the proximal portion of the drainage lumen  1224  when a negative pressure, for example a negative pressure of about −45 mmHg, is applied to the proximal end of the drainage lumen. 
     As will be appreciated by one of ordinary skill in the art, volumetric flow rate and distribution for a catheter or tube comprising a plurality of openings or perforations can be directly measured or calculated in a variety of different ways. As used herein, “volumetric flow rate” means actual measurement of the volumetric flow rate downstream and adjacent to each opening or using a method for “Calculated Volumetric Flow Rate” described below. 
     For example, actual measurement of the dispersed fluid volume over time can be used to determine the volumetric flow rate through each opening  1332 ,  1334 ,  1336 ,  1338 ,  1340 . In one exemplary experimental arrangement, a multi-chamber vessel comprising individual chambers sized to receive sections  1310 ,  1312 ,  1314 ,  1316 ,  1318 ,  1320  of the retention portion  1330  could be sealed around and enclose the retention portion  1330 . Each opening  1332 ,  1334 ,  1336 ,  1338 ,  1340  could be sealed in one of the chambers. An amount of fluid volume drawn from the respective chamber into the tube  3222  through each opening  1332 ,  1334 ,  1336 ,  1338 ,  1340  could be measured to determine an amount of fluid volume drawn into each opening over time when a negative pressure is applied. The cumulative amount of fluid volume collected in the tube  3222  by a negative pressure pump system would be equivalent to the sum of fluid drawn into each opening  1332 ,  1334 ,  1336 ,  1338 ,  1340 . 
     Alternatively, volumetric fluid flow rate through different openings  1332   1334 ,  1336 ,  1338 ,  1340  can be calculated mathematically using equations for modeling fluid flow through a tubular body. For example, volumetric flow rate of fluid passing through openings  1332   1334 ,  1336 ,  1338 ,  1340  and into the drainage lumen  1224  can be calculated based on a mass transfer shell balance evaluation, as described in detail below in connection with the Mathematical Examples and  FIGS. 15A-15C . Steps for deriving mass balance equations and for calculating a flow distribution between or volumetric flow rates for the openings  1332   1334 ,  1336 ,  1338 ,  1340  are also described in detail below in connection with  FIGS. 15A-15C . 
     Another exemplary retention portion  2230  with openings  2332   2334 ,  2336 ,  2338 ,  2340  is illustrated in  FIG. 12 . As shown in  FIG. 12 , the retention portion  2230  comprises numerous smaller perforations or openings  2332   2334 ,  2336 ,  2338 ,  2340 . Each of the openings  2332   2334 ,  2336 ,  2338 ,  234  can have a substantially identical cross-sectional area. As shown in  FIG. 12 , the retention portion  2330  comprises six sections  2310 ,  2312 ,  2314 ,  2316 ,  2318 ,  2320 , such as are described above, wherein each section comprises a plurality of the openings  2332   2334 ,  2336 ,  2338 ,  2340 . In the example shown in  FIG. 12 , a number of openings  2332 ,  2334 ,  2336 ,  2338 ,  2340  per section increases towards the distal end  1220  of the tube  1222 , such that a total area of openings  1332  in each section increases compared to a proximally adjacent section. 
     As shown in  FIG. 12 , openings  2332  of the first section  2310  are arranged along a first virtual line V 1 , which is substantially parallel to a curvilinear central axis X 1  of the retention portion  2230 . Openings  2334 ,  2336 ,  2338 ,  2340  of the second  2312 , third  2314 , fourth  2316 , and fifth  2318  sections, respectively, are positioned on the sidewall of the tube  2222  in a gradually increasing number of rows, such that openings  2334 ,  2336 ,  2338 ,  2340  of these section also line up around a circumference of the tube  2222 . For example, some of the openings  2334  of the second section  2312  are positioned such that a second virtual line V 2  extending around a circumference of the sidewall of the tube  2222  contacts at least a portion of multiple openings  2334 . For example, the second section  2312  can comprise two or more rows of perforations or openings  2334 , in which each opening  2334  has an equal cross-sectional area. Further, in some examples, at least one of the rows of the second section  2312  can be aligned along a third virtual line V 3 , which is parallel with the curvilinear central axis X 1  of the tube  2222 , but is not co-extensive with the first virtual line V 1 . In a similar manner, the third section  2314  can comprise five rows of perforations or openings  2336 , in which each opening  2336  has an equal cross-sectional area; the fourth section  2316  can comprise seven rows of perforations or opening  2338 ; and the fifth section  2318  can comprise nine rows of perforations or openings  2340 . As in previous examples, the sixth section  2320  comprises a single opening, namely the open distal end  2220  of the tube  2222 . In the example of  FIG. 12 , each of the openings has the same area, although the area of one or more openings can be different if desired. 
     Another exemplary retention portion  3230  with openings  3332   3334 ,  3336 ,  3338 ,  3340  is illustrated in  FIG. 13 . The retention portion  3230  of  FIG. 13  includes a plurality of similarly sized perforations or openings  3332 ,  3334 ,  3336 ,  3338 ,  3340 . As in previous examples, the retention portion  3230  can be divided into six sections  3310 ,  3312 ,  3314 ,  3316 ,  3318 ,  3320 , each of which comprises at least one opening. The proximal-most or first section  3310  includes one opening  3332 . The second section  3312  includes two openings  3334  aligned along the virtual line V 2  extending around a circumference of the sidewall of the tube  3222 . The third section  3314  comprises a grouping of three openings  3336 , positioned at vertices of a virtual triangle. The fourth section  3316  comprises a grouping of four openings  3338  positioned at corners of a virtual square. The fifth section  3318  comprises ten openings  3340  positioned to form a diamond shape on the sidewall of the tube  3222 . As in previous examples, the sixth section  3320  comprises a single opening, namely the open distal end  3220  of the tube  3222 . The area of each opening can range from about 0.001 mm 2  and about 2.5 mm 2 . 
     Another exemplary retention portion  4230  with openings  4332   4334 ,  4336 ,  4338 ,  4340  is illustrated in  FIG. 14 . The openings  4332   4334 ,  4336 ,  4338 ,  4340  of the retention portion  4330  have different shapes and sizes. For example, the first section  4310  includes a single circular opening  4332 . The second section  4312  has a circular opening  4334  with a larger cross sectional area than the opening  4332  of the first section  4310 . The third section  4314  comprises three triangular shaped openings  4336 . The fourth section  4316  comprises a large circular opening  4338 . The fifth section  4318  comprises a diamond shaped opening  4340 . As in previous examples, the sixth section  4320  comprises the open distal end  4220  of the tube  4222 .  FIG. 14  illustrates one example of an arrangement of different shapes of openings in each section. It is understood that the shape of each opening in each section can be independently selected, for example the first section  4310  can have one or more diamond-shaped openings or other shapes. The area of each opening can range from about 0.001 mm 2  and about 2.5 mm 2 . 
     EXAMPLES 
     Calculation of Volumetric Flow Rate and Percentage of Flow Distribution 
     Having described various arrangements of openings for retention portions of the ureteral catheter  1212 , a method for determining the Calculated Percentage of Flow Distribution and Calculated Volumetric Flow Rate through the catheter will now be described in detail. A schematic drawing of an exemplary catheter with sidewall openings showing a position of portions of the tube or drainage lumen used in the following calculations is shown in  FIG. 16 . Calculated Percentage of Flow Distribution refers to a percentage of total fluid flowing through proximal portions of the drainage lumen which entered the drainage lumen through different openings or sections of the retention portion. Calculated Volumetric Flow rate refers to fluid flow per unit time through different portions of the drainage lumen or openings of the retention portion. For example, a volumetric flow rate for a proximal portion of the drainage lumen describes a rate of flow for a total amount of fluid passing through the catheter. A volumetric flow rate for an opening refers to a volume of fluid which passes through the opening and into the drainage lumen per unit time. In Tables 3-5 below flow is described as a percentage of total fluid flow or of a total volumetric flow rate for a proximal portion of the drainage lumen. For example, an opening having a flow distribution of 100% means that all fluid entering the drainage lumen passed through the opening. An opening having a distribution of 0% would indicate that none of the fluid in the drainage lumen entered the drainage lumen through that opening. 
     These volumetric flow rate calculations were used to determine and model fluid flow through the retention portion  1230  of the ureter catheter  1212  shown in  FIGS. 7 and 10-10E . Further, these calculations show that adjusting the area of openings and linear distribution of openings along the retention portion effects a distribution of fluid flow through different openings. For example, reducing the area of the proximal-most opening decreases the proportion of fluid drawn into the catheter through the proximal most opening and increases the proportion of fluid drawn into more distal openings of the retention portion. 
     For the following calculations, a tube length of 86 cm having an inner diameter of 0.97 mm and an end hole inner diameter of 0.97 mm was used. Density of urine was 1.03 g/mL and had a coefficient of friction μ of 8.02×10-3 Pa·S (8.02×10-3 kg/s·m) at 37° C. The urine volumetric flow rate passing through the catheter was 2.7 ml per minute (Q Total ) as determined by experimental measurement. 
     Calculated Volumetric Flow Rate is determined by a volumetric mass balance equation in which a sum total of volumetric flow through all perforations or openings  1232  of the five sections of the retention portion (referred to herein as volumetric flow Q 2  to Q 6 ) and through the open distal end  1220  (referred to herein as volumetric flow Q 1 ) equals the total volumetric flow (Q Total ) exiting the proximal end of the tube  1222  at a distance of 10 cm to 60 cm away from the last proximal opening, as shown in Equation 2. 
         Q   Tota1   =Q   1   +Q   2   +Q   3   +Q   4   +Q   5   +Q   6   (Equation 2)
 
     A Modified Loss Coefficient (K′) for each of the sections is based on three types of loss coefficients within the catheter model, namely: an Inlet Loss Coefficient taking into account a pressure loss resulting at a pipe inlet (e.g., the openings and open distal end of the tube  1222 ); a Friction Loss Coefficient which takes into account pressure loss resulting from friction between the fluid and pipe wall; and a Flow Junction Loss Coefficient taking into account pressure loss resulting from the interaction of two flows coming together. 
     The Inlet Loss Coefficient is dependent on a shape of the orifice or opening. For example, a tapered or nozzle shaped orifice would increase flow rate into the drainage lumen  1224 . In a similar manner, a sharp-edged orifice would have different flow properties than an orifice with less defined edges. For purposes of the following calculations, it is assumed that the openings  1232  are side orifice openings and the open distal end  1220  of the tube  1222  is a sharp-edged opening. The cross sectional area of each opening is considered constant through the tube sidewall. 
     The Friction Loss Coefficient approximates pressure loss resulting from friction between the fluid and the adjacent inner wall of the tube  1222 . Friction loss is defined according to the following equations: 
     
       
         
           
             
               
                 
                   
                       
                   
                    
                   
                     Re 
                     = 
                     
                       
                         ρ 
                          
                         U 
                          
                         D 
                       
                       μ 
                     
                   
                 
               
               
                 
                   ( 
                   
                     Equation 
                      
                     
                         
                     
                      
                     3.1 
                   
                   ) 
                 
               
             
             
               
                 
                   
                       
                   
                    
                   
                     f 
                     = 
                     
                       
                         c 
                         f 
                       
                       
                         R 
                          
                         e 
                       
                     
                   
                 
               
               
                 
                   ( 
                   
                     Equation 
                      
                     
                         
                     
                      
                     3.2 
                   
                   ) 
                 
               
             
             
               
                 
                   
                     K 
                     
                       1 
                       - 
                       2 
                     
                   
                   = 
                   
                     
                       K 
                       
                         2 
                         - 
                         3 
                       
                     
                     = 
                     
                       
                         K 
                         
                           3 
                           - 
                           3 
                         
                       
                       = 
                       
                         
                           K 
                           
                             4 
                             - 
                             3 
                           
                         
                         = 
                         
                           
                             K 
                             
                               5 
                               - 
                               3 
                             
                           
                           = 
                           
                             
                               K 
                               f 
                             
                             = 
                             
                               f 
                                
                               
                                 L 
                                 D 
                               
                             
                           
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   
                     Equation 
                      
                     
                         
                     
                      
                     3.3 
                   
                   ) 
                 
               
             
           
         
       
     
     The Flow Junction Loss Coefficients are derived from loss coefficients for combining flow at a branch angle of 90 degrees. Values for the loss coefficients were obtained from Charts 13.10 and 13.11 of Miller D S,  Internal Flow Systems,  1990, incorporated by reference herein. The charts use the ratio of the inlet orifice area (referred to as A1 in the charts) to the pipe cross-sectional area (referred to as A3 in the charts) and the ratio of the inlet orifice volumetric flow rate (Q1 in the charts) to the resulting combined pipe volumetric flow rate (Q3 in the charts). For example, for an area ratio of 0.6 between an area of the opening and an area of the drainage lumen, the following Flow Junction Loss Coefficients (K 13  and K 23 ) would be used. 
     
       
         
           
               
               
            
               
                   
                   
               
               
                   
                 Flow Ratio (Q 1 /Q 3 ) 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 0.1 
                 0.2 
                 0.3 
                 0.4 
                 0.5 
                 0.6 
                 0.7 
                 0.8 
                 0.9 
                 1.0 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 K 13   
                 −0.58 
                 −0.04 
                 0.11 
                 0.45 
                 0.75 
                 1.13 
                 1.48 
                 1.81 
                 2.16 
                 2.56 
               
               
                 K 23   
                 0.15 
                 0.27 
                 0.39 
                 0.48 
                 0.56 
                 0.63 
                 0.69 
                 0.72 
                 0.74 
                 0.76 
               
               
                   
               
            
           
         
       
     
     To calculate the Total Manifold Loss Coefficient (K), it is necessary to separate the model into so-called “reference stations” and progressively work through and balance the pressure and flow distributions of the two paths (e.g., flow through the opening and flow through the drainage lumen of the tube) to reach each station starting from the distal tip to the most proximal “Station”. A graphical representation of the different stations used for this calculation is shown in  FIG. 38 . For example, a most-distal “Station” A is the distal open end  1220  of the tube  122 . A second Station A′ is the distal most opening on the sidewall of the tube  122  (e.g., the opening(s) of the fifth section  1318  in  FIGS. 31-34 ). The next station B is for flow through the drainage lumen  1224  just proximal to the A′ opening. 
     To calculate loss between Station A (the distal opening) and Station B for fluid entering through the open distal end of the tube  1222  (Path 1), the modified loss coefficient (K′) is equal to: 
     
       
         
           
             
               
                 
                   
                     K 
                     ′ 
                   
                   = 
                   
                     
                       Inlet 
                        
                       
                           
                       
                        
                       Loss 
                     
                     + 
                     
                       Friction 
                        
                       
                           
                       
                        
                       Loss 
                     
                     + 
                     
                       Flow 
                        
                       
                           
                       
                        
                       Junction 
                        
                       
                           
                       
                        
                       Loss 
                     
                   
                 
               
               
                 
                   ( 
                   
                     Equation 
                      
                     
                         
                     
                      
                     4.1 
                   
                   ) 
                 
               
             
             
               
                 
                   
                     K 
                     B 
                     ′ 
                   
                   = 
                   
                     
                       
                         K 
                         
                           1 
                           - 
                           1 
                         
                       
                       × 
                       
                         
                           ( 
                           
                             
                               
                                 A 
                                 Pipe 
                               
                               
                                 A 
                                 1 
                               
                             
                             × 
                             
                               Q 
                               1 
                             
                           
                           ) 
                         
                         2 
                       
                     
                     + 
                     
                       
                         K 
                         
                           1 
                           - 
                           2 
                         
                       
                       × 
                       
                         Q 
                         1 
                         2 
                       
                     
                     + 
                     
                       
                         K 
                         
                           1 
                           - 
                           3 
                         
                       
                       × 
                       
                         
                           ( 
                           
                             
                               Q 
                               1 
                             
                             + 
                             
                               Q 
                               2 
                             
                           
                           ) 
                         
                         2 
                       
                     
                   
                 
               
               
                 
                   ( 
                   
                     Equation 
                      
                     
                         
                     
                      
                     4.2 
                   
                   ) 
                 
               
             
           
         
       
     
     In a similar manner, a second path to Station B is through the opening(s)  1334  of the fifth section  1318  (shown in  FIGS. 11-14 ) of the retention portion  1330 . A modified loss calculation for Path 2 is calculated as follows: 
     
       
         
           
             
               
                 
                   
                     K 
                     ′ 
                   
                   = 
                   
                     
                       Inlet 
                        
                       
                           
                       
                        
                       Loss 
                     
                     + 
                     
                       Flow 
                        
                       
                           
                       
                        
                       Junction 
                        
                       
                           
                       
                        
                       Loss 
                     
                   
                 
               
               
                 
                   ( 
                   
                     Equation 
                      
                     
                         
                     
                      
                     5.1 
                   
                   ) 
                 
               
             
             
               
                 
                   
                     K 
                     B 
                     ′ 
                   
                   = 
                   
                     
                       
                         K 
                         
                           2 
                           - 
                           1 
                         
                       
                       × 
                       
                         
                           ( 
                           
                             
                               
                                 A 
                                 Pipe 
                               
                               
                                 A 
                                 2 
                               
                             
                             × 
                             
                               Q 
                               2 
                             
                           
                           ) 
                         
                         2 
                       
                     
                     + 
                     
                       
                         K 
                         
                           2 
                           - 
                           2 
                         
                       
                       × 
                       
                         
                           ( 
                           
                             
                               Q 
                               1 
                             
                             + 
                             
                               Q 
                               2 
                             
                           
                           ) 
                         
                         2 
                       
                     
                   
                 
               
               
                 
                   ( 
                   
                     Equation 
                      
                     
                         
                     
                      
                     
                       ( 
                       5.2 
                       ) 
                     
                   
                 
               
             
           
         
       
     
     The modified loss coefficients of both Path 1 and Path 2 must equate to ensure the volumetric flow rates (Q 1  and Q 2 ) reflect the balanced distribution within the manifold at Station B. The volumetric flow rates are adjusted until equal modified loss coefficients for both paths is achieved. The volumetric flow rates can be adjusted because they represent a fractional portion of a total volumetric flow rate (Q′ Total ), which is assumed to be unity for the purpose of this step-by-step solution. Upon equating the two modified loss coefficients, one can then proceed to equating the two paths to reach station C (the fourth section  1316  in  FIGS. 11-14 ). 
     Loss coefficients between Station B (flow through drainage lumen in the fifth section  1318 ) and Station C (flow through lumen in the fourth section  1316 ) are calculated in a similar manner as shown by Equations 5.1 and 5.2). For example, for Path 1 (Station B to Station C), the modified loss coefficient (K′) for the opening(s) of the fourth section  1316  is defined as: 
         K ′=Loss to Station  B +Friction Loss+Flow Junction Loss  (Equation 6.1)
 
         K′   C   =K′   B   +K   2-3 ×( Q   1   +Q   2 ) 2   +K   2-4 ×( Q   1   +Q   2   +Q   3 ) 2   (Equation 6.2)
 
     For Path 2 (Station B to C), the modified loss coefficient (K′) based on the flow area of the opening(s) of the fourth section  1316  are defined as: 
     
       
         
           
             
               
                 
                   
                       
                   
                    
                   
                     
                       K 
                       ′ 
                     
                     = 
                     
                       
                         Inlet 
                          
                         
                             
                         
                          
                         Loss 
                       
                       + 
                       
                         Flow 
                          
                         
                             
                         
                          
                         Junction 
                          
                         
                             
                         
                          
                         Loss 
                       
                     
                   
                 
               
               
                 
                   ( 
                   
                     Equation 
                      
                     
                         
                     
                      
                     7.1 
                   
                   ) 
                 
               
             
             
               
                 
                   
                     K 
                     C 
                     ′ 
                   
                   = 
                   
                     
                       
                         K 
                         
                           3 
                           - 
                           1 
                         
                       
                       × 
                       
                         
                           ( 
                           
                             
                               
                                 A 
                                 Pipe 
                               
                               
                                 A 
                                 3 
                               
                             
                             × 
                             
                               Q 
                               3 
                             
                           
                           ) 
                         
                         2 
                       
                     
                     + 
                     
                       
                         K 
                         
                           3 
                           - 
                           2 
                         
                       
                       × 
                       
                         
                           ( 
                           
                             
                               Q 
                               1 
                             
                             + 
                             
                               Q 
                               2 
                             
                             + 
                             
                               Q 
                               3 
                             
                           
                           ) 
                         
                         2 
                       
                     
                   
                 
               
               
                 
                   ( 
                   
                     Equation 
                      
                     
                         
                     
                      
                     7.2 
                   
                   ) 
                 
               
             
           
         
       
     
     As with the previous stations, the modified loss coefficients of both Path 1 and Path 2 must equate to ensure the volumetric flow rates (Q 1 , Q 2 , and Q 3 ) reflect the balanced distribution within the manifold up to Station C. Upon equating the two modified loss coefficients, one can then proceed to equating the two paths to reach Station D, Station E and Station F. The step-by-step solution process proceeds through each station as demonstrated until calculating the modified loss coefficient for the final station, Station F in this case. The Total Loss Coefficient (K) for the manifold can then be calculated using an actual Q Total  (volumetric flow rate through a proximal portion of the drainage lumen) determined through experimental measurement. 
     
       
         
           
             
               
                 
                   K 
                   = 
                   
                     
                       K 
                       F 
                       ′ 
                     
                     
                       Q 
                       
                         T 
                          
                         o 
                          
                         t 
                          
                         a 
                          
                         l 
                       
                     
                   
                 
               
               
                 
                   ( 
                   
                     Equation 
                      
                     
                         
                     
                      
                     8 
                   
                   ) 
                 
               
             
           
         
       
     
     The fractional volumetric flow rates calculated through the step-by-step exercise can then be multiplied by the actual total volumetric flow rate (Q Total ) to determine the flow through each opening  1232  (shown in  FIGS. 10-10E ) and open distal end  1220 . 
     EXAMPLES 
     Examples are provided below and shown in Tables 3-5 and  FIGS. 15A-15C  for the calculated volumetric flow rates. 
     Example 1 
     Example 1 illustrates a distribution of fluid flow for a retention member tube with different sized openings, which corresponds to the embodiment of the retention member  1330  shown in  FIG. 11 . As shown in Table 3, the proximal most opening (Q6) had a diameter of 0.48 mm, the distal-most opening (Q5) on the sidewall of the tube had a diameter of 0.88 mm, and the open distal end (Q6) of the tube had a diameter of 0.97 mm. Each of the openings was circular. 
     The Percentage of Flow Distribution and Calculated Volumetric Flow Rate were determined as follows. 
     
       
         
           
               
             
               
                   
               
               
                 Path to Station B through distal end of tube (Path 1) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 f 
                 8.4 = 
                 C f /Re (C f  = 64 for circular cross-section) 
               
               
                 K INLET   
                 0.16 
                 (Contraction coefficient. for sharp edged 
               
               
                   
                   
                 orifice entering pipe) 
               
               
                 K ORIFICE   
                 2.8 
                 (Contraction coefficient. for sharp edged 
               
               
                   
                   
                 orifice w/no outlet pipe) 
               
               
                 K FRICTION  = 
                 f*(L/D) 
                 (Dependent on the length between orifices) 
               
            
           
           
               
               
            
               
                 Part 1-1 = 
                 Inlet loss coef × (A T /A 1  × Q′ 1 ) 2   
               
               
                 Part 1-2 = 
                 Catheter friction loss × Q′ 1   2   
               
               
                 Part 1-3 = 
                 Through flow junction loss to station 2 × (Q′ 1  + Q′ 2 ) 2   
               
            
           
           
               
               
               
            
               
                 A 2 /A T  = 
                 0.82 
                   
               
               
                 Q′ 2 /(Q′ 1  + 
                 0.83 
               
               
                 Q′ 2 ) = 
               
               
                 K 1-3  = 
                 0.61 
                 (From Miller, see table above) 
               
               
                 Part 1-1 = 
                 0.0000 
               
               
                 Part 1-2 = 
                 0.0376 
               
               
                 Part 1-3 = 
                 0.0065 
               
               
                 K′ = 
                 0.0442 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                   
               
               
                 Path to Station B through sidewall opening (Path 2) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 Part 2-1 = 
                 Orifice loss coef × (A T /A 2  × Q′ 2 ) 2   
               
               
                 Part 2-2 = 
                 Branch flow junction loss to station 2 × (Q′ 1  + Q′ 2 ) 2   
               
            
           
           
               
               
               
            
               
                 A 2 /A T  = 
                 0.82 
                   
               
               
                 Q′ 2 /(Q′ 1  + 
                 0.83 
               
               
                 Q′ 2 ) = 
               
               
                 K 2-2  = 
                 1.3 
                 (From Chart 13.10 of Miller) 
               
               
                 Part 2-1 = 
                 0.0306 
               
               
                 Part 2-2 = 
                 0.0138 
               
               
                 K′ = 
                 0.0444 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                   
               
               
                 Path to Station C from Station B (Path 1 + Path 2) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 Part 2-3 = 
                 Catheter friction loss × (Q′ 1  + Q′ 2 ) 2   
               
               
                 Part 2-4 = 
                 Through flow junction loss to station 3 × (Q′ 1  + Q′ 2  + Q′ 3 ) 2   
               
            
           
           
               
               
               
            
               
                 A 3 /A T  = 
                 0.61 
                   
               
               
                 Q′ 3 /(Q′ 1  + 
                 0.76 
               
               
                 Q′ 2  + Q′ 3 ) = 
               
               
                 K 2-4  = 
                 0.71 
                 (From Chart 13.11 of Miller) 
               
               
                 Loss 
                 0.044 
               
               
                 coefficient to 
               
               
                 Station 2 = 
               
               
                 Part 2-3 = 
                 0.921 
               
               
                 Part 2-4 = 
                 0.130 
               
               
                 K′ = 
                 1.095 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                   
               
               
                 Path to Station C through sidewall opening (Path 3) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 Part 3-1 = 
                 Orifice loss coef × (A T /A 3  × Q′ 3 ) 2   
               
               
                 Part 3-2 = 
                 Branch flow junction loss to station 3 × (Q′ 1  + Q′ 2  + Q′ 3 ) 2   
               
            
           
           
               
               
               
            
               
                 A 3 /A T  = 
                 0.61 
                   
               
               
                 Q′ 3 /(Q′ 1  + 
                 0.76 
               
               
                 Q′ 2  + Q′ 3 ) = 
               
               
                 K 3-2  = 
                 1.7 
                 (From Chart 13.10 of Miller) 
               
               
                 Part 3-1 = 
                 0.785 
               
               
                 Part 3-2 = 
                 0.311 
               
               
                 K′ = 
                 1.096 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                   
               
               
                 Path to Station D from Station C (Path 1 + Path 2 + Path 3) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Part 3-3 = 
                 Catheter friction loss × (Q′ 1  + Q′ 2  + Q′ 3 ) 2   
               
               
                   
                 Part 3-4 = 
                 Through flow junction loss to station 4 × 
               
               
                   
                   
                 (Q′ 1  + Q′ 2  + Q′ 3  + Q′ 4 ) 2   
               
            
           
           
               
               
               
               
            
               
                   
                 A 4 /A T  = 
                 0.46 
                   
               
               
                   
                 Q′ 4 /(Q′ 1  + Q′ 2  + 
                 0.70 
               
               
                   
                 Q′ 3  + Q′ 4 ) = 
               
               
                   
                 K 3-4  = 
                 0.77 
                 (From Chart 13.11 of Miller) 
               
               
                   
                 Loss 
                 1.10 
               
               
                   
                 coefficient to 
               
               
                   
                 Station 3 = 
               
               
                   
                 Part 3-3 = 
                 15.90 
               
               
                   
                 Part 3-4 = 
                 1.62 
               
               
                   
                 K′ = 
                 18.62 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                   
               
               
                 Path to Station D through sidewall opening (Path 4) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Part 4-1 = 
                 Orifice loss coef × (A T /A 4  × Q′ 4 ) 2   
               
               
                   
                 Part 4-2 = 
                 Branch flow junction loss to station 4 × 
               
               
                   
                   
                 (Q′ 1  + Q′ 2  + Q′ 3  + Q′ 4 ) 2   
               
            
           
           
               
               
               
               
            
               
                   
                 A 4 /A T  = 
                 0.46 
                   
               
               
                   
                 Q′ 4 /(Q′ 1  + Q′ 2  + 
                 0.70 
               
               
                   
                 Q′ 3  + Q′ 4 ) = 
               
               
                   
                 K 4-2  = 
                 2.4 
                 (From Chart 13.10 of Miller) 
               
               
                   
                 Part 4-1 = 
                 13.59 
               
               
                   
                 Part 4-2 = 
                 5.04 
               
               
                   
                 K′ = 
                 18.62 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                   
               
               
                 Path to Station E from Station D (Path 1 + 
               
               
                 Path 2 + Path 3 + Path 4) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 Part 4-3 = 
                 Catheter friction loss × (Q′ 1  + Q′ 2  + Q′ 3  + Q′ 4 ) 2   
               
               
                 Part 4-4 = 
                 Through flow junction loss to station 5 × 
               
               
                   
                 (Q′ 1  + Q′ 2  + Q′ 3  + Q′ 4  + Q′ 5 ) 2   
               
            
           
           
               
               
               
            
               
                 A 5 /A T  = 
                 0.36 
                   
               
               
                 Q′ 5 /(Q′ 1  + Q′ 2  + 
                 0.65 
               
               
                 Q′ 3  + Q′ 4  + Q′ 5 ) = 
               
               
                 K 3-4  = 
                 0.78 
                 (From Chart 13.11 of Miller) 
               
               
                 Loss 
                 18.6 
               
               
                 coefficient to 
               
               
                 Station 4 = 
               
               
                 Part 4-3 = 
                 182.3 
               
               
                 Part 4-4 = 
                 13.3 
               
               
                 K′ = 
                 214.2 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                   
               
               
                 Path to Station E through sidewall opening (Path 5) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Part 5-1 = 
                 Orifice loss coef × (A T /A 5  × Q′ 5 ) 2   
               
               
                   
                 Part 5-2 = 
                 Branch flow junction loss to station 5 × 
               
               
                   
                   
                 (Q′ 1  + Q′ 2  + Q′ 3  + Q′ 4  + Q′ 5 ) 2   
               
            
           
           
               
               
               
               
            
               
                   
                 A 5 /A T  = 
                 0.36 
                   
               
               
                   
                 Q′ 5 /(Q′ 1  + Q′ 2  + 
                 0.65 
               
               
                   
                 Q′ 3  + Q′ 4  + Q′ 5 ) = 
               
               
                   
                 K 4-2  = 
                 3.3 
                 (From Chart 13.10 of Miller) 
               
               
                   
                 Part 5-1 = 
                 157.8 
               
               
                   
                 Part 5-2 = 
                 56.4 
               
               
                   
                 K′ = 
                 214.2 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                   
               
               
                 Path to Station F from Station E (through paths 1-5) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 Part 5-3 = 
                 Catheter friction loss × (Q′ 1  + Q′ 2  + Q′ 3  + Q′ 4  + Q′ 5 ) 2   
               
               
                 Part 5-4 = 
                 Through flow junction loss to station 6 × 
               
               
                   
                 (Q′ 1  + Q′ 2  + Q′ 3  + Q′ 4  + Q′ 5  + Q′ 6 ) 2   
               
            
           
           
               
               
               
            
               
                 A 6 /A T  = 
                 0.24 
                   
               
               
                 Q′ 6 /(Q′ 1  + Q′ 2  + 
                 0.56 
               
               
                 Q′ 3  + Q′ 4  + 
               
               
                 Q′ 5  + Q′ 6 ) = 
               
               
                 K 3-4  = 
                 0.77 
                 (From Chart 13.11 of Miller) 
               
               
                 Loss 
                 214.2 
               
               
                 coefficient to 
               
               
                 Station 5 = 
               
               
                 Part 5-3 = 
                 1482.9 
               
               
                 Part 5-4 = 
                 68.3 
               
               
                 K′ = 
                 1765.4 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                   
               
               
                 Path to Station F through sidewall opening (path 6) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Part 6-1 = 
                 Orifice loss coef × (A T /A 6  × Q′ 6 ) 2   
               
               
                   
                 Part 6-2 = 
                 Branch flow junction loss to station 6 × 
               
               
                   
                   
                 (Q′ 1  + Q′ 2  + Q′ 3  + Q′ 4  + Q′ 5  + Q′ 6 ) 2   
               
            
           
           
               
               
               
               
            
               
                   
                 A 6 /A T  = 
                 0.24 
                   
               
               
                   
                 Q′ 6 /(Q′ 1  + Q′ 2  + 
                 0.56 
               
               
                   
                 Q′ 3  + Q′ 4  + 
               
               
                   
                 Q′ 5  + Q′ 6 ) = 
               
               
                   
                 K 4-2  = 
                 5.2 
                 (From Chart 13.10 of Miller) 
               
               
                   
                 Part 6-1 = 
                 1304.3 
               
               
                   
                 Part 6-2 = 
                 461.2 
               
               
                   
                 K′ = 
                 1765.5 
               
               
                   
                   
               
            
           
         
       
     
     In order to calculate flow distribution for each “Station” or opening, the calculated K′ values were multiplied by actual total volumetric flow rate (Q Total ) to determine the flow through each perforation and distal end hole. Alternatively, calculated results could be presented as a percentage of total flow or a flow distribution as shown in Table 3. As shown in Table 3 and in  FIG. 15C , the Percentage of Flow Distribution (% Flow Distribution) through the proximal most opening (Q6) was 56.1%. Flow through the two proximal-most openings (Q6 and Q5) was 84.6%. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                   
                   
                   
                   
                 Cumulative 
               
               
                   
                 % Flow 
                 Diameter 
                 Length 
                 Length 
               
               
                 Position 
                 Distribution 
                 (mm) 
                 (mm) 
                 (mm) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Q 6 ′ (proximal) 
                 56.1% 
                 0.48 
                 0 
                 0 
               
               
                 Q 5 ′ 
                 28.5% 
                 0.58 
                 10 
                 10 
               
               
                 Q 4 ′ 
                 10.8% 
                 0.66 
                 10 
                 20 
               
               
                 Q 3 ′ 
                  3.5% 
                 0.76 
                 10 
                 30 
               
               
                 Q 2 ′ 
                  0.9% 
                 0.88 
                 10 
                 40 
               
               
                 Q 1 ′ (distal) 
                  0.2% 
                 0.97 
                 15 
                 55 
               
               
                 Q TOTAL   
                  100% 
               
               
                   
               
            
           
         
       
     
     As demonstrated in Example 1, the increasing diameters of perforations going from the proximal to distal regions of the retention portion of the tube results in more evenly distributed flow across the entire retention portion. 
     Example 2 
     In Example 2, each opening has the same diameter and area. As shown in Table 4 and  FIG. 15A , in that case, flow distribution through the proximal-most opening is 86.2% of total flow through the tube. Flow distribution through the second opening is 11.9%. Therefore, in this example, it was calculated that 98.1% of fluid passing through the drainage lumen entered the lumen through the two proximal-most openings. Compared to Example 1, Example 2 has increased flow through the proximal end of the tube. Therefore, Example 1 provides a wider flow distribution in which a greater percentage of fluid enters the drainage lumen through openings other than the proximal-most opening. As such, fluid can be more efficiently collected through multiple openings reducing fluid backup and improving distribution of negative pressure through the renal pelvis and/or kidneys. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 4 
               
               
                   
               
               
                   
                   
                   
                   
                 Cumulative 
               
               
                   
                 % Flow 
                 Diameter 
                 Length 
                 Length 
               
               
                 Position 
                 Distribution 
                 (mm) 
                 (mm) 
                 (mm) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Q 6 ′ (proximal) 
                 86.2% 
                 0.88 
                 0 
                 0 
               
               
                 Q 5 ′ 
                 11.9% 
                 0.88 
                 22 
                 22 
               
               
                 Q 4 ′ 
                  1.6% 
                 0.88 
                 22 
                 44 
               
               
                 Q 3 ′ 
                  0.2% 
                 0.88 
                 22 
                 66 
               
               
                 Q 2 ′ 
                 0.03% 
                 0.88 
                 22 
                 88 
               
               
                 Q 1 ′ (distal) 
                 0.01% 
                 0.97 
                 22 
                 110 
               
               
                 Q TOTAL   
                  100% 
               
               
                   
               
            
           
         
       
     
     Example 3 
     Example 2 also illustrates flow distribution for openings having the same diameter. However, as shown in Table 5, the openings are closer together (10 mm vs. 22 mm). As shown in Table 5 and  FIG. 15B , 80.9% of fluid passing through the drainage lumen entered the drainage lumen through the proximal most opening (Q6). 96.3% of fluid in the drainage lumen entered the drainage lumen through the two proximal-most openings (Q5 and Q6). 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 5 
               
               
                   
               
               
                   
                   
                   
                   
                 Cumulative 
               
               
                   
                 % Flow 
                 Diameter 
                 Length 
                 Length 
               
               
                 Position 
                 Distribution 
                 (mm) 
                 (mm) 
                 (mm) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Q 6 ′ (proximal) 
                 80.9% 
                 0.88 
                 0 
                 0 
               
               
                 Q 5 ′ 
                 15.4% 
                 0.88 
                 10 
                 10 
               
               
                 Q 4 ′ 
                  2.9% 
                 0.88 
                 10 
                 20 
               
               
                 Q 3 ′ 
                  0.6% 
                 0.88 
                 10 
                 30 
               
               
                 Q 2 ′ 
                  0.1% 
                 0.88 
                 10 
                 40 
               
               
                 Q 1 ′ (distal) 
                 0.02% 
                 0.97 
                 15 
                 55 
               
               
                 Q TOTAL   
                  100% 
               
               
                   
               
            
           
         
       
     
     Referring generally now to  FIGS. 17-41 , and more specifically to  FIG. 17 , there are shown two exemplary ureteral catheters  5000 ,  5001  positioned within the urinary tract of a patient. The ureteral catheter  5000 ,  5001  comprises: a drainage lumen  5002 ,  5003  for draining fluid such as urine from at least one of a patient&#39;s kidney  2 ,  4 , renal pelvis  20 ,  21  or in the ureter  6 ,  8  adjacent to the renal pelvis  20 ,  21 . The drainage lumen  5002 ,  5003  comprises a distal portion  5004 ,  5005  configured to be positioned in a patient&#39;s kidney  2 ,  4 , renal pelvis  20 ,  21  and/or in the ureter  6 ,  8  adjacent to the renal pelvis  20 ,  21  and a proximal portion  5006 ,  5007  through which fluid  5008  is drained to the bladder  10  or outside of the body of the patient. 
     In some examples, the distal portion  5004 ,  5005  comprises an open distal end  5010 ,  5011  for drawing fluid into the drainage lumen  5002 ,  5003 . The distal portion  5004 ,  5005  of the ureteral catheter  5000 ,  5001  further comprises a retention portion  5012 ,  5013  for maintaining the distal portion  5004 ,  5005  of the drainage lumen or tube  5002 ,  5003  in the ureter and/or kidney. The retention portion  5012 ,  5013  can be flexible and/or bendable to permit positioning of the retention portion  5012 ,  5013  in the ureter, renal pelvis, and/or kidney. For example, the retention portion  5012 ,  5013  is desirably sufficiently bendable to absorb forces exerted on the catheter  5000 ,  5001  and to prevent such forces from being translated to the ureters. Further, if the retention portion  5012 ,  5013  is pulled in the proximal direction P (shown in  FIG. 17 ) toward the patient&#39;s bladder  10 , the retention portion  5012 ,  5013  can be sufficiently flexible to begin to unwind, straightened or collapsed so that it can be drawn through the ureter  6 ,  8 . 
     In some examples, the retention portion comprises a funnel support. The funnel support comprises at least one sidewall. The at least one sidewall of the funnel support comprises a first diameter and a second diameter, the first diameter being less than the second diameter. The second diameter of the funnel support is closer to an end of the distal portion of the drainage lumen than the first diameter. 
     The proximal portion of the drainage lumen or drainage tube is essentially free of or free of openings. While not intending to be bound by any theory, it is believed that when negative pressure is applied at the proximal end of the proximal portion of the drainage lumen, that openings in the proximal portion of the drainage lumen or drainage tube may be undesirable as such openings may diminish the negative pressure at the distal portion of the ureteral catheter and thereby diminish the draw or flow of fluid or urine from the kidney and renal pelvis of the kidney. It is desirable that the flow of fluid from the ureter and/or kidney is not prevented by occlusion of the ureter and/or kidney by the catheter. Also, while not intending to be bound by any theory, it is believed that when negative pressure is applied at the proximal end of the proximal portion of the drainage lumen, ureter tissue may be drawn against or into openings along the proximal portion of the drainage lumen, which may irritate the tissues. 
     Some examples of ureteral catheters comprising a retention portion comprising a funnel support according to the present invention are shown in  FIGS. 2 and 7-10E, 17-41 . In  FIGS. 2  and  7 - 10 E, the funnel support is formed by a coil of tubing. In  FIGS. 17-41 , other examples of the funnel support are shown. Each of these funnel supports according to the present invention will be discussed in detail below. 
     Referring now to  FIGS. 18A-C , in some examples, there is shown a distal portion  5004  of the ureteral catheter, indicated generally as  5000 . The distal portion  5004  comprises a retention portion  5012  comprising a funnel support  5014 . The funnel support  5014  comprises at least one sidewall  5016 . The at least one sidewall  5016  of the funnel support  5014  comprises a first (outer) diameter D 4  and a second (outer) diameter D 5 , the first outer diameter D 4  being less than the second outer diameter D 5 . The second outer diameter D 5  of the funnel support  5014  is closer to the distal end  5010  of the distal portion  5004  of the drainage lumen  5002  than is the first outer diameter D 4 . In some examples the first outer diameter D 4  can range from about 0.33 mm to 4 mm (about 1 Fr to about 12 Fr (French catheter scale)), or about 2.0±0.1 mm. In some examples, the second outer diameter D 5  is greater than first outer diameter D 4  and can range from about 1 mm to about 60 mm, or about 10 mm to 30 mm, or about 18 mm±2 mm. 
     In some examples, the at least one sidewall  5016  of the funnel support  5014  can further comprise a third diameter D 7  (shown in  FIG. 18B ), the third diameter D 7  being less than the second outer diameter D 5 . The third diameter D 7  of the funnel support  5014  is closer to the distal end  5010  of the distal portion  5004  of the drainage lumen  5002  than is the second diameter D 5 . The third diameter D 7  is discussed in greater detail below regarding the lip. In some examples, the third diameter D 7  can range from about 0.99 mm to about 59 mm, or about 5 mm to about 25 mm. 
     The at least one sidewall  5016  of the funnel support  5014  comprises a first (inner) diameter D 6 . The first inner diameter D 6  is closer to the proximal end  5017  of the funnel support  5014  than is the third diameter D 7 . The first inner diameter D 6  is less than the third diameter D 7 . In some examples the first inner diameter D 6  can range from about 0.05 mm to 3.9 mm, or about 1.25±0.75 mm. 
     In some examples, an overall height H 5  of the sidewall  5016  along a central axis  5018  of the retention portion  5012  can range from about 1 mm to about 25 mm. In some examples, the height H 5  of the sidewall can vary at different portions of the sidewall, for example if the sidewall has an undulating edge or rounded edges such as is shown in  FIG. 24 . In some examples, the undulation can range from about 0.01 mm to about 5 mm or more, if desired. 
     In some examples, as shown in  FIGS. 2, 7-10E, and 17-41 , the funnel support  5014  can have a generally conical shape. In some examples, the angle  5020  between the outer wall  5022  near the proximal end  5017  of the funnel support  5014  and the drainage lumen  5002  adjacent to the base portion  5024  of the funnel support  5014  can range from about 100 degrees to about 180 degrees, or about 100 degrees to about 160 degrees, or about 120 degrees to about 130 degrees. The angle  5020  may vary at different positions about the circumference of the funnel support  5014 , such as is shown in  FIG. 22A , in which the angle  5020  ranges from about 140 degrees to about 180 degrees. 
     In some examples, the edge or lip  5026  of the distal end  5010  of the at least one sidewall  5016  can be rounded, square, or any shape desired. The shape defined by the edge  5026  can be, for example, circular (as shown in  FIGS. 18C and 23B ), elliptical (as shown in  FIG. 22B ), lobes (as shown in  FIGS. 28B, 29B and 31 ), square, rectangular, or any shape desired. 
     Referring now to  FIGS. 28A-31 , there is shown a funnel support  5300  wherein the at least one sidewall  5302  comprises a plurality of lobe-shaped longitudinal folds  5304  along the length L 7  of the sidewall  5302 . The number of folds  5304  can range from 2 to about 20, or about 6, as shown. In this example, the folds  5304  can be formed from one or more flexible materials, such as silicone, polymer, solid material, fabric, or a permeable mesh to provide the desired lobe shape. The folds  5304  can have a generally rounded shape as shown in cross-sectional view  51 B. The depth D 10  of each fold  5304  at the distal end  5306  of the funnel support  5300  can be the same or vary, and can range from about 0.5 mm to about 5 mm. 
     Referring now to  FIGS. 29A and 29B , one or more folds  5304  can comprise at least one longitudinal support member  5308 . The longitudinal support member(s)  5308  can span the entire length L 7  or a portion of the length L 7  of the funnel support  5300 . The longitudinal support members  5308  can be formed from a flexible yet partially rigid material, such as a temperature sensitive shape memory material, for example nitinol. The thickness of the longitudinal support members  5308  can range from about 0.01 mm to about 1 mm, as desired. In some examples, the nitinol frame can be covered with a suitable waterproof material such as silicon to form a tapered portion or funnel. In that case, fluid is permitted to flow down the inner surface  5310  of the funnel support  5300  and into the drainage lumen  5312 . In other examples, the folds  5304  are formed from various rigid or partially rigid sheets or materials bended or molded to form a funnel-shaped retention portion. 
     Referring now to  FIGS. 30 and 31 , the distal end or edge  5400  of the folds  5402  can comprise at least one edge support member  5404 . The edge support member(s)  5404  can span the entire circumference  5406  or one or more portions of the circumference  5406  of the distal edge  5400  of the funnel support  5408 . The edge support member(s)  5404  can be formed from a flexible yet partially rigid material, such as a temperature sensitive shape memory material, for example nitinol. The thickness of the edge support member(s)  5404  can range from about 0.01 mm to about 1 mm, as desired. 
     In some examples, such as are shown in  FIGS. 18A-C , the distal end  5010  of the drainage lumen  5002  (or funnel support  5014 ) can have an inwardly facing lip  5026  oriented towards the center of the funnel support  5014 , for example of about 0.01 mm to about 1 mm, to inhibit irritating the kidney tissue. Thus, the funnel support  5014  can comprise a third diameter D 7  less than the second diameter D 5 , the third diameter D 7  being closer to an end  5010  of the distal portion  5004  of the drainage lumen  5002  than the second diameter D 5 . The outer surface  5028  of the lip  5026  can be rounded, a square edge, or any shape desired. The lip  5026  may assist in providing additional support to the renal pelvis and internal kidney tissues. 
     Referring now to  FIG. 24 , in some examples, the edge  5200  of the distal end  5202  of the at least one sidewall  5204  can be shaped. For example, the edge  5200  can comprise a plurality of generally rounded edges  5206  or scallops, for example about 4 to about 20 or more rounded edges. The rounded edges  5206  can provide more surface area than a straight edge to help support the tissue of the renal pelvis or kidney and inhibit occlusion. The edge  5200  can have any shape desired, but preferably is essentially free of or free of sharp edges to avoid injuring tissue. 
     In some examples, such as are shown in  FIGS. 18A-C  and  22 A- 23 B, the funnel support  5014  comprises a base portion  5024  adjacent to the distal portion  5004  of the drainage lumen  5002 . The base portion  5024  comprises at least one interior opening  5030  aligned with an interior lumen  5032  of the drainage lumen  5002  of the proximal portion  5006  of the drainage lumen  5002  for permitting fluid flow into the interior lumen  5032  of the proximal portion  5006  of the drainage lumen  5002 . In some examples, the cross-section of the opening  5030  is circular, although the shape may vary, such as ellipsoid, triangular, square, etc. 
     In some examples, such as is shown in  FIGS. 22A-23B , a central axis  5018  of the funnel support  5014  is offset with respect to a central axis  5034  of the proximal portion  5006  of the drainage lumen  5002 . The offset distance X from the central axis  5018  of the funnel support  5014  with respect to the central axis  5034  of the proximal portion  5006  can range from about 0.1 mm to about 5 mm. 
     The at least one interior opening  5030  of the base portion  5024  has a diameter D 8  (shown, for example, in  FIGS. 18C and 23B ) ranging from about 0.05 mm to about 4 mm. In some examples, the diameter D 8  of the interior opening  5030  of the base portion  5024  is about equal to the first inner diameter D 6  of the adjacent proximal portion  5006  of the drainage lumen. 
     In some examples, the ratio of the height H 5  of the at least one sidewall  5016  funnel support  5014  to the second outer diameter D 5  of the at least one sidewall  5016  of the funnel support  5014  ranges from about 1:25 to about 5:1. 
     In some examples, the at least one interior opening  5030  of the base portion  5024  has a diameter D 8  ranging from about 0.05 mm to about 4 mm, the height H 5  of the at least one sidewall  5016  of the funnel support  5014  ranges from about 1 mm to about 25 mm, and the second outer diameter D 5  of the funnel support  5014  ranges from about 5 mm to about 25 mm. 
     In some embodiments, the thickness T 1  (shown in  FIG. 18B , for example) of the at least one sidewall  5016  of the funnel support  5014  can range from about 0.01 mm to about 1.9 mm, or about 0.5 mm to about 1 mm. The thickness T 1  can be generally uniform throughout the at least one sidewall  5016 , or it may vary as desired. For example, the thickness T 1  of the at least one sidewall  5016  can be less or greater near the distal end  5010  of the distal portion  5004  of the drainage lumen  5002  than at the base portion  5024  of the funnel support  5014 . 
     Referring now to  FIGS. 18A-21 , along the length of the at least one sidewall  5016 , the sidewall  5016  can be straight (as shown in  FIGS. 18A and 20 ), convex (as shown in  FIG. 19 ), concave (as shown in  FIG. 21 ), or any combination thereof. As shown in  FIGS. 19 and 21 , the curvature of the sidewall  5016  can be approximated from the radius of curvature R from the point Q such that a circle centered at Q meets the curve and has the same slope and curvature as the curve. In some examples, the radius of curvature ranges from about 2 mm to about 12 mm. In some examples, the funnel support  5014  has a generally hemispherical shape, as shown in  FIG. 19 . 
     In some examples, the at least one sidewall  5016  of the funnel support  5014  is formed from a balloon  5100 , for example as shown in  FIGS. 35A, 35  B,  38 A and  38 B. The balloon  5100  can have any shape that provides a funnel support to inhibit occlusion of the ureter, renal pelvis, and/or the rest of the kidney. As shown in  FIGS. 35A and 35B , the balloon  5100  has the shape of a funnel. The balloon can be inflated after insertion or deflated before removal by adding or removing gas or air through the gas port(s)  5102 . The gas port(s)  5102  can simply be contiguous with the interior  5104  of the balloon  5100 , e.g., the balloon  5100  can be adjacent to the interior  5106  or encase the exterior  5108  of an adjacent portion of the proximal portion  5006  of the drainage lumen  5002 . The diameter D 9  of the sidewall  5110  of the balloon  5100  can range from about 1 mm to about 3 mm, and can vary along its length such that the sidewall has a uniform diameter, tapers toward the distal end  5112  or tapers toward the proximal end  5114  of the funnel support  5116 . The outer diameter D 10  of the distal end  5112  of the funnel support  5116  can range from about 5 mm to about 25 mm. 
     In some examples, the at least one sidewall  5016  of the funnel support  5014  is continuous along the height H 5  of the at least one sidewall  5016 , for example as shown in  FIGS. 18A, 19, 20, and 21 . In some examples, the at least one sidewall  5016  of the funnel support  5014  comprises a solid wall, for example the sidewall  5016  is not permeable through the sidewall after 24 hours of contact with a fluid such as urine on one side. 
     In some examples, the at least one sidewall of the funnel support is discontinuous along the height or the body of the at least one sidewall. As used herein, “discontinuous” means that the at least one sidewall comprises at least one opening for permitting the flow of fluid or urine therethrough into the drainage lumen, for example by gravity or negative pressure. In some examples, the opening can be a conventional opening through the sidewall, or openings within a mesh material, or openings within a permeable fabric. The cross-sectional shape of the opening can be circular or non-circular, such as rectangular, square, triangular, polygonal, ellipsoid, as desired. In some examples, an “opening” is a gap between adjacent coils in a retention portion of a catheter comprising a coiled tube or conduit. 
     As used herein, “opening” or “hole” means a continuous void space or channel through the sidewall from the outside to the inside of the sidewall, or vice versa. In some examples, each of the at least one opening(s) can have an area which can be the same or different and can range from about 0.002 mm 2  to about 100 mm 2 , or about 0.002 mm 2  to about 10 mm 2 . As used herein, the “area” or “surface area” or “cross-sectional area” of an opening means the smallest or minimum planar area defined by a perimeter of the opening. For example, if the opening is circular and has a diameter of about 0.36 mm (area of 0.1 mm 2 ) at the outside of the sidewall, but a diameter of only 0.05 mm (area of 0.002 mm 2 ) at some point within the sidewall or on the opposite side of the sidewall, then the “area” would be 0.002 mm 2  since that is the minimum or smallest planar area for flow through the opening in the sidewall. If the opening is square or rectangular, the “area” would be the length times the width of the planar area. For any other shapes, the “area” can be determined by conventional mathematical calculations well known to those skilled in the art. For example, the “area” of an irregular shaped opening is found by fitting shapes to fill the planar area of the opening, calculating the area of each shape and adding together the area of each shape. 
     In some examples, at least a portion of the sidewall comprises at least one (one or more) openings. Generally, the central axis of the opening(s) can be generally perpendicular to the planar outer surface of the sidewall, or the opening(s) can be angled with respect to the planar outer surface of the sidewalls. The dimensions of the bore of the opening may be uniform throughout its depth, or the width may vary along the depth, either increasing, decreasing, or alternating in width through the opening from the exterior surface of the sidewall to the interior surface of the sidewall. 
     Referring now to  FIGS. 9A-9E, 10A, 10E, 11-14, 27, 32A, 32B, 33 and 34 , in some examples at least a portion of the sidewall comprises at least one (one or more) openings. The opening(s) can be positioned anywhere along the sidewall. For example, the openings can be uniformly positioned throughout the sidewall, or positioned in specified regions of the sidewall, such as closer to the distal end of the sidewall or closer to the proximal end of the sidewall, or in vertical or horizontal or random groupings along the length or circumference of the sidewall. While not intending to be bound by any theory, it is believed that, when negative pressure is applied at the proximal end of the proximal portion of the drainage lumen, openings in the proximal portion of the funnel support that are directly adjacent to the ureter, renal pelvis and/or other kidney tissue may be undesirable as such openings may diminish the negative pressure at the distal portion of the ureteral catheter and thereby diminish the draw or flow of fluid or urine from the kidney and renal pelvis of the kidney, as well as perhaps irritate the tissue. 
     The number of openings can vary from 1 to 1000 or more, as desired. For example, in  FIG. 27 , six openings (three on each side) are shown. As discussed above, in some examples, each of the at least one opening(s) can have an area which can be the same or different and can range from about 0.002 mm 2  to about 50 mm 2 , or about 0.002 mm 2  to about 10 mm 2 . 
     In some examples, as shown in  FIG. 27 , the openings  5500  can be positioned closer the distal end  5502  of the sidewall  5504 . In some examples, the opening(s) are positioned in the distal half  5506  of the sidewall towards the distal end  5502 . In some examples, the openings  5500  are evenly distributed around the circumference of the distal half  5506  or even closer to the distal end  5502  of the sidewall  5504 . 
     In contrast, in  FIG. 32B , the openings  5600  are positioned near the proximal end  5602  of an inner sidewall  5604 , and do not directly contact the tissue since there is an outer sidewall  5606  between the opening  5600  and the tissue. Alternatively or additionally, one or more opening(s)  5600  can be positioned near the distal end of the inner sidewall, as desired. The inner sidewall  5604  and outer sidewall  5606  can be connected by one or more supports  5608  or ridges connecting the outside  5610  of the inner sidewall  5604  to the inside  5612  of the outer sidewall  5606 . 
     In some examples, such as are shown in  FIGS. 25 and 26 , the at least one sidewall  5700 ,  5800  of the funnel support  5702 ,  5802  comprises mesh  5704 ,  5804 . The mesh  5704 ,  5804  comprises a plurality of openings  5706 ,  5806  therethrough for permitting fluid flow into the drainage lumen  5708 ,  5808 . In some examples, the maximum area of an opening can be less than about 100 mm 2 , or less than about 1 mm 2 , or about 0.002 mm 2  to about 1 mm 2 , or about 0.002 mm 2  to about 0.05 mm 2 . The mesh  5704 ,  5804  can be formed from any suitable metallic or polymeric material such as are discussed above. 
     In some examples, the funnel support further comprises a cover portion over the distal end of the funnel support. This cover portion can be formed as an integral part of the funnel support or connected to the distal end of the funnel support. For example, as shown in  FIG. 26 , the funnel support  5802  comprises a cover portion  5810  across the distal end  5812  of the funnel support  5802  and projecting from the distal end  5812  of the funnel support  5802 . The cover portion  5810  can have any shape desired, such as flat, convex, concave, undulating, and combinations thereof. The cover portion  5810  can be formed from mesh or any polymeric solid material as discussed above. The cover portion  5810  can assist in supporting the pliant tissue in the kidney region to facilitate urine production. 
     In some examples, the funnel support comprises a porous material, for example as shown in  FIGS. 39 and 40 .  FIGS. 39 and 40  and suitable porous materials are discussed in detail below. Briefly, in  FIGS. 39 and 40 , the porous material itself is the funnel support. In  FIG. 39 , the funnel support is a wedge of porous material. In  FIG. 40 , the porous material is in the shape of a funnel. In some examples, such as  FIG. 33 , the porous material  5900  is positioned within the interior  5902  of the sidewall  5904 . In some examples, such as  FIG. 34 , the funnel support  6000  comprises a porous liner  6002  positioned adjacent to the interior  6004  of the sidewall  6006 . The thickness T 2  of the porous liner  6002  can range from about 0.5 mm to about 12.5 mm, for example. The area of the openings within the porous material can be about 0.002 mm 2  to about 100 mm 2 , or less. 
     Referring now to  FIGS. 37A and 37B , for example, a retention portion  130  of a ureteral catheter  112  comprises a catheter tube  122  having a widened and/or tapered distal end portion which, in some examples, is configured to be positioned in the patient&#39;s renal pelvis and/or kidney. For example, the retention portion  130  can be a funnel-shaped structure comprising an outer surface  185  configured to be positioned against the ureter and/or kidney wall and comprising an inner surface  186  configured to direct fluid toward a drainage lumen  124  of the catheter  112 . The retention portion  130  can comprise a proximal end  188  adjacent to the distal end of the drainage lumen  124  and having a first diameter D 1  and a distal end  190  having a second diameter D 2  that is greater than the first diameter D 1  when the retention portion  130  is in its deployed position. In some examples, the retention portion  130  is transitionable from a collapsed or compressed position to the deployed position. For example, the retention portion  130  can be biased radially outward such that when the retention portion  130  is advanced to its fluid collecting position, the retention portion  130  (e.g., the funnel portion) expands radially outward to the deployed state. 
     The retention portion  130  of the ureteral catheter  112  can be made from a variety of suitable materials that are capable of transitioning from the collapsed state to the deployed state. In one example, the retention portion  130  comprises a framework of tines or elongated members formed from a temperature sensitive shape memory material, such as nitinol. In some examples, the nitinol frame can be covered with a suitable waterproof material such as silicon to form a tapered portion or funnel. In that case, fluid is permitted to flow down the inner surface  186  of the retention portion  130  and into the drainage lumen  124 . In other examples, the retention portion  130  is formed from various rigid or partially rigid sheets or materials bended or molded to form a funnel-shaped retention portion as illustrated in  FIGS. 37A and 37B . 
     In some examples, the retention portion of the ureteral catheter  112  can include one or more mechanical stimulation devices  191  for providing stimulation to nerves and muscle fibers in adjacent tissues of the ureter(s) and renal pelvis. For example, the mechanical stimulation devices  191  can include linear or annular actuators embedded in or mounted adjacent to portions of the sidewall of the catheter tube  122  and configured to emit low levels of vibration. In some examples, mechanical stimulation can be provided to portions of the ureters and/or renal pelvis to supplement or modify therapeutic effects obtained by application of negative pressure. While not intending to be bound by theory, it is believed that such stimulation affects adjacent tissues by, for example, stimulating nerves and/or actuating peristaltic muscles associated with the ureter(s) and/or renal pelvis. Stimulation of nerves and activation of muscles may produce changes in pressure gradients or pressure levels in surrounding tissues and organs which may contribute to or, in some cases, enhance therapeutic benefits of negative pressure therapy. 
     With reference to  FIGS. 38A and 38B , according to another example, a retention portion  330  of a ureteral catheter  312  comprises a catheter tube  322  having a distal portion  318  formed in a helical structure  332  and an inflatable element or balloon  350  positioned proximal to the helical structure  332  to provide an additional degree of retention in the renal pelvis and/or fluid collection location. A balloon  350  can be inflated to pressure sufficient to retain the balloon in the renal pelvis or ureter, but low enough to avoid distending or damaging these structures. Suitable inflation pressures are known to those skilled in the art and are readily discernible by trial and error. As in previously-described examples, the helical structure  332  can be imparted by bending the catheter tube  322  to form one or more coils  334 . The coils  334  can have a constant or variable diameter and height as described above. The catheter tube  322  further comprises a plurality of drainage ports  336  disposed on the sidewall of the catheter tube  322  to allow urine to be drawn into the drainage lumen  324  of the catheter tube  322  and to be directed from the body through the drainage lumen  324 , for example on the inwardly facing and/or outwardly facing sides of the coil  334 . 
     As shown in  FIG. 38B , the inflatable element or balloon  350  can comprise an annular balloon-like structure having, for example, a generally heart-shaped cross section and comprising a surface or cover  352  defining a cavity  353 . The cavity  353  is in fluid communication with an inflation lumen  354  extending parallel to the drainage lumen  324  defined by the catheter tube  322 . The balloon  350  can be configured to be inserted in the tapered portion of the renal pelvis and inflated such that an outer surface  356  thereof contacts and rests against an inner surface of the ureter and/or renal pelvis. The inflatable element or balloon  350  can comprise a tapered inner surface  358  extending longitudinally and radially inward towards the catheter tube  322 . The inner surface  358  can be configured to direct urine toward the catheter tube  322  to be drawn into the drainage lumen  324 . The inner surface  358  can also be positioned to prevent fluid from pooling in the ureter, such as around the periphery of the inflatable element or balloon  350 . The inflatable retention portion or balloon  350  is desirably sized to fit within the renal pelvis and can have a diameter ranging from about 10 mm to about 30 mm. 
     With reference to  FIGS. 39 and 40 , in some examples, an assembly  400  including a ureteral catheter  412  comprising a retention portion  410  is illustrated. The retention portion  410  is formed from a porous and/or sponge-like material that is attached to a distal end  421  of a catheter tube  422 . The porous material can be configured to channel and/or absorb urine and direct the urine toward a drainage lumen  424  of the catheter tube  422 . As shown in  FIG. 40 , the retention portion  410  can be a porous wedge shaped-structure configured for insertion and retention in the patient&#39;s renal pelvis. The porous material comprises a plurality of holes and/or channels. Fluid can be drawn through the channels and holes, for example, by gravity or upon inducement of negative pressure through the catheter  412 . For example, fluid can enter the wedge-shaped retention portion  410  through the holes and/or channels and is drawn toward a distal opening  420  of the drainage lumen  424 , for example, by capillary action, peristalsis, or as a result of the inducement of negative pressure in the holes and/or channels. In other examples, as shown in  FIG. 40 , the retention portion  410  comprises a hollow, funnel structure formed from the porous sponge-like material. As shown by arrow A, fluid is directed down an inner surface  426  of the funnel structure into the drainage lumen  424  defined by the catheter tube  422 . Also, fluid can enter the funnel structure of the retention portion  410  through holes and channels in the porous sponge-like material of a sidewall  428 . For example, suitable porous materials can include open-celled polyurethane foams, such as polyurethane ether. Suitable porous materials can also include laminates of woven or non-woven layers comprising, for example, polyurethane, silicone, polyvinyl alcohol, cotton, or polyester, with or without antimicrobial additives such as silver, and with or without additives for modifying material properties such as hydrogels, hydrocolloids, acrylic, or silicone. 
     With reference to  FIG. 41 , according to another example, a retention portion  500  of a ureteral catheter  512  comprises an expandable cage  530 . The expandable cage  530  comprises one or more longitudinally and radially extending hollow tubes  522 . For example, the tubes  522  can be formed from an elastic, shape memory material such as nitinol. The cage  530  is configured to transition from a contracted state, for insertion through the patient&#39;s urinary tract, to a deployed state for positioning in the patient&#39;s ureters and/or kidney. The hollow tubes  522  comprise a plurality of drainage ports  534  which can be positioned on the tubes, for example, on radially inward facing sides thereof. The ports  534  are configured to permit fluid to flow or be drawn through the ports  534  and into the respective tubes  522 . The fluid drains through the hollow tubes  522  into a drainage lumen  524  defined by a catheter body  526  of the ureteral catheter  512 . For example, fluid can flow along the path indicated by the arrows  532  in  FIG. 41 . In some examples, when negative pressure is induced in the renal pelvis, kidneys, and/or ureters, portions of the ureter wall and/or renal pelvis may be drawn against the outward facing surfaces of the hollow tubes  522 . The drainage ports  534  are positioned and configured so as not to be appreciably occluded by ureteral structures upon application of negative pressure to the ureters and/or kidney. 
     In some examples, the ureteral catheter comprising a funnel support can be deployed into a patient&#39;s urinary tract, and more specifically in the renal pelvis region/kidney using a conduit through the urethra and into the bladder. The funnel support  6100  is in a collapsed state (shown in  FIG. 36 ) and sheathed in a ureteral sheath  6102 . To deploy the ureteral catheter, the medical professional would insert a cystoscope into the urethra to provide a channel for tools to enter the bladder. The ureteral orifice would be visualized and guide wire would be inserted through the cystoscope and ureter until the tip of the guide wire reaches the renal pelvis. The cystoscope likely would be removed, and a “pusher tube” would be fed over the guide wire up to the renal pelvis. The guidewire would be removed while the “pusher tube” stays in place to act as deployment sheath. The ureteral catheter would be inserted through the pusher tube/sheath and the catheter tip would be actuated once it extends beyond the end of the pusher tube/sheath. The funnel support would expand radially to assume the deployed position. 
     Exemplary Ureteral Stents: 
     Referring now to  FIG. 1 , in some examples, the ureteral stent  52 ,  54  comprises an elongated body comprising a proximal end  62 , a distal end  58 , a longitudinal axis, and at least one drainage channel that extends along the longitudinal axis from the proximal end to the distal end to maintain patency of fluid flow between a kidney and a bladder of the patient. In some examples, the ureteral stent further comprises a pigtail coil or loop(s) on at least one of the proximal end or the distal end. In some examples, the body of the ureteral stent further comprises at least one perforation on a sidewall thereof. In other examples, the body of the ureteral stent is essentially free of or free of perforation(s) on a sidewall thereof. 
     Some examples of ureteral stents  52 ,  54  that can be useful in the present systems and methods include CONTOUR™ ureteral stents, CONTOUR VL™ ureteral stents, POLARIS™ Loop ureteral stents, POLARIS™ Ultra ureteral stents, PERCUFLEX™ ureteral stents, PERCUFLEX™ Plus ureteral stents, STRETCH™ VL Flexima ureteral stents, each of which are commercially available from Boston Scientific Corporation of Natick, Mass. See “Ureteral Stent Portfolio”, a publication of Boston Scientific Corp., (July 2010), hereby incorporated by reference herein. The CONTOUR™ and CONTOUR VL™ ureteral stents are constructed with soft Percuflex™ Material that becomes soft at body temperature and is designed for a 365-day indwelling time. Variable length coils on distal and proximal ends allow for one stent to fit various ureteral lengths. The fixed length stent can be 6 F-8 F with lengths ranging from 20 cm-30 cm, and the variable length stent can be 4.8 F-7 F with lengths of 22-30 cm. Other examples of suitable ureteral stents include INLAY® ureteral stents, INLAY® OPTIMA® ureteral stents, BARDEX® double pigtail ureteral stents, and FLUORO-4™ silicone ureteral stent, each of which are commercially available from C.R. Bard, Inc. of Murray Hill, N.J. See “Ureteral Stents”, http://www.bardmedical.com/products/kidney-stone-management/ureteral-stents/(Jan. 21, 2018), hereby incorporated by reference herein. 
     The stents  52 ,  54  can be deployed in one or both of the patient&#39;s kidneys or kidney area (renal pelvis or ureters adjacent to the renal pelvis), as desired. Typically, these stents are deployed by inserting a stent having a nitinol wire therethrough through the urethra and bladder up to the kidney, then withdrawing the nitinol wire from the stent, which permits the stent to assume a deployed configuration. Many of the above stents have a planar loop  58 ,  60  on the distal end (to be deployed in the kidney), and some also have a planar loop  62 ,  64  on the proximal end of the stent which is deployed in the bladder. When the nitinol wire is removed, the stent assumes the pre-stressed planar loop shape at the distal and/or proximal ends. To remove the stent, a nitinol wire is inserted to straighten the stent and the stent is withdrawn from the ureter and urethra. 
     Other examples of suitable ureteral stents  52 ,  54  are disclosed in PCT Patent Application Publication WO 2017/019974, which is incorporated by reference herein. In some examples, as shown, for example, in FIGS. 1-7 of WO 2017/019974 and in  FIG. 3  herein (same as FIG. 1 of WO 2017/019974), the ureteral stent  100  can comprise: an elongated body  101  comprising a proximal end  102 , a distal end  104 , a longitudinal axis  106 , an outer surface  108 , and an inner surface  110 , wherein the inner surface  110  defines a transformable bore  111  that extends along the longitudinal axis  106  from the proximal end  102  to the distal end  104 ; and at least two fins  112  projecting radially away from the outer surface  108  of the body  101 ; wherein the transformable bore  111  comprises: (a) a default orientation  113 A (shown on the left in  FIG. 59 ) comprising an open bore  114  defining a longitudinally open channel  116 ; and (b) a second orientation  113 B (shown on the right in  FIG. 59 ) comprising an at least essentially closed bore  118  or closed bore defining a longitudinally essentially closed drainage channel  120  along the longitudinal axis  106  of the elongated body  101 , wherein the transformable bore  111  is moveable from the default orientation  113 A to the second orientation  113 B upon radial compression forces  122  being applied to at least a portion of the outer surface  108  of the body  101 . 
     In some examples, as shown in  FIG. 3 , the drainage channel  120  of the ureteral stent  100  has a diameter D which is reduced upon the transformable bore  111  moving from the default orientation  113 A to the second orientation  113 B, wherein the diameter is reducible up to the point above where urine flow through the transformable bore  111  would be reduced. In some examples, the diameter D is reduced by up to about 40% upon the transformable bore  111  moving from the default orientation  113 A to the second orientation  113 B. In some examples, the diameter D in the default orientation  113 A can range from about 0.75 to about 5.5 mm, or about 1.3 mm or about 1.4 mm. In some examples, the diameter D in the second orientation  113 B can range from about 0.4 to about 4 mm, or about 0.9 mm. 
     In some examples, one or more fins  112  comprise a flexible material that is soft to medium soft based on the Shore hardness scale. In some examples, the body  101  comprises a flexible material that is medium hard to hard based on the Shore hardness scale. In some examples, one or more fins have a durometer between about 15 A to about 40 A. In some examples, the body  101  has a durometer between about 80 A to about 90 A. In some examples, one or more fins  112  and the body  101  comprise a flexible material that is medium soft to medium hard based on the Shore hardness scale, for example having a durometer between about 40 A to about 70 A. 
     In some examples, one or more fins  112  and the body  101  comprise a flexible material that is medium hard to hard based on the Shore hardness scale, for example having a durometer between about 85 A to about 90 A. 
     In some examples, the default orientation  113 A and the second orientation  113 B support fluid or urine flow around the outer surface  108  of the stent  100  in addition to through the transformable bore  111 . 
     In some examples, one or more fins  112  extend longitudinally from the proximal end  102  to the distal end  104 . In some examples, the stent has two, three or four fins. 
     In some examples, the outer surface  108  of the body has an outer diameter in the default orientation  113 A ranging from about 0.8 mm to about 6 mm, or about 3 mm. In some examples, the outer surface  108  of the body has an outer diameter in the second orientation  113 B ranging from about 0.5 mm to about 4.5 mm, or about 1 mm. In some examples, one or more fins have a width or tip ranging from about 0.25 mm to about 1.5 mm, or about 1 mm, projecting from the outer surface  108  of the body in a direction generally perpendicular to the longitudinal axis. 
     In some examples, the radial compression forces are provided by at least one of normal ureter physiology, abnormal ureter physiology, or application of any external force. In some examples, the ureteral stent  100  purposefully adapts to a dynamic ureteral environment, the ureteral stent  100  comprising: an elongated body  101  comprising a proximal end  102 , a distal end  104 , a longitudinal axis  106 , an outer surface  108 , and an inner surface  110 , wherein the inner surface  110  defines a transformable bore  111  that extends along the longitudinal axis  106  from the proximal end  102  to the distal end  104 ; wherein the transformable bore  111  comprises: (a) a default orientation  113 A comprising an open bore  114  defining a longitudinally open channel  116 ; and (b) a second orientation  113 B comprising an at least essentially closed bore  118  defining a longitudinally essentially closed channel  120 , wherein the transformable bore is moveable from the default orientation  113 A to the second orientation  113 B upon radial compression forces  122  being applied to at least a portion of the outer surface  108  of the body  101 , wherein the inner surface  110  of the body  101  has a diameter D which is reduced upon the transformable bore  111  moving from the default orientation  113 A to the second orientation  113 B, wherein the diameter is reducible up to the point above where fluid flow through the transformable bore  111  would be reduced. In some examples, the diameter D is reduced by up to about 40% upon the transformable bore  111  moving from the default orientation  113 A to the second orientation  113 B. 
     Other examples of suitable ureteral stents are disclosed in US Patent Application Publication US 2002/0183853 A1, which is incorporated by reference herein. In some examples, as shown, for example, in FIGS. 4, 5 and 7 of US 2002/0183853 A1 and in  FIGS. 4-6  herein (same as FIG. 1 of 4, 5 and 7 of US 2002/0183853 A1), the ureteral stent comprises an elongated, body  10  comprising a proximal end  12 , a distal end  14  (not shown), a longitudinal axis  15 , and at least one drainage channel (for example,  26 ,  28 ,  30  in  FIG. 4 ;  32 ,  34 ,  36  and  38  in  FIG. 5 ; and  48  in  FIG. 6 ) that extends along the longitudinal axis  15  from the proximal end  12  to the distal end  14  to maintain patency of fluid flow between a kidney and a bladder of the patient. In some examples, the at least one drainage channel is partially open along at least a longitudinal portion thereof. In some examples, the at least one drainage channel is closed along at least a longitudinal portion thereof. In some examples, the at least one drainage channel is closed along the longitudinal length thereof. In some examples, the ureteral stent is radially compressible. In some examples, the ureteral stent is radially compressible to narrow the at least one drainage channel. In some examples, the elongated body  10  comprises at least one external fin  40  along the longitudinal axis  15  of the elongated body  10 . In some examples, the elongated body comprises one to four drainage channels. The diameter of the drainage channel can be the same as described above. 
     Systems for Inducing Negative Pressure 
     A system for removing fluid from the urinary tract of a patient is provided, comprising: a ureteral stent or ureteral catheter for maintaining patency of fluid flow between at least one of a kidney and a bladder of the patient; a bladder catheter comprising a drainage lumen for draining fluid from the bladder of the patient; and a pump in fluid communication with a distal end of the drainage lumen, the pump comprising a controller configured to actuate the pump to apply negative pressure to the proximal end of the catheter to induce negative pressure in a portion of the urinary tract of the patient to remove fluid from the urinary tract of the patient. 
     With reference to  FIG. 7 , an exemplary system  1100  for inducing negative pressure in a urinary tract of a patient for increasing renal perfusion is illustrated. The system  1100  comprises one or two ureteral catheters  1212  (or alternatively ureteral stents shown in  FIG. 1 ) connected to a fluid pump  2000  for generating the negative pressure. More specifically, the patient&#39;s urinary tract comprises the patient&#39;s right kidney  2  and left kidney  4 . The kidneys  2 ,  4  are responsible for blood filtration and clearance of waste compounds from the body through urine. Urine produced by the right kidney  2  and the left kidney  4  is drained into a patient&#39;s bladder  10  through tubules, namely a right ureter  6  and a left ureter  8 , which are connected to the kidneys at the renal pelvis  20 ,  21 . Urine may be conducted through the ureters  6 ,  8  by peristalsis of the ureter walls, as well as by gravity. The ureters  6 ,  8  enter the bladder  10  through a ureter orifice or opening  16 . The bladder  10  is a flexible and substantially hollow structure adapted to collect urine until the urine is excreted from the body. The bladder  10  is transitionable from an empty position (signified by reference line E) to a full position (signified by reference line F). Normally, when the bladder  10  reaches a substantially full state, fluid or urine is permitted to drain from the bladder  10  to a urethra  12  through a urethral sphincter or opening  18  located at a lower portion of the bladder  10 . Contraction of the bladder  10  can be responsive to stresses and pressure exerted on a trigone region  14  of the bladder  10 , which is the triangular region extending between the ureteral openings  16  and the urethral opening  18 . The trigone region  14  is sensitive to stress and pressure, such that as the bladder  10  begins to fill, pressure on the trigone region  14  increases. When a threshold pressure on the trigone region  14  is exceeded, the bladder  10  begins to contract to expel collected urine through the urethra  12 . 
     As shown in  FIGS. 7 and 7A , distal portions of the ureteral catheter(s) are deployed in the renal pelvis  20 ,  21  near the kidneys  2 ,  4 . Proximal portions of the one or more of the catheter(s)  1212  empty into the bladder. A proximal portion of the bladder catheter is connected to a source of negative pressure, such as a fluid pump  2000 . The shape and size of the connector can be selected based on the type of pump  2000  being used. In some examples, the connector can be manufactured with a distinctive configuration so that it can only be connected to a particular pump type, which is deemed to be safe for inducing negative pressure in a patient&#39;s bladder, ureter, or kidneys. In other examples, as described herein, the connector can be a more generic configuration adapted for attachment to a variety of different types of fluid pumps. System  1100  is but one example of a negative pressure system for inducing negative pressure that can be used with the bladder catheters disclosed herein. 
     Referring now to  FIGS. 1, 2, 7, 7A, 17 , in some examples the system  100  comprises a bladder catheter  116 . The distal ends  120 ,  121  of the ureteral catheters  112 ,  114  can drain directly into the bladder, and the fluid can drain through the bladder catheter  116 , and optionally along the sides of the bladder catheter tube. 
     Exemplary Bladder Catheters 
     Any of the ureteral catheters disclosed herein can be used as bladder catheters useful in the present methods and systems. In some examples, the bladder catheter  116  comprises a deployable seal and/or anchor  136  for anchoring, retaining, and/or providing passive fixation for indwelling portions of the urine collection assembly  100  and, in some examples, to prevent premature and/or untended removal of assembly components during use. The anchor  136  is configured to be located adjacent to the lower wall of the patient&#39;s bladder  10  (shown in  FIGS. 1 ,  2 ,  7 ,  7 A,  17 ) to prevent patient motion and/or forces applied to indwelling catheters  112 ,  114 ,  116  from translating to the ureters. The bladder catheter  116  comprises an interior of which defines a drainage lumen  140  configured to conduct urine from the bladder  10  to an external urine collection container  712  (shown in  FIG. 44 ). In some examples, the bladder catheter  116  tube size can range from about 8 Fr to about 24 Fr. In some examples, the bladder catheter  116  can have an external tube diameter ranging from about 2.7 to about 8 mm. In some examples, the bladder catheter  116  can have an internal diameter ranging from about 2.16 to about 10 mm. The bladder catheter  116  can be available in different lengths to accommodate anatomical differences for gender and/or patient size. For example, the average female urethra length is only a few inches, so the length of a tube  138  can be rather short. The average urethra length for males is longer due to the penis and can be variable. It is possible that woman can use bladder catheters  116  with longer length tubes  138  provided that the excess tubing does not increase difficulty in manipulating and/or preventing contamination of sterile portions of the catheter  116 . In some examples, a sterile and indwelling portion of the bladder catheter  116  can range from about 1 inch to 3 inches (for women) to about 20 inches for men. The total length of the bladder catheter  116  including sterile and non-sterile portions can be from one to several feet. 
     The catheter tube  138  can comprise one or more drainage ports  142  configured to be positioned in the bladder  10  for drawing urine into the drainage lumen  140 . For example, fluid or urine that flows into the patient&#39;s bladder  10  from the ureteral catheters  112 ,  114  is expelled from the bladder  10  through the ports  142  and drainage lumen  140 . The drainage lumen  140  may be pressurized to a negative pressure to assist in fluid collection. 
     With specific reference to  FIG. 2 , the deployable seal and/or anchor  136  is disposed at or adjacent to a distal end  148  of the bladder catheter  116 . The deployable anchor  136  is configured to transition between a contracted state for insertion into the bladder  10  through the urethra  12  and urethral opening  18  and a deployed state. The anchor  136  is configured to be deployed in and seated adjacent to a lower portion of the bladder  10  and/or against the urethral opening  18 . For example, the anchor  136  can be positioned adjacent to the urethral opening  18  to enhance suction of a negative pressure applied to the bladder  10  or to partially, substantially, or entirely seal the bladder  10  to ensure that urine in the bladder  10  is directed through the drainage lumen  140  and to prevent leakage to the urethra  12 . For a bladder catheter  116  including an 8 Fr to 24 Fr elongated tube  138 , the anchor  136  can have a diameter of about 10 mm to about 100 mm) in the deployed state. 
     Exemplary Bladder Anchor Structures 
     Any of the ureteral catheters disclosed herein can be used as bladder catheters useful in the present methods and systems. For example, the bladder catheter can comprise a mesh as a bladder anchor, such as is shown in  FIGS. 1 and 2 . In another example, the bladder catheter  116  can comprise a coil as a bladder anchor, such as is shown in  FIG. 7 . In another example, the bladder catheter  116  can comprise a mesh funnel as a bladder anchor, such as is shown in  FIG. 7A . In another example, the bladder catheter  116  can comprise a funnel as a bladder anchor, such as is shown in  FIG. 17 . 
     With reference to  FIG. 41 , in another example of a bladder catheter, an expandable cage can anchor the bladder catheter in the bladder. The expandable cage comprises a plurality of flexible members or tines extending longitudinally and radially outward from a catheter body of a bladder catheter which, in some examples, can be similar to those discussed above with respect to the retention portion of the ureteral catheter of  FIG. 41 . The members can be formed from a suitable elastic and shape memory material such as nitinol. In a deployed position, the members or tines are imparted with a sufficient curvature to define a spherical or ellipsoid central cavity. The cage is attached to an open distal open end of the catheter tube or body, to allow access to a drainage lumen defined by the tube or body. The cage is sized for positioning within the lower portion of the bladder and can define a diameter and length ranging from 1.0 cm to 2.3 cm, and preferably about 1.9 cm (0.75 in). 
     In some examples, the cage further comprises a shield or cover over distal portions of the cage to prevent or reduce the likelihood that tissue, namely, the distal wall of the bladder, will be caught or pinched as a result of contact with the cage or member. More specifically, as the bladder contracts, the inner distal wall of the bladder comes into contact with the distal side of the cage. The cover prevents the tissue from being pinched or caught, may reduce patient discomfort, and protect the device during use. The cover can be formed at least in part from a porous and/or permeable biocompatible material, such as a woven polymer mesh. In some examples, the cover encloses all or substantially all of the cavity. In some examples, the cover covers only about the distal ⅔, about the distal half, or about the distal third portion or any amount, of the cage  210 . 
     The cage and cover are transitionable from a contracted position, in which the members are contracted tightly together around a central portion and/or around the bladder catheter  116  to permit insertion through a catheter or sheath to the deployed position. For example, in the case of a cage constructed from a shape memory material, the cage can be configured to transition to the deployed position when it is warmed to a sufficient temperature, such as body temperature (e.g., 37° C.). In the deployed position, the cage has a diameter D that is preferably wider than the urethral opening, and prevents patient motion from translating through the ureteral catheters  112 ,  114  to the ureters. The open arrangement of the members  212  or tines does not obstruct or occlude the distal opening  248  and/or drainage ports of the bladder catheter  216 , making manipulation of the catheters  112 ,  114  easier to perform. 
     The bladder catheter is connected to the vacuum source, such as pump assembly  710  by, for example, flexible tubing  166  defining a fluid flow path. 
     Exemplary Fluid Sensors: 
     With reference again to  FIG. 1 , in some examples, the assembly  100  further comprises sensors  174  for monitoring physical parameters or fluid characteristics of fluid or urine being collected from the ureters  6 ,  8  and/or bladder  10 . As discussed herein in connection with  FIG. 44 , information obtained from the sensors  174  can be transmitted to a central data collection module or processor and used, for example, to control operation of an external device, such as the pump  710  (shown in  FIG. 44 ). The sensors  174  can be integrally formed with one or more of the catheters  112 ,  114 ,  116  such as, for example, embedded in a wall of the catheter body or tube and in fluid communication with drainage lumens  124 ,  140 . In other examples, one or more of the sensors  174  can be positioned in a fluid collection container  712  (shown in  FIG. 44 ) or in internal circuitry of an external device, such as the pump  710 . 
     Exemplary sensors  174  that can be used with the urine collection assembly  100  can comprise one or more of the following sensor types. For example, the catheter assembly  100  can comprise a conductance sensor or electrode that samples conductivity of urine. The normal conductance of human urine is about 5-10 mS/m. Urine having a conductance outside of the expected range can indicate that the patient is experiencing a physiological problem, which requires further treatment or analysis. The catheter assembly  100  can also comprise a flow meter for measuring a flow rate of urine through the catheter(s)  112 ,  114 ,  116 . Flow rate can be used to determine a total volume of fluid excreted from the body. The catheter(s)  112 ,  114 ,  116  can also comprise a thermometer for measuring urine temperature. Urine temperature can be used to collaborate the conductance sensor. Urine temperature can also be used for monitoring purposes, as urine temperature outside of a physiologically normal range can be indicative of certain physiological conditions. In some examples, the sensors  174  can be urine analyte sensors configured to measure a concentration of creatinine and/or proteins in urine. For example, various conductivity sensors and optical spectrometry sensors may be used for determining analyte concentration in urine. Sensors based on color change reagent test strips may also be used for this purpose. 
     Method of Insertion of a System: 
     Having described the system  100  comprising the ureteral catheter(s) and/or ureteral stent(s) and bladder catheter, some examples of methods for insertion and deployment of the ureteral stent(s) or ureteral catheter(s) and bladder catheter will now be discussed in detail. 
     With reference to  FIG. 42A , an example of steps for positioning a system in a patient&#39;s body and, optionally, for inducing negative pressure in a patient&#39;s urinary tract, such as bladder, ureter and/or kidney&#39;s are illustrated. As shown at box  610 , a medical professional or caregiver inserts a flexible or rigid cystoscope through the patient&#39;s urethra and into the bladder to obtain visualization of the ureteral orifices or openings. Once suitable visualization is obtained, as shown at box  612 , a guidewire is advanced through the urethra, bladder, ureteral opening, ureter, and to a desired fluid collection position, such as the renal pelvis of the kidney. Once the guidewire is advanced to the desired fluid collection position, a ureteral stent or ureteral catheter of the present invention (examples of which are discussed in detail above) is inserted over the guidewire to the fluid collection position, as shown at box  614 . In some examples, the location of the ureteral stent or ureteral catheter can be confirmed by fluoroscopy, as shown at box  616 . Once the position of the distal end of the ureteral stent or ureteral catheter is confirmed, as shown at box  618 , the retention portion of the ureteral catheter can be deployed. For example, the guidewire can be removed from the catheter, thereby allowing the distal end and/or retention portion to transition to a deployed position. In some examples, the deployed distal end portion of the catheter does not entirely occlude the ureter and/or renal pelvis, such that urine is permitted to pass outside the catheter and through the ureters into the bladder. Since moving the catheter can exert forces against urinary tract tissues, avoiding complete blockage of the ureters avoids application of force to the ureter sidewalls, which may cause injury. 
     After the ureteral stent or ureteral catheter is in place and deployed, the same guidewire can be used to position a second ureteral stent or second ureteral catheter in the other ureter and/or kidney using the same insertion and positioning methods described herein. For example, the cystoscope can be used to obtain visualization of the other ureteral opening in the bladder, and the guidewire can be advanced through the visualized ureteral opening to a fluid collection position in the other ureter. A second ureteral stent or second ureteral catheter can be drawn alongside the guidewire and deployed in the manner described herein. Alternatively, the cystoscope and guidewire can be removed from the body. The cystoscope can be reinserted into the bladder over the first ureteral catheter. The cystoscope is used, in the manner described above, to obtain visualization of the ureteral opening and to assist in advancing a second guidewire to the second ureter and/or kidney for positioning of the second ureteral stent or second ureteral catheter. Once the ureteral stents or catheters are in place, in some examples, the guidewire and cystoscope are removed. In other examples, the cystoscope and/or guidewire can remain in the bladder to assist with placement of the bladder catheter. 
     Once the ureteral catheters are in place, as shown at box  620 , the medical professional, caregiver or patient can insert a distal end of a bladder catheter in a collapsed or contracted state through the urethra of the patient and into the bladder. The bladder catheter can be a bladder catheter of the present invention as discussed in detail above. Once inserted in the bladder, as shown at box  622 , an anchor connected to and/or associated with the bladder catheter is expanded to a deployed position. In some examples, the bladder catheter is inserted through the urethra and into the bladder without using a guidewire and/or cystoscope. In other examples, the bladder catheter is inserted over the same guidewire used to position the ureteral stents or catheters. 
     In some examples, the ureteral stent or ureteral catheter is deployed and remains in the patient&#39;s body for at least 24 hours or longer. In some examples, the ureteral stent or ureteral catheter is deployed and remains in the patient&#39;s body for at least 30 days or longer. In some examples, the ureteral stent(s) or ureteral catheter(s) can be replaced periodically, for example every week or every month, to extend the length of therapy. 
     In some examples, the bladder catheter is replaced more often that the ureteral stent or ureteral catheter. In some examples, multiple bladder catheters are placed and removed sequentially during the indwell time for a single ureteral stent or ureteral catheter. For example, a physician, nurse, caregiver or patient can place the bladder catheter(s) in the patient at home or in any healthcare setting. Multiple bladder catheters can be provided to the healthcare professional, patient or caregiver in a kit, optionally with instructions for placement, replacement and optional connection of the bladder catheter(s) to the negative pressure source or drainage to a container, as needed. In some examples, negative pressure is applied each evening for a predetermined number of evenings (such as for 1 to 30 evenings or more). Optionally, the bladder catheter can be replaced each evening before application of negative pressure. 
     In some examples, the urine is permitted to drain by gravity or peristalsis from the urethra. In other examples, a negative pressure is induced in the bladder catheter to facilitate drainage of the urine. While not intending to be bound by any theory, it is believed that a portion of the negative pressure applied to the proximal end of the bladder catheter is transmitted to the ureter(s), renal pelvis or other portions of the kidney(s) to facilitate drainage of the fluid or urine from the kidney. 
     With reference to  FIG. 42B , steps for using the system for inducement of negative pressure in the ureter(s) and/or kidney(s) are illustrated. As shown at box  624 , after the indwelling portions of the ureteral stents or ureteral catheters and bladder catheters are correctly positioned and any anchoring/retention structures, if present, are deployed, the external proximal end of the bladder catheter is connected to a fluid collection or pump assembly. For example, the bladder catheter can be connected to a pump for inducing negative pressure at the patient&#39;s bladder, renal pelvis and/or kidney. 
     Once the bladder catheter and pump assembly are connected, negative pressure is applied to the renal pelvis and/or kidney and/or bladder through the drainage lumen of the bladder catheter, as shown at box  626 . The negative pressure is intended to counter congestion mediated interstitial hydrostatic pressures due to elevated intra-abdominal pressure and consequential or elevated renal venous pressure or renal lymphatic pressure. The applied negative pressure is therefore capable of increasing flow of filtrate through the medullary tubules and of decreasing water and sodium re-absorption. 
     As a result of the applied negative pressure, as shown at box  628 , urine is drawn into the bladder catheter at the drainage port(s) at the distal end thereof, through the drainage lumen of the bladder catheter, and to a fluid collection container for disposal. As the urine is being drawn to the collection container, at box  630 , optional sensors disposed in the fluid collection system can provide a number of measurements about the urine that can be used to assess physical parameters, such as the volume of urine collected, as well as information about the physical condition of the patient and composition of the urine produced. In some examples, the information obtained by the sensors is processed, as shown at box  632 , by a processor associated with the pump and/or with another patient monitoring device and, at box  634 , is displayed to the user via a visual display of an associated feedback device. 
     Exemplary Fluid Collection System: 
     Having described an exemplary system and method of positioning such a system in the patient&#39;s body, with reference to  FIG. 44 , a system  700  for inducing negative pressure to a patient&#39;s bladder, ureter(s), renal pelvis and/or kidney(s) will now be described. The system  700  can comprise the ureteral stent(s) and/or ureteral catheter(s), bladder catheter or the system  100  described hereinabove. As shown in  FIG. 44 , the bladder catheter  116  of the system  100  is connected to one or more fluid collection containers  712  for collecting urine drawn from the bladder. The fluid collection container  712  connected to the bladder catheter  116  can be in fluid communication with an external fluid pump  710  for generating negative pressure in the bladder, ureter(s) and/or kidney(s) through the bladder catheter  116  and/or ureteral catheter(s)  112 ,  114 . As discussed herein, such negative pressure can be provided for overcoming interstitial pressure and forming urine in the kidney or nephron. In some examples, a connection between the fluid collection container  712  and pump  710  can comprise a fluid lock or fluid barrier to prevent air from entering the bladder, renal pelvis or kidney in case of incidental therapeutic or non-therapeutic pressure changes. For example, inflow and outflow ports of the fluid container can be positioned below a fluid level in the container. Accordingly, air is prevented from entering medical tubing or the catheter through either the inflow or outflow ports of the fluid container  712 . As discussed previously, external portions of the tubing extending between the fluid collection container  712  and the pump  710  can include one or more filters to prevent urine and/or particulates from entering the pump  710 . 
     As shown in  FIG. 44 , the system  700  further comprises a controller  714 , such as a microprocessor, electronically coupled to the pump  710  and having or associated with computer readable memory  716 . In some examples, the memory  716  comprises instructions that, when executed, cause the controller  714  to receive information from sensors  174  located on or associated with portions of the assembly  100 . Information about a condition of the patient can be determined based on information from the sensors  174 . Information from the sensors  174  can also be used to determine and implement operating parameters for the pump  710 . 
     In some examples, the controller  714  is incorporated in a separate and remote electronic device in communication with the pump  710 , such as a dedicated electronic device, computer, tablet PC, or smart phone. Alternatively, the controller  714  can be included in the pump  710  and, for example, can control both a user interface for manually operating the pump  710 , as well as system functions such as receiving and processing information from the sensors  174 . 
     The controller  714  is configured to receive information from the one or more sensors  174  and to store the information in the associated computer-readable memory  716 . For example, the controller  714  can be configured to receive information from the sensor  174  at a predetermined rate, such as once every second, and to determine a conductance based on the received information. In some examples, the algorithm for calculating conductance can also include other sensor measurements, such as urine temperature, to obtain a more robust determination of conductance. 
     The controller  714  can also be configured to calculate patient physical statistics or diagnostic indicators that illustrate changes in the patient&#39;s condition over time. For example, the system  700  can be configured to identify an amount of total sodium excreted. The total sodium excreted may be based, for example, on a combination of flow rate and conductance over a period of time. 
     With continued reference to  FIG. 19 , the system  700  can further comprise a feedback device  720 , such as a visual display or audio system, for providing information to the user. In some examples, the feedback device  720  can be integrally formed with the pump  710 . Alternatively, the feedback device  720  can be a separate dedicated or a multipurpose electronic device, such as a computer, laptop computer, tablet PC, smart phone, or other handheld electronic devices. The feedback device  720  is configured to receive the calculated or determined measurements from the controller  714  and to present the received information to a user via the feedback device  720 . For example, the feedback device  720  may be configured to display current negative pressure (in mmHg) being applied to the urinary tract. In other examples, the feedback device  720  is configured to display current flow rate of urine, temperature, current conductance in mS/m of urine, total urine produced during the session, total sodium excreted during the session, other physical parameters, or any combination thereof. 
     In some examples, the feedback device  720  further comprises a user interface module or component that allows the user to control operation of the pump  710 . For example, the user can engage or turn off the pump  710  via the user interface. The user can also adjust pressure applied by the pump  710  to achieve a greater magnitude or rate of sodium excretion and fluid removal. 
     Optionally, the feedback device  720  and/or pump  710  further comprise a data transmitter  722  for sending information from the device  720  and/or pump  710  to other electronic devices or computer networks. The data transmitter  722  can utilize a short-range or long-range data communications protocol. An example of a short-range data transmission protocol is Bluetooth®. Long-range data transmission networks include, for example, Wi-Fi or cellular networks. The data transmitter  722  can send information to a patient&#39;s physician or caregiver to inform the physician or caregiver about the patient&#39;s current condition. Alternatively, or in addition, information can be sent from the data transmitter  722  to existing databases or information storage locations, such as, for example, to include the recorded information in a patient&#39;s electronic health record (EHR). 
     With continued reference to  FIG. 44 , in addition to the urine sensors  174 , in some examples, the system  700  can further comprise one or more patient monitoring sensors  724 . Patient monitoring sensors  724  can include invasive and non-invasive sensors for measuring information about the patient&#39;s physical parameters, such as urine composition, as discussed in detail above, blood composition (e.g., hematocrit ratio, analyte concentration, protein concentration, creatinine concentration) and/or blood flow (e.g., blood pressure, blood flow velocity). Hematocrit is a ratio of the volume of red blood cells to the total volume of blood. Normal hematocrit is about 25% to 40%, and preferably about 35% and 40% (e.g., 35% to 40% red blood cells by volume and 60% to 65% plasma). 
     Non-invasive patient monitoring sensors  724  can include pulse oximetry sensors, blood pressure sensors, heart rate sensors, and respiration sensors (e.g., a capnography sensor). Invasive patient monitoring sensors  724  can include invasive blood pressure sensors, glucose sensors, blood velocity sensors, hemoglobin sensors, hematocrit sensors, protein sensors, creatinine sensors, and others. In still other examples, sensors may be associated with an extracorporeal blood system or circuit and configured to measure parameters of blood passing through tubing of the extracorporeal system. For example, analyte sensors, such as capacitance sensors or optical spectroscopy sensors, may be associated with tubing of the extracorporeal blood system to measure parameter values of the patient&#39;s blood as it passes through the tubing. The patient monitoring sensors  724  can be in wired or wireless communication with the pump  710  and/or controller  714 . 
     In some examples, the controller  714  is configured to cause the pump  710  to provide treatment for a patient based information obtained from the urine analyte sensor  174  and/or patient monitoring sensors  724 , such as blood monitoring sensors. For example, pump  710  operating parameters can be adjusted based on changes in the patient&#39;s blood hematocrit ratio, blood protein concertation, creatinine concentration, urine output volume, urine protein concentration (e.g., albumin), and other parameters. For example, the controller  714  can be configured to receive information about a blood hematocrit ratio or creatinine concentration of the patient from the patient monitoring sensors  724  and/or analyte sensors  174 . The controller  714  can be configured to adjust operating parameters of the pump  710  based on the blood and/or urine measurements. In other examples, hematocrit ratio may be measured from blood samples periodically obtained from the patient. Results of the tests can be manually or automatically provided to the controller  714  for processing and analysis. 
     As discussed herein, measured hematocrit values for the patient can be compared to predetermined threshold or clinically acceptable values for the general population. Generally, hematocrit levels for females are lower than for males. In other examples, measured hematocrit values can be compared to patient baseline values obtained prior to a surgical procedure. When the measured hematocrit value is increased to within the acceptable range, the pump  710  may be turned off ceasing application of negative pressure to the ureter or kidneys. In a similar manner, the intensity of negative pressure can be adjusted based on measured parameter values. For example, as the patient&#39;s measured parameters begin to approach the acceptable range, intensity of negative pressure being applied to the ureter and kidneys can be reduced. In contrast, if an undesirable trend (e.g., a decrease in hematocrit value, urine output rate, and/or creatinine clearance) is identified, the intensity of negative pressure can be increased in order to produce a positive physiological result. For example, the pump  710  may be configured to begin by providing a low level of negative pressure (e.g., between about 0.1 mmHg and 10 mmHg). The negative pressure may be incrementally increased until a positive trend in patient creatinine level is observed. However, generally, negative pressure provided by the pump  710  will not exceed about 50 mmHg. 
     With reference to  FIGS. 45A and 45B , an exemplary pump  710  for use with the system is illustrated. In some examples, the pump  710  is a micro-pump configured to draw fluid from the catheter(s)  112 ,  114  (shown, for example, in  FIG. 1 ) and having a sensitivity or accuracy of about 10 mmHg or less. Desirably, the pump  710  is capable of providing a range of flow of urine between 0.05 ml/min and 3 ml/min for extended periods of time, for example, for about 8 hours to about 24 hours per day, for one (1) to about 30 days or longer. At 0.2 ml/min, it is anticipated that about 300 mL of urine per day is collected by the system  700 . The pump  710  can be configured to provide a negative pressure to the bladder of the patient, the negative pressure ranging from about 0.1 mmHg and about 150 mmHg, or about 0.1 mmHg to about 50 mmHg, or about 5 mmHg to about 20 mmHg (gauge pressure at the pump  710 ). For example, a micro-pump manufactured by Langer Inc. (Model BT100-2J) can be used with the presently disclosed system  700 . Diaphragm aspirator pumps, as well as other types of commercially available pumps, can also be used for this purpose. Peristaltic pumps can also be used with the system  700 . In other examples, a piston pump, vacuum bottle, or manual vacuum source can be used for providing negative pressure. In other examples, the system can be connected to a wall suction source, as is available in a hospital, through a vacuum regulator for reducing negative pressure to therapeutically appropriate levels. 
     In some examples, at least a portion of the pump assembly can be positioned within the patient&#39;s urinary tract, for example within the bladder. For example, the pump assembly can comprise a pump module and a control module coupled to the pump module, the control module being configured to direct motion of the pump module. At least one (one or more) of the pump module, the control module, or the power supply may be positioned within the patient&#39;s urinary tract. The pump module can comprise at least one pump element positioned within the fluid flow channel to draw fluid through the channel. Some examples of suitable pump assemblies, systems and methods of use are disclosed in U.S. Patent Application No. 62/550,259, entitled “Indwelling Pump for Facilitating Removal of Urine from the Urinary Tract”, filed on Aug. 25, 2017, which is incorporated by reference herein in its entirety. 
     In some examples, the pump  710  is configured for extended use and, thus, is capable of maintaining precise suction for extended periods of time, for example, for about 8 hours to about 24 hours per day, or for 1 to about 30 days or longer, except for replacement time of bladder catheters. Further, in some examples, the pump  710  is configured to be manually operated and, in that case, includes a control panel  718  that allows a user to set a desired suction value. The pump  710  can also include a controller or processor, which can be the same controller that operates the system  700  or can be a separate processor dedicated for operation of the pump  710 . In either case, the processor is configured for both receiving instructions for manual operation of the pump and for automatically operating the pump  710  according to predetermined operating parameters. Alternatively, or in addition, operation of the pump  710  can be controlled by the processor based on feedback received from the plurality of sensors associated with the catheter. 
     In some examples, the processor is configured to cause the pump  710  to operate intermittently. For example, the pump  710  may be configured to emit pulses of negative pressure followed by periods in which no negative pressure is provided. In other examples, the pump  710  can be configured to alternate between providing negative pressure and positive pressure to produce an alternating flush and pump effect. For example, a positive pressure of about 0.1 mmHg to 20 mmHg, and preferably about 5 mmHg to 20 mmHg can be provided followed by a negative pressure ranging from about 0.1 mmHg to 50 mmHg. 
     Steps for removing excess fluid from a patient using the devices and systems described herein are illustrated in  FIG. 49 . As shown in  FIG. 49 , the treatment method comprises deploying a ureteral stent or a urinary tract catheter, such as a ureteral catheter, in the ureter and/or kidney of a patient such that flow of urine from the ureter and/or kidney, as shown at box  910 . The catheter may be placed to avoid occluding the ureter and/or kidney. In some examples, a fluid collecting portion of the stent or catheter may be positioned in the renal pelvis of the patient&#39;s kidney. In some examples, a ureteral stent or ureteral catheter may be positioned in each of the patient&#39;s kidneys. In other examples, a urine collection catheter may be deployed in the bladder or ureter, as shown in box  911 . In some examples, the ureteral catheter comprises one or more of any of the retention portions described herein. For example, the ureteral catheter can comprise a tube defining a drainage lumen comprising a helical retention portion and a plurality of drainage ports. In other examples, the catheter can include a funnel-shaped fluid collection and retention portion or a pigtail coil. Alternatively, a ureteral stent, having, for example, a pigtail coil, can be deployed. 
     As shown at box  912 , the method further comprises applying negative pressure to at least one of the bladder, the ureter and/or kidney through the bladder catheter to induce or facilitate production of fluid or urine in the kidney(s) and to extract the fluid or urine from the patient. Desirably, negative pressure is applied for a period of time sufficient to reduce the patient&#39;s blood creatinine levels by a clinically significant amount. 
     Negative pressure may continue to be applied for a predetermined period of time. For example, a user may be instructed to operate the pump for the duration of a surgical procedure or for a time period selected based on physiological characteristics of the patient. In other examples, patient condition may be monitored to determine when sufficient treatment has been provided. For example, as shown at box  914 , the method may further comprise monitoring the patient to determine when to cease applying negative pressure to the patient&#39;s bladder, ureter and/or kidneys. In some examples, a patient&#39;s hematocrit level is measured. For example, patient monitoring devices may be used to periodically obtain hematocrit values. In other examples, blood samples may be drawn periodically to directly measure hematocrit. In some examples, concentration and/or volume of urine expelled from the body through the bladder catheter may also be monitored to determine a rate at which urine is being produced by the kidneys. In a similar manner, expelled urine output may be monitored to determine protein concentration and/or creatinine clearance rate for the patient. Reduced creatinine and protein concentration in urine may be indicative of over-dilution and/or depressed renal function. Measured values can be compared to the predetermined threshold values to assess whether negative pressure therapy is improving patient condition, and should be modified or discontinued. For example, as discussed herein, a desirable range for patient hematocrit may be between 25% and 40%. In other examples, as described herein, patient body weight may be measured and compared to a dry body weight. Changes in measured patient body weight demonstrate that fluid is being removed from the body. As such, a return to dry body weight represents that hemodilution has been appropriately managed and the patient is not over-diluted. 
     As shown at box  916 , a user may cause the pump to cease providing negative pressure therapy when a positive result is identified. In a similar manner, patient blood parameters may be monitored to assess effectiveness of the negative pressure being applied to the patient&#39;s kidneys. For example, a capacitance or analyte sensor may be placed in fluid communication with tubing of an extracorporeal blood management system. The sensor may be used to measure information representative of blood protein, oxygen, creatinine, and/or hematocrit levels. Measured blood parameter values may be measured continuously or periodically and compared to various threshold or clinically acceptable values. Negative pressure may continue to be applied to the patient&#39;s bladder, kidney or ureter until a measured parameter value falls within a clinically acceptable range. Once a measured values fails within the threshold or clinically acceptable range, as shown at box  916 , application of negative pressure may cease. 
     In some examples, there is provided a method of removing excess fluid from a patient for systemic fluid volume management associated with chronic edematous, hypertension, chronic kidney disease and/or acute heart failure. According to another aspect of the disclosure, a method for removing excess fluid for a patient undergoing a fluid resuscitation procedure, such as coronary graft bypass surgery, by removing excess fluid from the patient is provided. During fluid resuscitation, solutions such as saline solutions and/or starch solutions, are introduced to the patient&#39;s bloodstream by a suitable fluid delivery process, such as an intravenous drip. For example, in some surgical procedures, a patient may be supplied with between 5 and 10 times a normal daily intake of fluid. Fluid replacement or fluid resuscitation can be provided to replace bodily fluids lost through sweating, bleeding, dehydration, and similar processes. In the case of a surgical procedure such as coronary graft bypass, fluid resuscitation is provided to help maintain a patient&#39;s fluid balance and blood pressure within an appropriate rate. Acute kidney injury (AKI) is a known complication of coronary artery graft bypass surgery. AKI is associated with a prolonged hospital stay and increased morbidity and mortality, even for patients who do not progress to renal failure. See Kim, et al.,  Relationship between a perioperative intravenous fluid administration strategy and acute kidney injury following off - pump coronary artery bypass surgery: an observational study, Critical Care  19:350 (1995). Introducing fluid to blood also reduces hematocrit levels which has been shown to further increase mortality and morbidity. Research has also demonstrated that introducing saline solution to a patient may depress renal functional and/or inhibit natural fluid management processes. As such, appropriate monitoring and control of renal function may produce improved outcomes and, in particular, may reduce post-operative instances of AKI. 
     A method of treating a patient for removing excess fluid is illustrated in  FIG. 50 . As shown at box  1010 , the method comprises deploying a ureteral stent or ureteral catheter in the ureter and/or kidney of a patient such that flow of urine from the ureter and/or kidney is not prevented by occlusion of the ureter and/or kidney. For example, a distal end of the ureteral stent or fluid collecting portion of the catheter may be positioned in the renal pelvis. In other examples, the catheter may be deployed in the kidney or ureter. The catheter can comprise one or more of the ureter catheters described herein. For example, the catheter can comprise a tube defining a drainage lumen and comprising a helical retention portion and a plurality of drainage ports. In other examples, the catheter can include a pigtail coil. 
     As shown at box  1012 , a bladder catheter can be deployed in the patient&#39;s bladder. For example, the bladder catheter may be positioned to at least partially seal the urethra opening to prevent passage of urine from the body through the urethra. The bladder catheter can, for example, include an anchor for maintaining the distal end of the catheter in the bladder. As described herein, other arrangements of coils and helices, funnel, etc. may be used to obtain proper positioning of the bladder catheter. The bladder catheter can be configured to collect fluid which entered the patient&#39;s bladder prior to placement of the ureteral catheter(s), as well as fluid collected from the ureters, ureteral stents, and/or ureteral catheters during treatment. The bladder catheter may also collect urine which flows past the fluid collection portion(s) of the ureteral catheter and enters the bladder. In some examples, a proximal portion of the ureteral catheter may be positioned in a drainage lumen of the bladder catheter. In a similar manner, the bladder catheter may be advanced into the bladder using the same guidewire used for positioning of the ureteral catheter(s). In some examples, negative pressure may be provided to the bladder through the drainage lumen of the bladder catheter. In other examples, negative pressure may only be applied to the bladder catheter(s). In that case, the ureteral catheter drains into the bladder by gravity. 
     As shown at box  1014 , following deployment of the ureteral stents and/or ureteral catheter(s) and the bladder catheter, negative pressure is applied to the bladder, ureter and/or kidney through the bladder catheter. For example, negative pressure can be applied for a period of time sufficient to extract urine comprising a portion of the fluid provided to the patient during the fluid resuscitation procedure. As described herein, negative pressure can be provided by an external pump connected to a proximal end or port of the bladder catheter. The pump can be operated continually or periodically dependent on therapeutic requirements of the patient. In some cases, the pump may alternate between applying negative pressure and positive pressure. 
     Negative pressure may continue to be applied for a predetermined period of time. For example, a user may be instructed to operate the pump for the duration of a surgical procedure or for a time period selected based on physiological characteristics of the patient. In other examples, patient condition may be monitored to determine when a sufficient amount of fluid has been drawn from the patient. For example, as shown at box  1016 , fluid expelled from the body may be collected and a total volume of obtained fluid may be monitored. In that case, the pump can continue to operate until a predetermined fluid volume has been collected from the ureteral and/or bladder catheters. The predetermined fluid volume may be based, for example, on a volume of fluid provided to the patient prior to and during the surgical procedure. As shown at box  1018 , application of negative pressure to the bladder, ureter and/or kidneys is stopped when the collected total volume of fluid exceeds the predetermined fluid volume. 
     In other examples, operation of the pump can be determined based on measured physiological parameters of the patient, such as measured creatinine clearance, blood creatinine level, or hematocrit ratio. For example, as shown at box  1020 , urine collected form the patient may be analyzed by one or more sensors associated with the catheter and/or pump. The sensor can be a capacitance sensor, analyte sensor, optical sensor, or similar device configured to measure urine analyte concentration. In a similar manner, as shown at box  1022 , a patient&#39;s blood creatinine or hematocrit level could be analyzed based on information obtain from the patient monitoring sensors discussed hereinabove. For example, a capacitance sensor may be placed in an existing extracorporeal blood system. Information obtained by the capacitance sensor may be analyzed to determine a patient&#39;s hematocrit ratio. The measured hematocrit ratio may be compared to certain expected or therapeutically acceptable values. The pump may continue to apply negative pressure to the patient&#39;s ureter and/or kidney until measured values within the therapeutically acceptable range are obtained. Once a therapeutically acceptable value is obtained, application of negative pressure may be stopped as shown at box  1018 . 
     In other examples, as shown at box  2024 , patient body weight may be measured to assess whether fluid is being removed from the patient by the applied negative pressure therapy. For example, a patient&#39;s measured bodyweight (including fluid introduced during a fluid resuscitation procedure) can be compared to a patient&#39;s dry body weight. As used herein, dry weights is defined as normal body weight measured when a patient is not over-diluted. For example, a patient who is not experiencing one or more of: elevated blood pressure, lightheadedness or cramping, swelling of legs, feet, arms, hands, or around the eyes, and who is breathing comfortably, likely does not have excess fluid. A weight measured when the patient is not experiencing such symptoms can be a dry body weight. Patient weight can be measured periodically until the measured weight approaches the dry body weight. When the measured weight approaches (e.g., is within between 5% and 10% of dry body weight), as shown at box  1018 , application of negative pressure can be stopped. 
     The aforementioned details of treatment using the systems of the present invention can be used to treat a variety of conditions that can benefit from increased urine or fluid output or removal. For example, a method for preserving renal function by application of negative pressure to decrease interstitial pressure within tubules of the medullar region to facilitate urine output and to prevent venous congestion-induced nephron hypoxia in the medulla of the kidney is provided. The method comprises: deploying a ureteral stent or ureteral catheter into a ureter or kidney of a patient to maintain patency of fluid flow between a kidney and a bladder of the patient; deploying a bladder catheter into the bladder of the patient, wherein the bladder catheter comprises a distal end configured to be positioned in a patient&#39;s bladder, a drainage lumen portion having a proximal end, and a sidewall extending therebetween; and applying negative pressure to the proximal end of the catheter to induce negative pressure in a portion of the urinary tract of the patient for a predetermined period of time to remove fluid from the urinary tract of the patient. 
     In another example, a method for treatment of acute kidney injury due to venous congestion is provided. The method comprises: deploying a ureteral stent or ureteral catheter into a ureter or kidney of a patient to maintain patency of fluid flow between a kidney and a bladder of the patient; deploying a bladder catheter into the bladder of the patient, wherein the bladder catheter comprises a distal end configured to be positioned in a patient&#39;s bladder, a drainage lumen portion having a proximal end, and a sidewall extending therebetween; and applying negative pressure to the proximal end of the catheter to induce negative pressure in a portion of the urinary tract of the patient for a predetermined period of time to remove fluid from the urinary tract of the patient, thereby reducing venous congestion in the kidney to treat acute kidney injury. 
     In another example, a method for treatment of New York Heart Association (NYHA) Class III and/or Class IV heart failure through reduction of venous congestion in the kidney(s) is provided. The method comprises: deploying a ureteral stent or ureteral catheter into a ureter or kidney of a patient to maintain patency of fluid flow between a kidney and a bladder of the patient; deploying a bladder catheter into the bladder of the patient, wherein the bladder catheter comprises a distal end configured to be positioned in a patient&#39;s bladder, a drainage lumen portion having a proximal end, and a sidewall extending therebetween; and applying negative pressure to the proximal end of the catheter to induce negative pressure in a portion of the urinary tract of the patient for a predetermined period of time to remove fluid from the urinary tract of the patient to treat volume overload in NYHA Class III and/or Class IV heart failure. 
     In another example, a method for treatment of Stage 4 and/or Stage 5 chronic kidney disease through reduction of venous congestion in the kidney(s) is provided. The method comprises: deploying a ureteral stent or ureteral catheter into a ureter or kidney of a patient to maintain patency of fluid flow between a kidney and a bladder of the patient; deploying a bladder catheter into the bladder of the patient, wherein the bladder catheter comprises a distal end configured to be positioned in a patient&#39;s bladder, a drainage lumen portion having a proximal end, and a sidewall extending therebetween; and applying negative pressure to the proximal end of the catheter to induce negative pressure in a portion of the urinary tract of the patient to remove fluid from the urinary tract of the patient to reduce venous congestion in the kidney(s). 
     In some examples, a kit is provided for removing fluid from the urinary tract of a patient. The kit comprises: a ureteral stent or ureteral catheter comprising a drainage channel for facilitating flow of fluid from the ureter and/or kidney through the drainage channel of the ureteral stent or ureteral catheter towards the bladder of the patient; and a pump comprising a controller configured to induce a negative pressure in at least one of the ureter, kidney or bladder of the patient to draw urine through a drainage lumen of a catheter deployed in the patient&#39;s bladder. In some examples, the kit further comprises at least one bladder catheter. In some examples, the kit further comprises instructions for one or more of the following: inserting/deploying the ureteral stent(s) and/or ureteral catheter(s), inserting/deploying the bladder catheter, and operating the pump to draw urine through a drainage lumen of the bladder catheter deployed the patient&#39;s bladder. 
     In some examples, another kit comprises: a plurality of disposable bladder catheters, each bladder catheter comprising a drainage lumen portion having a proximal end, a distal end configured to be positioned in a patient&#39;s bladder, and a sidewall extending therebetween; and a retention portion extending radially outward from a portion of the distal end of the drainage lumen portion, and being configured to be extended into a deployed position in which a diameter of the retention portion is greater than a diameter of the drainage lumen portion; instructions for inserting/deploying the bladder catheter; and instructions for connecting the proximal end of the bladder catheter to a pump and for operating the pump to draw urine through the drainage lumen of the bladder catheter, for example by applying negative pressure to the proximal end of the bladder catheter. 
     EXPERIMENTAL EXAMPLES OF INDUCING NEGATIVE PRESSURE USING URETERAL CATHETERS 
     Inducement of negative pressure within the renal pelvis of farm swine was performed for the purpose of evaluating effects of negative pressure therapy on renal congestion in the kidney. An objective of these studies was to demonstrate whether a negative pressure delivered into the renal pelvis significantly increases urine output in a swine model of renal congestion. In Example 1, a pediatric Fogarty catheter, normally used in embolectomy or bronchoscopy applications, was used in the swine model solely for proof of principle for inducement of negative pressure in the renal pelvis. It is not suggested that a Fogarty catheter be used in humans in clinical settings to avoid injury of urinary tract tissues. In Example 2, the ureteral catheter  112  shown in  FIGS. 2A and 2B , and including a helical retention portion for mounting or maintaining a distal portion of the catheter in the renal pelvis or kidney, was used. 
     Example 1 
     Method 
     Four farm swine  800  were used for purposes of evaluating effects of negative pressure therapy on renal congestion in the kidney. As shown in  FIG. 21 , pediatric Fogarty catheters  812 ,  814  were inserted to the renal pelvis region  820 ,  821  of each kidney  802 ,  804  of the four swine  800 . The catheters  812 ,  814  were deployed within the renal pelvis region by inflating an expandable balloon to a size sufficient to seal the renal pelvis and to maintain the position of the balloon within the renal pelvis. The catheters  812 ,  814  extend from the renal pelvis  802 ,  804 , through a bladder  810  and urethra  816 , and to fluid collection containers external to the swine. 
     Urine output of two animals was collected for a 15 minute period to establish a baseline for urine output volume and rate. Urine output of the right kidney  802  and the left kidney  804  were measured individually and found to vary considerably. Creatinine clearance values were also determined. 
     Renal congestion (e.g., congestion or reduced blood flow in the veins of the kidney) was induced in the right kidney  802  and the left kidney  804  of the animal  800  by partially occluding the inferior vena cava (IVC) with an inflatable balloon catheter  850  just above to the renal vein outflow. Pressure sensors were used to measure IVC pressure. Normal IVC pressures were 1-4 mmHg. By inflating the balloon of the catheter  850  to approximately three quarters of the IVC diameter, the IVC pressures were elevated to between 15-25 mmHg. Inflation of the balloon to approximately three quarters of IVC diameter resulted in a 50-85% reduction in urine output. Full occlusion generated IVC pressures above 28 mmHg and was associated with at least a 95% reduction in urine output. 
     One kidney of each animal  800  was not treated and served as a control (“the control kidney  802 ”). The ureteral catheter  812  extending from the control kidney was connected to a fluid collection container  819  for determining fluid levels. One kidney (“the treated kidney  804 ”) of each animal was treated with negative pressure from a negative pressure source (e.g., a therapy pump  818  in combination with a regulator designed to more accurately control the low magnitude of negative pressures) connected to the ureteral catheter  814 . The pump  818  was an Air Cadet Vacuum Pump from Cole-Parmer Instrument Company (Model No. EW-07530-85). The pump  818  was connected in series to the regulator. The regulator was an V-800 Series Miniature Precision Vacuum Regulator—⅛ NPT Ports (Model No. V-800-10-W/K), manufactured by Airtrol Components Inc. 
     The pump  818  was actuated to induce negative pressure within the renal pelvis  820 ,  821  of the treated kidney according to the following protocol. First, the effect of negative pressure was investigated in the normal state (e.g., without inflating the IVC balloon). Four different pressure levels (−2, −10, −15, and −20 mmHg) were applied for 15 minutes each and the rate of urine produced and creatinine clearance were determined. Pressure levels were controlled and determined at the regulator. Following the −20 mmHg therapy, the IVC balloon was inflated to increase the pressure by 15-20 mmHg. The same four negative pressure levels were applied. Urine output rate and creatinine clearance rate for the congested control kidney  802  and treated kidney  804  were obtained. The animals  800  were subject to congestion by partial occlusion of the IVC for 90 minutes. Treatment was provided for 60 minutes of the 90 minute congestion period. 
     Following collection of urine output and creatinine clearance data, kidneys from one animal were subjected to gross examination then fixed in a 10% neutral buffered formalin. Following gross examination, histological sections were obtained, examined, and magnified images of the sections were captured. The sections were examined using an upright Olympus BX41 light microscope and images were captured using an Olympus DP25 digital camera. Specifically, photomicrograph images of the sampled tissues were obtained at low magnification (20× original magnification) and high magnification (100× original magnification). The obtained images were subjected to histological evaluation. The purpose of the evaluation was to examine the tissue histologically and to qualitatively characterize congestion and tubular degeneration for the obtained samples. 
     Surface mapping analysis was also performed on obtained slides of the kidney tissue. Specifically, the samples were stained and analyzed to evaluate differences in size of tubules for treated and untreated kidneys. Image processing techniques calculated a number and/or relative percentage of pixels with different coloration in the stained images. Calculated measurement data was used to determine volumes of different anatomical structures. 
     Results 
     Urine Output and Creatinine Clearance 
     Urine output rates were highly variable. Three sources of variation in urine output rate were observed during the study. The inter-individual and hemodynamic variability were anticipated sources of variability known in the art. A third source of variation in urine output, upon information and belief believed to be previously unknown, was identified in the experiments discussed herein, namely, contralateral intra-individual variability in urine output. 
     Baseline urine output rates were 0.79 ml/min for one kidney and 1.07 ml/min for the other kidney (e.g., a 26% difference). The urine output rate is a mean rate calculated from urine output rates for each animal. 
     When congestion was provided by inflating the IVC balloon, the treated kidney urine output dropped from 0.79 ml/min to 0.12 ml/min (15.2% of baseline). In comparison, the control kidney urine output rate during congestion dropped from 1.07 ml/min to 0.09 ml/min (8.4% of baseline). Based on urine output rates, a relative increase in treated kidney urine output compared to control kidney urine output was calculated, according to the following equation: 
       (Therapy Treated/Baseline Treated)/(Therapy Control/Baseline Control)=Relative increase 
       (0.12 ml/min/0.79 ml/min)/(0.09 ml/min/1.07 ml/min)=180.6% 
     Thus, the relative increase in treated kidney urine output rate was 180.6% compared to control. This result shows a greater magnitude of decrease in urine production caused by congestion on the control side when compared to the treatment side. Presenting results as a relative percentage difference in urine output adjusts for differences in urine output between kidneys. 
     Creatinine clearance measurements for baseline, congested, and treated portions for one of the animals are shown in  FIG. 22 . 
     Gross Examination and Histological Evaluation 
     Based on gross examination of the control kidney (right kidney) and treated kidney (left kidney), it was determined that the control kidney had a uniformly dark red-brown color, which corresponds with more congestion in the control kidney compared to the treated kidney. Qualitative evaluation of the magnified section images also noted increased congestion in the control kidney compared to the treated kidney. Specifically, as shown in Table 1, the treated kidney exhibited lower levels of congestion and tubular degeneration compared to the control kidney. The following qualitative scale was used for evaluation of the obtained slides. 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Lesion 
                 Score 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 Congestion 
               
            
           
           
               
               
               
            
               
                   
                 None: 
                 0 
               
               
                   
                 Mild: 
                 1 
               
               
                   
                 Moderate: 
                 2 
               
               
                   
                 Marked: 
                 3 
               
               
                   
                 Severe: 
                 4 
               
            
           
           
               
            
               
                 Tubular degeneration 
               
            
           
           
               
               
               
            
               
                   
                 None: 
                 0 
               
               
                   
                 Mild: 
                 1 
               
               
                   
                 Moderate: 
                 2 
               
               
                   
                 Marked: 
                 3 
               
               
                   
                 Severe: 
                 4 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 TABULATED RESULTS 
               
            
           
           
               
               
            
               
                   
                 Histologic lesions 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                 Tubular 
                   
               
               
                   
                 Slide 
                 Conges- 
                 hyaline 
                 Granu- 
               
               
                 Animal ID/Organ/Gross lesion 
                 number 
                 tion 
                 casts 
                 lomas 
               
               
                   
               
               
                 6343/Left Kidney/Normal 
                 R16-513-1 
                 1 
                 1 
                 0 
               
               
                 6343/Left Kidney/Normal with 
                 R16-513-2 
                 1 
                 1 
                 0 
               
               
                 hemorrhagic streak 
               
               
                 6343/Right Kidney/Congestion 
                 R16-513-3 
                 2 
                 2 
                 1 
               
               
                 6343/Right Kidney/Congestion 
                 R16-513-4 
                 2 
                 1 
                 1 
               
               
                   
               
            
           
         
       
     
     As shown in Table 1, the treated kidney (left kidney) exhibited only mild congestion and tubular degeneration. In contrast, the control kidney (right kidney) exhibited moderate congestion and tubular degeneration. These results were obtained by analysis of the slides discussed below. 
       FIGS. 48A and 48B  are low and high magnification photomicrographs of the left kidney (treated with negative pressure) of the animal. Based on the histological review, mild congestion in the blood vessels at the corticomedullary junction was identified, as indicated by the arrows. As shown in  FIG. 48B , a single tubule with a hyaline cast (as identified by the asterisk) was identified. 
       FIGS. 48C and 48D  are low and high resolution photomicrographs of the control kidney (right kidney). Based on the histological review, moderate congestion in the blood vessel at the corticomedullary junction was identified, as shown by the arrows in  FIG. 48C . As shown in  FIG. 48D , several tubules with hyaline casts were present in the tissue sample (as identified by asterisks in the image). Presence of a substantial number of hyaline casts is evidence of hypoxia. 
     Surface mapping analysis provided the following results. The treated kidney was determined to have 1.5 times greater fluid volume in Bowman&#39;s space and 2 times greater fluid volume in tubule lumen. Increased fluid volume in Bowman&#39;s space and the tubule lumen corresponds to increased urine output. In addition, the treated kidney was determined to have 5 times less blood volume in capillaries compared to the control kidney. The increased volume in the treated kidney appears to be a result of (1) a decrease in individual capillary size compared to the control and (2) an increase in the number of capillaries without visible red blood cells in the treated kidney compared to the control kidney, an indicator of less congestion in the treated organ. 
     Summary 
     These results indicate that the control kidney had more congestion and more tubules with intraluminal hyaline casts, which represent protein-rich intraluminal material, compared to the treated kidney. Accordingly, the treated kidney exhibits a lower degree of loss of renal function. While not intending to be bound by theory, it is believed that as severe congestion develops in the kidney, hypoxemia of the organ follows. Hypoxemia interferes with oxidative phosphorylation within the organ (e.g., ATP production). Loss of ATP and/or a decrease in ATP production inhibits the active transport of proteins causing intraluminal protein content to increase, which manifests as hyaline casts. The number of renal tubules with intraluminal hyaline casts correlates with the degree of loss of renal function. Accordingly, the reduced number of tubules in the treated left kidney is believed to be physiologically significant. While not intending to be bound by theory, it is believed that these results show that damage to the kidney can be prevented or inhibited by applying negative pressure to a ureteral catheter inserted into the renal pelvis to facilitate urine output. 
     Example 2 
     Method 
     Four (4) farm swine (A, B, C, D) were sedated and anesthetized. Vitals for each of the swine were monitored throughout the experiment and cardiac output was measured at the end of each 30-minute phase of the study. Ureteral catheters, such as the ureteral catheter  112  shown in  FIGS. 2A and 2B , were deployed in the renal pelvis region of the kidneys of each of the swine. The deployed catheters were a 6 Fr catheter having an outer diameter of 2.0±0.1 mm. The catheters were 54±2 cm in length, not including the distal retention portion. The retention portion was 16±2 mm in length. As shown in the catheter  112  in  FIGS. 2A and 2B , the retention portion included two full coils and one proximal half coil. The outer diameter of the full coils, shown by line D 1  in  FIGS. 2A and 2B , was 18±2 mm. The half coil diameter D 2  was about 14 mm. The retention portion of the deployed ureteral catheters included six drainage openings, plus an additional opening at the distal end of the catheter tube. The diameter of each of the drainage openings was 0.83±0.01 mm. The distance between adjacent drainage openings  132 , specifically the linear distance between drainage openings when the coils were straightened, was 22.5±2.5 mm. 
     The ureteral catheters were positioned to extend from the renal pelvis of the swine, through the bladder, and urethra, and to fluid collection containers external to each swine. Following placement of the ureteral catheters, pressure sensors for measuring IVC pressure were placed in the IVC at a position distal to the renal veins. An inflatable balloon catheter, specifically a PTS® percutaneous balloon catheter (30 mm diameter by 5 cm length), manufactured by NuMED Inc. of Hopkinton, N.Y., was expanded in the IVC at a position proximal to the renal veins. A thermodilution catheter, specifically a Swan-Ganz thermodilution pulmonary artery catheter manufactured by Edwards Lifesciences Corp. of Irvine, Calif., was then placed in the pulmonary artery for the purpose of measuring cardiac output. 
     Initially, baseline urine output was measured for 30 minutes, and blood and urine samples were collected for biochemical analysis. Following the 30-minute baseline period, the balloon catheter was inflated to increase IVC pressure from a baseline pressure of 1-4 mmHg to an elevated congested pressure of about 20 mmHg (+/−5 mmHg). A congestion baseline was then collected for 30 minutes with corresponding blood and urine analysis. 
     At the end of the congestion period, the elevated congested IVC pressure was maintained and negative pressure diuresis treatment was provided for swine A and swine C. Specifically, the swine (A, C) were treated by applying a negative pressure of −25 mmHg through the ureteral catheters with a pump. As in previously-discussed examples, the pump was an Air Cadet Vacuum Pump from Cole-Parmer Instrument Company (Model No. EW-07530-85). The pump was connected in series to a regulator. The regulator was a V-800 Series Miniature Precision Vacuum Regulator—⅛ NPT Ports (Model No. V-800-10-W/K), manufactured by Airtrol Components Inc. The swine were observed for 120 minutes, as treatment was provided. Blood and urine collection were performed every 30 minutes, during the treatment period. Two of the swine (B, D) were treated as congested controls (e.g., negative pressure was not applied to the renal pelvis through the ureteral catheters), meaning that the two swine (B, D) did not receive negative pressure diuresis therapy. 
     Following collection of urine output and creatinine clearance data for the 120-minute treatment period, the animals were sacrificed and kidneys from each animal were subjected to gross examination. Following gross examination, histological sections were obtained and examined, and magnified images of the sections were captured. 
     Results 
     Measurements collected during the Baseline, Congestion, and Treatment periods are provided in Table 2. Specifically, urine output, serum creatinine, and urinary creatinine measurements were obtained for each time period. These values allow for the calculation of a measured creatinine clearance as follows: 
     
       
         
           
             
               Creatinine 
                
               
                   
               
                
               Clearance 
                
               
                 : 
               
                
               
                   
               
                
               CrCl 
             
             = 
             
               Urine 
                
               
                   
               
                
               Output 
                
               
                   
               
                
               
                 ( 
                 
                   ml 
                   / 
                   min 
                 
                 ) 
               
               * 
               
                 
                   Urinary 
                    
                   
                       
                   
                    
                   Creatinine 
                    
                   
                       
                   
                    
                   
                     ( 
                     
                       mg 
                        
                       
                         / 
                       
                        
                       dl 
                     
                      
                     
                         
                     
                     ) 
                   
                 
                 
                   Serum 
                    
                   
                       
                   
                    
                   Creatinine 
                    
                   
                       
                   
                    
                   
                     ( 
                     
                       mg 
                        
                       
                         / 
                       
                        
                       dl 
                     
                     ) 
                   
                 
               
             
           
         
       
     
     In addition, Neutrophil gelatinase-associated lipocalin (NGAL) values were measured from serum samples obtained for each time period and Kidney Injury Molecule 1 (KIM-1) values were measured from the urine samples obtained for each time period. Qualitative histological findings determined from review of the obtained histological sections are also included in Table 2. 
     
       
         
           
               
               
             
               
                   
                 TABLE 2 
               
             
            
               
                   
                   
               
               
                   
                 Animal 
               
            
           
           
               
               
               
               
               
            
               
                   
                 A 
                 B 
                 C 
                 D 
               
               
                 Treatment assignment 
                 Treatment 
                 Control 
                 Treatment 
                 Control 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Baseline: 
                   
                   
                   
                   
               
               
                 Urine output (ml/min) 
                 3.01 
                 2.63 
                 0.47 
                 0.98 
               
               
                 Serum creatinine (mg/dl) 
                 0.8 
                 0.9 
                 3.2 
                 1.0 
               
               
                 Creatinine clearance (ml/min) 
                 261 
                 172 
                 5.4 
                 46.8 
               
               
                 Serum NGAL (ng/ml) 
                 169 
                 * 
                 963 
                 99 
               
               
                 Urinary KIM-1 (ng/ml) 
                 4.11 
                 * 
                 3.59 
                 1.16 
               
               
                 Congestion: 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Urine output (ml/min) 
                 0.06 
                 (2%) 
                 0.53 
                 (20%) 
                 0.12 
                 (25%) 
                 0.24 
                 (25%) 
               
               
                 Serum creatinine (mg/dl) 
                 1.2 
                 (150%) 
                 1.1 
                 (122%) 
                 3.1 
                 (97%) 
                 1.2 
                 (120%) 
               
               
                 Creatinine clearance (ml/min) 
                 1.0 
                 (0.4%) 
                 30.8 
                 (18%) 
                 1.6 
                 (21%) 
                 16.2 
                 (35%) 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Serum NGAL (ng/ml) 
                 102 
                 (60%) 
                 * 
                 809 
                 (84%) 
                 126 
                 (127%) 
               
               
                 Urinary KIM-1 (ng/ml) 
                 24.3 
                 (591%) 
                 * 
                 2.2 
                 (61%) 
                 1.39 
                 (120%) 
               
            
           
           
               
               
               
               
               
            
               
                 Treatment: 
                   
                   
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Urine output (ml/min) 
                 0.54 
                 (17%) 
                 ** 
                 0.47 
                 (101%) 
                 0.35 
                 (36%) 
               
               
                 Serum creatinine (mg/dl) 
                 1.3 
                 (163%) 
                   
                 3.1 
                 (97%) 
                 1.7 
                 (170%) 
               
               
                 Creatinine clearance (ml/min) 
                 30.6 
                 (12%) 
                   
                 18.3 
                 (341%) 
                 13.6 
                 (29%) 
               
               
                 Serum NGAL (ng/ml) 
                 197 
                 (117%) 
                   
                 1104 
                 (115%) 
                 208 
                 (209%) 
               
               
                 Urinary KIM-1 (ng/ml) 
                 260 
                 (6326%) 
                   
                 28.7 
                 (799%) 
                 233 
                 (20000%) 
               
            
           
           
               
               
               
               
               
            
               
                 Histological findings: 
                   
                   
                   
                   
               
               
                 Blood volume in capillary space 
                 2.4% 
                 ** 
                 0.9% 
                 4.0% 
               
               
                 Hyaline casts 
                 Mild/Mod 
                   
                 None 
                 Mod 
               
               
                 Degranulation 
                 Mild/Mod 
                   
                 None 
                 Mod 
               
               
                   
               
               
                 Data are raw values (% baseline) 
               
               
                 * not measured 
               
               
                 ** confounded by phenylephrine 
               
            
           
         
       
     
     Animal A: The animal weighed 50.6 kg and had a baseline urine output rate of 3.01 ml/min, a baseline serum creatinine of 0.8 mg/dl, and a measured CrCl of 261 ml/min. It is noted that these measurements, aside from serum creatinine, were uncharacteristically high relative to other animals studied. Congestion was associated with a 98% reduction in urine output rate (0.06 ml/min) and a &gt;99% reduction in CrCl (1.0 ml/min). Treatment with negative pressure applied through the ureteral catheters was associated with urine output and CrCl of 17% and 12%, respectively, of baseline values, and 9× and &gt;10×, respectively, of congestion values. Levels of NGAL changed throughout the experiment, ranging from 68% of baseline during congestion to 258% of baseline after 90 minutes of therapy. The final value was 130% of baseline. Levels of KIM-1 were 6 times and 4 times of baseline for the first two 30-minute windows after baseline assessment, before increasing to 68×, 52×, and 63× of baseline values, respectively, for the last three collection periods. The 2-hour serum creatinine was 1.3 mg/dl. Histological examination revealed an overall congestion level, measured by blood volume in capillary space, of 2.4%. Histological examination also noted several tubules with intraluminal hyaline casts and some degree of tubular epithelial degeneration, a finding consistent with cellular damage. 
     Animal B: The animal weighed 50.2 kg and had a baseline urine output rate of 2.62 ml/min and a measured CrCl of 172 ml/min (also higher than anticipated). Congestion was associated with an 80% reduction in urine output rate (0.5 ml/min) and an 83% reduction in CrCl (30 ml/min). At 50 minutes into the congestion (20 minutes after the congestion baseline period), the animal experienced an abrupt drop in mean arterial pressure and respiration rate, followed by tachycardia. The anesthesiologist administered a dose of phenylephrine (75 mg) to avert cardiogenic shock. Phenylephrine is indicated for intravenous administration when blood pressure drops below safe levels during anesthesia. However, since the experiment was testing the impact of congestion on renal physiology, administration of phenylephrine confounded the remainder of the experiment. 
     Animal C: The animal weighed 39.8 kg and had a baseline urine output rate of 0.47 ml/min, a baseline serum creatinine of 3.2 mg/dl, and a measured CrCl of 5.4 ml/min. Congestion was associated with a 75% reduction in urine output (0.12 ml/min) and a 79% reduction in CrCl (1.6 ml/min). It was determined that baseline NGAL levels were &gt;5× the upper limit of normal (ULN). Treatment with negative pressure applied to the renal pelvis through the ureteral catheters was associated with a normalization of urine output (101% of baseline) and a 341% improvement in CrCl (18.2 ml/min). Levels of NGAL changed throughout the experiment, ranging from 84% of baseline during congestion to 47% to 84% of baseline between 30 and 90 minutes. The final value was 115% of baseline. Levels of KIM-1 decreased 40% from baseline within the first 30 minutes of congestion, before increasing to 8.7×, 6.7×, 6.6×, and 8× of baseline values, respectively, for the remaining 30-minute windows. Serum creatinine level at 2 hours was 3.1 mg/dl. Histological examination revealed an overall congestion level, measured by blood volume in capillary space, of 0.9%. The tubules were noted to be histologically normal. 
     Animal D: The animal weighed 38.2 kg and had a baseline urine output of 0.98 ml/min, a baseline serum creatinine of 1.0 mg/dl, and a measured CrCl of 46.8 ml/min. Congestion was associated with a 75% reduction in urine output rate (0.24 ml/min) and a 65% reduction in Cr Cl (16.2 ml/min). Continued congestion was associated with a 66% to 91% reduction of urine output and 89% to 71% reduction in CrCl. Levels of NGAL changed throughout the experiment, ranging from 127% of baseline during congestion to a final value of 209% of baseline. Levels of KIM-1 remained between 1× and 2× of baseline for the first two 30-minute windows after baseline assessment, before increasing to 190×, 219×, and 201× of baseline values for the last three 30-minute periods. The 2-hour serum creatinine level was 1.7 mg/dl. Histological examination revealed an overall congestion level 2.44× greater than that observed in tissue samples for the treated animals (A, C) with an average capillary size 2.33 times greater than that observed in either of the treated animals. The histological evaluation also noted several tubules with intraluminal hyaline casts as well as tubular epithelial degeneration, indicating substantial cellular damage. 
     Summary 
     While not intending to be bound by theory, it is believed that the collected data supports the hypothesis that venous congestion creates a physiologically significant impact on renal function. In particular, it was observed that elevation of the renal vein pressure reduced urine output by 75% to 98% within seconds. The association between elevations in biomarkers of tubular injury and histological damage is consistent with the degree of venous congestion generated, both in terms of magnitude and duration of the injury. 
     The data also appears to support the hypothesis that venous congestion decreases the filtration gradients in the medullary nephrons by altering the interstitial pressures. The change appears to directly contribute to the hypoxia and cellular injury within medullary nephrons. While this model does not mimic the clinical condition of AKI, it does provide insight into the mechanical sustaining injury. 
     The data also appears to support the hypothesis that applying negative pressure to the renal pelvis through ureteral catheters can increase urine output in a venous congestion model. In particular, negative pressure treatment was associated with increases in urine output and creatinine clearance that would be clinically significant. Physiologically meaningful decreases in medullary capillary volume and smaller elevations in biomarkers of tubular injury were also observed. Thus, it appears that by increasing urine output rate and decreasing interstitial pressures in medullary nephrons, negative pressure therapy may directly decrease congestion. While not intending to be bound by theory, by decreasing congestion, it may be concluded that negative pressure therapy reduces hypoxia and its downstream effects within the kidney in a venous congestion mediated AKI. 
     The experimental results appear to support the hypothesis that the degree of congestion, both in terms of the magnitude of pressure and duration, is associated with the degree of cellular injury observed. Specifically, an association between the degree of urine output reduction and the histological damage was observed. For example, treated Swine A, which had a 98% reduction in urine output, experienced more damage than treated Swine C, which had a 75% reduction in urine output. As would be expected, control Swine D, which was subjected to a 75% reduction in urine output without benefit of therapy for two and a half hours, exhibited the most histological damage. These findings are broadly consistent with human data demonstrating an increased risk for AKI onset with greater venous congestion. See e.g., Legrand, M. et al.,  Association between systemic hemodynamics and septic acute kidney injury in critically ill patients: a retrospective observational study. Critical Care  17:R278-86, 2013. 
     Example 3 
     Method 
     Inducement of negative pressure within the renal pelvis of farm swine using ureteral catheters was performed for the purpose of evaluating effects of negative pressure therapy on hemodilution of the blood. An objective of these studies was to demonstrate whether a negative pressure delivered into the renal pelvis significantly increases urine output in a swine model of fluid resuscitation. 
     Two pigs were sedated and anesthetized using ketamine, midazolam, isoflurane and propofol. One animal (#6543) was treated with a ureteral catheter and negative pressure therapy as described herein. The other, which received a Foley type bladder catheter, served as a control (#6566). Following placement of the ureretal catheters, the animals were transferred to a sling and monitored for 24 hours. 
     Fluid overload was induced in both animals with a constant infusion of saline (125 mL/hour) during the 24 hour follow-up. Urine output volume was measured at 15 minute increments for 24 hours. Blood and urine samples were collected at 4 hour increments. As shown in  FIG. 21 , a therapy pump  818  was set to induce negative pressure within the renal pelvis  820 ,  821  (shown in  FIG. 21 ) of both kidneys using a pressure of −45 mmHg (+/−2 mmHg). 
     Results 
     Both animals received 7 L of saline over the 24 hour period. The treated animal produced 4.22 L of urine while the control produced 2.11 L. At the end of 24 hours, the control had retained 4.94 L of the 7 L administered, while the treated animal retained 2.81 L of the 7 L administered.  FIG. 26  illustrates the change in serum albumin. The treated animal had a 6% drop in the serum albumin concentration over 24 hours, while the control animal had a 29% drop. 
     Summary 
     While not intending to be bound by theory, it is believed that the collected data supports the hypothesis that fluid overload induces clinically significant impact on renal function and, consequently induces hemodilution. In particular, it was observed that administration of large quantities of intravenous saline cannot be effectively removed by even healthy kidneys. The resulting fluid accumulation leads to hemodilution. The data also appears to support the hypothesis that applying negative pressure diuresis therapy using ureteral catheters to fluid overloaded animals can increase urine output, improve net fluid balance and decrease the impact of fluid resuscitation on development of hemodilution. 
     The preceding examples and embodiments of the invention have been described with reference to various examples. Modifications and alterations will occur to others upon reading and understanding the foregoing examples. Accordingly, the foregoing examples are not to be construed as limiting the disclosure.