Patent Publication Number: US-11045143-B2

Title: Catheter with connectable hub for monitoring pressure

Description:
This application claims the benefit of provisional application Ser. No. 62/514,793, filed Jun. 3, 2017, provisional application Ser. No. 62/544,680, filed Aug. 11, 2017, provision application Ser. No. 62/590,513, filed Nov. 24, 2017 and provisional application 62/622,871, filed Jan. 27, 2018. The entire contents of each of these applications are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This application relates to a catheter and connectable hub for monitoring intra-abdominal pressure through the urinary bladder. 
     2. Background 
     Traditionally, physicians relied on visual cues or physical examination to detect increase in intra-abdominal pressure (IAP). More recently Dr. Kirkpatrick and colleagues, in an article “Is Clinical Examination an Accurate Indicator of Raised Intra-Abdominal Pressure in Critically Injured Patients,” CJS, June 2000, 43, No. 3, 207-211, showed that IAP measured through the patient&#39;s bladder was significantly more accurate than physical examination. That is, it was demonstrated that the clinical abdominal examination was insensitive and inaccurate when compared with urinary bladder pressure measurements. 
     Various tools for measuring IAP have been developed over the years. Many researchers have documented IAP measurements through almost every natural or manmade orifice in the body. Earlier crude forms of measuring IAP used bladder catheters, nasogastric tubes, and rectal tubes attached to a manometer. The nasogastric or the rectal route was better suited in rare cases of bladder rupture or situations where bladder catheters were contraindicated. However, due to local interferences, the nasogastric and the rectal tube measurements were neither reproducible nor logical as were the bladder catheters. 
     Thus, measuring of IAP through the bladder became more suitable. In 1989 Iberti and colleagues in an article entitled, “Determination of Intra-abdominal Pressure Using a Transurethral Bladder Catheter: Clinical Validation of the Technique,” Anesthesiology, January 1989, 70(1), 47-50, validated the correlation of IAP using a catheter inserted in the bladder. Their study was key in using bladder pressure as the gold standard for measuring IAP. In 1995, Kron and colleagues published a study in “The Measurement of Intra-Abdominal Pressure as a Criterion for Abdominal Re-exploration, 1984 Ann Surg., 199, 28-30, comparing catheters in various body locations for measuring IAP. They measured IAP from the stomach using a nasogastric tube, from the rectum using a modified rectal tube, from the bladder using a modified bladder catheter, and direct abdominal pressure using a laparoscopic insufflator needle. They found that the bladder catheter had the best measurement of IAP and that the gastric and the rectal catheter measurements were less reliable due to dependence on the position of the catheter. Thus, clinicians generally agreed that the urinary bladder is the best-suited location for measurement of IAP. 
     The need for measuring IAP has become more important as physicians increasingly realized that organ failure and death were directly related to increase in IAP in certain high-risk patients. High abdominal pressure has been found to cause a decrease in function of the intestines, liver and blood vessels resulting in adverse consequences for the patients. Consequently, accurate measurement of IAP can help decrease patient morbidity and mortality. It has also been more recently discovered that pediatric and neonate population may also have need for IAP measurement to determine specific conditions. 
     Currently, there are few products available on the market to measure the IAP through the bladder. One device, the Bard IAP device, has a “valve clamp” which diverts urine from the main catheter drainage channel to measure IAP via converting hydrostatic pressure to a readable pressure gauge. This mechanism of IAP measurements is archaic and does not provide continuous pressure measurement when used with the standard 2-channel bladder drainage catheter. Two other manufacturers, Holtech and ConvaTec, also use a column of urine by connecting their kit to an existing bladder catheter. Their systems are cumbersome and the IAP readings are also not continuous. Biometrix has developed an IAP monitoring device which like other manufacturers relies on tapping into the main bladder drainage catheter, using a valve to measure the hydrostatic pressure. In 2008 Sugrue and colleagues, in an article “Prospective Study of Intra-Abdominal Hypertension and Renal Function after Laparotomy, British Journal of Surgery, 1999, 82, 235-238, suggested the use of 3-channel bladder drainage catheter so that the smaller channel, which was used for bladder irrigation, could be used to attach a pressure-monitoring device. The use of an extra channel made it possible to have continuous bladder drainage while measuring the bladder pressure. However, this bladder catheter did not provide a continuous pressure read because intermittently the operator needed to add 50 ml of water or saline to the bladder to record the IAP pressure. Thus, the pressure reading at best was intermittent since pressure readings were not performed when fluid was being added to the bladder. Consequently, although this was a step toward increasing the amount of pressure readings/recordings, it still was unable to conduct continuous pressure monitoring. Furthermore, it was still the same cumbersome IAP device set up which required a skilled person to add water before each IAP reading. Control of the amount of water added is critical since adding too much water to the bladder can falsely increase the pressure readings and also increase infection risk, thus further complicating the use. 
     It has also been recognized that most patients that have a need for measurement of IAP also need to have continuous drainage of the urinary bladder and thus devices need to account for this process. 
     Consequently, current devices placed in the bladder for measuring pressure require a continuous water column to maintain pressure readings. Thus, they fail to measure IAP continuously but only measure pressure intermittently. They also all rely on tapping into an existing bladder drainage catheter, which adds complications. Furthermore, they do not reduce the complexity of the procedure since they require constant retrograde insertion of a relatively large amount of fluid into the bladder, e.g., 50 cc, which increases the ICU workload. Still further, these devices increase the risk of complications and infections associated with fluid injection into the bladder. Fluid injection is also complicated since it needs to be closely monitored since too much fluid in the bladder can give false elevation of IAP readings, causing clinicians to take unnecessary steps in response to what is mistakenly believed is excess IAP. 
     It would therefore be advantageous to provide a device insertable into the bladder that accurately measures abdominal pressure without requiring adding water to the bladder to obtain such pressure readings. Such device would advantageously avoid the complications and risks associated with such fluid insertion. Furthermore, it would be advantageous if such device could continuously measure bladder pressure without interruption. This would advantageously enable a constant monitoring of IAP so critical time periods are not missed. It would further be advantageous to provide a device that improves the accuracy of the pressure reading in the bladder to more accurately determine IAP so necessary steps can be taken to address IAP only when warranted. Still further, it would be advantageous if such device could satisfy the foregoing needs and provide these enumerated advantages while being simple to use so that so that any of clinical staff with basic knowledge of bladder catheter insertion will be able to insert the device without relying on specially trained staff members. 
     SUMMARY 
     The present invention overcomes the deficiencies and disadvantages of the prior art. The present invention advantageously provides a multi-lumen catheter insertable into the bladder in the same manner as a regular bladder drainage catheter to determine intra-abdominal pressure without requiring insertion of water into the bladder. The catheters of the present invention utilize a gas-charged chamber to measure bladder pressure across a large surface area, and thus, accurately determine intra-abdominal pressure, and enable pressure to be measured continuously without interrupting urine flow and without interruptions to add water to the bladder. 
     Some embodiments of the catheter of the present invention utilize a stabilizing balloon to help retain the catheter in the bladder during the procedure. 
     In accordance with one aspect of the present invention, a multi-lumen catheter for monitoring pressure in a patient is provided comprising an expandable outer balloon at a distal portion of the catheter. An expandable inner balloon is positioned within the outer balloon. A first lumen communicates with the inner balloon and the inner balloon and first lumen form a gas filled chamber to monitor pressure within the bladder. The outer balloon has a circumferential area greater than a circumferential area of the inner balloon, wherein in response to pressure within the bladder exerted on the first outer wall of the expanded outer balloon, the outer balloon deforms and exerts a pressure on the second outer wall of the expanded inner balloon to deform the inner balloon and compress the gas within the inner balloon and the first lumen to provide a finer measurement. A second lumen communicates with the bladder to remove fluid from the bladder. A pressure transducer communicates with the gas filled chamber for measuring bladder pressure based on gas compression caused by deformation of the expanded inner balloon deformed by the expanded outer balloon. 
     In some embodiments, the gas filled chamber monitors pressure within the bladder to thereby monitor pressure within an abdomen of the patient. 
     In some embodiments, the pressure transducer measures average pressure continuously throughout insertion of the catheter within the urethra without requiring infusion of water into the bladder. 
     In some embodiments, the pressure transducer is an external transducer connectable to the catheter. In some embodiments, the pressure transducer is contained within a hub and the hub includes an elongated member extending distally therefrom, and connection of the pressure transducer to a first port of the catheter automatically inserts the elongated member into the first lumen to advance gas into the inner balloon to expand the inner balloon. In some embodiments, the first lumen is not vented to atmosphere when the pressure transducer is connected to the catheter and advances gas to expand the inner balloon. 
     In some embodiments, the gas within the inner balloon and/lumen is air to provide an air filled chamber. 
     In some embodiments, the second lumen has a side opening distal of the inner and outer balloons; in other embodiments the side opening is proximal of the inner and outer balloons. The catheter can include a third lumen communicating with the outer balloon to expand the outer balloon. In some embodiments, the hub includes a second elongated member insertable into the third lumen to automatically advance gas into the outer balloon to expand the outer balloon when the hub is connected to the catheter. In some embodiments, the outer balloon is in communication with the first lumen and gas advanced through the first lumen also expands the outer balloon. 
     In some embodiments, the catheter has a fourth lumen and a temperature sensor positioned within the fourth lumen to measure core body temperature. A wire can extend from the temperature sensor through the fourth lumen and external of the catheter into the hub connected to the catheter. The hub can have a first opening to receive a connector of the wire to automatically connect the temperature sensor to a cable extendable from the hub and connectable to an external temperature monitor. 
     In some embodiments, connection of the pressure transducer to the catheter a) automatically connects the temperature sensor to a temperature monitor cable; and b) automatically advances air through the first lumen to expand the inner balloon. 
     In some embodiments, the catheter includes a stabilizing balloon proximal of the outer balloon for stabilizing the catheter, and the catheter includes a fifth lumen communicating with the stabilizing balloon to expand the stabilizing balloon. 
     In some embodiments, the outer balloon has a circumference engageable with a wall of the bladder at multiple contact regions to provide multiple reference points for calculation of an average pressure of the bladder wall. In some embodiments, the outer balloon has a distal region having a larger transverse cross-section than a proximal region. 
     In accordance with another aspect of the present invention, a multi-lumen catheter for monitoring intra-abdominal pressure is provided comprising a distal balloon at a distal portion of the catheter and a first lumen communicating with the distal balloon. The distal balloon and first lumen form a gas filled chamber to monitor pressure within the bladder to thereby monitor pressure within an abdomen of the patient, wherein in response to pressure within the bladder the distal balloon deforms to compress the gas within the distal balloon. The first lumen has a first proximal port communicating with the first lumen. A second lumen communicates with the bladder to remove fluid from the bladder and a temperature sensor is positioned in a third lumen of the catheter and has a wire extending through the third lumen. A hub is connectable to the first port of the catheter and includes a pressure transducer for measuring pressure based on gas compression within the first lumen, wherein connection of the hub to the first port automatically connects the wire to an electrical connector in the hub for connection to a temperature monitor. 
     In some embodiments, connection of the hub to the first port automatically advances gas into the distal balloon to expand the distal balloon, the first lumen remaining sealed to outside air during expansion of the distal balloon. The hub can include an elongated member extending distally therefrom and insertable into the first lumen to advance gas into the distal balloon upon connection of the hub to the first port. The hub can include a shroud over the elongated member and the shroud in some embodiments, snap fits over the first port. In some embodiments, the first port has a valve and the elongated member is insertable through the valve when the hub is connected to the catheter. The catheter in some embodiments includes a stabilizing balloon positioned proximal of the distal balloon for stabilizing the catheter. 
     In accordance with another aspect of the present invention, a multi-lumen catheter for monitoring intra-abdominal pressure is provided comprising a distal balloon at a distal portion of the catheter and a first lumen communicating with the distal balloon. The distal balloon and first lumen form a gas filled chamber to monitor pressure within the bladder to thereby monitor pressure within an abdomen of the patient, wherein in response to pressure within the bladder the distal balloon deforms to compress the gas within the distal balloon. The first lumen has a first proximal port communicating with the first lumen. A second lumen communicates with the bladder to remove fluid from the bladder. A hub is connectable to the first port of the catheter, the hub including a pressure transducer for measuring pressure based on gas compression with the first lumen. An elongated member extends distally from the hub, wherein connection of the hub to the first port automatically inserts the elongated member into the first lumen to advance gas through the first lumen to expand the distal balloon, the first lumen not vented to atmosphere when the hub is connected to the first port. 
     In some embodiments, a shroud is positioned over the elongated member and the shroud can be snap fit over the first port or attached in other ways. In some embodiments, the first port has a valve and the elongated member is insertable through the valve when the hub is connected to the catheter. The catheter can include a stabilizing balloon proximal of the distal balloon for stabilizing the catheter. 
     In accordance with another aspect of the present invention, a method for measuring intra-abdominal pressure is provided comprising the steps of: 
     providing a catheter having first and second lumens, an expandable first balloon and a temperature sensor; 
     inserting the catheter through the urethra into a bladder of a patient; 
     connecting a hub containing a pressure transducer to the first lumen to automatically advance air through the first lumen of the catheter to expand the first balloon from a deflated condition to a more expanded condition and to automatically connect the temperature sensor to a connector within the hub; 
     obtaining a first pressure reading of the bladder based on deformation of the balloon without injecting fluid into the bladder; 
     transmitting the first pressure reading to an external monitor connected to the hub; 
     obtaining a second pressure reading of the bladder based on deformation of the balloon without injecting fluid into the bladder; 
     transmitting the second pressure reading to the external monitor connected to the hub; and 
     obtaining consecutive continuous pressure readings of the bladder without injecting fluid into the bladder. 
     The method can further include the step of draining the bladder through the second lumen of the catheter. In some embodiments, the step of obtaining pressure readings obtains average pressure. 
     In some embodiments, the catheter includes an outer balloon positioned over the first balloon and the outer balloon is expandable through a separate lumen of the catheter and deformable based on bladder pressure to deform the first balloon to provide finer measurements of bladder pressure. In some embodiments, the step of connecting a pressure transducer advances an elongated member extending from the hub into the first lumen to advance air into the first balloon. In some embodiments, the temperature sensor is positioned in a lumen of the catheter independent of the first lumen. 
     In accordance with another aspect of the present invention, a multi-lumen catheter for monitoring intra-abdominal pressure is provided. The catheter includes an elongated body configured and dimensioned for insertion into a bladder of a patient, a first lumen, a second lumen, and a first balloon at a distal portion. The first lumen communicates with the first balloon and the second lumen communicates with the bladder to remove fluid from the bladder. The first balloon is filled with a gas to form along with the first lumen a gas filled chamber to monitor pressure within the bladder to thereby monitor pressure within an abdomen of the patient. A sensor is positioned at the distal portion of the catheter to measure pressure about a circumferential area of the balloon. 
     In accordance with another aspect of the present invention, a multi-lumen catheter is provided for monitoring intra-abdominal pressure, the catheter comprising an elongated body configured and dimensioned for insertion into the bladder of a patient, a first lumen, a second lumen, and a first balloon at a distal portion. The first lumen communicates with the first balloon and the second lumen communicates with the bladder to remove fluid from the bladder. The first balloon is filled with a gas to form a gas filled chamber to monitor pressure within the bladder to thereby monitor pressure within an abdomen of the patient. A pressure sensor is positioned at the distal portion of the catheter for continuously measuring pressure of the bladder to provide continuous readings of bladder pressure. 
     In accordance with another aspect of the present invention, a multi-lumen catheter for monitoring intra-abdominal pressure is provided. The catheter includes an elongated body configured and dimensioned for insertion into a bladder of a patient, a first lumen, a second lumen, a third lumen, a first balloon at a distal portion and a second balloon proximal of the first balloon. The first lumen communicates with the first balloon, the second lumen communicates with the bladder to remove fluid from the bladder, and the third lumen communicates with the second balloon to inflate the second balloon to stabilize the catheter. The first balloon is filled with a gas to form a gas filled chamber to monitor pressure within the bladder to thereby monitor pressure within an abdomen of the patient. A sensor measures pressure within the bladder as the first balloon changes shape in response to changes in pressure in the bladder. 
     In accordance with another aspect of the present invention, a multi-lumen catheter is provided for monitoring intra-abdominal pressure, the catheter comprising an elongated body configured and dimensioned for insertion into a bladder of a patient, a first lumen, a second lumen, and a first balloon at a distal portion. The first lumen communicates with the first balloon and the second lumen communicates with the bladder to remove fluid from the bladder, the first balloon filled with a gas to form a gas filled chamber to monitor pressure within the bladder to thereby monitor pressure within an abdomen of the patient. A pressure sensor measures pressure of the bladder and the first lumen extends distally of the first balloon. 
     In accordance with another aspect of the present invention, a multi-lumen catheter for monitoring intra-abdominal pressure is provided comprising an elongated body configured and dimensioned for insertion into a bladder of a patient, a first lumen, a second lumen and a first balloon at a distal portion. A first side port communicates with the first lumen and the first lumen communicates with the first balloon. The second lumen communicates with the bladder to remove fluid from the bladder. The first balloon is filled with a gas to form a gas filled chamber to monitor pressure within the bladder to thereby monitor pressure within the abdomen. A pressure sensor measures pressure of the bladder and is positioned distal of the first side port for measuring pressure within the bladder resulting in a change of shape of the first balloon in response to changes in pressure in the bladder. 
     In accordance with another aspect of the present invention, a multi-lumen catheter for monitoring intra-abdominal pressure is provided. The catheter includes an elongated body configured and dimensioned for insertion into a bladder of a patient, a first lumen, a second lumen, and a third lumen, the lumens being independent. A first balloon is positioned at a distal portion and the first lumen communicates with the first balloon. The second lumen communicates with the bladder to remove fluid from the bladder. The first balloon and first lumen are filled with a gas to form a gas filled fully closed chamber to monitor pressure within the bladder to thereby monitor pressure within an abdomen of the patient. A pressure sensor measures pressure within the bladder based on deformation of the first balloon in response to pressure within the bladder exerted on an outer wall of the balloon, the pressure sensor measuring bladder pressure continuously and communicating with an external monitor to visually display pressure readings, the sensor providing continuous pressure measurements throughout its duration of insertion without requiring infusion of water into the bladder. 
     In accordance with another aspect of the present invention, a multi-lumen catheter for monitoring intra-abdominal pressure is provided. The catheter includes an elongated body configured and dimensioned for insertion into a bladder of a patient, a first lumen, a second lumen, an outer balloon at a distal portion and an inner balloon within the outer balloon. The first lumen communicates with the inner balloon and the second lumen communicates with the bladder to remove fluid from the bladder. The inner balloon and first lumen are filled with a gas to form a gas filled chamber to monitor pressure within the bladder to thereby monitor pressure within an abdomen of the patient. The outer balloon has a circumferential area greater than a circumferential area of the inner balloon and inflated with a fluid (liquid or a gas, e.g., air) wherein in response to pressure within the bladder exerted on an outer wall of the outer balloon, the outer balloon deforms and exerts a pressure on an outer wall of the inner balloon to deform the inner balloon and compress the gas, e.g., air, within the inner balloon and the first lumen. The pressure sensor measures bladder pressure based on gas compression caused by deformation of the inner balloon. As noted herein, the balloon(s) can be expanded by a gas such as air. 
     In accordance with another aspect of the present invention, a system for monitoring intra-abdominal pressure is provided comprising a catheter having an elongated body configured and dimensioned for insertion into the bladder of a patient, a first lumen, a second lumen, a third lumen, and a first balloon at a distal portion. The first lumen communicates with the first balloon and the second lumen communicates with the bladder to remove fluid from the bladder. The first balloon and first lumen are filled with a gas to form a gas filled fully closed chamber to monitor pressure within the bladder to thereby monitor pressure within an abdomen of the patient. A pressure sensor measures bladder pressure continuously and communicates with an external monitor to visually display pressure readings, the sensor providing continuous pressure measurements during its insertion without requiring infusion of water into the bladder. An indicator indicates if the measured pressure exceeds a threshold value. 
     The indicator can be a visual and/or audible indicator. 
     In accordance with another aspect, the present invention provides a method for measuring intra abdominal pressure comprising the steps of a) providing a catheter having first and second lumens and a balloon; b) inserting the catheter into a bladder of a patient; c) injecting gas into the first lumen of the catheter to expand the balloon from a deflated condition to a partially inflated condition; d) obtaining a first pressure reading of the bladder based on deformation of the balloon without injecting fluid into the bladder; e) transmitting the first pressure reading to an external monitor connected to the catheter; f) obtaining a second pressure reading of the bladder based on deformation of the balloon without injecting fluid into the bladder; g) transmitting the second pressure reading to the external monitor connected to the catheter; and h) obtaining consecutive continuous pressure readings of the bladder without injecting fluid into the bladder. 
     The method can include measuring the temperature of a body of a patient utilizing a temperature sensor within the first lumen. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that those having ordinary skill in the art to which the subject invention appertains will more readily understand how to make and use the surgical apparatus disclosed herein, preferred embodiments thereof will be described in detail hereinbelow with reference to the drawings, wherein: 
         FIG. 1A  is a side view of a first embodiment of the catheter of the present invention having a pressure balloon, a stabilizing balloon and a sensor positioned in the air lumen, both balloons shown in the deflated (collapsed) condition; 
         FIG. 1B  is a side view similar to  FIG. 1A  showing the two balloons in the inflated (expanded) condition; 
         FIG. 2  is a schematic view of the system utilizing the catheter of  FIG. 1A  with an alarm system; 
         FIG. 3  is a close-up view of the tip of the catheter of  FIG. 1A ; 
         FIG. 4  is a close-up view of the sensor of  FIG. 1A  within the air lumen; 
         FIG. 5  is an enlarged transverse cross-sectional view of the catheter of  FIG. 1 ; 
         FIG. 6  is an enlarged transverse cross-sectional view of an alternate embodiment of a catheter of the present invention having four lumens; 
         FIG. 7  is a side view of an alternate embodiment of the catheter of the present invention similar to  FIG. 1A  except having a single balloon, the balloon shown in the inflated condition, 
         FIGS. 8A and 8B  are side views of an alternate embodiment of the catheter of the present invention having two balloons and a pressure sensor and a separate temperature sensor in the air lumen, the two balloons shown in the deflated condition, with  FIG. 8A  showing the distal end and  FIG. 8B  showing the proximal end of the catheter; 
         FIG. 9  is a side view similar to  FIG. 8A  showing the two balloons in the inflated condition; 
         FIG. 10A  is a close up view of the distal portion of the catheter of  FIG. 8A ; 
         FIG. 10B  is an enlarged transverse cross-sectional view of the catheter of  FIG. 8A ; 
         FIG. 11  is a side view of another alternate embodiment of the catheter of the present invention having two balloons, a sensor in the air lumen and an external transducer, the two balloons shown in the inflated condition; 
         FIG. 12  is a side view of another alternate embodiment of the catheter of the present invention having two balloons, a temperature sensor in the air lumen and the pressure sensor external of the catheter, the two balloons shown in the inflated condition; 
         FIG. 13A  is a side view of another alternate embodiment of the catheter of the present invention having two balloons and a pressure sensor positioned within the pressure balloon, the two balloons shown in the inflated condition; 
         FIG. 13B  is an enlarged view of the distal portion of the catheter of  FIG. 13A ; 
         FIG. 14A  is a side view of another alternate embodiment of the catheter of the present invention having dual pressure sensors, the first sensor positioned within the air lumen and the second sensor positioned external of the catheter, the two balloons shown in the inflated condition; 
         FIG. 14B  is an enlarged view of the distal portion of the catheter of  FIG. 14A ; 
         FIG. 15  is a side view of another alternate embodiment of the catheter of the present invention having an outer and inner pressure balloon and a stabilizing balloon, the balloons shown in the inflated condition; 
         FIG. 16  is a side view similar to  FIG. 15  illustrating an alternate embodiment having a larger outer balloon; 
         FIG. 17A  is a side view similar to  FIG. 15  illustrating an alternate embodiment having a pear-shaped outer balloon; 
         FIG. 17B  is a side view similar to  FIG. 17A  showing an alternate embodiment wherein the drainage opening is between the two balloons; 
         FIG. 18A  is a side view of another alternate embodiment of the catheter of the present invention having a port for connection to an external pressure transducer and an outer and inner pressure balloon, the two balloons shown in the inflated condition; 
         FIG. 18B  is close up view of the distal end of the catheter of  FIG. 18A ; 
         FIG. 19  is a perspective view of the catheter of  FIG. 18A  with a pressure transducer hub attached to the catheter; 
         FIGS. 20A, 20B and 20C  are enlarged front, side and perspective views of the outer balloon of  FIG. 18A  in the expanded condition; 
         FIGS. 21A, 21B and 21C  are enlarged front, side and perspective views of the stabilizing balloon of  FIG. 18A  in the expanded condition; 
         FIGS. 22A, 22B and 22C  are enlarged front, side and perspective views of the inner balloon of  FIG. 18A  in the expanded condition; 
         FIG. 23  is a transverse cross-sectional view of the catheter of  FIG. 18  illustrating the five lumens of the catheter; 
         FIG. 24A  is a cutaway side view showing the pressure transducer hub prior to connection to the catheter of  FIG. 18A , a portion of the hub wall and catheter connector removed to show internal components; 
         FIG. 24B  is a side view similar to  FIG. 24A  showing the hub attached to the catheter; 
         FIG. 25A  is a perspective view of the transducer hub of  FIG. 24A ; 
         FIG. 25B  is a perspective view of the proximal end of the catheter showing a connector for the thermocouple wire; 
         FIG. 26  is a side view of alternate embodiment of the pressure transducer hub having a shroud over the elongated member for snap fitting onto the catheter; 
         FIG. 27  is a schematic view of an alternate embodiment of the pressure transducer hub extendable into two side ports of the catheter; 
         FIG. 28A  is a perspective view of an alternate embodiment of the transducer hub and connector; 
         FIG. 28B  is a cutaway side view of the hub and connector of  FIG. 28A  showing the pressure transducer prior to connection to the catheter of  FIG. 18A , a portion of the hub wall and connector removed to show internal components; 
         FIG. 28C  is a cutaway side view similar to  FIG. 28B  showing the hub attached to the catheter; 
         FIG. 28D  is a cutaway side view similar to  FIG. 28B  from the other side; 
         FIG. 29A  is a cutaway side view of the hub and connector of an alternate embodiment showing the pressure transducer prior to connection to the catheter of  FIG. 18A , a portion of the hub wall and catheter connector removed to show internal components 
         FIG. 29B  is a cutaway side view of the hub and connector of  FIG. 29A ; and 
         FIG. 29C  is a cutaway view similar to  FIG. 29B  showing the hub attached to the connector of  FIG. 29A  when attached. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Increased abdominal pressure can cause many adverse conditions including diminishing the function of the intestines, liver, and blood vessels. Simply viewing or feeling the abdomen does not provide sufficient information or reading of health conditions. 
     It is recognized that urinary bladder pressure directly correlates to the intra-abdominal pressure. Although pressure readings can be determined by access to the esophagus or rectum, the bladder has been found to be the most accurate and the least invasive. In trauma or burn patients for example, time is critical and the less complicated the method for determining bladder pressure the better the clinical results. 
     The catheters of the present invention measure abdominal pressure via measurement of bladder pressure without filling the bladder with water. This avoids the risks associated with retrograde filling of the bladder with water as such retrograde filling not only increases the complications and workload for the intensive care (IC) staff and can create inaccuracies by providing false elevation of IAP readings, but can adversely affect the patient by increasing the risk of infection. Furthermore, by avoiding refilling of the bladder, bladder pressure can be measured continuously. This is because in devices requiring filling the bladder with water, water needs to be periodically added to the bladder to replace the water drained from the bladder and measurement readings are interrupted during water insertion. Due to these repeated interruptions, pressure cannot be read continuously. Note in some cases, as much as 50 cc of fluid needs to be repeatedly added to the bladder. 
     Thus, the catheters of the present invention efficiently and effectively measure bladder pressure without requiring filling the bladder with water. Also, as will become apparent from the discussion below, the catheters of the present invention provide a more accurate reading of pressure and enable continuous monitoring of the bladder pressure. This is all achieved in an easy to insert device. 
     It should be noted that the catheters of the present invention can be utilized for measuring other pressure in a patient and are not limited to intra-abdominal pressure. 
     Furthermore, in some embodiments, the catheter of the pressure invention provides a dual sensor to provide a backup pressure reading. In some embodiments, a dual pressure balloon arrangement is provided. This various embodiments are discussed in more detail below. 
     Referring now to the drawings and particular embodiments of the present invention wherein like reference numerals identify similar structural features of the devices disclosed herein, there is illustrated in  FIGS. 1A-5  a catheter of a first embodiment of the present invention. The catheter (device) is designated generally by reference numeral  10  and is configured for insertion into and positioning within the bladder of the patient for measuring intra-abdominal pressure. This measurement is to check if the intra-abdominal pressure exceeds a specified threshold since if such threshold is exceeded, there is a risk to the patient as discussed above and steps need to be taken to reduce the pressure such as draining additional fluid from the abdomen, opening the abdomen, etc. 
     The catheter  10  of the present invention can in some embodiments include an alarm or indicator to alert the user if pressure within the bladder, which correlates to pressure within the abdomen, rises to an unacceptable level, i.e., beyond a threshold or predetermined value (pressure). The indicator or alarm can be on the catheter or alternatively on an external device such as the monitor as discussed in more detail below. The alarm can also be connected via wireless connection to a phone or remote device to alert the appropriate personnel. The indicator or alarm can alternatively or in addition be activated if a change in pressure measurement exceeds a specified rate over a specified period of time. 
     Turning now to details of the catheter  10 , which is also referred to herein as the device  10 , and with initial reference to  FIGS. 1A, 1B, 3 and 4  the catheter  10  of this embodiment has an elongated flexible shaft  12  having a lumen (channel)  14  extending within the shaft  12  and communicating at its distal region with balloon  16  to fluidly communicate with balloon  16  to inflate the balloon. Balloon  16  is utilized for monitoring pressure and is also referred to herein as the “pressure balloon.” A fluid port  15  is positioned at a proximal region  17  of the catheter  10  for communication with an infusion source for infusion of gas, e.g., air, through the lumen  14  and into the balloon  16 . The catheter  10  is shown in  FIG. 1A  with balloon  16  in the deflated condition (position) and in  FIG. 1B  with the balloon  16  in the inflated condition (position). The shaft  12  also includes a second lumen (channel)  20  and third lumen (channel)  24  extending therein (see also  FIG. 5 ). In a preferred embodiment, the second lumen  20  is the largest lumen and is configured for continuous drainage of bodily contents from the bladder and can be connected to a drainage bag for collection of urine. Second lumen  20  has a side opening  22  at a distal portion, best shown in  FIG. 3 , communicating with the bladder. The third lumen  24  terminates at its distal end within balloon  26  to fluidly communicate with balloon  26  to inflate the balloon  26 . The balloon  26  is inflatable to stabilize the catheter  10  to limit movement of the catheter  10  to keep it in place within the bladder and is also referred to herein as “the stabilizing balloon  26 .” A fluid port  28  is positioned at a proximal region  17  of the catheter  10  for communication with an infusion source for infusion of fluid through the lumen  24  and into the balloon  26 . The balloon  26  can be filled with fluid, e.g., liquid such as water or saline, or a gas, e.g., air. In  FIG. 1A , the balloon  26  is shown in the deflated condition and in  FIG. 1B  in the inflated condition. 
     Note  FIG. 5  is a transverse cross-section of the catheter showing the three lumens of various shapes. These cross-sectional shapes of the lumens are provided by way of example as one or more of the lumens can be circular, oval or other symmetrical or asymmetrical shapes in transverse cross section. This also applies to the cross-sectional views of the other embodiments herein, e.g.,  FIGS. 6, 10B and 23  wherein the lumens can be shapes other than those shown. As noted above, preferably the drainage lumen is the largest lumen but in alternate embodiments one or more of the other lumens could be larger than the drainage lumen. 
     A sensor  30  is positioned within lumen  14  adjacent balloon  16 . The wire(s)  32  are shown extending through lumen  14 , the sensor  30  and wire(s)  32  being of sufficiently small size so as not to interfere with air flow though lumen  14 . The sensor  30  measures pressure of the bladder. The sensor  30  is part of a transducer for converting the variation in pressure to an electrical signal for transmission to an external monitor. The pressure sensor also includes a temperature sensor to measure core temperature of the body as seen inside the bladder. Transmission wire(s)  34  of the temperature sensor extend adjacent wire  32  through lumen  14  and terminate external of the catheter  10  for connection to an external monitor. The transducer can be wired directly to the monitor or alternatively wired to a converter external of the catheter for converting the signal received by the transducer and transmitting a signal to the monitor, e.g., a bedside monitor, to display the pressure readings. This is shown schematically in  FIG. 2 . The readings can be displayed in quantitative form, graphical form or other displays to provide an indicator to the clinician of the bladder pressure. The monitor, or a separate monitor, will also display the temperature readings from sensor  30 . Alternatively, the sensor/transducer can be connected to the monitor via a Bluetooth wireless connection. 
     Wires  32  and  34  can extend though lumen  14  and exit side port  15  for connection to a converter or monitor or alternatively can be inserted through the lumen  14 , piercing the wall to enter the lumen  14  distal of the side port. 
     An alarm system can also be provided wherein the system includes a comparator for comparing the measured pressure (and/or temperature) to a threshold (predetermined) value, and if such threshold is exceeded, an indicator, e.g., an alarm, is triggered to indicate to the hospital personnel the excessive pressure and/or temperature. An alarm system can alternatively or in addition be activated if a change in pressure measurement exceeds a specified rate over a specified period of time. This would alert the staff to an imminent risk of ACS prior to intra-abdominal pressure exceeding a certain value, e.g., 20 mm hg, since due to this link, the relationship between intra-abdominal pressure and abdominal cavity volume is believed to be linear up to an intra-abdominal pressure of 12-15 mm hg and increasing exponentially thereafter. 
     The alarm system can be part of the catheter (as shown in  FIG. 2 ) or alternatively external to the catheter  10 . 
     The lumen  14  and space  16   a  within balloon  16  together form a closed gas, e.g., air, chamber, i.e., the lumen  14  forming an air column. With the balloon  16  filled with air, pressure on the external wall of the balloon will force the balloon to deform inwardly, thereby compressing the air contained within the balloon space  16   a  and within the lumen  14 . The pressure sensor  30  is located in a distal portion of the lumen  14  at the region of the balloon  16  and thus is positioned at the distal end of the air column. Therefore, the pressure is sensed at the distal region as the sensor  30  detects change in air pressure in lumen  14  due to balloon deformation. Placement of the sensor  30  at a distal location provides a pressure reading closer to the source which advantageously increases the accuracy because it reduces the risk of transmission issues by reducing the amount of interference which could occur due to water, air, clots, tissue, etc. if the transmission is down the air lumen (air column). 
     Additionally, the pressure measurement occurs about a more circumferential area of the balloon  16  providing a pressure reading of a region greater than a point pressure sensor reading. Also, average pressure over an area of the bladder wall can be computed. Thus, the area reading gleans information on pressure over more of the bladder wall. Stated another way, the balloon has a relatively large surface area with multiple reference points to contribute to average pressure readings of the surface around it by the sensor. 
     The air column is charged by insertion of air through the side port  15  which communicates with lumen  14 . The side port  15  includes a valve to provide a seal to prevent escape of air from a proximal end. The balloon  16  can be composed of impermeable material, or in alternative embodiments, a permeable or semi-permeable material with an impermeable coating. This seals the air column at the distal end to prevent escape of air through the distal end, i.e., through the wall of the balloon  16 . Thus, with the lumen sealed at the proximal and distal ends, a closed air system is provided, and without the requirement for repeated water insertion, a fully closed unit is provided. 
     In some embodiments, when the lumen  14  is air charged, the balloon  16  is not fully inflated. This improves the accuracy of the balloon  16  transmitting pressure from external the balloon to the interior of the balloon and into the lumen, i.e., air column, by ensuring the balloon has sufficient compliancy to prevent the balloon from introducing artifact into the pressure reading which would diminish its accuracy. 
     In some embodiments, the pressure balloon  16  is of a size to receive at least about 3 cc (3 ml) of fluid. However, other sizes/volumes are also contemplated such as about 2 cc or about 1 cc. Additionally, these volumes represent the maximum volume of fluid for the balloon, however, as noted above, in preferred embodiments, the pressure balloon  16  is not fully inflated so it would receive less than the maximum volume. Thus, with a balloon of X volume, the fluid would receive X-Y fluid, with Y representing the amount of desired extra space to achieved desired compliancy of the balloon while still enable sufficient inflation of the balloon to achieve its pressure induced deformation function. 
     Note in this embodiment, the stabilizing balloon  26  is positioned proximal of the pressure balloon  16 . Also, in this embodiment, the stabilizing balloon  26  is larger than the pressure balloon  16 . By way of example, the stabilizing balloon  26  can have a fully expanded diameter of about 23 mm and the pressure balloon  16  can have a fully expanded diameter of about 15 mm, although other dimensions or diameters for these balloons are also contemplated. By way of example, the stabilizing balloon  26  can have a capacity of about 10 cc (10 ml) of air, although other sizes/volumes are also contemplated. Note these sizes/volumes for both balloons are provided by way of example and other sizes are also contemplated. Alternatively, the stabilizing balloon can be the same size or smaller than the pressure balloon. Various shapes of the balloons are also contemplated. 
     Additionally, although the balloon  26  is positioned proximal of the balloon  16 , it is also contemplated that the balloon  26  be positioned distal of balloon  16 . The axial spacing of the balloons  16 ,  26  enable the stabilizing balloon  26  to engage the bladder wall to provide a sufficient radial force thereon for securing/mounting the catheter within the bladder without interfering with the function of balloon  16 . 
     It should be appreciated that although the stabilizing balloon is shown in the embodiment of  FIG. 1 , it is also contemplated as an alternative that the catheter and system of  FIGS. 1 and 2  can be utilized without the stabilizing balloon  26  as shown for example in  FIG. 7 . Similarly, although the various embodiments (catheter) disclosed herein utilize a stabilizing balloon, it is also contemplated that alternatively the catheter of these various embodiments not include a stabilizing balloon. In the embodiment of  FIG. 7 , catheter  50  has two lumens: 1) a lumen for drainage of the bladder which has a side opening at a distal end to communicate with the bladder (similar to lumen  20  of  FIG. 1A ); and 2) an air lumen filling pressure balloon  16  via insertion of air through side port  55 . The sensor  30  is positioned within the air lumen in the same manner as sensor  30  is in lumen  14  or in the alternative positions disclosed herein. Thus, the pressure and temperature sensing described in conjunction with  FIG. 1  is fully applicable to the embodiment of  FIG. 7 . Besides the elimination of the stabilizing balloon and its lumen and side port, catheter  50  is the same as catheter  10 , 
     Note that although only one sensor is shown in  FIG. 3 , it is also contemplated that multiple sensors can be provided. Also, note that the sensor  30  is positioned in lumen  14  at a mid-portion of the balloon, i.e., just proximal where the opening in lumen  14  communicates with the interior  16   a  of the balloon  16 . It is also contemplated that the sensor can be placed at another portion within the lumen  14 , e.g., a more proximal portion, with respect to the lumen opening. Also, the lumen opening need not be at the mid portion of the balloon and can be at other regions of the balloon to communicate with the interior space  16   a . Note if multiple sensors are provided, they can be positioned at various locations within the lumen  14 . 
     As shown, the sensor  30  and its transmission wires are located in the same lumen  14  also used for initial inflation gas, e.g., air, for balloon  16  and for the air charged column. This minimizes the overall transverse cross-section (e.g., diameter) of the catheter  10  by minimizing the number of lumens since additional lumens require additional wall space of the catheter. However, it is also contemplated in an alternate embodiment that the sensor is in a dedicated lumen separate from the inflation lumen  14 . This can be useful if a larger sensor or additional wires are utilized which would restrict the air lumen if provided therein. This is also useful if a specific sized lumen for the sensor and wires is desired to be different than the sized lumen for the air column. Provision of a separate lumen is shown in the cross-sectional view of  FIG. 6  wherein in this alternate embodiment catheter  40  has four lumens: 1) lumen  42  for drainage of the bladder which has a side opening at a distal end to communicate with the bladder (similar to lumen  20  of  FIG. 1 ); 2) lumen  44  for filling pressure balloon  16 ; 3) lumen  46  for filling stabilizing balloon  26 ; and 4) lumen  50  in which sensor  30  and its transmission wires  32  and temperature sensor wires  34  are contained. In all other respects catheter  40  is identical to catheter  10  and its balloons, air channel, sensor, etc. would perform the same function as catheter  10 . Therefore, for brevity, further details of catheter  40  are not discussed herein as the discussion of catheter  10  and its components and function are fully applicable to the catheter  40  of the embodiment of  FIG. 6 . As noted above, the cross-sectional shapes of the lumens can be circular, oval, etc. or other shapes. 
     Turning now to the use of the catheter  10 , the catheter  10  is inserted into the bladder. Note catheter  50  would be used in the same manner. The balloon  26  is inflated to secure the catheter  10  in place during the procedure by insertion of a fluid (liquid or gas) through side port  28  which is in fluid communication with lumen  24 . The system is charged by inflation of the balloon  16 , i.e., preferably partial inflation for the reasons discussed above, by insertion of air via a syringe through port  15  which is in fluid communication with lumen  14 . As discussed above, the catheter  10  is a closed system with the balloon  16  sealed so that air inserted through lumen  14  and into balloon  16  cannot escape through balloon  16 . Thus, a closed chamber is formed comprising the internal space  16   a  of the balloon  16  and the internal lumen  14  communicating with the internal space  16   a  of balloon  16 . With the balloon  16  inflated, pressure monitoring can commence. When external pressure is applied to an outer surface  16   b  of the balloon  16 , caused by outward abdominal pressure which applies pressure to the bladder wall and thus against the wall of balloon  16 , the gas e.g., air, within the chamber is compressed. The sensor  30  at the distal end of lumen  14  provides continuous pressure readings, converted to an electrical signal by the transducer within the distal end of lumen  14 , and then electrically communicates through wire(s)  32  extending through lumen  14 , exiting through the proximal side port  15  and connected to an external monitor. Note the wire can terminate at the proximal end in a plug in connector which can be connected directly to the monitor or alternatively plugged into a converter to convert the signals from the transducer in the embodiments wherein the converter is interposed between the wires and monitor (see e.g., the system of  FIG. 2 ) to provide the aforedescribed graphic display. Although, the system is capable of continuous pressure and temperature monitoring, it can also be adapted if desired for periodic monitoring so the pressure and temperature readings can be taken at intervals or on demand by the clinician. 
     In the embodiments wherein an indicator is provided, if the measured pressure exceeds a threshold value, and/or a change in pressure measurement exceeds a specific rate over a specific time period, the indicator would alert the clinician, e.g., via a visual indication or an audible indication that the threshold is exceeded. The indicator in some embodiments can include an audible or visual alarm (shown schematically in  FIG. 2 ). In the embodiments having an indicator, the indicator can be provided on a proximal end of the catheter which extends out of the patient or the indicator can be part of an external component such as the monitor or a separate alarm system. A visual, audible, or other indicator can likewise be provided in any of the other embodiments disclosed herein to indicate if the measured temperature exceeds a predetermined value, and such indicator can include an alarm and can be part of the catheter or a separate component. 
     In the embodiment of  FIGS. 1-7 , within the distal end of the air lumen  14  is a pressure transducer and pressure sensor  30  which also includes a temperature sensor. In the alternate embodiment of  FIGS. 8A-10B , the temperature sensor is separate from the pressure sensor. More specifically, catheter  60  has an elongated flexible shaft  62  having a lumen (channel)  64  extending within the shaft  62  and fluidly communicating at a distal region with balloon  66  to inflate the balloon. Balloon  66  (also referred to as the pressure balloon) is utilized for monitoring pressure. A fluid side port  65  is positioned at a proximal region  67  of the catheter  60  for communication with an infusion source for infusion of gas e.g., air, through the lumen  64  and into the balloon  66 . The catheter  60  is shown in  FIG. 8A  with balloon  66  in the deflated condition (position) and in  FIG. 9  with the balloon  66  in the inflated condition (position). The shaft  62  also includes a second lumen (channel)  70  and third lumen (channel)  74  extending therein. The second lumen  70  is preferably the largest lumen and is configured for drainage of the bladder. Second lumen  70  has a side opening  72  at a distal portion communicating with the bladder. The third lumen  74  communicates at a distal region with stabilizing balloon  76  to fluidly communicate with balloon  76  to inflate the balloon. The stabilizing balloon  76  is inflatable to stabilize the catheter  60  to limit movement of the catheter  60  to keep it in place within the bladder. A side fluid port  75  is positioned at a proximal region  67  of the catheter  60  for communication with an infusion source for infusion of fluid through the lumen  74  and into the balloon  76 . 
     Sensor  80  is positioned in lumen  64  for sensing pressure in response to balloon deformation in the same manner as sensor  30 . Sensor  82  is positioned in lumen  64  distal of sensor  80  for measuring core temperature. Temperature sensor  82  can be a thermocouple, a thermistor or other types of temperature sensors. As shown in  FIG. 9 , the temperature sensor is distal of the balloon  66  and its transmission wire(s)  83  extend proximally within lumen  64 , exiting a proximal end (through side port  65 ) for communication with a monitor or alternatively a converter which communicates with the monitor. Wire(s)  81  of sensor  80  also extends through lumen  64 , alongside wire  83 , exiting through the side port  65  or a proximal end wall or a side wall of the lumen. It is also contemplated that alternatively one or both of sensors  80  and  82 , and their associated wires  81 ,  83 , can be positioned in a separate “fourth” lumen such as in the embodiment of  FIG. 6  so that the “inflation lumen” and the “sensor lumen” are independent. 
     In use, catheter  60  is inserted into the bladder and stabilizing balloon  76  is inflated to secure the catheter  60  in place. The system is charged by inflation of the balloon  66 , i.e., preferably partially inflated for the reasons discussed above, by insertion of gas, e.g., air, through port  65  which is in fluid communication with lumen  64  in a closed system formed by the internal space  66   a  of the balloon  66  and the internal lumen  64  communicating with the internal space  66   a  of balloon  66 . With the balloon  66  inflated, pressure monitoring can commence as external pressure applied to an outer surface of the balloon  66  compresses the gas within the chamber. The sensor  80  at the distal end of lumen  64  provides continuous pressure readings, converted to an electrical signal by the transducer within the distal end of lumen, and then electrically communicates through wires  82  extending through lumen  64  to an external monitor either directly or via a converter. The sensor  82  at the distal end of lumen  64  provides continuous temperature readings via wires  83  communicating directly or indirectly with the monitor, Although, the system is capable of continuous pressure and continuous temperature monitoring, as with the other systems disclosed herein, it can also be adapted if desired for periodic monitoring so the pressure and/or temperature readings can be taken at intervals or on demand by the clinician. 
     In the alternative embodiment of  FIG. 11 , catheter  90  is identical to the catheter  60  of  FIG. 8  except that the pressure transducer is positioned external of the catheter rather than in the air (or other gas) lumen. That is, instead of the pressure transducer including the sensor being positioned within the distal end of the air lumen, the pressure sensor  92  is positioned within lumen  94  at the distal end of the lumen and transmission wire(s)  93  connect the sensor  92  to the pressure transducer  96  positioned outside of the patient at a proximal region of catheter  90 . As shown, the pressure transducer  96  can be positioned in a side port of catheter  90 . In alternate embodiments, it is positioned outside the catheter. The temperature sensor  95  is positioned within lumen  94  along with transmission wire  97  in the same manner as temperature  82  and wires  83  are positioned in catheter  60  described above. The temperature sensor  95  can be a separate sensor positioned distal of the pressure sensor  92  as shown or alternatively it can be part of sensor  92  as in the embodiment of  FIG. 1 . In all other respects, catheter  90  is identical to catheter  60  and therefore for brevity further discussion is not provided since the structure and function of the balloons, the lumens, the positioning of the sensors in the lumens, the continuous pressure monitoring, etc., as well as the aforedescribed alternative arrangements of catheter  60 , are fully applicable to the catheter  90 . 
     In the alternative embodiment of  FIG. 12 , catheter  100  is identical to catheter  60  of  FIG. 8  except that the pressure transducer and pressure sensor are positioned external of the patient at a proximal region of the catheter rather than in the air lumen. That is, instead of the pressure transducer sensor being positioned within and at the distal end of the air lumen, the transducer and pressure sensor  102  are positioned at a side port  103  of the catheter  100 . In alternative embodiments, they are positioned outside the catheter. In yet other embodiments, the pressure sensor and/or pressure transducer can be positioned within the air (or other gas) lumen at a proximal end of the air lumen. The temperature sensor  107  is positioned within lumen  104  along with transmission wire(s)  108  in the same manner as temperature sensor  82  and wire  83  are positioned in catheter  60  described above. The system is charged by inflation of the balloon  106 , i.e., preferably partially inflated for the reasons discussed above, by insertion of air via a syringe or other injection device through the side port  103  which is in fluid communication with lumen  104 . The catheter  100  is a closed system with the balloon  106  sealed so that air inserted through lumen  104  and into balloon  106  cannot escape through balloon  106 . Thus, a closed chamber is formed comprising the internal space of the balloon  106  and the internal lumen  104  communicating with the internal space of balloon  106 . With the balloon  106  inflated, pressure monitoring can commence. When external pressure is applied to an outer surface of the balloon  106 , caused by outward abdominal pressure which applies pressure to the bladder wall and thus against the wall of balloon  16 , the gas (e.g., air) within the chamber of the balloon  106  is compressed. This compresses the air within the lumen  104  creating an air charged column along the lumen  104 . The sensor  102  at the proximal end of catheter  100  measures pressure of the air column at its proximal end and can provide continuous pressure readings, converted to an electrical signal by the transducer at the proximal end or external of the catheter  100 , and then electrically communicates through wire(s) to an external monitor. The balloon  106 , like balloon  16 , balloon  66  and the other pressure balloons described herein, is of sufficiently large size to provide a sufficient circumferential area for detection of pressure changes along several parts of the bladder wall, thereby providing an average pressure and enabling more accurate pressure readings. Balloon  109  is a stabilizing balloon like balloon  76  inflated through a separate lumen. 
     Note the wire(s) of the sensor  102  can terminate at the proximal end in a plug in connector which can be connected directly to the monitor or alternatively plugged into a converter to convert the signals from the transducer in the embodiments where the converter is interposed between the wires and monitor (see e.g. the system of  FIG. 2 ) to provide the aforedescribed graphic display. Although, the system is capable of continuous pressure and temperature monitoring, it can also be adapted if desired for periodic monitoring so the pressure and/or temperature readings can be taken at intervals or on demand by the clinician. In all other respects, catheter  100  is identical to catheter  60  and therefore for brevity further discussion is not provided since the structure and function of the balloons, the continuous pressure monitoring, etc., as well as the aforedescribed alternative arrangements of catheter  60 , are fully applicable to the catheter  100 . 
       FIGS. 13A and 13B  illustrate an alternate embodiment wherein catheter  110  includes a pressure sensor within the balloon. More specifically, catheter  110  has an elongated flexible shaft  112  having a lumen (channel)  114  extending within the shaft  112  and communicating at its distal region with balloon  116  to fluidly communicate with balloon  116  to inflate the balloon. Balloon  116  (also referred to as the pressure balloon) is utilized for monitoring pressure. A fluid side port  115  is positioned at a proximal region  117  of the catheter  110  for communication with an infusion source for infusion of gas through the lumen  114  and into the balloon  116 . The shaft  112  also includes a second lumen (channel)  120  and third lumen (channel)  122  extending therein. Second lumen  120  has a side opening  124  at a distal portion communicating with the bladder. The third lumen  122  communicates at a distal region with stabilizing balloon  126  to fluidly communicate with balloon  126  to inflate the balloon to limit movement of the catheter  110  to keep it in place within the bladder for drainage. A fluid port  113  is positioned at a proximal region  117  of the catheter  110  for communication with an infusion source for infusion of fluid through the lumen  122  and into the balloon  126 . 
     The pressure sensor  130  is carried by catheter  110  and positioned within the balloon  116  to measure pressure in response to deformation of the balloon in response to pressure exerted on an outer wall of balloon  116 . The pressure transducer can include the sensor  130  or can be a separate component positioned at a proximal end of the catheter external of the catheter  110 . The temperature sensor  132  can be positioned within the balloon  116 , can be part of sensor  130 , or alternatively positioned within lumen  114  (as shown in  FIG. 13B ), with its transmission wire(s)  127  extending within the gas, e.g., air, lumen  114  along with the wires of sensor  130  in the same manner as in catheter  60  described above. 
     In all other respects, catheter  110  is identical to catheter  60  and therefore for brevity further discussion is not provided since the structure and function of the balloons, lumens, continuous pressure monitoring, etc. as well as the aforedescribed alternative arrangements of catheter  60 , are fully applicable to the catheter  110 . 
     As discussed above, the pressure balloons disclosed herein have a large circumferential area (and large volume) to provide multiple reference points for pressure readings and to provide an average pressure to enable more accurate readings. Thus, the pressure balloon provides for gross measurement. In an alternate embodiment shown in  FIG. 15 , the pressure balloon for detecting pressure, designated by reference numeral  142 , forms an outer balloon of catheter  140 . Contained within the outer balloon  142  is an inner balloon  143 . The inner balloon  143  provides a smaller diameter balloon and a smaller circumference (and volume) than the outer balloon  14 . The inner balloon  143  together with the lumen  144  forms a smaller gas, e.g., air, column than in the embodiments discussed above where the larger balloon internal space communicates directly with the air lumen. This provides finer measurements. Thus, the compliant outer balloon  142  compresses the compliant inner balloon  143  which compresses the air within air lumen  144 . The closed system is thereby formed by the internal space of the inner balloon  143  and the lumen  144 . In certain instances, the smaller balloon air column can provide a more accurate reading from the average pressure determined by the larger outer balloon  142 . 
     The inner balloon  143  and outer balloon  142  can be separately/independently inflated and closed with respect to each other so there is no communication, e.g. passage of gas or liquid, between the inner and outer balloons  143 ,  142 . 
     The pressure transducer and pressure sensor  150  can be positioned within the lumen  144  in the same manner as sensor  30  of  FIG. 1  and can function in the same manner. Alternatively, the pressure transducer can be at a proximal end of the catheter  140  as in the embodiment of  FIG. 12  or external of the catheter. A temperature sensor can be part of sensor  150  as in the embodiment of  FIG. 1  or alternatively it can be a separate component which can be positioned for example distal of the pressure sensor within the gas, i.e., air, lumen as in the embodiment of  FIG. 8A . The transmission wires of the pressure sensor  150  and the temperature sensor extend through lumen  144 . 
     The catheter  140  can optionally include a stabilizing balloon  145  similar to balloon  76  of  FIG. 8 . The catheter  140  would have a lumen, e.g., lumen  146 , to inflate the stabilizing balloon  145 . Lumen  148  with side opening  149  provides for drainage of the bladder. Lumen  144  which is used to inflate the inner balloon  143  and create the gas column has an opening at a distal region to communicate with inner balloon  143 . A separate lumen  147  has an opening at a distal region to communicate with the outer balloon  142  to fill the outer balloon  142 . 
     In use, catheter  140  is inserted into the bladder and stabilizing balloon  145  is inflated to secure the catheter  140  in place. The system is charged by inflation of the inner balloon  143 , i.e., preferably partially inflated for the reasons discussed above, by insertion of air through a side port which is in fluid communication with lumen  144  in a closed system formed by the internal space  143   a  of the inner balloon  143  and the internal lumen  144  communicating with the internal space of inner balloon  143 . Outer balloon  142  is filled, i.e., preferably partially inflated for the reasons discussed above, via injection of air through a separate lumen. With the outer balloon  142  inflated, pressure monitoring can commence as external pressure applied to the larger circumferential outer surface of the outer balloon  142  compresses and deforms the outer balloon  142  which compresses the inner balloon  143 . As the inner balloon  143  is compressed and deformed in response to compression/deformation of the outer balloon  142  based on changes to bladder pressure, the sensor  150  at the distal end of lumen  144  provides continuous pressure readings, converted to an electrical signal by the transducer within the distal end of lumen  144 , and then electrically communicates through wires  152  extending through lumen  144  to an external monitor either directly or via a converter. Although, the system is capable of continuous pressure and continuous temperature monitoring, as in the other embodiments disclosed herein it can also be adapted if desired for periodic monitoring so the pressure and/or temperature readings can be taken at intervals or on demand by the clinician. 
     Note that although separate lumens are provided for the inflation of inner balloon  143  and outer balloon  142 , in an alternate embodiment, a single lumen can be utilized to inflate both balloons  143  and  142 . 
       FIG. 16  illustrates an alternate embodiment of catheter  140 , designated by reference numeral  140 ′. Catheter  140 ′ is identical to catheter  140  except a larger outer balloon  142 ′ is provided to cover more surface area for pressure readings. In all other respects, catheter  140 ′ is identical to catheter  140  and for brevity further discussion is not provided since the features and functions of catheter  140 , and its alternatives such as single or two lumens for inner and outer balloon inflation, are fully applicable to catheter  140 ′. For ease of understanding, the components of catheter  140 ′ which are identical to catheter  140  are given the same reference numerals as catheter  140 . 
     Note that the larger balloon  142 ′ can be used with the catheters of any of the embodiments described herein. Thus, a pressure balloon of the larger size balloon  142 ′ can be used instead of the smaller pressure balloons illustrated in the drawings. Note the size of the balloons is provided by way of example and are not necessarily drawn to scale comparatively to the other components. 
       FIG. 17A  illustrates an alternate embodiment of catheter  140 , designated by reference numeral  140 ″. Catheter  140 ″ is identical to catheter  140  except a pear shaped larger outer balloon  142 ″ is provided. The larger balloon  142 ″ covers more surface area for pressure readings. The pear shape could in certain applications decrease the risk of obstructing the ureter and provide more tactile continuity of the balloon to the bladder wall giving a better transmission of abdominal pressure to the internal sensor. In all other respects, catheter  140 ″ is identical to catheter  140  and for brevity further discussion is not provided since the features and functions of catheter  140 , and its alternatives such as single or two lumens for inner and outer balloon inflation, are fully applicable to catheter  140 ″. For ease of understanding, the components of catheter  140 ″ which are identical to catheter  140  are given the same reference numerals as catheter  140 .  FIG. 17B  illustrates a catheter identical to catheter  140 ″ with identical balloons, the only difference being that the side opening  149 ′ is positioned proximal of the balloon  143  rather than distal of the balloon as in  FIG. 17A . That is, opening  149 ′, in communication with the catheter lumen  148 ′ for drainage of the bladder, is positioned between the stabilizing balloon  145  and the inner and outer pressure (and inner) pressure balloon  142 ″ (and  143 ). Thus, it is distal of the stabilizing balloon  145  and proximal of the outer balloon  142 ″. 
     Note that the positioning of the side opening for drainage of  FIG. 17B , which communicates with the drainage lumen of the catheter, can be utilized with any of the catheters disclosed herein. Thus, in the catheters disclosed in the various embodiments herein, instead of the drainage opening positioned distal of the pressure balloon(s), it can be proximal of the pressure balloon and distal of the stabilizing balloon so it is between the two balloons. 
     Note that the pear shaped balloon  142 ″ can be used with the catheters of any of the embodiments described herein. Thus, a pressure balloon of the pear shape of balloon  142 ″, and of larger size if desirable, can be used instead of the pressure balloons illustrated in the drawings. 
       FIGS. 18-25B  illustrate an alternate embodiment of the catheter of the present invention. The pressure balloon for detecting pressure, designated by reference numeral  202 , forms an outer balloon of catheter  200 . Contained within the outer balloon  202  is an inner balloon  204 . The inner balloon  204  provides a smaller diameter balloon and a smaller circumference (and volume) than the outer balloon  202 . The inner balloon  204  together with the lumen  214 , which communicates with the inner balloon  204  for inflation thereof, forms a smaller gas, e.g., air, column as in the embodiments of  FIGS. 15-17 . This provides finer measurements. Thus, the compliant outer balloon  202  compresses the outer wall  205  of the compliant inner balloon  204  which compresses the air (or other gas) within air lumen  214 . The closed system is thereby formed by the internal space  204   a  of the inner balloon  204  and the lumen  214 . The smaller balloon air column can in certain instances provide a more accurate reading from the average pressure determined by the larger outer balloon  202 . 
     The pressure transducer and pressure sensor are external to catheter  200  and mounted to port  218  at the proximal end  201  of catheter  200 . More specifically, a transducer hub or housing, designated generally by reference numeral  240 , contains the pressure transducer and sensor and is mounted to the angled side port  218 . In the embodiment of  FIG. 18A , the hub  240  is mounted over the port  218  and can be locked or secured thereto such as by a friction fit, snap fit, threaded attachment, a latch, etc., maintaining an airtight seal so the air is contained within the lumen  214  and balloon  204 . The hub  240  has an elongated (rod-like) member or nose  242  extending distally therefrom ( FIG. 24A ) dimensioned to be inserted through the proximal opening in port  218  and into air lumen  214 . (Note the air lumen  214  as in the other lumens extend into their respective angled side ports). The elongated member  242  also has a channel  244  extending therethrough to allow the pressure wave to travel through to the pressure sensor. Although in preferred embodiments no additional air needs to be injected into inner balloon  204  via lumen  214  after attachment of hub  240 , it is also contemplated that a port or opening can be provided in hub  240  to receive an injection device for injection of additional air. Such additional air can communicate with and flow through channel  244  of elongated member  242 , into lumen  214  and into inner balloon  204  for inflation, or alternatively, a side port or opening in angled port downstream of the elongated member  242  could be provided. 
     To charge the system, when the hub  240  is mounted to the side port  218 , the elongated member  242  extends into lumen  214  to advance air through the air lumen  214  into inner balloon  204  to expand inner balloon  204 . In some embodiments, 0.2 cc of air can be displaced/advanced by the member  242 , although other volumes are also contemplated. Thus, as can be appreciated, mounting of the hub  240  to the catheter  200  automatically pressurizes the air lumen/chamber and expands the inner balloon  204 . Note the inner balloon  204  can be partially or fully inflated (expanded), dependent on the amount of air advanced into the inner balloon  204 . Further note that the lumen  214  is not vented to atmosphere when the transducer hub  240  is attached and air is advanced through the air lumen. The port  218  can include a closable seal through which the elongated member  242  is inserted but maintains the seal when the elongated member  242  remains in the lumen  214 . 
     Lumen  214  which is used to inflate the inner balloon  204  and create the air column has an opening at a distal region to communicate with the interior of inner balloon  204 . Lumen  212  of catheter has an opening at a distal region to communicate with the outer balloon  202  to fill the outer balloon  202 . Angled port (extension)  222  at the proximal end of catheter  200  receives an inflation device to inflate, either fully or partially, the outer balloon  202 . 
     Note as in the other embodiments disclosed herein, air is described as the preferred gas for creating the column and expanding the balloon, however, other gasses are also contemplated, for each of the embodiments herein. 
     The outer balloon  202  can be shaped such that a distal region  207   a  ( FIGS. 20A-20C ) has an outer transverse cross-sectional dimension, e.g., diameter, greater than an outer transverse cross-sectional dimension, e.g., diameter, of the proximal region  207   b . A smooth transition (taper) can be provided between the distal region  207   a  and proximal region  207   b . Note the balloon  202  can be pear shaped as shown in  FIGS. 20B and 20C  although other configurations are also contemplated. This pear shape in some applications is designed to conform to the shape of the bladder. 
     The inner and outer balloons  204 ,  202  can by way of example be made of urethane, although other materials are also contemplated such as silicone or EVA. 
     A temperature sensor  230  ( FIG. 18B ), such as a thermocouple, is positioned within the catheter  200  at a distal end to measure core body temperature. The sensor  230  is shown positioned in a lumen  216  separate from the lumens  214  and  212 . One or more wires  232  extend from the sensor  230  through the lumen  216 , exiting the lumen  216  and catheter  200  at a proximal end between the angled extensions/ports of the catheter  200 , e.g., between the port  218  for the inner balloon  204  and the port  222  for the outer balloon  202 . A connector  234 , e.g., a male connector, is at the proximal terminal end of the wire  232  as shown in  FIG. 25B . The transducer hub  240  includes a connector  247  with openings  249  ( FIG. 25A ) which receive the connector  234  of the wire  232 . When the hub  240  is mounted to port  218  of catheter  200 , the connector  234  of the wire is automatically connected to a connector carried by or within the hub  240  which is in communication with a temperature monitor. Note the connector, e.g., female connector, within or carried by the hub  240  can already be mounted to an external temperature monitor via a cable when the hub  240  is mounted to catheter  218  or alternatively the hub  240  can first be mounted to port  218  of the catheter  200  and then a cable is connected between the temperature monitor and catheter  200 . In the illustrated embodiment of  FIG. 25A , the wire connector  234  can plug into the openings  249  of connector  247  positioned on the hub  240 . Note the connector  247  can also be internal of the hub  240  with an opening in the wall of the hub to enable access for the wire connector. Also note that alternatively the wire can include a female connector and the hub can have a male connector. Other types of connectors/connections are also contemplated. 
     As can be appreciated, connection of the transducer hub  240  to the catheter  200  (port  218 ) a) automatically connects the temperature sensor  230  to a connector for communication with a temperature monitor cable; and b) automatically advances air through the first lumen  214  to expand the inner balloon  204 . 
     The catheter  200  can optionally include a stabilizing balloon  206  similar to balloon  76  of  FIG. 8A . The stabilizing balloon  206  can be made of silicone, although other materials are also contemplated. If provided, the catheter  200  would have a lumen, e.g., lumen  210 , to inflate the stabilizing balloon  206 . Angled side port  217  can be provided in communication with lumen  210  for injection of a liquid or gas to expand the stabilizing balloon  206 . The foregoing description of the stabilizing balloons in connection with other embodiments is fully applicable to balloon  206 . Catheter  200  also includes a lumen  211  with a distal side opening  211   a  ( FIG. 18B ) to provide for drainage of the bladder as in the aforedescribed embodiments. In the illustrated embodiment, the side opening  211   a  is distal of outer balloon  202  and inner balloon  204  and distal of the stabilizing balloon  210  which as shown is proximal of outer balloon  202  and inner balloon  204 . In alternate embodiments, the stabilizing balloon  206  can be distal of the outer balloon  202 . 
     Thus, in the embodiment of  FIG. 18A , catheter  200  has five lumens: 1) lumen  214  communicating with inner balloon  204  to inflate the inner balloon  204  and forming the air filled chamber; 2) lumen  212  communicating with outer balloon  202  for inflating outer balloon  202 ; 3) lumen  210  communicating with the stabilizing balloon  206  to inflate stabilizing balloon  206 ; 4) drainage lumen  211  having a side opening  211   a  at a distal end for drainage of the bladder; and 5) lumen  216  for the temperature sensor wire(s)  232 . Catheter  200  also has three angled extensions/ports at its proximal end  201 : 1) port  218  for access to lumen  214  to inflate the inner balloon  204 ; 2) port  222  for access to lumen  212  to inflate outer balloon  202 ; and 3) port  217  for access to lumen  210  to inflate stabilizing balloon  206 . Drainage lumen  211  extends linearly terminating at region  223 . Lumen  216  terminates proximally at the region of the angled ports  218 ,  222  through which wire  232  can exit from the catheter  200  for connection to a temperature monitor via hub  240 . Note the location of the ports can vary from that illustrated in  FIG. 18 . Also, location of the lumens and the cross-sectional dimension and size of the lumen can vary from that shown in  FIG. 23  as  FIG. 23  provides just one example of the location and size, e.g., diameter, of the lumens as well as the shape/cross-sectional configuration and location. The catheter  200 , as in the foregoing embodiments, can have an atraumatic tip  209 . 
     In use, catheter  200  is inserted into the bladder and stabilizing balloon  206  is inflated to secure the catheter  200  in place. The system is charged by inflation of the inner balloon  204 , i.e., preferably partially inflated for the reasons discussed above, by advancement of air through lumen  214  upon attachment of the pressure transducer  240  to the port  218  of catheter  200 . Such attachment moves elongated member  242  into lumen  214  to displace the air (or other gas) already in the lumen  214  to expand the inner balloon  204 . A closed system is formed by the internal space  204   a  of the inner balloon  204  and the internal lumen  214  communicating with the internal space  204   a  of inner balloon  204 . In a preferred embodiment, additional air does not need to be added to the balloon  204 /lumen  214 . Outer balloon  202  is filled, i.e., preferably partially inflated for the reasons discussed above, via injection of air through the separate port  222  which communicates with lumen  212  of catheter  200 . With the outer balloon  202  inflated, pressure monitoring can commence as external pressure applied to the larger circumferential outer surface of the outer balloon  202  compresses and deforms the outer balloon  202  which exerts a force on the outer wall of inner balloon  204  and compresses the inner balloon  204 . As the inner balloon  204  is compressed and deformed in response to compression/deformation of the outer balloon  202  based on changes to bladder pressure, the pressure sensor within the external hub  240  attached at the proximal end of the catheter  200  provides continuous pressure readings, converted to an electrical signal by the transducer within the hub  240 , and then electrically communicates through a connector, e.g. cable  245 , to an external monitor either directly or via a converter to display pressure readings. Although, the system is capable of continuous pressure and continuous temperature monitoring, it can also be adapted if desired for periodic monitoring so the pressure and/or temperature readings can be taken at intervals or on demand by the clinician. Temperature readings are also taken during the procedure as temperature sensor  230  is connected to a temperature monitor via wire  232  connected to a connector of hub  240  which is connected to the temperature monitor to display temperatures. The temperature monitor can be separate from the pressure display monitor or alternatively integrated into one monitor. Cable  245  can connect to the temperature monitor as well (directly or via a converter) or a separate cable extending from the hub  240  could be provided for connection to the temperature monitor. 
     Note that although separate lumens are provided for the inflation of inner balloon  202  and outer balloon  204 , in an alternate embodiment, a single lumen can be utilized to inflate both balloons  202  and  204 . In such embodiment, catheter  200  can have one less angled port and one less lumen since inflation of the outer balloon  202  would be through port  218  and lumen  214 . 
     The proximal and distal end of the inner balloon  204  in the illustrated embodiment are within the confines of the outer balloon  202 , i.e., the proximal end of the inner balloon  204  is distal of the proximal end of the outer balloon  202  and the distal end of the inner balloon  204  is proximal of the distal end of the outer balloon  202 . Thus, in this illustrated embodiment, the inner balloon  204  is fully encapsulated within the outer balloon  202 . 
     With this inner/outer balloon arrangement, the larger outer surface of the outer balloon  202  takes gross measurements and then the forces are concentrated on the smaller inner balloon  204  to amplify/concentrate pressure on the small area of the inner balloon so small changes can be detected and waves transmitted to the pressure transducer (via the length of the lumen to a proximal transducer, e.g. an external pressure transducer). 
     As noted above, preferably no additional air needs to be added after mounting of hub  240 . However, it is also contemplated that in alternate embodiments a port can be provided in communication with hub  240  to enable subsequent injection of air though lumen  214  and into inner balloon  204 . Additionally, outer balloon  202  can in some embodiments receive additional fluid injection via port  222  during the procedure. 
       FIG. 26  illustrates an alternate embodiment of the pressure transducer hub. In this embodiment, hub  250  has a shroud  254  (shown schematically) positioned over elongated member  252 . This helps protect/shield the elongated member  252 . When the transducer  240  is mounted to the port  260  of the catheter, the shroud  254  fits over cover  260  of port  218  and is retained by a snap fit or by other methods of securement. 
     In the aforedescribed embodiments, mounting of the transducer hub a) automatically connects the temperature sensor to a connector for communication with a temperature monitor cable; and b) automatically advances air through the first lumen to expand the inner balloon. In the embodiment of  FIG. 27 , the pressure transducer hub  270  has a second elongated member  274  extending therefrom. When transducer hub  270  is mounted to the catheter, e.g., port  218 , elongated member  272  enters the air lumen in the same manner as elongated member  242  of  FIG. 24A . Additionally, elongated member  274  automatically enters the lumen  210  at port  222  which communicates with the outer balloon  202 . Therefore, in this embodiment, mounting of the transducer hub  270  a) automatically connects the temperature sensor to a connector for communication with temperature monitor cable as in the embodiment of  FIGS. 18-25B ; b) automatically advances air through the first lumen to expand the inner balloon as in the embodiment of  FIGS. 18-25B ; and c) automatically advances air through lumen  210  communicating with the outer balloon  202  to inflate (expand) the outer balloon  202 . The catheter of  FIG. 27  (and  FIG. 26 ) is otherwise identical to catheter  200  of  FIG. 18A  so for brevity further discussion is not provided since the description of the function and elements of catheter  200  are fully applicable to the catheter of  FIG. 27  (and to the catheter of  FIG. 26 ). 
       FIGS. 28A-28D  show an alternate embodiment of the hub/connector. The pressure transducer is external to catheter  280  and mounted to port  282  at the proximal end  281  of catheter  280  via connector (housing)  290 . Catheter  280  is identical to catheter  200  of  FIG. 18A  except for the connector and transducer hub temperature sensor connection. More specifically, transducer hub or housing, designated generally by reference numeral  300 , contains the pressure transducer and sensor  309  and is mounted to the angled side port  282 . In the embodiment of  FIG. 28A , the hub  300  is mounted to the catheter  280  by connection to housing  290 . Housing  290  is connected to port  282  via a barbed fitting  295  providing an interference fit with the port  282 . The hub  300  is locked or secured to connector  290  such as by a snap fit provided by the latch arms discussed below, although other attachments are also contemplated such as a friction fit, threaded attachment, other form of latch, etc., as well as other types of snap fits to provide an attachment that maintains an airtight seal so the air is contained within the air lumen and balloon  202  of the catheter  280 . (As noted above catheter  280  is identical to catheter  200  except for its connector so catheter  280  includes (not shown) the inner and outer pressure balloons, stabilizing balloon, temperature sensor, etc. The catheter  280  can also have a single pressure balloon as in the aforementioned embodiments. 
     The housing  290  attached to catheter  280  has a proximal opening  294  and a channel (lumen)  296  to receive an elongated (rod-like) member or nose  302  extending distally from transducer hub  300 . As shown channel  296  has a first diameter region  296   a  to match with the lumen  283  of the port  282 , a second larger diameter region  296   b  proximal of region  296   a  to receive the male rod  302  of the hub  300 , and a still larger diameter region  296   c  proximal of region  296   b  to receive the valve  299  and valve  298  and allow expansion thereof. As shown, valve  298  is dome shaped and is distal of valve  299 . Conical cap  293 , proximal of valve  299 , provides a lead in to the valve  299  for the rod  302 . Thermistor pins  292  receive thermistor connectors  308 . Note valves  288 ,  299  are one example of valves that can be provided as other valves to provide an airtight seal are also contemplated. A single valve is also contemplated. 
     Hub  300  is mounted to connector  290  and includes a housing  304  from which a pair of distally extending snap fit connector arms  306  extend. The latch arms  306  are sufficiently flexible to enable attachment and have an enlarged distal portion  307 , illustratively shown as arrow shaped although other enlarged shapes could be provided. The elongated member  302  extends between the latch arms  306 . When the hub  300  is mounted to the connector  290 , the elongated member  302  extends into the channel  296  to advance air to inflate the inner balloon. The enlarged ends  307  of latch arms  306  enter recesses  291  and engage shoulders  291   a  to retain the hub  300 . Note to release (disconnect) the hub  300 , the ends  307  are pressed radially inwardly to disengage from shoulder  291   a  and the hub  300  is pulled proximally. Note that alternatively a different number of latch arms could be provided. 
     The housing (connector)  290  has a lumen  296  for communication with the lumen  283  in the side port  282  of catheter  280  which communicates with the air lumen and inner balloon of the catheter  280 . As noted above, the lumen  296  is dimensioned to receive the elongated rod  302  of transducer hub  300 . The wire for the sensor extends in housing  300 . 
     When transducer hub  300  is attached to connector  290 , such attachment inserts the elongated rod  302  into lumen  296  to advance air though the air lumen in the catheter and into the balloon  204 . (Note the air lumen extends into its angled side port  282 ). The elongated member  302  also has a channel or lumen  305  extending therethrough to allow the pressure wave to travel through to the pressure sensor. Although in preferred embodiments no additional air needs to be injected into balloon  204  after attachment of hub  300 , it is also contemplated that a port or opening can be provided in hub  300  to receive an injection device for injection of additional air. Such additional air can communicate with and flow through channel  305  of elongated member  302 , into the air lumen and balloon  204  for inflation, or alternatively, a side port or opening in the angled port downstream (distal) of the elongated member  302  could be provided. Attachment of hub  300  to housing  290  also automatically connects thermistor connectors  308  to thermistor pins  292  to automatically connect the temperature sensor to the hub  300  for communication via a cable to a temperature monitor. 
     To charge the system, when the hub  300  is mounted to the side port  282  via attachment to connector  290 , the elongated member  302  extends into lumen  296  to advance air through the air lumen into balloon  204  (or the pressure balloon in the embodiments with a single pressure balloon) to expand the balloon  204 . That is, connection of the transducer hub  300  to the catheter  280  (port  282 ) automatically advances air through the connector lumen  296 , the port lumen  283  and the first lumen  214  to expand the balloon  204 . (Such connection also automatically connects the temperature sensor to the hub  300 ). In some embodiments, 0.2 cc of air can be displaced/advanced by the member  102 , although other volumes are also contemplated. Thus, as can be appreciated, mounting of the hub  300  to the catheter  280  automatically pressurizes the air lumen/chamber and expands the balloon. Note the balloon can be partially or fully inflated (expanded), dependent on the amount of air advanced into the balloon. Further note that preferably the lumen is not vented to atmosphere when the transducer hub  300  is attached and air is advanced through the air lumen. The port  282  includes a closable seal, e.g., valves  298  and  299 , through which the elongated member  302  is inserted but maintains the seal when the elongated member  302  remains in the lumen  296 . Note that catheter  280  is identical in all other respects to catheter  200  so that the description of catheter  200  and its components and function (and alternatives) are fully applicable to catheter  280 , the difference being the connector  290  of catheter  292  to receive transducer hub  300 . The transducer hub is also different, e.g., has latch arms and a different configuration. 
     In the alternative embodiment of  FIGS. 29A-29C , the latch arms are reversed so that they are located on the connector rather than on the transducer hub. More specifically, transducer hub (housing), designated by reference numeral  320 , has an elongated member  322  with a channel  323  and is identical to elongated member  302  of  FIG. 28A  for advancing air through the lumen and into the pressure balloon. Pressure transducer  324  is contained within the housing  320 . Recesses  325  are dimensioned to receive the latch arms  317  of the connector or housing  310  which is connected to the side port  282  of catheter  280 . (Catheter  280  is the same as catheter  280  of  FIG. 28A  except for connector  310 ). Extending proximally from housing  310  are two latch arms  16  with enlarged region  317  which engage the shoulders  326  formed by recesses  325  in hub  320  in a similar manner as latch arms  306  of  FIG. 28A  engage in recesses  291  and shoulder  291   a . Connectors  328  in hub  320  engage thermistor pins  312  of connector  310  for connection of the temperature sensor. Connection of the hub  320 , like hub  300 , automatically advances air to inflate the pressure balloon and automatically connects the temperature sensor. 
     To disconnect (release) the hub  320 , ends  317  of latch arms  316  are pressed radially inwardly to disengage from shoulder  326  so hub  320  can be pulled proximally out of connector  310 . 
     Note the lumen which is used to inflate the pressure balloon  20  and create the air column has an opening at a distal region to communicate with the interior of the pressure balloon. If an outer balloon is provided, an additional lumen can be provided in the catheter to communicate with the outer balloon to fill the outer balloon and an additional angled port (extension) at the proximal end of the catheter would receive an inflation device to inflate, either fully or partially, the outer balloon. 
     Note in each of the embodiments disclosed herein, air is described as the preferred gas for creating the column and expanding the balloon, however, other gasses are also contemplated for each of the embodiments. 
     The pressure balloons of the embodiments herein can be symmetrically shaped as shown or alternatively shaped such that a distal region has an outer transverse cross-sectional dimension, e.g., diameter, greater than an outer transverse cross-sectional dimension, e.g., diameter, of the proximal region. A smooth transition (taper) can be provided between the distal region and proximal region, although other configurations are also contemplated. The inner (and outer) balloon can by way of example be made of urethane, although other materials are also contemplated. 
     The wire connector of the foregoing embodiments can plug into the openings of a connector positioned on or in the hub. The wire connector can be internal of the hub with an opening in the wall of the hub to enable access for the wire connector. Also note that alternatively the wire can include a female connector and the hub can have a male connector. Other types of connectors/connections are also contemplated. 
     In alternate embodiments, any of the catheters disclosed here can include a pulse oximetry sensor to measure oxygen saturation in the urethral or bladder tissue. The sensor can be located either proximal or distal to the pressure balloon and/or stabilizing balloon. It could also alternatively be mounted within one of the balloons. 
     It is also contemplated that in some embodiments a backup system be provided to determine pressure. The backup system can provide a double check of pressure readings to enhance accuracy. Such backup system can be used with any of the embodiments disclosed herein to provide a second pressure reading system. One example of such backup system is disclosed in  FIGS. 14A and 14B . In this embodiment, catheter  160  has the pressure transducer/pressure sensor  162  like sensor  30  of  FIG. 1  within the air (or other gas) lumen  164  communicating with pressure balloon  167 , forming a “first system”, plus a pressure transducer/pressure sensor  169  at a proximal end of the catheter as in  FIG. 12  or external of the catheter forming a “second system”. Thus, the pressure sensor  162  is at a distal end of the air charged lumen  164  and pressure sensor  169  is at proximal end of the air charged lumen  164 . Both sensors  162  and  169  are electrically connected to a monitor which provides a graphic display of pressure readings. The catheter  160  also includes a temperature sensor either as part of the sensor  162  or a separate component that can be positioned for example in the lumen  164  distal of sensor  162  as in the embodiment of  FIG. 8 . A stabilizing balloon  168  and an inflation lumen to inflate balloon  168  can also be provided. Lumen  163 , having a side opening  170  at its distal end, is configured to drain the bladder similar to lumen  20  and side opening  22  of the embodiment of  FIG. 1 . 
     In use, catheter  160  is inserted into the bladder and stabilizing balloon  168  is inflated to secure the catheter  160  in place. The system is charged by inflation of the balloon  167 , i.e., preferably partially inflated for the reasons discussed above, by insertion of air through side port  172  which is in fluid communication with the air lumen in a closed system formed by the internal space of the balloon  167  and the internal lumen  164  communicating with the internal space of balloon  167 . With the balloon  167  inflated, pressure monitoring can commence as external pressure applied to an outer surface of the balloon  167  compresses the air (or other gas) within the chamber. The sensor  162  at the distal end of lumen  64  provides continuous pressure readings, converted to an electrical signal by the transducer within the distal end of lumen, and then electrically communicates through its transmission wires extending through the air lumen to an external monitor either directly or via a converter. Additionally, pressure within the air charged column is measured at a proximal region by sensor  169  within side port  172  of catheter  160 . The sensor  162  at the distal end of lumen  164  provides continuous pressure readings, and such pressure readings can be confirmed by the proximal sensor. Such pressure readings can be performed continuously (along with continuous temperature monitoring) or alternatively can also be adapted if desired for periodic monitoring so the pressure and/or temperature readings can be taken at intervals or on demand by the clinician. Thus, air pressure readings at a proximal end plus microtip pressure readings at the distal end are provided. The sensors  162  and  169  can electrically communicate with an external monitor to display both pressure readings from sensors  162 ,  169 , or alternatively, if the pressure readings are different, they can be averaged to display a single measurement. Clearly, other displays of information can be provided to display the information from the two sensors  162 ,  169 . 
     The sensors disclosed herein can be microtip sensors within the air (or other gas) lumen or balloon. In alternative embodiments, fiber optic sensors within the air (or other gas) lumen or balloon can by utilized to transmit circumferential/area pressure. The pressure transducers can be housed within the catheter or alternatively external to the catheter. Additionally, core temperature sensors can be part of the pressure sensor or a separate axially spaced component. 
     The multi-lumen catheters disclosed herein provide an air (or other gas) charged balloon giving precise readings of intra-abdominal pressure and core temperature and the systems are charged via insertion of air through a side port. The multi-lumen catheters are easily inserted into the bladder in the same manner as standard bladder drainage catheters and enable continuous drainage of urine while continuously recording IAP without interrupting urine flow and without requiring retrograde filling of the bladder with water. Thus, these catheters provide a closed system. The catheters also have a balloon providing a large reservoir (large capacity) and large circumferential area/interface for obtaining more information from the bladder over multiple reference points (rather than a single point sensor) that provides an average pressure to provide a more accurate assessment of the surrounding environment as pressure measurement is not limited to one side of the bladder but can determine measurements on the opposing side as well. 
     As noted above the catheters in some embodiments can be connected to a bedside monitor through either a wire or blue-tooth wireless connection. The system can also in some embodiments include an indicator or alarm system to alert the staff at the site as well as remote staff through wired or wireless connections to external apparatus, e.g., hand held phones or remote monitors. 
     As noted above, an alarm or indicator can be provided in some embodiments to alert the staff. The indicator can be a visual indicator such as a light, LED, color change, etc. Alternatively, or additionally, the indicator can be an audible indicator which emits some type of sound or alarm to alert the staff. The indicator can be at the proximal region of the catheter or at other portions of the catheter, e.g., at a distal end portion, where known imaging techniques would enable the user to discern when the indicator is turned on. It is also contemplated that in addition to providing an alert to the user in some embodiments, the pressure monitoring system can be tied into a system to directly reduce abdominal pressure so that if the pressure exceeds a threshold level (value), the abdominal pressure can automatically be reduced. In such systems, an indicator can be provided on the proximal portion of the catheter, e.g., at a proximal end outside the patient&#39;s body, or separate from the catheter. The sensor can be in communication with the indicator, either via connecting wires extending through a lumen of the catheter or a wireless connection. The sensor can be part of a system that includes a comparator so that a comparison of the measured pressure to a predetermined threshold pressure value is performed and a signal is sent to the indicator to activate (actuate) the indicator if the measured pressure exceeds the threshold pressure to alert the clinician or staff that pressure within the abdomen is too high and a signal is also sent to a device or system to automatically actuate the device or system to reduce the abdominal pressure. If the measured temperature is below the threshold, the indicator is not activated. A similar system can be used for temperature measurement and indication. 
     It is also contemplated that a micro-air charged sensor could be provided in the retention (stabilizing) balloon. 
     It is also contemplated that microtip sensors and/or fiber optic sensors can be utilized to measure pressure, and these sensors can be utilized instead of or in addition to the air pressure readings utilizing the aforedescribed balloon(s) for measuring pressure. 
     Pulse oximeters for measuring oxygen levels (oxygen saturation) in the urethral and/or bladder tissue could also be provided. In some embodiments, the pulse oximetry sensors can be positioned on the catheter proximal to the retention balloon. Alternatively, the sensors can be positioned within the retention balloon, on the catheter distal to the pressure balloon or on other regions of the catheter. Another channel in the catheter can be provided for the sensor and its connector to external devices, e.g. readers. 
     The catheters disclosed herein are designed for insertion into the bladder. However, it is also contemplated that they can be adapted for insertion into the rectum, colostomy pouch, stomach, supra-pubic bladder drain, or other orifice directly connected with the abdominal cavity. 
     Although the apparatus and methods of the subject invention have been described with respect to preferred embodiments, those skilled in the art will readily appreciate that changes and modifications may be made thereto without departing from the spirit and scope of the present invention as defined by the appended claims.