Abstract:
A refined catheter for percutaneous access to the peritoneal cavity for the deliver/removal of fluid in medical procedure such as peritoneal dialysis including a flexible tubular member having a distal portion that features either a coiled segment with multiple secondary ports and/or a bolus tip with a large scalloped orifice on the side, and a proximal segment that can be oriented cephalad or caudally by means of a 90° angle and a connecting portion with a luer fitting and an inner diameter of at least 0.375 cm is maintained (3.75 mm) through the entire length of the catheter to optimize its flow rate capabilities.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates generally to catheters. More specifically, the invention relates to catheters useful in peritoneal dialysis procedures. 
       BACKGROUND OF THE INVENTION 
       [0002]    In the treatment of various diseases, percutaneous access to the peritoneal cavity is necessary. One example is peritoneal dialysis which is often indicated for acute or chronic renal failure. To effect dialysis through the peritoneal cavity, a percutaneous passage is surgically formed through the cutaneous and subcutaneous tissues, rectus muscle and through the peritoneum itself. This passage permits insertion and implantation of a distal portion of the catheter within the peritoneal cavity. A separate tunnel directed either caudally or cephallad is then formed through the subcutaneous and cutaneous tissues with a tunnel exit site in the suprapubic region of the external abdominal wall, or the presternal area if so preferred. A proximal portion of the catheter is inserted through this tunnel, thereby maintaining an end of the proximal portion in a downward direction along the abdominal wall. Examples of catheters used in peritoneal dialysis are disclosed in U.S. Pats. Nos. 3,633,585; 4,184,497; 4,278,092; 4,279,252; 4,392,855; 4,687,471, 4,772,269; and 4,935,004. 
         [0003]    Over the last two decades there has been a greater understanding of the function of the peritoneal dialysis catheter and its interaction with the dialysis systems used in terms of its hydraulic function; ease of operation and maintenance. Modern catheters, Twardowski&#39;s (U.S. Pat. No. 4,772,269) swan neck and Cruz&#39;s (U.S. Pat. No. 4,935,004) pail handle, signify major advances in catheters. For example, these devices address the issue of catheter failure caused by outflow obstruction either from dislocation within the peritoneal space or occlusion caused by omental tissue or other intra-abdominal organs. 
         [0004]    The materials used for their manufacture, their design and specifications give each catheter its character, and usually drives the operability of the device including implanting and function once in place. 
         [0005]    As new, more efficient dialysis delivery systems become available, the need for similarly efficient catheters becomes more apparent. Additionally the patients&#39; input in selecting among various dialysis technologies is increasingly encouraged. As the consumer learns of options in terms of dialysis modality (for example, hemodialysis versus peritoneal dialysis and in center versus home dialysis), the need to offer devices that will suit them in terms of function and comfort becomes prominent. Efficiency, unemcumberance from garments and aesthetic qualities of the catheter have been recently recognized as important by patients and caregivers. 
         [0006]    As can be seen, design, materials, implantation into the human body and maintaining hygiene and sterility while the catheter is in the environment of use all continue to present ongoing issues. With an ongoing emphasis on reducing costs and returning patients to a home treatment environment, these concerns persist. Even with patient training there is a need for procedures and devices which enable proper patient care and self care. 
         [0007]    Once the patient returns to the home-environment, the healthcare professional loses sight and control over the general environment of treatment. While economies of scale are forcing healthcare, especially dialysis, into less expensive treatment environments, there are countervailing considerations. For example, the age and mental acuity, among other factors, of the patient is a consideration in the training of the patient to properly execute their own care. Further, the complexity of the care required needs to be measured in moving the patient home from the clinic or hospital environment. Other factors include the maintenance or monitoring of devices implanted in the patient as well as instruments that have been placed in the home for the patient&#39;s use in treatment. 
         [0008]    If the proper care is not taken in execution of the treatment, the goal of economizing in care is lost with the need for further medical treatment. Profilactically training, providing supplies and periodic monitoring of patient, investments in the treatment environment all assist in accomplishing stated goals. 
         [0009]    Additionally, the design and implementation of devices to be inserted into the patient are also of concern. Ensuring the integrity of in vivo devices—which by their very nature are reused—is of paramount concern. Many considerations come into play as discussed above including the proper placement and sealing of these devices within the body cavity. Additionally, the positioning of these devices from distal to proximal portions so that they are comfortable and secure with continuing use and with the activities of daily life. 
         [0010]    Another paramount concern in the design and implementation of these devices is sterility not only during dialysis but also when not in use. For example, dialysis patients may suffer incontinence either due to age or medical condition. Diapers can provide an environment which fosters bacteria is less than acceptable to devices such as catheters. Further disabilities such as ostomies or other physical impairment may make certain types of bathing a preference if not a requirement. 
         [0011]    Hence, while previous catheters have solved certain concerns, there is a need for further developments which foster advances in the care of dialysis patients. 
       SUMMARY OF THE INVENTION 
       [0012]    Prior to the development of the present invention, a need existed for a catheter for percutaneous access to the peritoneal cavity in which distal and proximal portions of the catheter are ultimately caudally directed. The proximal segment of the catheter is to be used with the 180° bend that would dictate the caudal orientation of the exiting segment. The orientation of the site where the catheter exits the skin affects the long-term functional life of the catheter. The area or environment where the skin and catheter interface must be structurally sound and stable. Thus with patients in the erect posture the catheter would not suffer the stress of gravity or tugging. Further, a need existed for a peritoneal dialysis catheter which would securely anchor within the rectus muscle tissue without use of anchoring beads or flanges. A need also existed for a peritoneal dialysis catheter in which the distal and proximal portions of the catheter were non-planar to thereby function as a safeguard from inadvertent dislodging of the catheter from the patient. This invention describes a catheter with flow capabilities such as to efficiently move fluid at a minimum rate of one liter per minute without causing jet stream related discomfort. The invention provides a catheter which exits above the waistline which at the same time provides an optional hood to cover the proximal end of the catheter to ensure sterility. 
         [0013]    Benefits of an exit site located in the thorax include the ability for patients to bathe in a tub without the catheter exit site soaking in stagnant water, its use in patients with urinary/fecal incontinence wearing diapers, patients with colostomy/ileostomy infants and anyone needing to wear a diaper. 
         [0014]    Other advantages and aspects of the invention will become apparent upon making reference to the specification, claims, and drawings to follow. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a front elevational view of a dialysis catheter. 
           [0016]      FIG. 2  is a partial frontal view of the catheter shown in  FIG. 1 . 
           [0017]      FIG. 3  is a partial side elevational view of the catheter shown in  FIGS. 1 and 2 . 
           [0018]      FIG. 4  is a frontal elevational view of a catheter shown in accordance with a preferred embodiment of the invention. 
           [0019]      FIG. 5  is a partial frontal view of the catheter of  FIG. 4 . 
           [0020]      FIG. 6  is a partial side elevational view of the cathether shown in  FIG. 4 . 
           [0021]      FIG. 7  is a partial side elevational view of a bolus tip in accordance with one aspect of the invention. 
           [0022]      FIG. 8  is a partial top elevational view of the bolus tip shown in  FIG. 7 . 
           [0023]      FIGS. 9A and 9B  are alternative embodiments of the invention showing a partial cutaway side view of the proximal end of the catheter covered by a protective hood ( FIG. 9A ) and a cutaway top plan view of the catheter of the proximal end of the invention covered by a protective hood ( FIG. 9B ). 
           [0024]      FIG. 10 . is a view depicting the catheter in its environments of use. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    This invention is susceptible of illustration in varying embodiments and in many different forms. There is shown in the drawings and will herein be described in detail a preferred embodiment of the invention. The present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiment illustrated. 
         [0026]    Referring now to the drawings,  FIGS. 1-3  disclose one embodiment of a prior catheter  10  comprised of flexible tubing, preferably a thermoplastic material such as polyurethane. Thermoplastic material is preferred over silicone because such material may re-form at body temperatures enabling the catheter to conform in vivo to internal body contours. Thus avoiding device related stress on the surrounding tissues by device “memory”. Thermoset materials, such as silicone, cannot be so modified. The polyurethanes also by virtue of their greater strength allow thinner walls and larger ID than silicone catheters with similar external diameters. 
         [0027]    The catheter  10  is comprised of a distal portion  12  which, as later explained, will extend into the peritoneal cavity of the patient and a proximal portion  14 . As will be later explained, a first segment  14 ′ of proximal portion  14  passes through the subcutaneous and cutaneous tissue of a patient, whereas a second segment  14 ″ extends externally from the patient and downwardly along the abdominal wall exiting through skin at a site below the belt line. 
         [0028]    In accordance with the invention,  FIGS. 4-6  depict a catheter which is designed to provide an ascending portion along the anterior wall of the trunk to exit in the pre-sternal region after undergoing a 180° turn. As with the catheter of  FIGS. 1-3 , the catheter of  FIGS. 4-6  may be directed to define a caudal exit of the device through the tegument. 
         [0029]    Distal portion  12  includes a distal end  16  which, in a preferred embodiment, comprises a spiral or coiled configuration  18  which lies in a single plane when the catheter is in a natural, unstressed condition. Spiral  18  includes a plurality of openings  20  which permits passage of fluid such as a dialysate. The invention may add about one inch to this portion  18  and the “bolus” tip,  FIGS. 7 and 8 , to enhance the flow capability by decreasing the resistance to flow; flow equaling pressure over resistance. 
         [0030]    The need for high flow capable devices with minimum “whipping” or jet stream forces are desirable the catheter of the invention may have an optional “bolus” tip with a side line opening in a shape to decrease the force of the fluid column as it exits and makes it flow around the tip. This bolus makes the installation and withdrawal of large volumes of fluid (dialysate) without pain/discomfort possible. As seen in  FIG. 7  the outer diameter of the bolus  32  decreases from the area where it joins the catheter body  14  to the nose section  33 . The bolus body  32  generally 3 times the external diameter of catheter  14 . Body  14  and bolus  32  could be formed as one piece through an insert injection molding process such that the bolus  32  is integrally formed with the catheter  14 . 
         [0031]    The passage  34  forms a single fluid ingress and egress for the bolus  32  and the catheter  14 . As best seen in  FIGS. 7 and 8  the shape of port  34  is formed by removing a piece of the body  32  around greater than 180° of the circumference of the body  32 . The port  34  extends substantially around 190° of the circumference of the body  32 . As a result fluid delivered is dispensed and the discomfort caused by jet forces abates or disappears directly opposite to the center of the port  34 . The flow of the fluid passage is built up progressively 35 and 36, in the nose section  33  of the bolus body  32  so as to define a uniform arc terminating at the outer surface of the body  33 . Other features of the bolus are known from U.S. Pat. No. 5,571,093 which is incorporated herein by reference. 
         [0032]    Proximal portion  14  has a proximal end  31  which may be coupled to a source of dialysate and/or a container for dialysate drainage. In all embodiments of the present invention, distal portion  12  and proximal portion  14  are preferably linear in configuration. Distal portion  12  and proximal portion  14  are linked by a linear connecting portion  24 . Connecting portion  24  has a length which is substantially co-extensive with the thickness of the rectus muscle. As a result, connecting portion  24  is substantially embedded within the rectus muscle upon implantation of catheter  10 . In all embodiments of the present invention, connecting portion  24  carries about its circumference a porous cuff  26  which preferably extends for about 1 cm of the length of connecting portion  14 . Cuff  26  may be made from a woven relatively bioincompatible material known in the art, such as Dacron® Velour. Cuff  26  results in a thorough embedding and anchoring of connecting portion  14  within the rectus muscle. An optional additional porous cuff  28  may also be carried on proximal portion  24 . 
         [0033]    Distal portion  12  and proximal portion  14  are intrically formed with and angularly joined to connecting portion  24 . Preferably, the angular joinder of distal portion  12  and proximal portion  14  to connecting portion  24  is achieved by molding bend segments  30  into catheter  10 . As a result of such molding process, bend segments  30  remain in catheter  10  even when catheter  10  is in its natural unstressed condition. Proximate to each bend  30  is an angle a°,  FIG. 4 . As molded, angle a° is approximately 90°. Generally cuff  28  is equidistant between the bends  30  on span  24 . Angle a° formed between the longitudinal axis of the connecting portion and longitudinal axis of distal portion  12  should be such that when catheter  10  is implanted into a patient, distal portion  12  is directed caudally into the peritoneal cavity. Likewise, angle a° should be such that upon implantation of catheter  10  into a patient, proximal end  22  is directed cephalade (upwardly) along the external abdominal wall of the patient. To assure such caudal direction of distal portion  12  and upward direction of proximal portion  14 , such angles (a°) are preferably 90° angles. 
         [0034]    Preferably, distal portion  12  and proximal portion  14  are non-planar with each other,  FIGS. 5 and 6 . Unlike prior art peritoneal catheters in which distal and proximal catheter portions are co-planar, the present invention uses non-planar distal and proximal portions to prevent inadvertent withdrawing or dislodging the catheter from the patient and relieve stress of “tugging”. Specifically, if the proximal portion  14  of the catheter  10  is pulled upon, the non-planar and angular orientation of catheter  10 ,  FIGS. 4-6 , will prevent withdrawal of the catheter from the patient by abutting against the inner surfaces of the peritoneal cavity. 
         [0035]    Catheter  10  may include a longitudinal, radio-opaque stripe as is known in the art, for ease of implantation and for x-ray confirmation of catheter position during implantation. This stripe (not shown) in the unstressed configuration will be consistently oriented to the 12 o&#39;clock position. 
         [0036]    In order to minimize tunnel infection and tunnel exit site infection, it is essential that distal end  16  of distal portion  12  be directed caudally within the peritoneal cavity and that proximal end  22  of proximal portion  14  also be downwardly directed along the external abdomen wall,  FIG. 10 . One advantage of the invention is that the catheter emerges from the body in the upper abdominal region well above the waistline. This allows use of the catheter with PD patients that have any number of complications such as incontinence problems the need for tub bathing, as well as any other environmental or use concerns which might otherwise lead to contamination of the catheter. 
         [0037]    Catheter  10  may be implanted by any technique known in the art. For example, in the “Y-Tec” method, distal portion  12  and connecting portion  24  are inserted through a surgically formed percutaneous passage into the peritoneal cavity. Next, a tunnel is formed through the subcutaneous and cutaneous tissue which exits through a second opening formed in the epidermis. The proximal portion  14  may then be urged through the tunnel so that first segment  14 ′ passes through the subcutaneous and cutaneous tissue while second segment  14 ″,  FIG. 4 , is positioned external to the abdomen wall. The tunnel assures that proximal portion  14  is maintained in a caudal direction. Finally, the percutaneous passage to the peritoneal cavity is sutured closed. 
         [0038]    The non-planar orientation of distal portion  12  and proximal portion  14 , are angularly off-set. Hence, if external force is exerted on proximal portion  14 , catheter  10  will not easily be dislodged or withdrawn from the patient. In prior art catheters having co-planar distal and proximal portions, such force is imparted directly to the distal portion  12  causing dislodgement of the catheter. Distal portion  12 , by being non-planar with proximal portion  14 , will merely abut against the inner surfaces of the peritoneal cavity to prevent withdrawal or dislodgement of catheter  10 . 
         [0039]      FIG. 5  discloses the significance of the configuration of connecting portion  14 . As disclosed in  FIG. 5 , the length of connecting portion  14  is longer and is generally co-extensive with the thickness of the patients rectus muscle. Preferably, porous cuff  28  is also co-extensive with the length of connecting portion  24 . Hence, connecting portion  24  is imbedded in rectus muscle tissue which, as previously mentioned, efficaciously grows into the pores of cuff  28 . Bent segment  30  on distal portion  12  caudally directs distal end  16  into the peritoneal cavity  FIG. 10 . Likewise, bent segment  30  on proximal portion  14 , with the assistance of a surgically formed tunnel, downwardly directs first segment  14 ′ through subcutaneous tissue which emerges through the epidermis. Second segment  14 ′ emerges caudally at an exit site E. A second porous cuff  26  may be carried on first segment  14 ″ to permit ingrowth of subcutaneous tissue. However, in some instances, the embedding and efficacious anchoring of cuff  28  into rectus muscle may prove sufficient. As positioned once implanted, the proximal portion of the catheter exits the abdominal wall cephalad presternal off of the midline,  FIG. 10 . 
         [0040]    Additionally the invention incorporates the presence of an integral adaptor  22  which maintains an interior diameter of 3.75 mm and enhances flow capabilities by eliminating the flow restricting retracing effects of “mounted on” adaptors. These “built in” connecting segments prevent accidental disconnection. In another embodiment of the present invention the distal end of the distal portion may be linear, rather than comprising the spiral configuration disclosed in  FIG. 4 . 
         [0041]    The device of the invention has an inner diameter of 3.75 mm. Having at least 3.75 mm inner diameter throughout, provides a tremendous impact in flow capability, (Bernoulli&#39;s principle). For example, considering improving dialysis efficiency, such as in the case of Cyler assisted dialysis where on the average ten short cycles are done automatically but currently used systems with poor flow spend too much of the time moving fluid in and out of the patient&#39;s abdomen. For example, time savings for most patients doing manual exchanges may present a differential where instead of spending 40 minutes or more on dialysis, dialysis exchanges may be completed in less than seven minutes. 
         [0042]    Preliminary clinical investigation has revealed no subsequent tunnel site or tunnel exit site infection many months after catheter implantation which indicates that upon ingrowth of rectus muscle tissue into porous cuff  26  on connecting portion  24 , catheter migration is eliminated. Finally, despite the absence of any anchoring buttons or flanges such as those found in the prior art, initial observations have revealed no catheters which have become inadvertently dislodged or withdrawn. 
         [0043]    The goal of achieving a “stable” device/catheter/tegument/interface is accomplished with the invention which brings us closer to the idea a stable cutaneo/peritoneal fistula for medical treatment purposes. 
         [0044]    This invention is classified as a “simple” device according to Cruz classification (Cruz, C., et al. “Access for Peritoneal Dialysis in Clinical Nephrology”, Dialysis &amp; Transplants”, Mallucche, H., Sawaya, B. P., Hakim, Rm et al. Eds. Pp. 1-18, Delsemhosen II, 1999. Some of the New Catheters are Better, Seminars in Dialysis V, 3. 202-4 1992)) simple catheter can be implanted by minimally invasive methods (percutaneously or openly). Percutaneous methods include laparoscopy or “blind” methods. Regardless of the method of implantation, the key step is the positioning of the proximal cuff  26  in the midst of the rectus abdominal muscle. A “purse string” suture of heavy “O” absorbable material will secure this position without fear of dislodgement until the in-growth of tissue gives structural support to the catheter. 
         [0045]    The radio-opaque reference line, positioned at 12 o&#39;clock, ensures the distal part  12  is and remains in the pelvis. Before the proximal  14  segment is exteriorized a dialysis exchange is performed to verify the hydraulic function of the catheter. If the function is deemed acceptable, the exit site and tunnel are created in conventional manner such as by using a tunneling device which will accompany the catheter packaging. 
         [0046]    Following the catheter is capped and irrigated on day one and seven after insertion. Ideally continued use of the catheter ought to be delayed for 2 weeks. The Catheter Adapter  31  will have an external luer compatible with all the dialysis administration sets available. This “universal” connector will obviate the need to stock more than one “system” and keep the inner diameter of the entire system consistently at 3.75 mm resulting in improved flow rates. 
         [0047]    In accordance with a further embodiment of the invention, there is shown in  FIGS. 9A and 9B . As can be seen the proximal end  14  of the catheter  10  may be covered by the hood  50 . The hood  50  may be molded from any number of materials to provide a sealing edge  52 . The sealing edge  52  may be molded to close through any number of means such as grooved flanges or a closure. Sealing edge  52  functions to protect the sterility of proximal portion  14  and more specifically the integral adaptor  22 . When in use the hood may be pulled back to expose the adaptor  22 . 
         [0048]    While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention and the scope of protection is only limited by the scope of the accompanying