Peritoneal access.B Bhatla, R Khanna, ZJ Twardowski
Department of Internal Medicine, University of Missouri-Columbia 65212, USA., USA
Keywords: Bacterial Infections, etiology,Catheterization, adverse effects,Catheters, Indwelling, Equipment Contamination, Human, Peritoneal Dialysis, adverse effects,instrumentation,methods,
One of the most important components of the peritoneal dialysis system is permanent and trouble-free access to the peritoneal cavity. The double cuff Terickhoff catheter, developed in 1968 for the treatment of patients with intermittent peritoneal dialysis, is also widely used for continuous ambulatory peritoneal dialysis (CAPD). Even today, twenty-six years later, the Terickhoff catheter in its original form is the most widely used catheter type and has become the gold standard of peritoneal access. The catheter, along with all its modified versions, is made of silicon rubber and has cuffs made of Dacron velour. Silastic catheters are soft, flexible, atraumatic to tissues and are biocompatible. The Dacron velour cuff permits profuse collagen tissue ingrowth between the fibres providing a strong bondage between it and the surrounding tissues. After implantation, the double cuff Tenckhoff catheter has three segments: 1) an intraperitoneal segment, 2) an intramural segment contained within the abdominal wall tunnel, and 3) an external segment situated outside the skin exit-site. CAPD increases catheter related complications due to both higher intra-abdominal pressure and daily manipulations. These complications, such as catheter tip migration, dialysate leaks and exit site infection, are encountered frequently and in addition are related partly to improper insertion and post implantation care. Despite the introduction of newer modifications, catheter exit site and tunnel infections occur frequently and lead to prolonged treatment, recurrent peritonitis and catheter failure. Recent improvement in peritonitis rates due to the use of the Y-set has allowed the focus of attention to shift to peritoneal access.
Straight and coiled Terickhoff catheters:
These catheters consist of silicon rubber tubing with a 2.6 mm internal diameter and 5 mm external diameter. They are provided with one or two polyester (Dacron R), 1 cm long cuffs. The intraperitoneal segment has an open end and multiple 0.5 mm perforations over a distance of 11 cm from the tip. The coiled Terickhoft catheter differs from the straight in having a coiled 18.5 cm long perforated distal end. All Tenckhoff catheters are provided with a barium impregnated radio-opaque stripe to assist in radiological visualization of the catheter.
Rottembourg et al compared straight with coiled Tenckhoff catheters. 41.6% of straight catheters dislodged and 85% of these had to be replaced; on the other hand, only 10% of the coiled catheters became dislodged and of these only 20% have to be replaced. Except for perioperative pain, which was higher with coiled catheters, the frequency of other complications such as infection, dialysate leakage, exit site and tunnel infection and cuff extrusion were similar in the two groups.
For the straight catheters, cumulative catheter survival was 65% at one year and 600% at two years; for the coiled catheters, these rates were 83% at one year and 78% at two years. Swartz et al reported overall survival of 88%, 71%, and 61% at 1, 2, and 3 years respectively in their experience with 213 coiled catheters.
Ruben and Adair prospectively studied single and double cuff Tenckhoff catheters. 25% each of single cuff and double cuff catheters had complications requiring no removal while 19% of single cuff and 28%of double cuff catheters had complications requiring removal. In their long-term patients, the primary reason for catheter removal was failure of peritonitis to resolve. The catheter's life span was 38% at 22 months for both single and double cuff catheters.
Toronto Western hospital catheters:
These catheters were designed by Oreopoulos and Zellerman in 1976. Its main distinguishing feature is the silicon rubber discs towards the end of the intraperitoneal segment. These discs are to prevent the free movement of the catheter tip in the peritoneal cavity and thereby help the catheter tip remain in the true pelvis. The other modifications include Dacron flange 1 cm in diameter at the base of the peritoneal cuff and a silastic bead 1 mm distal to the Dacron flange to provide a groove between them, in which the surgeon ties the peritoneum tightly. Grefberg reported his comparative experience with Terickhoff and Toronto Western Hospital (TWH) catheters. At 18 months, cumulative life span of both catheters were similar at 80%. Eleven of the 59 Tenckhoff and 1 of the 24 TWH catheters became obstructed. Despite the advantage of TWH catheters over Terickhoff catheters regarding catheter obstruction, they abandoned its use because laparotomy was needed whenever the catheter was removed and the bowel was perforated during removal of 2 TWH catheters. Flanigan et al demonstrated less frequent drainage problems with TWH catheters as compared to single and double cuff Tencknoff catheters. But survival of the catheters with TWH catheters was lower than with Tenckhoff catheters, probably due to higher incidence of refractory peritonitis in their patients using such catheters.
Swan neck catheters:
Swan neck catheters feature a permanent bend between cuffs. As a result of this design, catheters can be placed in an arcuate tunnel in an unstressed condition with both external and internal segments of tunnel directed downwards. In some, the peritoneal level features of TWH catheter were maintained.
Swan neck prototypes were initially designed in 1985 with 80? arc angle but later on modified with 170-180? arc angle in view of tendency of cuff extrusion with 80? angle. Swan neck modification of Tenckhoff and TWH catheters are available.
Swan neck Missouri catheter is identical to the swan neck TWH catheter with the exception that it does not have intraperitoneal discs. Swan neck Missouri coiled (curled) catheters come with 5 cm or 3 cm intercuff distance and can be used depending on whether the patient is loan, average or obese.
Swan neck presternal catheter (with prestemal skin exit) was designed with the assumption that the chest wall is subjected to minimal movements, decreasing chances of trauma and contamination and incision over chest-wall heals better. Chest wall also has less fat thickness. Also, in patient with abdominal ostomies and in children with diapers, a chest exit location decreases chances of cross examination. Presternal catheters may allow tub bath to patients and may give better body image. This catheter is composed of two silicon rubber tubes, which are to be connected end to end at the time of implantation. The implanted lower (abdominal) tube constitutes the intraperitoneal catheter segment and a part of intramural segment. The upper or chest tube constitutes the remaining part of the intramural segment and the external catheter segment. The lower tube is just like swan neck Missouri catheter except that it is not bent and does not have a second cuff.
The upper tube carries two cuffs, a superficial and a middle or central spaced 5 cm apart. The tube between these two cuffs has 180? are angle bent. The distal lumen of the upper tube is attached to proximal lumen of the lower tube through titanium connector at the time of implantation. The tubing grip of the titanium connector is so strong that two parts of the catheter practically cannot separate spontaneously in the tunnel. Thus the implanted catheter has a very long subcutaneous tunnel from chest wall to abdominal wall. Fifteen of such catheters have been implanted in our confer with good results.
In comparison to TWH and Tenckhoff catheters, swan neck Missouri straight and coiled catheters had significantly higher survival probability,. Swan neck Missouri straight catheters showed Improvement in malfunction, leaks, cuff extrusion, and exit tunnel infections compared to Tenckhoff and TWH catheters.
Swan neck Missouri coiled catheters had similar survival and removal rates to swan neck Missouri straight catheters, but coiled catheters may show advantages with regard to decrease in infusion pain.
Accessories for Implantation:
Stencils have been developed for skin marking to facilitate creation of proper tunnels for swan neck catheters, The stencil follows exactly the shape of the intramural segments of the catheter. The holes for the exit site marking are located 2 cm for average and obese people and 1 cm for lean or average people from the cuff.
A 62 cm long stiffening stiletto is used to facilitate catheter insertion into the true pelvis. During insertion, about 1 cm of trio catheter is left beyond the tip of the stilette to protect bowel.
Tenckhoff trocar for bedside insertion, a Scanion tunneler for presternal catheter and exit trocar are used as tunneling devices. Peritoneoscope equipment is used for peritoneoscopic insertion. For Seldinger (guide wire) technique for catheter placement, a guide needle, a Seldinger guide wire and a tapered dilator with surrounding scored peel-away sheath is needed.
Implantation of Rigid Catheters:
When the need to start peritoneal dialysis is urgent, one may elect to access the peritoneal cavity through a rigid catheter, which may be inserted at bedside. Patients with previous abdominal surgery should not have this bedside insertion, since abdominal adhesions increase the risk of inadvertent viscus perforation. A small stab wound (2-3 mm) is made in the midline under local anesthesia, 2-3 cm below the umbilicus. With the stylet in place, the catheter is forced through the abdominal wall by a short thrust or preferably with a rotary movement. A "pop" is recognized as soon as the peritoneal cavity is entered. The tip of the catheter is directed toward the coccyx. Some inject 2 litres of dialysis fluid via a small gauge needle prior to stylet puncture. This infusion accomplishes two major objectives: first, it facilitates recognition of the "true" intraperitoneal space; second, it reduces the likelihood of viscus perforation. Stylet is withdrawn once catheter is in peritoneal cavity and catheter is advanced towards coccyx. After one or two good in and out exchanges, the catheter is firmly secured to the skin with the aid of a metal disc. Bleeding, dialysis solution leaks, poor drainage, extraperitoneal space penetration, viscus perforation, peritonitis, abdominal pain, and loss of rigid catheter in the peritoneum are some of the complications of rigid catheter. Minor bleeding stops after three or four exchanges or with pressure over the catheter insertion site. If bleeding is copious, 1000 units of heparin should, be added to each litre to prevent obstruction. Surgical exploration is required for large bleeding. Dialysis solution leak occurs in 14-36%,.
Implantation of soft catheters:
Because of the high frequency of dialysis solution leaks and poor drainage necessitating frequent catheter manipulation and resultant peritonitis with the use of rigid catheters, some centres, prefer to insert single or double cuff Tenckhoff catheters for treatment of acute renal failure. Preparation for implantation for acute renal failure is the same as for rigid catheter, but for chronic dialysis implantation more elaborate preparation is necessary. The belt line of the patient is identified and exit holes are marked with stencils at least 2 cm from belt line. One gram of vancomycin is given within 24 hours prior to insertion. In the evening preceding the surgery, a tap water enema is administered and the patient takes a shower.
Implantation method can be blind using Tenckhoff trocar, peritonooscope, Seldinger guide wire and peel-away sheath, or surgical using paramedian approach. Surgical method of insertion is most frequently used method. Moncrief and Popovicsh described a new technique for catheter insertion. Unlike any other technique, the distal (external) segment of the catheter is completely buried and remains in the subcutaneous tunnel until exteriorization after 3-8 weeks post catheter insertion. This technique allows tissue ingrowth into the cuff material without exposure to skin surface area. Moncrief and Popovich reported significant reduction in peritonitis incidence with this technique. Details of catheter insertions are previously described.
Plain X-ray of the abdomen is done in the recovery room to check position and identify any kinks. In the ward, rapid no-dwell exchanges with 1 litre dialysate containing 1000 units of heparin in each litre are done. If immediate peritoneal dialysis is needed, the patient should be in strict supine position with dwell time increased to 30-40 minutes. We do not commence peritoneal dialysis in the upright position sooner than 10 days post implantation, thus CAPD is not started for 10 days.
To delay bacterial colonization of the exit site and minimize trauma, the dressing should not be changed frequently. The surgical dressing is gently removed after one week. Nonionic surfactant is used to help gauze removal if it is attached to scab. Scab should not be forcibly removed. Care is taken to avoid catheter pulling and tugging. Dressing is changed weekly (with nonionic surfactant like Shur-ClensR) till healing is complete, which usually takes 4-8 weeks. The catheter should be anchored in such a way that the patient's movements are only minimally transmitted to the exit. After healing is complete, care of the catheter involves cleaning with soap and water and the exit can be left open without dressing cover after 6-12 months. The patient should use a shower and avoid submersion in water as with a tub bath.
The catheter may have to be removed because of malfunction or complicating medical conditions with a functioning catheter. Malfunction can be due to 1) intraluminal obstruction with blood or fibrin clot or omental tissue incarceration, 2) catheter tip migration out of the pelvis with poor drainage. 3) catheter kink along its course and 4) catheter tip caught in adhesions following severe peritonitis. Medical conditions requiring catheter removal although catheter may be functioning include 1) recurrent peritonitis with no identifiable cause, 2) peritonitis due to exit site and/or tunnel infection, 3) catheter with persistent exit site infection, 4) tunnel infection and abscess, 5) late recurrent dialysis leak through the exit site or into the layers of the abdominal wall, 6) unusual peritonitis such as fungal or mycobacterial, 7) bowel perforation with multiple organisms peritonitis, 8) severe abdominal pain either due to catheter impinging on internal organs or during solution inflow 9) catheter cuff extrusion with infection, and 10) accidental break in the continuity of the catheter.
The common complications of peritoneal dialysis catheters include: exititunnel infection., external cuff extrusions; obstruction, which is usually a sequelae of catheter tip migration out of the pelvis with subsequent omental wrapping or tip entrapment in peritoneal adhesions; dialysate leaks; peritonitis; and infusion or pressure pain.
Exit / Tunnel Infection
Pierratos defined exit site infection as "Redness of skin, induration or purulent discharge from exit site. Formations of the crust around the exit may not indicate infection. Positive cultures from the exit site in the absence of inflammation do not Indicate infection." This definition, however, is not sufficiently precise to delineate infected from noninfected exits in many instances. After prolonged evaluation for 3 years at our institution, exit site appearance in the immediate post implantation period and later, after exit is healed, is classified into 5 categories,,: acutely inflammed, equivocal, good and perfect see [Table - 1]. Exit trauma is an important cause of exit site infection. Trauma may cause bleeding, pain, formation of a scab, and deterioration of exit appearance. For severe trauma, prophylactic antibiotics should be used. Collagen fibers inhibit epithelial cell spread in the sinus tract. To encourage dermal ingrowth and to prevent epithelialization of the tunnel ("marsupialization"), devices of porous material were introduced,. However, the epithelium adjacent to the silicone catheter tends to migrate toward and beyond the subcutaneous cuff, and oxygen tension. On the other hand, too large an incision prolongs healing and allows movement in the sinus. Mechanical stress slows the heating process; thus the catheter should be relatively tightly anchored in the sinus and also well immobilized outside the tunnel, especially during the healing period.
Microorganisms grow rapidly in the presence of blood. Antibiotic penetration into the coagulum is poor, therefore antibiotics should be given prior to implantation. Bacteria, especially Staphylococcus aureus and Staphylococcus epidermidis, bind to humoral factors like fibronectin coating the catheters. But bacteria themselves may adhere to foreign bodies by electrostatic attachment or by Loudon-van- der Waal's forces. Adherent bacteria synthesize and excrete a variety of complex polysaccharides (biofilm), which serve to protect them from host defense mechanisms. Moreover, most peritoneal catheter exits and sinus tracts are colonized by bacteria.
When the scab is forcibly removed during cleaning, the epidermal layer is broken, thus prolonging the process of epidermization. Frequent dressing changes facilitate exit contamination; on the other hand, liquid serous or sanguineous exudate at the exit promote bacterial growth. Therefore, the exit should be kept dry and dressing changes should be infrequent. Oxidant cleansing agents like povidoneiodine and hydrogen peroxide are cytotoxic to mammalian cells and should not be used. Non-ionic, amphophilic. non-toxic surfactants like 20% poloxamer 188 (Shur-Clens R) should promote healing. Drainage of necrotic tissue immediate post-implantation is facilitated by gravity when the exit is directed downwards. Impaired nutrition, diabetes mellitus, uremia and corticosteroids are well known factors that slow wound healing.
Factors influencing infection of a healed exit-site:
Design of the catheter, its location in the created tunnel, bacterial colonization of the sinus. Staphylococcus aureus nasal carriage status, catheter skin exit direction, sinus tract length, number of cuffs and the materials for the external cuff and the tubing in the sinus are the factors influencing infection of healed catheter tunnel. The importance of Staphylococcus aureus as an etiologic agent of peritoneal catheter exit site infection has been well established. Nasal carriage status of Staphylococcus aureus is reported to be common in patients undergoing dialysis. A recent multi-centre study found an increased incidence of exit site infection in nasal carriers of staphylococcus aureus: in 85% of these infections, the strain from the nares and the strain causing infection were similar in phage typing and antibiotic profile. However, another study showed that strains causing exit site infections and strains cultured from nares are different. The sinus tract should be one or two centimetres in length to minimize bacterial colonization,. However such a short sinus tract predisposes to cuff extrusion. Double cuff catheter survival is longer than single Cuff and exit infection tends to be less frequent and significantly less resistant to treatment compared to single cuff catheters. Also a recently published national study of the United States Renal Data System creating a sinus between the tubing and the skin, Bacterial colonization with subsequent infection tends to occur in the sinus. However, a recent study showed that in almost all human peritoneal catheter tunnels the epithelium does not reach to the cuff but stops a few millimetres from the exit in the sinus tract. This suggests that granulation tissue per se can also inhibit epidermal cell spread. Epidermis starts entering into the sinus after 2-3 weeks in fast-healing exits while in slow-healing exits epidermis starts entering the sinus after 4-6 weeks when the epidermis covers approximately half of the visible sinus tract with the remaining half covered with granulation tissue.
Factors influencing exit-site healing:
The factors influencing the healing process are: tissue perfusion; mechanical factors; bacterial colonization of sinus: apithelization; local cleansing agents: exit direction; and systemic factors. Too tight a tunnel does not allow for drainage of necrotic tissue and leads to tissue edema, which decreases local perfusion. (USRDS) revealed an increased relative risk for the first peritonitis episode with a single cuff versus a double cuff catheter. Location of the deep cuff in the muscle provides better vascularization and stronger fibrous tissue ingrowth compared to a cuff located in subcutaneous tissue. The USRDS study 43 also revealed a reduced relative risk of first peritonitis episode for lateral catheter placement in the rectus muscle belly versus midline insertion with deep cuff in subcutaneous position.
The issue ingrowth into the cuff does not seem to constitute per se a critical barrier for infection spreading. Additionally, the external cuff anchors the catheter, restricting piston-like movements of the catheter in the sinus.
External cuff extrusion
Localization of the cult close to the exit predisposes to its extrusion. There are two forces that cause cuff extrusion: 1) the pushing force of catheter resilience and 2) pulling and tugging from daily manipulation of the catheter. The resilience of the straight catheter implanted in an unnatural shape plays the most important role in cuff extrusion. High pressure in the abdomen during CAPD may also tend to push out the external cuff. External cuff should be implanted 1-2 cm beneath the skin as a compromise between the requirement of a short sinus tract to prevent infections but not so short as to favour cuff extrusion. Also, resilience forces should be eliminated by creating the tunnel in a shape similar to the shape of the catheter.
Once there is cuff extrusion, if it is not infected, it can be left alone; however, usually the cuff gets infected and requires systemic antibiotics or surgical intervention. If there is no peritonitis or deep cuff infection the catheter may be saved at least for some time by shaving off the cuff .
Catheter tip migration
The best conditions for dialysate drainage are created with the catheter tip in the true pelvis because in the majority of people the omentum does not reach to the true pelvis. Catheter tip may migrate to upper abdomen due to "shape memory" if straight catheters are used and exit is directed caudally.
If the tip translocates to the left upper abdomen, the peristalsis of the descending colon may restore proper position of the tip; however, a tip translocated to the right upper abdomen usually does not return to the proper position because forces of both catheter resilience and ascending colon peristalsis push the tip upwards. Catheter implanted with a straight subcutaneous tunnel with external exit directed downward and intraperitoneal entrance directed upward migrates over to the upper abdomen more frequently compared to the opposite tunnel direction. To avoid this, the catheter should be implanted in its moulded shape.
In CAPD patients, pericatheter leaks are frequently due to high intra-abdominal pressure. Insertion of deep cuff into the belly of the rectus muscle as recommended by Helfrich et al markedly reduces chances of pericatheter leak. Leak can occur early or late. Contrary to the early leaks, which are usually external, the late leak infiltrates the abdominal wall. Leaking leads to ultrafiltration failure, fluid overload and localized edema. The best method of leak localization is CT scan with intraperitoneal contrast.
Infusion and pressure pain
Some patients feel pain due to "jet effect" of the rapidly flowing dialysis solution. Catheters with a coiled intraperitoneal segment are less likely to induce abdominal pain because of reduced "jet effect". Slower infusion rate, incomplete drainage, tidal mode for nightly peritoneal dialysis, solution alkalinization, lidocaine in solution and catheter replacement have been used for relieving pain.
The most common reason for catheter obstruction is occlusion of the tip by omentum or intraluminal clot. Pressure by the internal organs may also cause poor flow. Emptying the bladder and using laxatives may improve catheter function. Clotting may be prevented by rinsing out blood from the peritoneal cavity and using heparin when there is fibrin or blood. If all these are unsuccessful, urokinase 5000 IU diluted in normal saline may open the obstruction in 10-15% of cases.
Catheter kinking in the tunnel usually is associated with two-way obstruction and requires surgical correction. Omental wrapping or multiple adhesions require omentectomy or adhesiolysis through laparoscopy. Catheter migration out of the true pelvis may predispose to poor flow. While the great majority of malpositioned catheters are not obstructed, a catheter with its tip in the upper abdomen is still about six times more likely to be non-functional. In one series, 3% of the catheters were obstructed with the tip in the true pelvis. Relocation of the catheter is best done surgically using laparoscopic method.
Organ erosions leading to intra-abdominal bleeding and/or peritonitis have been reported with straight Terickhoff and Toronto Western Hospital catheters. No such complications have been reported with coiled catheters.
Catheters can be accidentally cut with scissors during dressing change. Repair kits are available for repair. Material breakdown of the catheters and cracks in catheters can be a rare problem, especially after repeated exposure to BetadineR (personal experience).
There are three essential prerequisites of optimum peritoneal catheter performance: catheter design, implantation technique, and post implantation care. Silicon rubber tubing with double polyester cuff is still the best design. A permanent bend between cuffs offers additional advantages because it allows implantation of the catheter in unstressed condition in an arcuate tunnel with both internal and external exits directed downward. Surgical or peritoneoscopic implantation virtually eliminates such complications as bowel perforation or massive bleeding. Exit should be located in a place only minimally subjected to pressure and movement Whereas supine peritoneal dialysis may be started immediately post implantation, ambulatory peritoneal dialysis should be postponed for at least 10 days after implantation to avoid early leaks. Exit site, tunnel infection, and peritonitis - although considerably reduced - are still the most troublesome complications. New humoral factors accelerating healing, delaying exteriorization of external segment of the catheter, and use of a new exit location on the chest instead of abdomen are new areas of research to further reduce these complications.
[Table - 1]