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Peritoneal Access Devices, Placement Techniques, and Maintenance
The success of peritoneal dialysis (PD) as kidney replacement therapy for end-stage kidney disease and acute kidney injury relies upon a functional access to the peritoneal space for exchange of water and solutes. This access represents a controlled cutaneoperitoneal fistula comprised of a catheter device that bridges the abdominal wall through which fluid exchanges occur. Knowledge of best practices in catheter placement and maintenance can optimize the success of therapy and minimize the risk of catheter complications. To serve as a practical resource for the management of adult kidney failure patients, this chapter will focus on current practices, describing the most commonly used catheter types, procedures for matching the most appropriate device to the patient, placement methods, break-in procedures, and catheter care and maintenance. Investigational PD devices and techniques are not discussed. Pediatric dialysis access is covered in Chapter 70 .
Selection of catheter devices and insertion techniques often varies depending on whether the access is needed for acute or long-term PD therapy, geographic availability of material resources, and local provider expertise in placing catheters.
Acute Catheters
Flexible silicone rubber cuffed catheters for long-term PD (described more fully in the following section) are also routinely utilized for acute peritoneal access. Temporary semirigid plastic noncuffed catheters continue to be used for acute kidney injury in some lower-resource countries. The rigid acute catheter is inserted by percutaneous puncture using an internal stylet. The small lumen and side holes tend to be associated with less efficient dialysis. Pericatheter leakage and tubing obstruction are common. Because the risk of infection is high with rigid noncuffed catheters, the generally accepted period of maximum use is 3 days.
Silicone rubber catheters have supplanted the rigid device for acute access because they have a larger-diameter lumen and side holes, resulting in better dialysate flow rates and less obstruction. They are less prone to leakage and have a lower incidence of peritonitis. If the patient does not recover kidney function, the catheter may be used for long-term dialysis without the need for a new access procedure.
Chronic Catheters
The majority of catheters for long-term use are constructed of silicone rubber. The most commonly employed PD catheter types are illustrated in Fig. 25.1 . The standard double Dacron (polyester) cuff and straight- and coiled-tip catheters with a straight or preformed arc bend in the intercuff segment constitute the mainstay of PD access around the world ( Fig. 25.1 A and B). A recent large randomized controlled study comparing straight- and coiled-tip catheter configurations implanted by open dissection significantly favored the straight-tip design; however, the incidence of flow dysfunction was very low for both groups. A critical review of this study noted that the results were not adjusted for midline muscle-sweeping vs. paramedian muscle-splitting catheter insertion sites or operator/facility locations of the procedure. Previous smaller randomized trials comparing straight- and coiled-tip catheters have produced conflicting results with regard to the superiority of one design over the other.
Even though standard catheters are available with single cuffs, there is evidence to support the superiority of double-cuff catheters in preventing peritonitis from periluminal entry of organisms. A large retrospective cohort study suggested that the effect of the number of cuffs on peritonitis may be era related. Patients initiating PD from 1996 to 2000 had a significantly lower peritonitis rate with double-cuff catheters than with single-cuff devices, attributed mostly to lower rates of Staphylococcus aureus. In a later interval, 2001–2005, no difference in peritonitis rates was observed based upon the number of cuffs. The widespread adoption of prophylactic exit site or intranasal antibiotics during the later period may have reduced exit site colonization and infection sufficiently to eliminate the need for protection by the second cuff. However, the benefit of a double cuff may be particularly important where prophylactic antibiotics are not used. Since patient adherence with prophylactic ointments is variable, having the added protection of a double cuff may be advantageous, especially among those with diabetes and immunosuppressed patients in whom the risk of S. aureus catheter infection is higher.
Most catheters for long-term use possess a white radiopaque stripe along the longitudinal axis of the tubing that permits radiographic visualization. The stripe also serves as a guide during catheter insertion to prevent accidental twisting or kinking of the tubing. The majority of adult catheters have a 2.6-mm internal diameter. One catheter brand possesses a 3.5-mm internal diameter and can be readily identified by its blue radiopaque stripe. Although the in vitro flow rate of the larger-bore catheter is faster, any therapeutic advantage of this device has yet to be proven in the in vivo state. The importance of recognizing the catheter bore size is to prevent interchange of repair kits and replacement catheter adapters that can result in a loose fit and accidental separation.
Extended two-piece catheters were originally designed to provide a presternal exit site (see Fig. 25.1 C). The extended catheter consists of a one-cuff abdominal catheter segment that attaches to a two-cuff subcutaneous extension segment using a double-barbed titanium connector to permit remote location of the exit site to the upper chest. Extended catheters are also used to provide remote exit site locations to the upper abdominal and back regions. The abdominal catheter can be placed by any insertion method. The subcutaneous extension catheter is implanted using a vascular tunneling rod or similar device supplied by the catheter manufacturer.
Various modifications of the basic catheter designs have been made in an attempt to address the common mechanical problems of tissue attachment, tip migration, and pericatheter leaks. However, none of these alternative configurations have been shown to outperform the catheter designs depicted in Fig. 25.1 but increase the cost and difficulty of device insertion and removal. Concerns for these common mechanical problems are more reliably addressed by proper implantation technique than by a catheter design.
Choosing a Peritoneal Catheter for Long-Term Use
Because patients come in all sizes and shapes with a variety of medical conditions, it is unrealistic to expect that one catheter type should fit all. The choice of catheter type should take into consideration the patient’s belt line, obesity, skin creases and folds, presence of scars, chronic skin conditions, incontinence, physical limitations, bathing habits, and occupation. The provider’s familiarity with a basic inventory of catheter types is essential to enable customization of the peritoneal access to the specific needs of the patient and to afford maximum flexibility in exit site location. An exit site located in an area susceptible to mechanical irritation, bacterial contamination, or in a position that the patient cannot easily see or take care of predisposes to exit site and tunnel infection.
Fig. 25.2 illustrates how a basic catheter inventory might be applied. Patients who wear their belt lines below the umbilicus or have lower abdominal skin folds are usually best fitted with a catheter having a straight intercuff segment that is bent to produce a laterally directed exit site emerging above the belt line. Patients who wear their belt lines above the umbilicus are often best served with a catheter with a preformed arc bend that allows the exit site to emerge below the belt line. Individuals who have large rotund abdomens, severe obesity, drooping skin folds, intestinal stomas, feeding tubes, suprapubic catheters, urinary or fecal incontinence, chronic yeast intertrigo, or desire to take deep tub baths are candidates for extended two-piece catheters to produce upper abdominal or presternal exit sites.
The most appropriate choice of catheter is the one that produces the best balance of pelvic location of the catheter tip, exit site easily visible to the patient, and can be inserted through the abdominal wall with the least amount of tubing stress. The catheter insertion site is the fulcrum of this best balance and will determine the pelvic position of the catheter tip and the range of reachable exit sites. Therefore, catheter selection begins with determination of the insertion site. With the patient in the supine position, the insertion site for each style and size of catheter is determined by marking the upper border of the deep cuff in the paramedian plane when the upper border of the catheter coil is aligned with the upper border of the pubic symphysis ( Fig. 25.3 ). For straight-tip catheters, a point 5 cm from the end is aligned with the upper border of the pubic symphysis. During the catheter placement procedure, the deep cuff is implanted within the rectus muscle (or just below) at the level of the insertion incision. Using this convention to determine the insertion site will prevent the catheter tip from being implanted too low in the pelvis, producing pressure or poking discomfort, early termination of dialysate outflow, and severe end of drain pain.
After determining the catheter insertion site, the subcutaneous tunnel path and exit site location for catheters with a swan-neck bend simply follows the arc-bend configuration of the tubing, marking the skin exit site 2–3 cm beyond the superficial cuff. Catheters with a straight intercuff segment should assume a gentle arc in the subcutaneous tissues to produce more of a laterally directed exit site. Illustrated in Fig. 25.4 is a convenient three-step algorithm for catheters with a straight intercuff segment to design a laterally directed tunnel and exit site that minimizes creation of excessive tubing stress and shape-memory resiliency forces that can lead to catheter tip migration and superficial cuff extrusion. The amount of subcutaneous tube straightening over time is a balance between the induced catheter shape memory resiliency forces and the resistance offered by the tissues. In the worst-case scenario of tube straightening, the algorithm prevents the superficial cuff from coming closer than 2 cm of the exit site. In actual practice, the cuff remains 3 to 4 cm from the exit site. Even though this configuration is referred to as a laterally directed exit site, note that the terminal end of the subcutaneous track is inclined slightly downward to prevent pooling of water and debris in the skin exit sinus.
If the catheter needs to be arced more than a laterally directed exit site, a swan-neck catheter should be used instead to eliminate induced resiliency forces. Upwardly directed exit sites should be avoided to prevent pooling of cutaneous bacteria and debris, perspiration, and shower water in the exit sinus, predisposing the patient to exit site and tunnel infection.
After mapping exit site locations, the patient assumes a sitting or standing position and the marked exit sites are checked to see which is best visualized by the patient and does not conflict with the belt line, skin creases, or apices of bulging skin folds. If none of the marked exit sites for the standard abdominal catheters are satisfactory, the patient is then considered for an extended catheter to produce an upper abdominal or presternal exit site location.
Some dialysis catheter manufacturers produce marking stencils for the most commonly used coiled-tip catheter designs. Properly constructed stencils contain critical catheter design information including the distance between the deep cuff and the coil, suggested subcutaneous tunnel configurations, and recommended exit site locations relative to the position of the superficial cuff. Additional features of a well-designed stencil plate permit its precise orientation on the trunk region according to fixed anatomical landmarks, such as the pubic symphysis, representing the anterior upper border of the true pelvis, and the anatomical midline of the torso. Stencils permit accurate and reproducible association of the catheter design elements to these anatomical landmarks to help determine the best catheter type and insertion site that will produce optimal pelvic position of the catheter coil and the exit site location, which is reachable from the determined catheter insertion site. An example of a marking stencil and its use to map two types of standard abdominal catheters is illustrated in Fig. 25.5 . Most commercially available stencils use the three-step algorithm depicted in Fig. 25.4 to indicate the suggested lateral configuration of the subcutaneous track of straight intercuff segment catheters. The subcutaneous tunnel track for swan neck catheters follows the precise shape of the preformed arc bend. It is important to note that because of variations in dimensions of catheters among manufacturers, stencils cannot be used interchangeably for different product lines.
The advantages offered by stencil-based preoperative mapping is that the patient can be fully informed of the catheter insertion procedure, including the device type and exit site location and to assure that the facility has acquired the selected catheter type for the day of the procedure. In addition to the preoperative evaluation, the marking stencil is used again at the time of the catheter placement procedure to retrace the previously determined insertion incision, tunnel configuration, and exit site location. Be aware that some manufacturers produce impractical stencils that show only the cutout patterns of a swan neck bend but do not allow for proper alignment of the stencil plate on the abdominal or chest wall.
Peritoneal Dialysis Catheter Placement Procedures
Independent of the catheter implantation approach, adherence to a number of universal details is required to ensure the best opportunity for creating a successful long-term peritoneal access. Best practices for preoperative preparation and peritoneal catheter placement are listed in Table 25.1 . Omission of any one of these practices can potentially lead to loss of the catheter. Some implantation techniques do not incorporate all of the best practices, such as percutaneous needle-guidewire approaches performed through the midline or positioning the deep cuff above the level of the fascia. It is essential that the practitioner be aware of deviations from recommended practices and be observant for the potential complications that may arise from such departures.
Table 25.1
Best Practices in Peritoneal Catheter Placement
| Patient Preparation |
|
| Procedure Performance |
|
PD catheters are ordinarily placed by open surgical dissection, percutaneous needle-guidewire with or without image guidance, and laparoscopy. Table 25.2 provides suggested guidelines for selecting a catheter implantation approach. A brief summary of each of these techniques follows.
Table 25.2
Suggested Guidelines for Selecting a Peritoneal Dialysis Catheter Insertion Approach
Modified from Crabtree JH, Shrestha BM, Chow KM, et al. Creating and maintaining optimal peritoneal dialysis access in the adult patient: 2019 update. Perit Dial Int . 2019;39:414–436, Table 2.
| Previous Major Surgery or Peritonitis (Order of Suggested Technique) |
No Previous Major Surgery or Peritonitis (Order of Suggested Technique) |
|
|---|---|---|
| Patient suitable for general anesthesia |
|
|
| Patient only suitable for local anesthesia |
|
|
Open Surgical Dissection
A transverse or vertical paramedian incision is made through the skin, subcutaneous tissues, and anterior rectus sheath. The underlying muscle fibers are split to expose the posterior rectus sheath. A small hole is made through the posterior sheath and peritoneum to enter the peritoneal cavity. A purse-string suture is placed around the opening. The catheter, usually straightened over an internal stylet, is advanced through the peritoneal incision toward the pelvis. Despite being an open procedure, the catheter is advanced mostly by feel, therefore, blindly, into the peritoneal cavity. The stylet is partially withdrawn as the catheter is advanced until the deep cuff abuts the posterior fascia. After satisfactory placement has been achieved, the stylet is completely withdrawn and the purse-string suture is tied. Encouraging the catheter tip to remain oriented toward the pelvis is achieved by oblique passage of the catheter through the rectus sheath in a craniocaudal direction. The catheter tubing is exited through the anterior rectus sheath at least 2.5 cm cranial to the level of the purse-string suture and deep cuff location. Attention to detail in placement of the purse-string suture and repair of the anterior fascia is imperative to prevent pericatheter leak and hernia. The catheter is tunneled subcutaneously to the selected exit site following a satisfactory test of flow function.
Percutaneous Needle-Guidewire Technique
Placement of catheters by blind percutaneous puncture is performed using a modification of the Seldinger technique. The convenience of this approach is that it can be performed at the bedside, under local anesthesia, and using prepackaged self-contained kits that include the dialysis catheter. The abdomen is prefilled with 1.5–2 L of saline or dialysis solution instilled with an 18-gauge introducer needle inserted through a 1.5–2 cm infraumbilical or paramedian incision. Alternatively, a Veress needle may be used to perform the prefill. A guidewire is passed through the needle into the peritoneal cavity and directed toward the pelvis. The needle is withdrawn. A dilator with an overlying peel-away sheath is advanced through the fascia over the guidewire. The dilator is removed. The PD catheter is advanced through the peel-away sheath over the guidewire. Alternatively, the guidewire is removed from the peel-away sheath and the PD catheter, straightened over an internal stylet, is advanced through the sheath. The stylet is partially withdrawn as the catheter is advanced. The dialysis catheter is directed toward the pelvis. As the deep catheter cuff advances, the sheath is peeled away. The deep cuff is advanced to the level of the fascia. The peel-away sheath and guidewire or internal stylet, if used, are removed. Ideally, the deep cuff should be pushed through the fascia into the rectus muscle and a purse-string suture placed around the catheter to minimize the risk of pericatheter leak.
The addition of image guidance using ultrasonography and fluoroscopy increases the reliability and safety of the percutaneous approach. Ultrasound can be used to visualize the passage of the needle into the peritoneal cavity and avoid the inferior epigastric vessels and bowel loops. Fluoroscopy permits confirmation of needle entry into the peritoneal cavity by observing the flow of injected contrast solution around loops of bowel. The retrovesical space is identified by contrast pooling in the appropriate location. The guidewire and catheter are advanced to this site. The remainder of the procedure proceeds as described for blind placement. Although the radiopaque tubing stripe permits fluoroscopic imaging of the final catheter configuration, the proximity of adhesions or omentum cannot be assessed. After testing flow function, the catheter is then tunneled subcutaneously to the selected exit site.
Laparoscopy
Laparoscopy provides a minimally invasive approach with complete visualization of the peritoneal cavity during the catheter implantation procedure. The advantage of laparoscopic catheter placement over other approaches is the ability to proactively employ adjunctive procedures that significantly improve catheter outcomes. Laparoscopically guided rectus sheath tunneling places the catheter in a long musculofascial tunnel directed toward the pelvis and effectively prevents catheter tip migration, eliminates pericatheter hernias, and reduces the risk of pericatheter leaks. Observed redundant omentum that lies in juxtaposition of the catheter tip can be displaced from the pelvis into the upper abdomen and fixed to the abdominal wall (omentopexy). Compartmentalizing adhesions that may affect completeness of dialysate drainage can be divided. Intraperitoneal structures that siphon up to the catheter tip during the intraoperative irrigation test can be laparoscopically resected, including epiploic appendices of the sigmoid colon, uterine tubes, and the vermiform appendix. Redundant and bulky rectosigmoid colon blocking the pelvic inlet can be suspended along the lateral abdominal wall (colopexy). Previously unsuspected abdominal wall hernias can be identified and repaired at the time of the catheter implantation procedure.
Through a lateral abdominal wall puncture site remote from the point of intended catheter insertion, the abdomen is insufflated with gas through a Veress needle to create an intraperitoneal working space. A laparoscopic port and laparoscope are inserted. Under laparoscopic guidance, the catheter is introduced at a second puncture site and placed in a musculofascial tunnel oriented toward the pelvis, usually through the use of a port device that creates the rectus sheath tunnel. The catheter tip is directed into the true pelvis under visual control. After removal of the port device used to insert the catheter, the deep cuff of the catheter is positioned in the rectus muscle just below the anterior rectus sheath entry point. A purse-string fascial suture is placed around the catheter at the level of the anterior sheath to minimize the risk of pericatheter leak. The pneumoperitoneum is released but laparoscopic ports are left in place until a test irrigation of the catheter demonstrates successful flow function. After any indicated adjunctive procedures are completed, the catheter is tunneled subcutaneously to the selected exit site.
Testing Hydraulic Function
It is important to test catheter flow function before ending the catheter placement procedure. If the catheter has poor hydraulic function, catheter position should be adjusted until satisfactory flow is achieved. There are no standard protocols for hydraulic testing. A simple test is to inject 60 mL of saline into the catheter. Easy return of some of this fluid and changes in the level of an air–fluid interface in the tubing during respiration confirm that the catheter is located in the peritoneal space and has no kinks. A more complete test of flow function consists of infusing 500 to 1000 mL of saline or dialysate and observing for unimpeded inflow and outflow, allowing a 100- to 200-mL residual volume to remain to avoid leaving peritoneal structures drawn up to the catheter side holes. The larger irrigation volumes may permit an opportunity for redundant omentum, epiploic appendices, uterine tubes, or vermiform appendix to siphon up to the catheter tip and cause slow or low volume drainage. Adjusting the position of the catheter may possibly correct the flow dysfunction. Advanced laparoscopic techniques can definitively identify and deal with the anatomical structures impairing the flow and reduce the risk for future mechanical complications. The larger irrigation volume also provides an assessment of hemostasis and washes out any collection of blood from the procedure.
Special Peritoneal Access Methods
Extended Two-Piece Catheters
The abdominal segment of two-piece extended catheters can be implanted by any of the above-mentioned insertion techniques. A secondary incision is made in the vicinity of the planned upper abdominal, presternal, or back exit site. A marking stencil is invaluable in devising the location of the secondary incision and exit site. The measured distance between the abdominal insertion incision and the secondary incision is used to calculate how much tubing length will be trimmed from one or both of the catheter segments in order to correctly span the distance. The trimmed catheters are joined with a double barbed titanium connector and the linked catheter segments are tunneled on the surface of the fascia from the abdominal insertion site to the remote secondary incision with a tunneling rod. The extension catheter is then passed from the secondary incision through a subcutaneous tunnel to the designated exit site using a stylet to complete the procedure.
Catheter Embedding
Commonly referred to as the Moncrief-Popovich technique, catheter embedding consists of implanting a PD catheter far in advance of anticipated need. Instead of bringing the external limb of the catheter out to the surface, it is embedded under the skin in the subcutaneous space. When kidney function declines to the point of needing to initiate dialysis, the external limb is brought to the outside through a small skin incision ( Fig. 25.6 ).
After externalization of an embedded catheter that has been afforded extended healing time within the abdominal wall, the patient is able to proceed directly to full volume PD without the necessity of a break-in period that ordinarily accompanies a newly placed catheter. Another important attribute of catheter embedding is greater patient acceptance for earlier commitment to PD by catheter placement ahead of time. Once an embedded catheter is in place, patients tend to remain faithful to their modality selection. Consequently, this technique can be used as a strategy to grow PD programs. The need for insertion of central venous catheters and temporary hemodialysis can be avoided in patients previously implanted with an embedded catheter. The embedding technique permits more efficient surgical scheduling of catheter implantation as an elective nonurgent procedure and helps to reduce stress on operating room access. Disadvantages of the catheter embedding strategy include the need for two procedures (implantation and externalization) as opposed to one and the possibility of futile placement in the event of an adverse change in the patient’s condition during the time period that the catheter is embedded.
Catheter embedding can be incorporated into any of the implantation approaches using any catheter device. The catheter is temporarily externalized through the future skin exit site prior to embedment. The exit site scar serves as a landmark to know where to come back to for externalization. After acceptable flow function of the catheter is confirmed, the tubing is flushed with heparin, plugged, and buried in the subcutaneous tissue. To minimize the risk of hematoma or seroma and to facilitate subsequent externalization, the catheter should be embedded in a linear or curvilinear subcutaneous track using a tunneling stylet as opposed to curling the tubing into a subcutaneous pocket. Embedding should not be performed if the anticipated need for dialysis is less than 4 weeks. Externalization of embedded catheters is easily performed as an office procedure. Catheters have been embedded for months to years with an 85% to 93% immediate function rate upon externalization. Catheter dysfunction is usually due to intraluminal fibrin clots or adhesions. Overall, 94% to 99% are successfully used for dialysis after radiologic or laparoscopic revision of nonfunctioning catheters.
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