Evaluating patients for chronic peritoneal dialysis and selection of modality

INTRODUCTION — Peritoneal dialysis is an effective therapy for end-stage kidney disease (ESKD). Modalities include continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD).

This topic provides a guide for clinicians who are considering peritoneal dialysis as a treatment option for patients. The topic reviews contraindications, timing of placement of the peritoneal catheter, and the selection of the peritoneal dialysis modality.

The prescription for peritoneal dialysis and the evaluation of decreased solute clearance and ultrafiltration are discussed elsewhere:

●(See "Prescribing peritoneal dialysis".)

●(See "Inadequate solute clearance in peritoneal dialysis".)

●(See "Peritoneal equilibration test".)

●(See "Management of hypervolemia in patients on peritoneal dialysis".)

EVALUATION

Initial discussion — Discussions regarding kidney replacement therapy (KRT) depend on the rate of decline in kidney function but generally begin when the estimated glomerular filtration rate (eGFR) is between 20 to 30 mL/min/1.73 m². Patients with rapid decline in kidney function may require a discussion and preparations earlier than this. (See "Overview of the management of chronic kidney disease in adults", section on 'Preparation for and initiation of kidney replacement therapy'.)

Initiating discussions at this level of kidney function allows for a timely referral for evaluation for kidney transplantation. A timely referral is important for some patients since they can start to accrue time on the deceased donor transplant waiting list when the eGFR decreases below 20 mL/min/1.73 m². (See "Kidney transplantation in adults: Evaluation of the potential kidney transplant recipient", section on 'Timing of referral'.)

At this time, a "life plan" for kidney care should be discussed [1,2]. The life plan, which takes into account the patient's goals, access options, and timelines for care, acknowledges that a patient may require more than one KRT modality over the course of their life and that the modalities are all selected in order to maximize quality and quantity of life. As an example, a patient who is an optimal candidate for transplantation may not expect to receive a deceased donor kidney for months or years, during which time they may elect to use peritoneal dialysis while there is still significant residual native kidney function.

The life plan must continually adapt to changes in the patient's clinical course. The same patient may end up having a well-functioning allograft for 20 years and then require dialysis again because of allograft failure. As the allograft fails, the patient may elect to have a fistula placed to prepare for in-center hemodialysis if, for example, his or her support system or living situation has changed.

Peritoneal dialysis can work well as a long-term therapy for almost any patient and should be included in most options discussions, even if it ends up being discouraged by providers due to valid concerns about feasibility. (See 'Potential barriers to peritoneal dialysis' below.)

Timing of catheter placement — We wait for the patient to have some minimal uremic symptoms prior to having the catheter placed. We usually allow two weeks for the catheter exit tunnel to heal before starting peritoneal dialysis and dialysis training.

However, a peritoneal dialysis catheter can be placed at any time prior to the patient starting dialysis. In fact, the peritoneal dialysis catheter may be used within hours of its placement providing volumes of instilled dialysate are kept low and the patient is kept in a supine position to minimize risk of pericatheter leaks. (See "Urgent-start peritoneal dialysis", section on 'Initial prescription'.)

Some clinicians place the catheter many weeks to months prior to the initiation of dialysis.

Once it is placed, the catheter must be monitored until it is time to start dialysis. Catheters should receive exit-site care with careful cleaning and topical antibiotic application prior to use. (See "Peritoneal catheter exit-site and tunnel infections in peritoneal dialysis in adults", section on 'Maintenance preventive care'.)

We also flush the catheter weekly with 1 liter of dialysate to ensure patency. However, there are no good studies demonstrating that this increases patency [3].

Some centers tunnel (ie, "bury") the catheter under the skin when it is placed. The catheter can be freed by making a small incision in the skin and extracting the tubing, thus creating the exit site at the time of extraction. This method allows the catheter to be ready when needed without having to perform exit-site care or risk exit-site infection prior to catheter use. These catheters cannot be flushed until they are extracted but are generally patent when they are finally used.

The ideal candidate — The most important qualification for the ideal peritoneal dialysis candidate is having the desire to perform his or her own care.

Other characteristics of an optimal candidate include the following:

●Significant residual kidney function – It is much easier to provide adequate peritoneal dialysis when clearance provided by residual kidney function can be added to that provided by dialysis for the total required clearance. This allows for a flexible dialysis schedule that is usually more acceptable to patients.

●Minimal or no abdominal surgery – Adhesions resulting from surgery decrease the effective peritoneal membrane surface area, which may limit dialysis.

●Understands instructions and able to communicate – A minimum threshold cognitive ability is required to understand how peritoneal dialysis works and to communicate when complications arise.

●Sufficient eyesight, manual strength, and dexterity – Older adults and patients with comorbidities (such as diabetic retinopathy or rheumatoid arthritis) may have difficulty physically performing the procedure.

●Suitable environment to store supplies and perform exchanges – Ideally, the patient should have a room that may be closed off (ie, a bedroom) in order to perform tubing connections in a sterile fashion.

However, not having all or any of these characteristics does not mean that a patient is not an acceptable candidate for peritoneal dialysis. Even when the candidate cannot perform the procedure (or does not wish to do so), a caregiver may perform "assisted" peritoneal dialysis.

Potential barriers to peritoneal dialysis — The only absolute contraindication to treatment with peritoneal dialysis is lack of a functional peritoneal membrane [4]. Thus, almost all barriers are relative, depending upon the motivation of the patient and the clinical experience of the clinician and the dialysis center [5,6].

There are a few patient factors that could, in some circumstances, cause the provider to recommend against peritoneal dialysis.

Peritoneal scarring — Advanced peritoneal scarring and adhesions resulting from prior surgeries, which cannot be corrected with surgical adhesiolysis, are major barriers to peritoneal dialysis. Adhesions limit the free flow of peritoneal dialysate and cause problems with filling, draining, solute clearance, and ultrafiltration. In a retrospective study of 120 patients operated on by a single laparoscopic surgeon, patients who had a history of major abdominal surgery (n = 55) required more procedures (adhesiolysis, hernia repair) compared with those who did not have such a history (n = 61), although postoperative complications were not different between groups [7].

It is difficult to predict the severity of adhesions without laparoscopy. If patients have significant risk factors for adhesions (such as multiple abdominal procedures, a history of a gallbladder or bowel perforation, or small bowel obstruction related to adhesions), we often recommend not pursuing peritoneal dialysis. However, if the patient still wishes to try peritoneal dialysis, despite the possibility that it may not work, we refer them for laparoscopy with simultaneous adhesiolysis and catheter placement. We allow the surgeon to make the decision during the operation as to whether a catheter will or will not function in the abdomen. If the surgeon thinks that peritoneal dialysis will not work due to adhesions, he/she aborts the surgery without placing the catheter.

This approach requires that the patient be carefully advised prior to surgery that peritoneal dialysis may not be possible. It is also necessary to work with a surgeon with significant experience in the placement of dialysis catheters.

Physical, cognitive, or psychological impairment — Occasionally, patients are unable to perform the dialysis procedure due to physical impairment (amputations, physical debility, etc), and there is not another caregiver available to help.

Lack of vision is not a contraindication to peritoneal dialysis. Blind patients may perform peritoneal dialysis using connection assist devices. Training in the use of a touch technique with the use of procedural audio instructions for home reference allowed three patients to perform peritoneal dialysis in their homes without increased risk of peritonitis [8].

Occasionally, the lack of cognitive ability of both the patient and the available caregiver are barriers to performing the procedure. Although peritoneal dialysis is simple to learn and perform and patients are given a series of steps (either written or by video or audio technology) to review every time they perform an exchange, sometimes, both the patient and caregiver are not able to follow the steps successfully. In addition, diminished ability for self-care secondary to cognitive impairment may predispose patients to complications such as peritonitis and exit-site infections [9].

A central processing disorder (such as a severe developmental delay) that makes it difficult for the patient to understand and cooperate with the dialysis procedure may allow peritoneal dialysis with a caregiver, but the patient may need a modality based on manual exchanges (continuous ambulatory peritoneal dialysis [CAPD]) rather than the cycler (automated peritoneal dialysis [APD]). A manual exchange takes only 15 to 30 minutes to perform, during which the caregiver can sit with the patient. In contrast, APD requires being tethered to an overnight cycler, which may provoke agitation and cause the individual to disrupt the system. In some institutions, CAPD is the preferred KRT for patients who cannot stay still long enough for APD or HD to be feasible.

If there is a concern about lack of ability to perform dialysis, the patient and caregiver may be evaluated by a home training staff prior to catheter placement using an artificial catheter/apron setup that mimics the true system.

If the patient and caregiver are unable to perform the procedure for physical or cognitive reasons, "assisted peritoneal dialysis" may be possible in some areas. With assisted peritoneal dialysis, a health care professional comes out to the residence to start a nocturnal cycler treatment at night and returns in the morning to take the patient off the machine.

Lack of appropriate environment — There must be a clean, dry, temperature-controlled location for storage of peritoneal fluids and for performing dialysis. Peritoneal dialysis requires the storage of multiple bags of fluid with varying osmolar strengths. If a patient lives in a very small dwelling or is homeless, the lack of storage space may be limiting factor.

In addition, many skilled nursing facilities do not permit peritoneal dialysis.

Anuria or large patient size — Anuria (ie, no residual kidney function) and large patient size both result in a high dialysis volume requirement (ie, numerous exchanges or relatively larger volume per exchange). Anuria means that all clearance must be provided by dialysis since no clearance is provided by the kidney. Patient size is directly related to the dialysis volume requirement. (See "Prescribing peritoneal dialysis", section on 'Kt/Vurea'.)

Both issues can usually be solved with the appropriate peritoneal dialysis prescription.

Active inflammatory process or cancer — Patients with active diverticulitis, inflammatory bowel disease, or abdominal cancer are more likely to develop peritonitis or mechanical catheter problems. Among such patients, the decision to pursue peritoneal dialysis must be individualized after consideration of the risks and benefits. (See "Risk factors and prevention of peritonitis in peritoneal dialysis", section on 'Risk factors'.)

Surgical ostomies — Surgical ostomies increase the risk of exit-site infection [10]. We use a presternal catheter for all patients with ostomies, so the exit site can be easily cleaned and so that any ostomy leakage will flow in a caudal direction, away from the peritoneal dialysis catheter.

Large abdominal wall hernia — Large abdominal wall hernias that cannot be repaired are potential barriers to peritoneal dialysis. The increased intra-abdominal pressure that is associated with peritoneal dialysis may worsen the hernia, which may be cosmetically displeasing to patients. However, in contrast with small hernias, large hernias are relatively unlikely to become incarcerated and therefore are not absolute contraindications for PD.

Patients with abdominal hernias are carefully evaluated by surgery prior to placement of the catheter. Most hernias can be repaired either at the time of peritoneal dialysis catheter placement (if the catheter is being placed surgically) or with a separate surgery prior to catheter placement.

Ventriculoperitoneal shunts — We generally do not offer peritoneal dialysis to most patients who have a ventriculoperitoneal shunt, although experience is limited and exceptions could be made if no alternative (such as hemodialysis) is available. Ventriculoperitoneal shunts theoretically increase the risk of peritonitis, shunt malfunction, and ascending infection (ie, meningitis).

Although there are no studies that support these theoretical risks, we believe the potentially devastating outcomes outweigh the benefits of peritoneal dialysis in most patients. A small study including 18 children with concurrent ventriculoperitoneal shunt and peritoneal dialysis catheter reported a peritonitis rate of 1 in 19.6 months with no report of meningitis subsequent to peritonitis [11]. There were also no reports of ventriculoperitoneal shunt dysfunction, possibly because the one-way valve in shunt devices coupled with existing pressure gradients prevent the intraperitoneal pressure from exceeding cerebrospinal fluid pressure [11].

AVAILABLE MODALITIES — Peritoneal dialysis can be performed in a continuous (continuous ambulatory peritoneal dialysis [CAPD]) or an automated form of intermittent dialysis (APD) [12]. Most patients on peritoneal dialysis in the United States are on APD.

Continuous ambulatory peritoneal dialysis — CAPD involves multiple exchanges during the day (usually three), followed by an overnight dwell. A modification involves one automated nighttime exchange with an exchange device, resulting in two overnight exchanges and three exchanges during the day; however, this is not commonly used [13]. When it is used, a standard cycler is required.

Automated peritoneal dialysis — APD uses a cycler to perform multiple overnight exchanges resulting in multiple short dwells. Variations of APD include continuous cycler peritoneal dialysis (CCPD), nightly intermittent peritoneal dialysis (NIPD), tidal peritoneal dialysis (TPD), and intermittent peritoneal dialysis (IPD) [14]. The major variations are CCPD and NIPD, which are differentiated from each other by the absence or presence of a daytime dwell.

Continuous cycler peritoneal dialysis — In CCPD, a cycler delivers three to six overnight exchanges, usually with a 14- to 16-hour daytime dwell (ie, with no exchange during the day). Some patients must also do a midday exchange (ie, two daytime dwells) to achieve adequate solute clearance [13].

Weekly clearances are similar to those obtained with CAPD, but some evidence suggests that ultrafiltration rates may be lower with CCPD compared with CAPD unless one carefully modifies the prescription [15]. We are generally able to achieve dialysis small solute clearance targets by individualizing patient prescriptions. (See "Prescribing peritoneal dialysis", section on 'Optimal amount of dialysis (target Kt/Vurea)' and "Prescribing peritoneal dialysis", section on 'Ultrafiltration'.)

Nightly intermittent peritoneal dialysis — NIPD is a modification of CCPD in which patients perform multiple nightly exchanges over 8 to 10 hours and do not utilize a daytime dwell. We occasionally use NIPD in patients who are just starting dialysis and have significant residual kidney function or in small patients who are rapid transporters. The absence of a daytime dwell decreases the clearance of middle-molecule and larger-molecular-weight solute. (See 'Rapid transporters' below and "Prescribing peritoneal dialysis", section on 'Automated peritoneal dialysis'.)

Tidal peritoneal dialysis — In TPD, exchanges consist of a partial drain (usually 80 to 90 percent of instilled volume plus anticipated ultrafiltration from that dwell). The patient may or may not have a daytime dwell. We use TPD in patients who have pain during inflow or draining and in patients who have problems with slow drainage [16]. Because the peritoneal cavity always contains 250 to 400 cc of dialysate, TPD tends to be associated with improved comfort and better drainage [17].

TPD is relatively more expensive because it requires a larger amount of dialysate and is technically more difficult to perform. When prescribing TPD, one must remember to drain the tidal volume and also any expected ultrafiltration that may have occurred during that dwell. Increased solute clearances have not been confirmed in all patients, despite such findings in animal models [13,18].

Intermittent peritoneal dialysis — IPD utilizes multiple, short exchanges that are performed on an intermittent basis. We use IPD in hospitalized patients, but it is not recommended for chronic use. A typical regimen consists of 12 to 15 2-liter, one-hour dwells performed three or four days per week. Over 50 hours of dialysis is required to attain clearances similar to those achieved by a week of CAPD.

SELECTION OF PERITONEAL DIALYSIS MODALITY

Initial modality — Once the patient has decided to do peritoneal dialysis, the peritoneal dialysis modality must be selected. We ask the patient to choose between continuous ambulatory peritoneal dialysis (CAPD) and a form of automated peritoneal dialysis (APD) (usually continuous cycler peritoneal dialysis [CCPD]) based upon their preferences and lifestyle.

Except for the effect on residual kidney function, studies have demonstrated similarities between CAPD and APD for most clinical outcomes [19-23]. In a systematic review of three randomized, controlled trials including 139 patients, CAPD and APD resulted in similar mortality and hospitalization rates, risk of peritonitis, and fluid leaks [19]. Studies have also not shown differences between modalities in volume management and technique survival [22,24].

The relative effects of CAPD and APD on residual kidney function are controversial [22]. A large, observational study of 505 CAPD and 78 APD patients showed a higher risk of loss of residual kidney function in the first year with APD compared with CAPD (adjusted hazard ratio [HR] 2.66, 95% CI 1.60-4.44) [25]. However, no difference was detected in a systematic review of randomized trials [19]. Larger randomized trials are needed to determine whether a particular modality better preserves kidney function.

Most patients choose APD, usually because it allows the patient to go to work or pursue other activities during the day without performing manual exchanges. In a prospective, randomized study, APD provided significantly more time for work, family, and social activities than CAPD [26]. Sleep apnea may also be more responsive to APD [27].

Patient who are not able to do the exchanges themselves are also more amenable to APD since connections/disconnections are generally only required twice a day.

However, some patients may prefer CAPD because it does not require the use of machinery (cycler) and does not require being "tethered" to the cycler for several hours at night, often prior to going to sleep [28].

Recommendations for the initial prescription are provided elsewhere. (See "Prescribing peritoneal dialysis", section on 'Initial prescription'.)

When a change in modality is required — Occasionally, changes in modality are required in order to achieve adequate solute clearance and fluid balance. The requirement for a specific modality is usually after a patient has lost residual kidney function, which has been contributing to total clearance or fluid balance. Among patients who have residual kidney function, all modalities are usually effective in achieving Kt/V and volume control targets. In order to mentally prepare the patient for possible changes in modality, a "life plan" should be discussed frequently over the course of their management of end-stage kidney disease (ESKD). (See 'Initial discussion' above.)

We use the results of the peritoneal equilibration test (PET) to help individualize the prescription. (See 'Peritoneal equilibration test' below and "Peritoneal equilibration test", section on 'Selection of peritoneal dialysis regimen'.)

Peritoneal equilibration test — The PET is a semiquantitative assessment of peritoneal membrane transport function in patients on peritoneal dialysis [13,29]. We perform a PET after approximately one month on peritoneal dialysis so that the early effects of peritoneal dialysis fluids do not confound the results of the test. (See "Peritoneal equilibration test".)

The patient's transport characteristics are classified (ie, rapid versus slow transporters) based upon published norms (figure 1). Among patients who have inadequate solute removal or ultrafiltration, the peritoneal dialysis prescription may be optimized for rapid and slow transporters [30,31].

Rapid transporters — Rapid transporters (other terms used are fast transporters or high transporters) are optimally dialyzed with APD using a regimen with short dwell times. Standard CAPD, which generally utilizes prolonged dwell times, is less preferred. Despite this, however, we believe CAPD may be used for fast transporters, if necessary, provided that the regimen is appropriately modified.

Rapid transporters achieve almost total equilibration between plasma and dialysate for urea and creatinine in a few hours. They also rapidly absorb dialysate glucose, which removes the osmotic stimulus to ultrafiltration (figure 1). The net effect is that they begin to absorb dialysate after two to three hours, which causes reductions in both net ultrafiltration volume, final drain volumes, and net solute clearance. Ultrafiltration volume is reduced because of the relatively early loss of osmotic stimulus. Solute clearance is reduced because the solutes that have diffused into the dialysate are absorbed back into the systemic circulation, and net clearance is related to solute concentration in the dialysate and total drain volume (figure 2).

Thus, standard CAPD may not yield sufficient fluid or solute removal. Modifications in the CAPD prescription to increase fluid and solute removal include using shorter dwell times and a higher-dextrose dialysate (2.5 percent) or a colloid-based solution such as icodextrin.

Persistent use of high-dextrose dialysate increases the risk of hyperglycemia, hypertriglyceridemia, and/or weight gain from the increase in glucose absorption. The alternative osmotic agent, icodextrin, may also be used as icodextrin decreases the risk of these complications but is generally only used for a limited number of exchanges per day, usually only one or two exchanges. In the United States, icodextrin is US Food and Drug Administration (FDA) approved for only one exchange per day. (See "Management of hypervolemia in patients on peritoneal dialysis", section on 'Icodextrin dialysate'.)

Slow transporters — Slow transporters are optimally dialyzed with a CAPD prescription that provides longer dwell times. However, slow transporters could also do APD, if the patient's prescription is appropriately individualized.

Slow transporters need long dwell times to adequately remove small solutes. The solute dialysate/plasma creatinine ratio increases almost linearly during a long-dwell exchange in a slow transporter. Clearance per exchange therefore increases almost linearly throughout the long-dwell exchange.

Ultrafiltration is generally not a problem in this setting, since glucose is also slowly absorbed such that ultrafiltrate continues to be generated late during the dwell. (figure 2). (See "Rapid transporters on maintenance peritoneal dialysis".)

If a slow transporter is maintained on APD, the prescription should be modified to use longer dwells. APD could be adjusted to provide two exchanges over nine hours on the cycler, with a last-bag fill and a midday exchange resulting in similar dwell times as a CAPD prescription.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Dialysis".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Peritoneal dialysis (The Basics)")

●Beyond the Basics topic (see "Patient education: Peritoneal dialysis (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Choosing peritoneal dialysis – Peritoneal dialysis can work well as a kidney replacement therapy (KRT) for almost any patient. We discuss peritoneal dialysis as a possible therapy with all patients with significant chronic kidney disease who are considering kidney replacement options (ie, dialysis and transplantation). Discussions generally start when the estimated glomerular filtration rate (eGFR) is between 20 to 30 mL/min/1.73 m². (See 'Initial discussion' above.)

●Potential barriers – The only absolute contraindication to treatment with peritoneal dialysis is lack of a peritoneal membrane. Important barriers include nonsurgically correctable peritoneal scarring, adhesions, hernias or ostomies; physical, cognitive or psychological impairment that prevents the patient and/or caregiver from performing exchanges; and lack of an appropriate environment to store supplies or perform exchanges. Other obstacles include a high dialysis clearance demand caused by anuria (lack of residual kidney function) or large patient size, particularly if the patient ends up being a slow transporter. (See 'Potential barriers to peritoneal dialysis' above.)

●Types of peritoneal dialysis – Peritoneal dialysis can be performed in a continuous (continuous ambulatory peritoneal dialysis [CAPD]) or an automated form of intermittent dialysis (APD). The selection of the initial modality is generally left up to the patient. (See 'Initial modality' above.)

●Changing peritoneal dialysis modality – Occasionally, a change in prescription or modality is required in order to achieve adequate solute clearance and fluid balance. This is usually after there is a decline in residual kidney function and when the peritoneal equilibration test (PET) identifies the patient as being a slow or rapid transporter. However, even in these circumstances, most patients can continue to use either CAPD or a form of APD, if the patient's prescription is appropriately individualized. (See 'When a change in modality is required' above.)