Nephrology Hypertension

Peritoneal Dialysis: Patient Selection

Identifying Patients

There are three types of PD patients: those that start their dialysis therapy with PD; those who turn to PD after complications from HD; and those who turn to PD after a failed transplant. It is important to remember that modality education should be offered to each group and patients should be reminded that there are options when it comes to the dialysis care.

There are only two absolute contra-indications for peritoneal dialysis: the absence of a functional peritoneal membrane and lack of a suitable home environment. Every other medical or psychosocial contraindication is relative and strategies to overcome should be discussed with the patient and care team as the patient learns about and chooses a dialysis modality.

The overwhelming majority of patients with advanced chronic kidney disease do not have any medical or psycho-social contraindication for peritoneal dialysis. Since there are few therapies that have as profound an impact on a patient's life-style as dialysis, it is essential to engage patients to determine which dialysis modality will allow them to lead what they believe to be fulfilling lives.

It is equally important to reassure the patients that the modality they select at initiation is not permanent and that in most circumstances, patients are able to change to an alternative dialysis modality if their medical or social condition changes or if the burden of the selected therapy differs from their expectations were. This can sometimes relieve the pressure on patients considering different dialysis therapies.

There are several medical and social issues that are useful to discuss with CKD patients as they weigh their dialysis options. It is important that these be elucidated when taking a patient’s history and completing a physical exam. These include patient age, cause of end-stage renal disease (diabetes, polycystic kidney disease, scleroderma), co-morbid conditions (previous cardiovascular disease), surgical history (previous abdominal surgery, aortic prosthetic grafts in patients with abdominal aortic aneurysm), body habitus, presence or absence of ascites and hernias, and living conditions and lifestyle considerations of a patient.

Elderly

Peritoneal dialysis has successfully been performed by octagenarians and nanogenarians. The risk of infectious and non-infectious complications are no different than that observed in younger age groups. Hence, chronological age is insufficient to deny a patient the choice in selecting their dialysis modality.

Advancing age, however, is often associated with a decrease in manual dexterity, visual acuity, frailty, and cognition. Elderly patients may be reluctant to impose the burden of home dialysis on their elderly partners, and in those patients who live alone, home dialysis may accentuate social isolation. Many times, family members are willing to provide support to allow the elderly to successfully perform peritoneal dialysis at home.

Peritoneal dialysis offers several advantages over in-center hemodialysis to elderly patients. Peritoneal dialysis obviates the need for frequent travel to and from a health-care facility which may be as important to a care-giver as to the patient. The life-plan of many elderly individuals may include recreational travel, which can be easier to accommodate with peritoneal dialysis. Creating and maintaining a vascular access and the need for anti-coagulation during the hemodialysis procedure are more likely to pose challenges for the elderly and should prompt consideration of peritoneal dialysis as an alternative. Lastly, daily fluid and solute removal, which is inherent to PD, offers greater hemodynamic stability and is often better tolerated than thrice weekly in-center hemodialysis.

Strategies to facilitate peritoneal dialysis for a frail patient

The use of peritoneal dialysis in frail individuals, irrespective of age, can be facilitated by connection-assist devices and assisted therapy. Connection-assist devices can overcome the challenges posed by decreased manual dexterity and/or visual acuity. Such devices are available from both major manufacturers of peritoneal dialysis supplies and may be used for both continuous ambulatory (CAPD) and automated therapies (APD).

Another strategy that has been successfully applied in different health care systems around the world is "assisted peritoneal dialysis." In assisted PD, either a family member or a healthcare provider (nurse or healthcare aide) helps deliver dialysis. In most such reports, the risk for infectious complications in patients performing assisted peritoneal dialysis is no different than seen with unassisted therapy. Assisted peritoneal dialysis is best performed using a cycler and the prescription can be designed such that a patient requires assistance only twice during any 24-hour period (at the time of connection to the cycler at night and disconnection in the morning).

In a report of assisted peritoneal dialysis from Canada, many patients required assistance for some but not all connections/disconnections and a significant minority graduated to complete independence after a short period of assisted peritoneal dialysis. Thus, the availability of assistance may increase the confidence of selected individuals about their ability to undertake home dialysis and serve as a bridge to independent home care dialysis.

Diabetes mellitus

The effect of peritoneal dialysis on glycemic control, potential for weight gain, and patient longevity are important to consider. Glucose absorption from the peritoneal dialysate and increased nutrient intake after the amelioration of uremic anorexia with the start of dialysis treatment has the potential to influence glycemic control. In most patients, this can be readily managed with appropriate adjustment of medical therapy.

In a recent clinical trial, glucose-sparing peritoneal dialysis prescriptions that use icodextrin for the long dwell were associated with a significant improvement in glycemic control and dyslipidemia. This strategy should be considered for selected patients. A recent study showed that significant weight gain in patients who begin treatment with peritoneal dialysis is no more frequent than those who start in-center hemodialysis and this consideration should not dissuade patients from considering the therapy either.

Finally, care should be exercised before using survival data from observational studies in making decisions about dialysis modality for a given patient. It remains unclear if differences in survival, between patients treated with different dialysis modalities are attributable to the therapy or to unmeasured differences in characteristics of patients who select the therapy. Thus, notwithstanding the purported challenges with peritoneal dialysis, most diabetics can choose the dialysis modality that fits best with their goals and expectations in life.

Polycystic kidney disease (PKD)

The ability of patients to tolerate instillation of peritoneal dialysate in the presence of enlarged kidneys, and reports suggesting a higher risk of hernias and diverticulitis, have raised some questions as to whether peritoneal dialysis is appropriate for treatment of end-stage renal disease in patients with polycystic kidney disease. Three recent case-control studies, one each from the United Kingdom, France, and Hong Kong, have shown no increased risk for infections in patients with PKD compared to patients with ESRD from other etiologies. While hernias may be more common, they are readily treatable and peritoneal dialysis can be performed peri-operatively. Hence, a diagnosis of polycystic kidney disease generally should have no bearing on selection of dialysis modality.

Scleroderma

In patients with systemic sclerosis, concern has been sometimes raised that peritoneal fibrosis may preclude successful performance of peritoneal dialysis. Scleroderma is a rare disease and the published clinical experience in the form of case-reports and case-series show that peritoneal dialysis can be successfully performed in these patients. Peritoneal dialysis can be initiated if a patient with scleroderma believes it is the best therapy for him/her.

Cardiovascular disease (coronary artery disease or congestive heart failure)

Several observational studies have demonstrated that patients with previous cardiovascular disease treated with peritoneal dialysis have a higher mortality risk than those treated with hemodialysis. The risk is more pronounced in older individuals. However, studies also indicate that the magnitude of risk elevation in such patients treated with peritoneal dialysis has diminished over time.

Observational studies are insufficient to deny patients a choice in selecting their dialysis modality but they do draw attention to the importance of individualizing the prescription to every patient's medical condition. Peritoneal dialysis offers continuous ultrafiltration allowing for greater hemodynamic stability. Furthermore, since the peritoneal dialysate contains no potassium, hyperkalemia is virtually never a problem in patients treated with peritoneal dialysis making it safer to initiate or maintain cardio-protective drugs like angiotensin-converting-enzyme inhibitors, angiotensin receptor blockers, or aldosterone antagonists.

On the other hand, the nature of therapy places a greater burden on the healthcare team to educate the patient on how to quickly adjust the dialysis prescription in response to day-to-day changes in salt and water intake. It also highlights the importance of ensuring that prescriptions are designed such that they mitigate the metabolic effects of peritoneal dialysis like dyslipidemia and to preferentially use glucose-sparing regimens in such patients. These considerations could inform decision-making about the most appropriate dialysis modality for any given patient.

Previous abdominal surgery

A history of previous abdominal surgery in and of itself is not a contra-indication for peritoneal dialysis but does increase the likelihood that the patient has intra-peritoneal adhesions. It is only the presence of extensive adhesions that precludes the successful performance of peritoneal dialysis. The more complicated the abdominal surgery or greater the intra-peritoneal bleeding or inflammation at the time of surgery, greater is the likelihood of extensive adhesions.

Yet, neither the surgical records nor any non-invasive imaging test can reliably predict the presence or absence of extensive intra-peritoneal adhesions that would preclude successful performance of peritoneal dialysis. The optimal approach in a patient who has a history of significant abdominal surgery in the past and who prefers peritoneal dialysis is for the surgeon to inspect the peritoneal cavity using a laparoscope with or without selective adhesiolysis during catheter placement. In those patients where extensive adhesions preclude the placement of a peritoneal dialysis catheter, the surgeon can place a vascular access at the same sitting.

Patients with prosthetic aortic prosthetic grafts

The initiation of peritoneal dialysis should be delayed by 4-6 weeks in patients who have had surgical repair of abdominal aortic aneurysm. After the initial post-operative period, peritoneal dialysis may be safer than starting hemodialysis with a central venous catheter. Since the aorta is retro-peritoneal, the prosthetic graft is unlikely to be infected if the patient was to develop peritoneal dialysis-related peritonitis. On the other hand, the graft is significantly more likely to be infected in the setting of bacteremia - not an uncommon complication in patients with central venous catheters.

Large body size

Large body size is not a contraindication to peritoneal dialysis. As with hemodialysis, there is an inverse relationship between body size and risk for death among US peritoneal dialysis patients. However, the risk of transfer to hemodialysis increases with increasing body size. The burden of uremic toxins in obese individuals is not much larger than in non-obese, which translates into no differences in achieving adequate clearances. The ability to achieve solute clearance targets is even less of a problem in a patient with significant residual renal function, which will be preserved longer with peritoneal than with hemodialysis.

The most important challenge in performing peritoneal dialysis in obese patients is maintaining a healthy exit site. An exit-site that is placed under the abdominal pannus would be at a very high risk of recurrent exit-site and tunnel infection. Careful exit site selection is essential. In some cases, using an extended abdominal or pre-sternal catheters should be used to ensure that the exit-site is located at a place where the patient can keep it dry and readily perform daily exit-site care.

The concern that peritoneal dialysis will be associated with greater weight gain which, in turn, could further limit the possibility of renal transplantation, has not been borne out in recent observational studies. Not only was the possibility of significant weight gain no different between patients treated with hemodialysis or peritoneal dialysis, for every strata of body size the adjusted odds of renal transplantation were significantly higher in patients treated with peritoneal dialysis. Thus, peritoneal dialysis can be successfully performed in obese patients; our program has successfully performed peritoneal dialysis in patients weighing up to 400 lb.

Presence of ascites

Patients with right heart failure and/or chronic liver disease with co-existing end-stage renal disease can present with large ascites. Placement of an indwelling catheter will allow for daily removal of "ascitic" fluid with each dialysis exchange, obviating the need for periodic paracentesis. Moreover, peritoneal dialysis affords greater hemodynamic stability than intermittent hemodialysis.

There are several challenges that also need to be appreciated - wound healing may be delayed in patients with tense ascites with/without abdominal wall edema. Furthermore, in patients with very large ascites, it may be advantageous to ensure that complete drainage of ascitic fluid is done gradually over a few days when starting PD.

The obligatory generation of ascitic fluid from increased hydrostatic pressure secondary to portal hypertension can result in large effluent volumes with peritoneal dialysis that may complicate hemodynamic management. Some have raised concern that daily peritoneal albumin losses may worsen hypoalbuminemia. These issues should allow for informed decision making for an occasional patient with end-stage renal disease who has a large ascites burden.

Hernia

Increased intra-peritoneal pressure with instillation of dialysate can lead to an increase in the size of a pre-existing hernia. Careful physical examination of the patient at the time of initial evaluation can allow for simultaneous repair of the hernia at the time of catheter placement. This will preclude the need to repair the hernia after the patient has been established on peritoneal dialysis therapy.

Larger hernias are best treated with tension-free herniorrhaphy with a polypropylene mesh. Since the mesh is pre-peritoneal, it is unlikely to be infected even in the setting of peritoneal dialysis-associated peritonitis and peritoneal dialysis can be safely performed in such patients.

Living conditions of a patient

The patient must have sufficient space at home to store supplies for performing peritoneal dialysis. Monthly supplies take up roughly as much space as a refrigerator. In the United States, manufacturers generally ship supplies to a patient's home once a month; in patients with space constraints at home, the frequency of delivery of supplies can be increased to once every 15 days.

The patient needs to have a large night stand or a similar structure to place the cycler if they choose to use automated peritoneal dialysis. It is also important for patients to ensure that pets don't sleep in their bed, particularly if they use a cycler at night.

Patients need to understand that their dialysis should be done in a clean space and without interruptions. Toddlers, pets, and others should not to be coming in and out of the room during an exchange. The space for dialysis should be clean and tidy. Most units conduct a home visit near the end of training to ensure patients have selected an appropriate space for dialysis.

Other lifestyle considerations

Patients are discouraged from lifting weights or objects that are heavier than 20 lb while dialysate is dwelling in their abdomen. In addition, those with abdominal exit-sites are strongly discouraged from soaking in a bath-tub. If this is an important consideration, it is advantageous to use a pre-sternal catheter.

Patients can engage in physical activities that lead to significant sweating or soaks the dressing over the exit site (like swimming). Patients should be encouraged to shower or at least wash their exit site afterwards. Swimming in the ocean or pools are generally safe, but swimming in lakes should be discouraged. These additional considerations may be relevant for some patients when selecting their dialysis modality.

Patient work up

There are no laboratory tests that are useful in helping a patient decide which dialysis modality is most appropriate. Similarly, imaging tests are not useful in determining the presence or extent of adhesions or whether a patient will be able to tolerate the volume of dialysate that is necessary for the successful performance of peritoneal dialysis. Patients should be encouraged to learn about the available dialysis modalities and choose the one they think will best fit their lifestyle.

Strategies to assist patients as they choose a dialysis modality?

All patients with advanced and progressive chronic kidney disease should be referred for multi-disciplinary patient education. Research has shown that patients are more likely to choose PD if they have been educated about dialysis options. The "education team" should consist of a "lead patient educator" with components also taught by dieticians and social workers. The value of such education can be enhanced if it includes either group or one-on-one interaction with patients treated with different dialysis modalities and visits to both an in-center hemodialysis and a home program. The nature of instruction should be a mix of didactic instruction, interactive discussion, and visuals provided by videos and/or DVDs.

The goal of the education program should be to educate patients about chronic kidney disease, its natural history and complications, the different renal replacement therapies, their advantages and disadvantages, potential complications, a review of some of the dietary restriction that may accompany a therapy, and financial/insurance issues. The education program should offer support to the patient and facilitate the decision-making process.

One of the key measures of success of such an education program should be the timely placement of the dialysis access - whether it is vascular access for hemodialysis or catheter for peritoneal dialysis. This would require timely referral for multi-disciplinary education.

In 2008, 44% of patients who started maintenance dialysis in the United States had no prior care from a nephrologist. It is critical that even the late-referred patients undergo multi-disciplinary chronic kidney disease education.

Timing of placement of peritoneal dialysis access

Optimally, one should wait at least 2 weeks from the time of placement of the catheter before it is used for full-volume peritoneal dialysis ('break-in' period). This allows for adequate healing of the tunnel tract and minimizes the risk of leaks. However, peritoneal dialysis can be started within hours of placement of a catheter if needed; using low-volume, supine exchanges.

The break-in period may need to be longer in patients in whom there is concern about impairment in wound-healing (for example, patients who have been treated with steroids or those with diabetes). Given these considerations, it is best to place a peritoneal dialysis catheter in advance of an anticipated need for dialysis. Centers should have protocols for catheter care post-op, which includes the use of non-occlusive dressings and flushing of the catheter to maintain patency.

Role of "buried" peritoneal dialysis catheters

If a patient has selected peritoneal dialysis as their modality of choice, the peritoneal dialysis catheter can be placed electively and the external limb of the peritoneal dialysis catheter be buried in the subcutaneous tissue. This takes away the need for the patient to perform daily exit-site care for prolonged periods of time before the need for dialysis and relieves the pressure from the healthcare team about determining precisely when the patient will require maintenance dialysis. This approach is particularly useful in centers where securing time in the operating room for catheter placement is limited.

The external limbs of peritoneal dialysis catheters have been successfully buried for up to 3 years; however, it is preferable to bury the external limb of the catheter only if the anticipated interval between the time of placement of the catheter and the need for dialysis is between 6 weeks and 6 months. When dialysis is necessary, a small incision is made at the desired location for the exit-site, and the catheter limb is exteriorized.

This is a low-risk procedure that can be performed in either the nephrologist's or surgeon's office under local anesthesia. Since the tunnel track would have healed completely, full-volume peritoneal dialysis can be started on the same day as the exteriorization of the catheter.

Patient outcomes in PD

At least two randomized, controlled clinical trials have been attempted to compare the outcomes of patients with end-stage renal disease treated with in-center hemodialysis and peritoneal dialysis. The most recent attempt was made in the Netherlands under the auspices of the NECOSAD study. Once the patients learnt about the disparate effects of different dialysis modalities on their lifestyle, over 90% of eligible patients refused to be randomized. It is unlikely that another randomized controlled trial of dialysis modalities will be attempted in any of the developed countries. There is a clinical trial that is presently underway in China with the goal of comparing in-center hemodialysis with peritoneal dialysis.

Currently, one must depend upon observational studies. Many such studies have been undertaken from different parts of the world. One should exercise great caution in using data from such observational studies to make decisions about which dialysis modality would be appropriate for any given patient. There is no assurance that any observed difference in survival between patients are indeed attributable to the dialysis modality. It is equally likely that the survival differences stem from patient or center difference rather than the specific effects of the modality ("residual confounding").

Given the uncertainty, it is inappropriate to use data from observational studies to deny a choice in modality selection. Moreover, in patients with as limited a life-expectancy as those with end-stage renal disease, there are outcomes that may be more relevant to a patient than survival such as health-related quality of life or satisfaction with care.

Early studies indicated that patients who started treatment with peritoneal dialysis had a lower risk for death during the early course of end-stage renal disease but a higher long-term risk. Over the last decade, the outcomes of peritoneal dialysis patients have improved considerably more than that of patients treated with in-center hemodialysis in different parts of the world.

Analysis of data from more recent cohorts shows that there is neither an early survival advantage nor a long-term risk with peritoneal dialysis as had been shown in earlier studies. Patients treated with PD, when compared to patients who begin HD with a working access are comparable. Thus, there is no significant difference in 4-, 5-, or 10-year survival of end-stage renal disease patients treated with either hemodialysis or peritoneal dialysis in the United States, Canada, and Australia and New Zealand. There remains an advantage to PD when compared to starting HD with a catheter.

Numerous studies have compared the health-related quality of life of patients treated with in-center hemodialysis and peritoneal dialysis and the preponderance of evidence suggests that there is no difference. At least two studies have demonstrated a significantly higher satisfaction with care in patients treated with peritoneal dialysis than those with in-center hemodialysis.

Technique Survival (or time-on-therapy)

Technique survival is often used as an outcome measure for patients treated with peritoneal dialysis. While each individual patient has many different vascular access sites, they have only one peritoneal membrane. Hence, the probability of a peritoneal dialysis patient developing a complication that necessitates the transfer to hemodialysis is significantly greater than the other way around.

There have been at least two notable issues highlighted by recent studies. First, the technique survival of peritoneal dialysis patients is directly related to unit census - the risk of transfer to hemodialysis is considerably lower for patients treated in larger units than the smaller ones. This implies that many of the causes of transfer to hemodialysis are potentially preventable. Second, the technique survival of peritoneal dialysis patients in the United States has improved in parallel with the improvement in patient survival. This is probably largely secondary to a significant reduction in infection risk of patients treated with peritoneal dialysis.

Guidelines and resources

  • International Society for Peritoneal Dialysis Guidelines on peritoneal dialysis access and peritoneal dialysis training available at http://www.ispd.org/lang-en/treatmentguidelines/guidelines

  • National Kidney Foundation KDOQI guidelines available at http://www.kidney.org/professionals/KDOQI/guideline_upHD_PD_VA/pd_guide1.htm

  • Caring for Australasians with Renal Impairment (CARI) available at http://www.cari.org.au/dialysis_accept_published.php

  • UK Renal Association Guidelines for peritoneal dialysis available at http://www.renal.org/Libraries/Guidelines/Peritoneal_Dialysis_FINAL_DRAFT_-_09_May_2010.sflb.ashx.

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