Current issues of continuous ambulatory peritoneal dialysis

Encapsulating Peritoneal Sclerosis—A Clinician's Approach to Diagnosis and Medical Treatment

Encapsulating peritoneal sclerosis (EPS) is recognized as a serious complication of continuous peritoneal dialysis. A preliminary diagnosis of EPS is usually based on clinical signs and symptoms, which commonly include abdominal pain, nausea, vomiting, anorexia, abdominal fullness, an abdominal mass, bowel obstruction, and radiologic findings, including abdominal roentgenogram, contrast studies, ultrasound studies, and computed tomography. The diagnosis is confirmed by laparoscopy or laparotomy showing the characteristic gross thickening of the peritoneum enclosing some or all of the small intestine in a cocoon of opaque tissue.

A variety of therapeutic approaches to EPS have been reported. This review discusses medical treatment of EPS and includes an overview of the clinical features and diagnostic aspects of the condition.

A Historical Review of Encapsulating Peritoneal Sclerosis

Publications providing insights into the pathophysiology of, and therapeutic strategies for, EPS are the focus of the present review. Referenced publications are limited to those written in English.

Are the Mesothelial-to-Mesenchymal Transition, Sclerotic Peritonitis Syndromes, and Encapsulating Peritoneal Sclerosis Part of the Same Process?

Mesothelial-to-mesenchymal transition (MMT) is an autoregulated physiological process of tissue repair that in uncontrolled conditions, such as peritoneal dialysis (PD), can lead to peritoneal fibrosis. The maximum expression of sclerotic peritoneal syndromes (SPS) is the encapsulating peritoneal sclerosis (EPS) for which no specific treatment exists. The SPS includes a wide range of peritoneal fibrosis that appears progressively and is considered as a reversible process, while EPS does not. EPS is a serious complication of PD characterized by a progressive intra-abdominal inflammatory process that results in bridles and severe fibrous tissue formation which cover and constrict the viscera. Recent studies show that transdifferentiated mesothelial cells isolated from the PD effluent correlate very well with the clinical events such as the number of hemoperitoneum and peritonitis, as well as with PD function (lower ultrafiltration and high Cr-MTC). In addition, in peritoneal biopsies from PD patients, the MMT correlates very well with anatomical changes (fibrosis and angiogenesis). However, the pathway to reach EPS from SPS has not been fully and completely established. Herein, we present important evidence pointing to the MMT that is present in the initial peritoneal fibrosis stages and it is perpetual over time, with at least theoretical possibility that MMT initiated the fibrosing process to reach EPS.

Seven-Year Follow-Up of Peritoneal Dialysis Patients in Taiwan

Background

There are no Taiwanese publications and only a few Asian publications on the long-term outcome of peritoneal dialysis (PD) patients. The aim of this study was to evaluate the outcome of PD patients in Taiwan during a 7-year follow-up period.

Patients and Methods

This study enrolled 67 patients (23 males, mean age 46.2 ± 14.5 years) on maintenance PD. We administered the Short-Form questionnaire on 30 September 1998 and recorded major events and outcomes until 30 September 2005. We compared differences in initial parameters between groups categorized by PD patient survival and PD technique survival. Causes of mortality and transfer to hemodialysis were determined. PD patient and PD technique survival rates were measured and risk factors for patient mortality and PD technique failure were analyzed.

Results

Those in patient survival or PD technique survival groups had lower mean age ( p < 0.001 and 0.018 respectively) and higher serum albumin level ( p = 0.015 and 0.041 respectively) compared to those that died or failed PD. The 7-year patient survival rate was 77% and the PD technique survival rate was 58%. The independent predictors for PD technique failure included lower Mental Component Summary scores [hazard ratio (HR) = 0.85, p = 0.031] and diabetes mellitus (HR = 4.63, p < 0.001), whereas lower serum albumin level (HR = 0.22, p = 0.031), lower Physical Component Summary scores (HR = 0.67, p = 0.047), and presence of diabetes mellitus (HR = 5.123, p = 0.009) were the independent predictors for patient mortality.

Conclusion

For our PD patients, both patient and technique survival rates are good. Better glycemic control, adequate nutrition, and enhancement of health-related quality of life are all of potential prognostic benefit.

The Relationship of P1 and Lewis Antigens with Peritoneal Dialysis–Related Escherichia Coli Peritonitis

It has been known that the P1 and Lewis antigens on red blood cells (RBCs) affect the risk of Escherichia coli–related urinary tract infection. In the present study, we investigated the associations between those antigens and peritoneal dialysis (PD)–related peritonitis and E. coli peritonitis.

We recruited 155 patients (66 men, 89 women) who were under PD treatment in July 2005, checked the P1 and Lewis antigen status of their RBCs, reviewed their medical charts, and recorded the dates and the causative pathogens of peritonitis episodes. The relationships between peritonitis and the antigens were analyzed.

The mean age of these PD patients was 52.5 ± 14.9 years, and the mean PD duration was 39.8 ± 38.2 months. A total of 66 peritonitis episodes occurred (over 93.4 patient– months) in 41 patients, with 8 patients having more than 1 episode. In particular, E. coli peritonitis accounted for 16 of the 66 peritonitis episodes. We fitted two multiple Cox proportional hazards models (with the robust variance method) for predicting the hazard rates of peritonitis-free and E. coli peritonitis-free survival times to our right-censored data with recurrent events. We found that patients on PD treatment for less than 4 years with (A) lower serum albumin, (B) one or more previous peritonitis episodes, or (C) negative Lewis a and positive Lewis b antigens (secretor) would be at higher risk of peritonitis. And, conditioning on blood type, the PD patients with one or more previous peritonitis episodes and (A) positive P1 antigen, (B) negative Lewis a and positive Lewis b antigens (secretor), or (C) positive Lewis a and negative Lewis b antigens (non-secretor) would be at higher risk of E. coli peritonitis.

Dialysis 101. Acute and chronic fluid shifts

For over 30 years, dialysis has been accepted as a proven therapeutic intervention in sustaining life for patients with end-stage renal disease. As a renal replacement therapy, dialysis only approximates renal function. Derangements in fluids, electrolytes, and acid-base homeostasis occur in the course of progressive renal insufficiency. Nephrons are able to adapt to physiologic needs and maintain a balance for many solutes, until the very late stages of chronic renal failure. This permits survival of the patient with minimal therapeutic intervention. The availability of highly permeable membranes has allowed development of continuous renal replacement therapies that gradually remove fluids and solutes resulting in better hemodynamic stability.

Outbreaks of infection and/or pyrogenic reactions in dialysis patients

These dialysis-related outbreaks demonstrate the ongoing potential for infection-related morbidity and mortality among dialysis patients. Many of these outbreaks could have been prevented by adequate water treatment, proper disinfection of water systems and dialysis machines, adherence to recommended reprocessing protocols in centers reusing dialyzers, and more stringent quality control monitoring. Finally, these outbreaks highlight the importance of active surveillance for adverse events among dialysis patients. The incidence of gram-negative bacteremia, pyrogenic reactions, and peritonitis should be monitored over time and any increase in incidence investigated.