Peritoneal Dialysis and Mortality, Kidney Transplant, and Transition to Hemodialysis: Trends From 1996-2015 in the United States

Rationale & Objective

Transitions between dialysis modalities can be disruptive to care. Our goals were to evaluate rates of transition from peritoneal dialysis (PD) to in-center hemodialysis (HD), mortality, and transplantation among incident PD patients in the US Renal Data System from 1996 to 2015 and identify factors associated with these outcomes.

Study Design

Observational registry-based retrospective cohort study.

Setting & Participants

Medicare patients incident to end-stage renal disease (ESRD) from January 1, 1996, through December 31, 2011 (for adjusted analyses; through December 31, 2014, for unadjusted analyses), and treated with PD 1 or more days within 180 days of ESRD incidence (n = 173,533 for adjusted analyses; n = 219,787 for unadjusted analyses).

Exposure & Predictors

Exposure: 1 or more days of PD. Predictors: patient- and facility-level characteristics obtained from Centers for Medicare & Medicaid Services Form 2728 and other data sources.

Outcomes

Patients were followed up for 3 years until transition to in-center HD, death, or transplantation.

Analytical Approach

Multivariable Cox regression was used to estimate hazards over time and associations with predictors.

Results

Compared with earlier cohorts, recent incident PD patient cohorts had lower rates of death (48% decline) and transition to in-center HD (13% decline). Among many other findings, we found that: (1) rates of transition to in-center HD and death were lowest in the 2008 to 2011 cohort, (2) longer time receiving PD was associated with higher mortality risk but lower risk for transition to in-center HD, and (3) larger PD programs (≥25 vs ≤6 patients) displayed lower risks for death and transition to in-center HD.

Limitations

Data collected on Form 2728 are only at the time of ESRD incidence and do not provide information at the time of transition to in-center HD, death, or transplantation.

Conclusions

Rates of transition from PD to in-center HD and death rates for PD patients decreased over time and were lowest in PD programs with 25 or more patients. Implications of the observed improved technique survival warrant further investigation, focusing on modifiable factors of center-level performance to create opportunities for improved patient outcomes.

Ysis Prescription and Peritoneal Membrane Transport Characteristics on Nutritional Status

These data suggest that dialysis dose is one of the major determinants of protein and energy intake in PD patients and that higher doses of dialysis tend to improve outcome. The data also suggest that with a long time on PD the peritoneal membrane probably has some underlying histological changes that preclude it from optimally responding to injury and may predispose it to irreversible damage. A possible early finding in this case is an increase in peritoneal transport in patients whose transport was initially stable. Peritoneal membrane transport properties are an important determinant of not only dialysis dose, but also nutritional status via both direct and indirect means. It is therefore important to identify the individual patient's peritoneal membrane transport characteristics. These transport characteristics may change over time. High transporters on CAPD represent a unique challenge. They have ultrafiltration problems and a tendency toward protein malnutrition presumably due to increased dialysate protein losses while on CAPD. One must consider that malnutrition in a rapid transporter may be due to the fact that the patient is on the wrong PD therapy. A change to NIPD may rectify some of the biochemical parameters, but these patients may not always improve. Reasons for this occasional lack of improvement are multifactorial, but emphasize our need to look at each patient as an individual and not focus only on laboratory parameters.

Analysis of Ultrafiltration Failure in Peritoneal Dialysis Patients by Means of Standard Peritoneal Permeability Analysis

Background

Ultrafiltration failure (UFF) is a complication of peritoneal dialysis (PD) treatment that occurs especially in long-term patients. Etiological factors include a large effective peritoneal surface area [measured as high mass transfer area coefficient (MTAC) of creatinine], a high effective lymphatic absorption rate (ELAR), a large residual volume, or combinations.

Objective

The prevalence and etiology of UFF were studied and the contribution of transcellular water transport (TCWT) was analyzed. A new definition of UFF and guidelines for the analysis of its etiology were derived from the results.

Setting

Peritoneal dialysis unit in the Academic Medical Center in Amsterdam.

Design

Cross-sectional study of standard peritoneal permeability analyses (4-hr dwells, dextran 70 as volume marker) with 1.36% glucose in 68 PD patients. Patients with negative net UF (change in intraperitoneal volume, dlPV < 0 mL) were analyzed further using 3.86% glucose, whenever possible.

Results

Among 68 patients (duration of PD 0.3 -178 months), 39 had negative net UF with 1.36% glucose. These patients had greater MTAC creatinine and glucose absorption, and higher ELAR (p < 10–4) than the patients with positive UF. dIPV and transcapillary UF rate (TCUFR) were lower (p < 10–5). Twenty of these patients could be studied using 3.86% glucose. dlPV was greater than 400 mL/4 hr in this test in 12 patients, implying that no clinically important UFF was present. Ultrafiltration failure (dIPV < 400 mL) was found in 8 patients, giving a prevalence of 23%. This last group had been treated with PD for a longer period (p = 0.03), had higher ELAR (p = 0.07), but lower residual volume (p = 0.03), and lower TCUFR (p = 0.01). Ultrafiltration failure was associated with a high MTAC creatinine in 3 patients, a high ELAR in 4 patients, and a combination of factors in one. As an additional possible cause, TCWT was studied, using the sodium gradient in the first hour of the dwell, corrected for diffus ion (dNA). Five patients had dNA > 5 mmol/L, indicating normal TCWT. The 3 patients with dNA < 5 mmol/L tended to be treated longer (p = 0.19) and had lower TCUFR (p = 0.04). A smaller difference was found between dlPV 3.86% and 1.36% (p = 0.04) compared to the dNA > 5 mmol/L group, but no differences were present for MTAC creatinine, ELAR, residual volume, or glucose absorption.

Conclusions

ln addition to known factors, impairment of TCWT can be a cause of UFF. A standardized dwell with 1.36% glucose overestimates UFF. Therefore, 3.86% glucose should be used for identification of patients with UFF, especially because it provides additional information on TCWT. Ultrafiltration failure can be defined as net UF < 400 mL/4 hr with 3.86% glucose during a 4-hour exchange.

No increase in small-solute transport in peritoneal dialysis patients treated without hypertonic glucose for fifty-four months

Background

Glucose is widely used as an osmotic agent in peritoneal dialysis (PD), but exerts untoward effects on the peritoneum. The potential protective effect of a reduced exposure to hypertonic glucose has never been investigated.

Methods

The cohort of PD patients attending our center which tackled the challenge of a restricted use of hypertonic glucose solutions has been prospectively followed since 1992. Small-solute transport was assessed using an equivalent of the glucose peritoneal equilibration test after 6 months, and then every year. Study was stopped on July 1st, 2008, before use of biocompatible solutions. Repeated measures in patients treated with PD for 54 months were analyzed by using (1) the slopes of the linear regression for D₄/D₀ ratios over time computed for each individual, and (2) a linear mixed model.

Results

In the study period, 44 patients were treated for a total of 2376 months, 2058 without hypertonic glucose. There was one episode of peritoneal infection every 18 patient-months. The mean of slopes of the linear regression for D₄/D₀ ratios was found to be significantly positive (Student’s test, p < .001) and the results of the mixed model reflected a similar significant increase for D₄/D₀ ratios over time. These results reflected a significant decrease of small-solute transport.

Conclusion

In this large series, minimizing the use of hypertonic glucose solutions was associated in patients on long term PD with an overall decrease of small-solute transport within 54 months, despite a high rate of peritoneal infection.

Electronic supplementary material

The online version of this article (10.1186/s12882-017-0690-7) contains supplementary material, which is available to authorized users.

The first peritonitis episode alters the natural course of peritoneal membrane characteristics in peritoneal dialysis patients

OBJECTIVE

Little or no evidence is available on the impact of the first peritonitis episode on peritoneal transport characteristics. The objective of this study was to investigate the importance of the very first peritonitis episode and distinguish its effect from the natural course by comparison of peritoneal transport before and after infection.

PARTICIPANTS

We analyzed prospectively collected data from 541 incident peritoneal dialysis (PD) patients, aged > 18 years, between 1990 and 2010. Standard Peritoneal Permeability Analyses (SPA) within the year before and within the year after (but not within 30 days) the first peritonitis were compared. In a control group without peritonitis, SPAs within the first and second year of PD were compared.

MAIN OUTCOME MEASUREMENTS

SPA data included the mass transfer area coefficient of creatinine, glucose absorption and peritoneal clearances of β-2-microglobulin (b2m), albumin, IgG and α-2-macroglobulin (a2m). From these clearances, the restriction coefficient to macromolecules (RC) was calculated. Also, parameters of fluid transport were determined: transcapillary ultrafiltration rate (TCUFR), lymphatic absorption (ELAR), and free water transport. Crude and adjusted linear mixed models were used to compare the slopes of peritoneal transport parameters in the peritonitis group to the control group. Adjustments were made for age, sex and diabetes.

RESULTS

Of 541 patients, 367 experienced a first peritonitis episode within a median time of 12 months after the start of PD. Of these, 92 peritonitis episodes were preceded and followed by a SPA within one year. Forty-five patients without peritonitis were included in the control group. Logistic reasons (peritonitis group: 48% vs control group: 83%) and switch to hemodialysis (peritonitis group: 22% vs control group: 3%) were the main causes of missing SPA data post-peritonitis and post-control. When comparing the slopes of peritoneal transport parameters in the peritonitis group and the control group, a first peritonitis episode was associated with faster small solute transport (glucose absorption, p = 0.03) and a concomitant lower TCUFR (p = 0.03). In addition, a discreet decrease in macromolecular transport was seen in the peritonitis group: mean difference in post- and pre-peritonitis values: IgG: -8 μL/min (p = 0.01), a2m: -4 μL/min (p = 0.02), albumin: -10 μL/min (p = 0.04). Accordingly, the RC to macromolecules increased after peritonitis: 0.09, p = 0.04.

CONCLUSIONS

The very first peritonitis episode alters the natural course of peritoneal membrane characteristics. The most likely explanation might be that cured peritoneal infection later causes long-lasting alterations in peritoneal transport state.

Pathophysiological changes to the peritoneal membrane during PD-related peritonitis: the role of mesothelial cells

The success of peritoneal dialysis (PD) is dependent on the structural and functional integrity of the peritoneal membrane. The mesothelium lines the peritoneal membrane and is the first line of defense against chemical and/or bacterial insult. Peritonitis remains a major complication of PD and is a predominant cause of technique failure, morbidity and mortality amongst PD patients. With appropriate antibiotic treatment, peritonitis resolves without further complications, but in some PD patients excessive peritoneal inflammatory responses lead to mesothelial cell exfoliation and thickening of the submesothelium, resulting in peritoneal fibrosis and sclerosis. The detrimental changes in the peritoneal membrane structure and function correlate with the number and severity of peritonitis episodes and the need for catheter removal. There is evidence that despite clinical resolution of peritonitis, increased levels of inflammatory and fibrotic mediators may persist in the peritoneal cavity, signifying persistent injury to the mesothelial cells. This review will describe the structural and functional changes that occur in the peritoneal membrane during peritonitis and how mesothelial cells contribute to these changes and respond to infection. The latter part of the review discusses the potential of mesothelial cell transplantation and genetic manipulation in the preservation of the peritoneal membrane.

Comparative effects of carvedilol and lercanidipine on ultrafiltration and solute transport in CAPD patients

BACKGROUND

Peritonitis, the type of buffer used in the dialysate, continue ambulatory peritoneal dialysis (CAPD) of greater than two years duration, increased exposure to dialysate glucose, diabetes mellitus, and the use of beta blockers may contribute to impaired ultrafiltration.

OBJECTIVES

The aim of the present study is to compare the effects of a calcium-channel blocker and a beta-blocker on the peritoneal transport and clearance.

METHODS

We studied 48 patients with ESRD on chronic peritoneal dialysis, included 27 females and 19 males with mean age 42.6 +/- 16.4 years. Two patients were excluded from the study due to peritonitis. Patients were treated either with carvedilol or lercanidipine. In all patients; peritoneal equilibration test (PET), ultrafiltration (UF), Kt/V ratio, creatinine clearance (CrCl), systolic blood pressure, diastolic blood pressure, serum BUN, creatinine, glucose, sodium, potassium, albumin, cholesterol, and triglyceride values were obtained before and after 8 weeks from the start of the drug treatment.

RESULTS

Lercanidipine and carvedilol showed a good antihypertensive effect in CAPD patients. Both drugs had a good tolerability profile and showed no effect on plasma lipids. There were no differences in terms of PET, ultrafiltration, Kt/V ratio, CrCl, systolic blood pressure, diastolic blood pressure, serum BUN, creatinine, glucose, sodium, and potassium values between both patient groups. After antihypertensive treatment, neither group showed a difference in the above-mentioned parameters (p > 0.05) except potassium, which was significantly higher in the carvedilol group (p < 0.05).

CONCLUSIONS

In CAPD patients. short-term usage of carvedilol has no effect on ultrafiltration and solute transport like lercanidipine. Both drugs showed a good antihypertensive effect.

Enterobacteriaceae peritonitis complicating peritoneal dialysis: A review of 210 consecutive cases

Enterobacteriaceae peritonitis is a serious complication in peritoneal dialysis (PD), but the clinical course of PD-related Enterobacteriaceae peritonitis remains unclear. We reviewed all Enterobacteriaceae peritonitis in our dialysis unit from 1995 to 2004. During this period, there were 1748 episodes of peritonitis recorded; 210 episodes (12.0%) in 123 patients were caused by Enterobacteriaceae. The most common species was Escherichia coli, accounting for 111 episodes. The primary response rate was 84.8% and complete cure rate was 58.1%. The presence of exit site infection was associated with a lower complete cure rate (43.2 versus 61.3%, P = 0.034). A total of 82 episodes (39.0%) did not respond to single antibiotic treatment despite sensitivity in vitro, and a second antibiotic was added. Patients treated with two antibiotics had a marginally lower risk of relapse and recurrence than those with one antibiotic (21.4 versus 36.1%, P = 0.051). The episodes that had recent antibiotic therapy had a marginally lower complete cure rate (49.3 versus 62.8%, P = 0.06). There was a gradual increase in the prevalence of resistance to several commonly used antibiotics over the years. Recent antibiotic therapy was associated with resistance to cefotaxime, ceftazidime, cefoperazone/sulbactam, and piperacillin/tazobactam. We conclude that Enterobacteriaceae peritonitis is a serious complication of PD. Recent antibiotic therapy is the major risk factor of antibiotic resistance. Exit site infection, and probably recent antibiotic therapy, is associated with poor therapeutic response. Contrary to the current recommendation, treatment with two antibiotics may reduce the risk of relapse and recurrence.

Clinical course of peritonitis due to Pseudomonas species complicating peritoneal dialysis: a review of 104 cases

BACKGROUND

Peritonitis due to Pseudomonas species is a serious complication in continuous ambulatory peritoneal dialysis (CAPD) patients. The clinical course of peritonitis due to Pseudomonas complicating CAPD remains unclear.

METHODS

All of the Pseudomonas species episodes of peritonitis in our dialysis unit were studied from 1995 to 1999. During this period, there were 859 episodes of peritonitis recorded, 113 of which were caused by the Pseudomonas species. Nine episodes were excluded because they were mixed growth. The remaining 104 episodes in 68 patients were reviewed.

RESULTS

The underlying renal diagnosis and prevalence of comorbid conditions of the 68 patients were similar to those found in our entire dialysis population. There was a history of antibiotic therapy within 30 days of the onset of peritonitis due to the Pseudomonas species in 69 episodes (66.3%). In 47 episodes (45.2%) there was a concomitant exit site infection. The overall primary response rate was 60.6% and the complete cure rate was 22.1%. The presence of exit site infection was associated with a lower primary response rate (22 in 47 vs. 41 in 57 episodes, P < 0.01) and a lower complete cure rate (5 in 47 vs. 18 in 57 episodes, P < 0.02). The episodes that had received recent antibiotic therapy had a significantly lower complete cure rate than the de novo cases (8 in 69 vs. 15 in 35 episodes, P < 0.001). Episodes receiving third-generation cephalosporin as part of the initial antibiotic regimen had a significantly higher primary response rate than the ones that initially received aminoglycoside (54 in 81 episodes vs. 8 in 22 episodes, P < 0.05), but their complete cure rates were similar. Twenty-four cases failed to respond to antibiotics and the Tenckhoff catheter was removed. The chance of returning to CAPD was higher when the Tenckhoff catheter was removed on day 10 than on day 15 (9 in 14 cases vs. 5 in 10 cases), although the result was not statistically significant. The Tenckhoff catheter was removed and replaced at another site simultaneously in another 14 cases after the effluent cleared up. None of these patients had a relapse of peritonitis within three months.

CONCLUSIONS

Recent antibiotic therapy is the major risk factor for peritonitis due to the Pseudomonas species. Exit site infection and recent antibiotic therapy are associated with poor therapeutic response to antibiotics. When the therapeutic response is suboptimal, early Tenckhoff catheter removal may help preserve the peritoneum for further peritoneal dialysis. Elective Tenckhoff catheter exchange after clearing up the peritoneal dialysis effluent may also reduce the likelihood of relapse. It is desirable to use third-generation cephalosporin in the initial antibiotic regimen for peritonitis treatment in localities with a high incidence of peritonitis due to the Pseudomonas species.

Current and future modalities for functional renal replacement

Approximately 310,000 Americans suffer from end-stage renal disease, with more than 70,000 new cases reported each year. Advances in immunosuppressive therapy for transplanted patients, in addition to the refined care of patients who are dependent on dialysis, have led to an improved survival for patients with renal failure. Structural, molecular, and pharmacologic developments continue to enhance the efficacy and safety of dialysis in the future. In addition, progressive improvements in the past 2 decades in organ transplantation, a greater insight into the immunobiology of graft rejection, and better surgical and medical management have resulted in improved outcomes. Although renal xenotransplantation is still in its early stages of development, additional research is leading this technology forward. Recent successes in harvesting and expanding renal cells in vitro and the development of biologically active synthetic materials allow for the creation of three-dimensional functioning renal units, which, in the future, may be applied ex vivo or in vivo for partial or full replacement of kidney function.

Sclerosing peritonitis in continuous ambulatory peritoneal dialysis patients: one center's experience and review of the literature

Sclerosing peritonitis (SP) is a severe life-threatening condition for patients undergoing continuous ambulatory peritoneal dialysis (CAPD). This report reviews our experience and that reported in the literature concerning the prevalence of SP in CAPD patients, predisposing factors, and in particular, the role of peritonitis, its clinical presentation, diagnosis, treatment, and prevention. A total of 1,288 end-stage renal disease (ESRD) patients entered our peritoneal dialysis (PD) program between September 1977 and September 1997, seven of whom (0.54%) developed SP. The annual incidence of SP was 0.37 per 1,000 patient years, male-to-female ratio was 2.5 (M/F:5/2), mean age was 39+/-16 (median, 37; range, 23 to 61) years, and the median duration on CAPD was 62 (range, 12 to 144) months. Five patients were on CAPD for > or =4 years and two for less than 4 years before they were diagnosed with SP. All SP patients presented with clinical symptoms suggestive of intestinal obstruction, and five patients had decreased solute or fluid removal and had to increase the daily dialysate volume (3/7) or the tonicity of the fluid (4.25%) (3/7) or to combine a regular hemodialysis (HD) session with CAPD (2/7). There was a mean weight loss of 5+/-6 (median, 2; range, 0 to 18) kg. All patients had an episode of peritonitis at a mean time of 2+/-1 (median, 1; range, 1 to 3) months before the diagnosis of SP. The peritonitis was due to Staphylococcus aureus in four and Staphylococcus epidermidis, fungi, and Escherichia coli in one each. The definitive diagnosis of SP was established by laparotomy in four patients or postmortem examination in one patient, while in the remaining two there was no surgical confirmation; however, we believe the diagnosis was extremely likely because of the presence of clinical and radiologic criteria for SP. After the diagnosis of SP, all patients had their catheters removed, CAPD was discontinued permanently, and they were transferred to HD. Although there are isolated case reports of successful outcomes after surgical intervention, especially in patients in whom a peritoneal "cocoon" is related to severe peritonitis, usually the prognosis following surgery is poor. Treatment with immunosuppressive agents has been reported to be beneficial in the treatment of SP, although this has not been confirmed by all investigators. Among our SP patients, five (72%) died of sepsis (3/5) in a mean period of 10+/-5 (median, 9; range, 6 to 17) months after the diagnosis of SP and two are still alive on HD. SP is a rare but serious complication of CAPD. Severe peritonitis, especially in patients on dialysis for more than 4 years, may lead to SP As the prevalence of SP increases in patients on long-term CAPD, early detection is important because of the high morbidity and mortality associated with this condition.

Peritoneal fluid markers of mesothelial cells and function

Peritoneal structural changes are likely to result in functional deterioration of the peritoneal membrane. For the purpose of early detection of these changes, markers of mesothelial cells that can be measured in peritoneal effluent could provide easily accessible information in individual peritoneal dialysis (PD) patients. In this review, current knowledge on a number of these markers is summarized, such as cancer antigen (CA) 125, phospholipids, hyaluronan, and factors involved in the coagulation system. Although only analyzed in limited studies so far, this approach to understanding changes in the peritoneal membrane seems to be valid and warrants further evaluation in the future, especially in combination with functional studies and peritoneal biopsies.

A prospective study of transperitoneal transport in patients undergoing peritoneal dialysis

A prospective one-year follow-up study of the functional characteristics of the peritoneal membrane was conducted in 20 peritoneal dialysis patients. Ten patients had at least one episode of peritonitis during the follow-up period. Changes in the transperitoneal transport of small solutes were evaluated by the mass transfer area coefficients (urea, creatinine, and glucose), ultrafiltration sieving coefficients (urea and creatinine), and peritoneal equilibration test results. Changes in the capacity of the peritoneal membrane to transport macromolecules were evaluated by means of albumin mass transfer rates. Finally, changes in transperitoneal water transport were evaluated by means of the ultrafiltration properties and the lymphatic flow rates. After one year of follow-up, transport of water and the investigated solutes had not changed significantly. Even episodes of peritonitis had no permanent influence on the transport function of the peritoneal membrane. The intraperitoneal residual volumes before instillation were significantly larger in patients who developed peritonitis during the follow-up period compared to patients who did not. Over a one-year period, no changes in peritoneal membrane characteristics could be demonstrated. A large residual volume of dialysate may be a marker of increased risk of getting peritonitis.

Longitudinal follow-up of CA125 in peritoneal effluent

Mesothelial changes occur during peritoneal dialysis. CA125 provides a way to study the mesothelial cells in the in vivo situation. In the present study longitudinal changes of CA125 were analyzed. In addition, the appearance of CA125 in peritoneal effluent and day-to-day variability were studied. CA125 was measured in the effluent of five stable CAPD patients during four hour dwells with 1.36% glucose, with 3.86% glucose and with 7.5% icodextrin. In addition, CA125 was determined on six consecutive days in four hour effluents of three patients and appearance rates (AR) were calculated. Longitudinal follow-up was performed in 31 patients in whom three to seven yearly observations had been made. Linear appearance of CA125 was present in all dwells. No difference was found between the appearance rates of CA125 with 3.86% glucose, compared to either 1.36% glucose or icodextrin. Mean day-to-day coefficient of variation was 6.4% for CA125 AR, but a wide variation existed in stable CA125 values among patients (mean 22.1, range 2 to 48 U/ml). A negative trend with duration of CAPD was present in the longitudinal study. A mean decrease of 2.2% per year could be calculated, but substantial interindividual differences existed. Sudden decreases of CA125 AR were found in five patients. Possible causes were found in all of them and included a severe or recurrent peritonitis, and temporary cessation of peritoneal dialysis. In one patient a sudden decrease preceded the manifestation of peritoneal sclerosis. It can be concluded that CA125 can be used for the in vivo follow-up of the mesothelium in peritoneal dialysis patients. The appearance of CA125 in effluent is linear in time and not influenced by the initial lysis of mesothelial cells. A gradual loss of mesothelial cells is likely to occur, although interindividual variability is substantial. An acceleration of the process may be caused by severe peritonitis and perhaps by temporary cessation of peritoneal dialysis. A sudden decrease in CA125 may be an alarming sign for the development or manifestation of peritoneal sclerosis.

A prospective study of peritoneal transport in CAPD patients

A prospective two year follow-up study of the functional characteristics of the peritoneal membrane was conducted in 61 CAPD patients. Peritoneal transport of solutes, calculated by mass transfer area coefficients for urea and creatinine, peritoneal clearances for proteins, percentage of absorption of glucose, as well as net ultrafiltration were measured every four months. After five months on CAPD a decrease was found for the transport of most solutes (P < 0.05, mean values, ml/min/1.73 m2): urea 18.1 to 16.2, creatinine 9.5 to 8.4, IgG 0.049 to 0.040 and alpha 2-macroglobulin 0.020 to 0.015, as well as for the absorption of glucose (57.9 to 53.2%, P < 0.05). Net ultrafiltration increased simultaneously from 44.6 to 100.5 ml/4 hr/1.73 m2, P < 0.05. From five months to two years on CAPD a significant increase in the transport of all solutes except alpha 2-macroglobulin was found, as well as a decrease in net ultrafiltration. Peritoneal transport at the end of the study was not significantly different from the starting values. Our findings indicate an initial effect of CAPD itself on peritoneal transport, probably due to the recent start of the treatment. Baseline values were reached after five months on CAPD. Thereafter a gradual increase in peritoneal solute transport occurred during two years of treatment. This can be explained by an increase in the effective peritoneal surface area.

Functional longevity of the human peritoneum: how long is continuous peritoneal dialysis possible? Results of a prospective medium long-term study

Long-term peritoneal dialysis requires the maintenance of the transport function of the peritoneal membrane, and appropriate studies of possible changes are necessary. The quantification of peritoneal mass transfer coefficients (MTCs) has been judged to be the ideal method for the evaluation of peritoneal diffusion. The aim of the present study was to show the results of the prospective evaluations in long-term continuous ambulatory peritoneal dialysis patients. We have studied the clinical incidents and peritoneal function of 56 patients who started continuous ambulatory peritoneal dialysis between 1980 and 1988, and have completed at least 3 years of follow-up. Ultrafiltration capacity was calculated with a standardized formula. All patients were studied for peritoneal diffusion of urea and creatinine at least once a year. The evaluation consisted of a kinetic study done by means of a peritoneal equilibration curve for urea and creatinine, applying a bicompartmental mathematical model to calculate the MTCs. The sequential mean values for urea-MTC did not show significant changes over the observation period (20.7 +/- 5.9 mL/min for the first year v 19.8 +/- 6 mL/min for the fifth year). Creatinine-MTC values showed a significant increase over this period in the paired data analysis. The decrease of the urea-MTC to creatinine-MTC ratio may be an early and appropriate index for measuring these changes when the individual values are in the normal range. On the other hand, peritoneal ultrafiltration capacity significantly decreased over this period (1,800 +/- 530 mL/d v 1,400 +/- 600 mL/d, P < 0.01). The high rate of accumulated days of peritoneal inflammation was related to these significant changes, and thus may be proposed to be a good prognostic index of long-term peritoneal survival. These long-term functional changes might be related to the effect of injuries on the preservation of the normal peritoneal structure. We conclude that after 5 to 11 years, the human peritoneum shows functional stability (diffusion and water transport) in patients with low rates of peritoneal inflammation. With a few exceptions, represented by patients with a high rate of peritoneal inflammation, long-term peritoneal dialysis accomplished its newly entrusted task.