Definitions of Differences and Changes in Peritoneal Membrane Water Transport Properties

A survey is given comparing measurements of transperitoneal water transport in different clinical situations with analyses based on the so-called "pore theory." This model links the measured changes to physical alterations of the peritoneal membrane. The calculations include "equivalent pore radius," effective "membrane area" and diffusive length, the transport resistance of the unstirred dialysate layer, and the residual intraperitoneal volume after dialysate drainage. The clinical appearances include individual differences in transperitoneal transport characteristics, changes in transperitoneal transport over time on continuous ambulatory peritoneal dialysis (CAPD) and during peritonitis, the pharmacological effect on the transport properties, and the effect of peritoneal catheter dislocation on ultrafiltration capacity. The main conclusions are as follow: During CAPD treatment the measurement of intraperitoneal solute equilibration and "mass-transfer-area coefficients" for urea and creatinine is less sensitive than the measurement of ultrafiltration volume in revealing peritoneal membrane changes. Differences and changes found have mostly a combined physical explanation, but one is more or less dominant. Changes in peritoneal membrane area seem to be the most dominant cause of changes in transperitoneal transport during time on CAPD and when sodium nitroprusside was added to the peritoneal dialysate. Changes during peritonitis can be explained by changes in pore radius and depth. Individual differences can be explained by differences in "membrane" area and in resistance of the unstirred dialysate fluid. High residual dialysate volume can give rise to clinical problems and should be considered when placing the catheter in the peritoneal cavity.     

Methicillin-resistant staphylococcal infections in an outpatient peritoneal dialysis program

In view of the increasing concern about hospital-acquired methicillin resistance, we examined the sensitivities and outcome of staphylococcal infections related to outpatient peritoneal dialysis over a 5-year period. Data on all episodes of peritonitis (n = 360) and catheter infections (n = 507) were gathered prospectively from January 1984 to December 1988. The numbers of patients on peritoneal dialysis each year ranged from 136 in 1984 to 109 in 1987. Fifteen methicillin-resistant staphylococcal infections (MRSI) related to outpatient peritoneal dialysis occurred. Three were due to methicillin-resistant Staphylococcus aureus found in infected exit sites (2.3% of all S aureus catheter infections). Two of these infections occurred in a continuous ambulatory peritoneal dialysis (CAPD) patient who carried methicillin-resistant S aureus in his nares. The other 12 methicillin-resistant organisms were coagulase-negative staphylococci that caused peritonitis. There was a significant increase in the percentage of episodes of coagulase-negative staphylococci peritonitis caused by methicillin-resistant organisms; from 5% (3/57) in 1984 through 1986 to 28% (9/32) in 1987 through 1988 (P less than 0.005). In view of the high percentage of coagulase-negative staphylococci peritonitis that is methicillin-resistant, vancomycin rather than cephalosporins should be used for initial treatment.     

Dialysate leaks in peritoneal dialysis

Dialysate leakage represents a major noninfectious complication of peritoneal dialysis (PD). An exit-site leak refers to the appearance of any moisture around the PD catheter identified as dialysate; however, the spectrum of dialysate leaks also includes any dialysate loss from the peritoneal cavity other than via the lumen of the catheter. The incidence of dialysate leakage is somewhat more than 5% in continuous ambulatory peritoneal dialysis (CAPD) patients, but this percentage probably underestimates the number of early leaks. The incidence of hydrothorax or pleural leak as a complication of PD remains unclear. Factors identified as potentially related to dialysate leakage are those related to the technique of PD catheter insertion, the way PD is initiated, and weakness of the abdominal wall. The pediatric literature tends to favor Tenckhoff catheters over other catheters as being superior with respect to dialysate leakage, but no consensus on catheter choice exists for adults in this regard. An association has been found between early leaks (< or =30 days) and immediate CAPD initiation and perhaps median catheter insertion. Risk factors contributing to abdominal weakness appear to predispose mostly to late leaks; one or more of them can generally be identified in the majority of patients. Early leakage most often manifests as a pericatheter leak. Late leaks may present more subtly with subcutaneous swelling and edema, weight gain, peripheral or genital edema, and apparent ultrafiltration failure. Dyspnea is the first clinical clue to the diagnosis of a pleural leak. Late leaks tend to develop during the first year of CAPD. The most widely used approach to determine the exact site of the leakage is with computed tomography after infusion of 2 L of dialysis fluid containing radiocontrast material. Treatments for dialysate leaks include surgical repair, temporary transfer to hemodialysis, lower dialysate volumes, and PD with a cycler. Recent recommendation propose a standard approach to the treatment of early and late dialysate leaks: 1-2 weeks of rest from CAPD, and surgery if recurrence. Surgical repair has been strongly suggested for leakage causing genital swelling. Delaying CAPD for 14 days after catheter insertion may prevent early leakage. Initiating CAPD with low dialysate volume has also been recommended as a good practice measure. Although peritonitis and exit-site infections are the most frequent causes of technical failure in peritoneal dialysis (PD), dialysate leaks represent one of the major noninfectious complications of PD. In some instances, dialysate leakage may lead to discontinuation of the technique (1). Despite its importance, the incidence, risk factors, management, and outcome of dialysate leakage are poorly characterized in the literature. We will review the limited available information on this topic in the next few sections.     

Treatment of peritonitis in APD: pharmacokinetic principles

Clinicians treating peritoneal dialysis (PD)-associated peritonitis should be aware that continuous ambulatory PD (CAPD) and automated PD (APD) have different effects on the pharmacokinetics of antibiotics. Results from various APD and comparative CAPD pharmacokinetic studies are reviewed. In APD patients, antibiotic half-lives were shorter during the cycler exchanges. Antibiotic peritoneal clearance was greater in patients treated with APD than those treated with CAPD regimens. Antibiotic clearance depends upon residual renal function and dialysate flow rate. To ensure that maximal antibiotic bioavailability occurs with intermittent intraperitoneal (IP) dosing, it is recommended that the antibiotic-containing dialysate must dwell at least 4 hours to ensure an adequate antibiotic depot in the body. Knowledge of antibiotic disposition in PD patients will assist clinicians in appropriate IP antibiotic dose selection and prevention of dose-related adverse effects.     

Peritoneal dialysis-associated peritonitis in Scotland (1999-2002).

BACKGROUND: Peritonitis is a major complication of peritoneal dialysis (PD). We have performed a national study of all patients on PD in Scotland over a 3.5 year period examining the causes of technique failure, rates of peritonitis, causative organisms, clinical outcomes and differences between automated peritoneal dialysis (APD) and continuous ambulatory peritoneal dialysis (CAPD). METHODS: All 10 adult renal units in Scotland participated in the study and the data include all 1205 patients who were on PD in Scotland from January 1999 to June 2002. The data were collected prospectively by the PD nurses and reported to the Scottish Renal Registry every 6 months. RESULTS: Refractory or recurrent peritonitis was the cause of technique failure in 167 patients (42.6% of all cases of technique failure). There were 928 cases of peritonitis in 1487 patient-years, which equates to an overall peritonitis rate of one episode every 19.2 months. The peritonitis rates for APD and CAPD were similar at one episode every 20.3 months and one episode every 18.6 months, respectively. These results include 88 cases of peritonitis due to relapse or re-infection. There was a statistically significant difference (P = 0.012) in peritonitis rates between units using nasal mupiricin (one episode every 21.9 months) and those that did not (one episode every 18.3 months). Coagulase-negative Staphylococcus was the most common cause of peritonitis (29%), although this rate is lower than in historic studies. The overall initial cure rate was 75%. The initial cure rate for APD was 77.2% and for CAPD was 73.7%. No causative organism was isolated in 17% of cases. CONCLUSION: PD-associated peritonitis is the leading cause of technique failure in Scotland. We validate previous studies showing a decrease in the proportion of peritonitis episodes that are caused by coagulase-negative staphylococci. APD peritonitis rates are not significantly better than CAPD peritonitis rates in Scotland, and the initial cure rates for APD and CAPD are similar.     

Specific characteristics of peritoneal leucocyte populations during sterile peritonitis associated with icodextrin CAPD fluids.

BACKGROUND: Icodextrin dialysate used for peritoneal dialysis contains an iso-molar glucose polymer solution, which provides sustained ultrafiltration over long dwell times and is considered a valuable approach to reduce intraperitoneal glucose exposure. However, several side effects have been described, including abdominal pain and allergic and hypersensitivity reactions. Also, reactions compatible with chemical peritonitis have been reported. Over the period of a few months (January 2002-May 2002), a remarkable increase in the number of continuous ambulatory peritoneal dialysis (CAPD) patients using icodextrin dialysate diagnosed with sterile peritonitis was observed in our unit. METHODS: Five of the CAPD patients using icodextrin dialysate in our unit and diagnosed with sterile peritonitis were screened for leucocyte count and leucocyte differentiation during a follow-up period of 77 +/- 23 days. In addition, expression of CD14, a receptor for lipopolysaccharide (LPS), on the peripheral and peritoneal monocyte population was analysed. These results were compared to CAPD patients suffering from bacterial peritonitis. RESULTS: The peritoneal leucocyte count of CAPD patients using icodextrin dialysate and diagnosed with sterile peritonitis did not decrease significantly before treatment with icodextrin dialysate was interrupted, whereas it currently disappeared within 2-4 days in proven bacterial peritonitis. The sterile, cloudy icodextrin effluent contained an excess of macrophages on the day of diagnosis, whereas in bacterial peritonitis essentially an increase in the granulocyte population was observed. No elevation in the eosinophil population was observed. In contrast to bacterial peritonitis, we observed no increase in CD14 expression on the peripheral and peritoneal macrophages on the day of presentation and during the follow-up period. CONCLUSIONS: Specific batches of the icodextrin CAPD fluids contain a macrophage chemotactic agent, which causes a sustained inflammatory state in the peritoneal cavity. Because no increase in the expression of the LPS receptor CD14 could be observed, the increased peritoneal leucocyte count is probably not caused by LPS or LPS-like (possibly peptidoglycan-like) contamination.     

Value of automatized blood culture systems in the diagnosis of continuous ambulatory peritoneal dialysis peritonitis

Peritonitis is a common clinical problem that occurs in patients with end-stage renal disease treated by peritoneal dialysis. The aim of this study was to evaluate the value of blood culture systems for the diagnosis of continuous ambulatory peritoneal dialysis (CAPD) peritonitis among 26 samples of peritoneal fluid obtained from patients with the suspicion of CAPD peritonitis. Significant growth was detected in 12 (70.5%) of 17 bacteria-positive samples. The most striking finding was that 8 (66.6%) of these 12 results were obtained only from blood culture bottles. The identified pathogens were methicillin-sensitive coagulase-negative staphylococci (n = 5), alpha-hemolytic streptococci (n = 2), Corynebacterium spp. (n = 2), Escherichia coli (n = 2), and Enterococcus faecalis (n = 1). Using blood culture bottles inoculated with peritoneal fluid at the bedside, rather than submitting the specimen to the laboratory for later processing, is advocated in the prompt diagnosis of CAPD peritonitis.     

腹膜透析相关性腹膜炎经验用药分析

目的 研究华山医院及宝山分院腹膜透析（腹透）相关性腹膜炎的致病菌、耐药性及患者转归,为临床经验用药提供依据。 方法 回顾性分析2007年1月至2010年1月上述两医院腹透中心收治的93例腹透相关性腹膜炎的临床表现、致病菌、耐药性及转归。 结果 75例腹透液培养阳性,阳性率为80.2％,其中革兰阳性球菌45例,革兰阴性杆菌21例,真菌2例,革兰阳性杆菌1例,革兰阴性球菌1例,多种菌混合感染5例。革兰阳性球菌主要以凝固酶阴性的葡萄球菌为主,所有革兰阳性球菌对万古霉素均敏感,但对头孢唑林耐药率高达60.0%,而且耐药率有明显的逐年增加趋势。革兰阴性菌对头孢他啶的耐药率达到46.1％,所有革兰阴性杆菌对亚胺培南均敏感。因腹膜炎而退出腹膜透析有16例,退出率为17.2％（16/93）。腹腔使用万古霉素对残肾功能无显著影响。 结论 两院腹透中心腹透相关腹膜炎致病菌以革兰阳性球菌为多数。头孢唑啉耐药性逐年增高,目前不再适合作为初始治疗的经验用药。腹腔使用万古霉素可推荐作为革兰阳性菌致腹膜炎的初始经验用药。     

Coccidioidal peritonitis associated with continuous ambulatory peritoneal dialysis

We report the first three cases of peritonitis due to the fungus Coccidioides immitis occurring during continuous ambulatory peritoneal dialysis (CAPD). At the time of diagnosis, none of the patients had evidence of active infection outside of the peritoneal cavity. Clues suggesting the diagnosis including a previous history of pulmonary coccidioidomycosis, an excess number of eosinophils in the peritoneal fluid, and failure to respond to therapy directed against bacteria. C immitis in peritoneal fluid was more readily isolated on specific fungal culture media than on routine bacterial culture media. In no instances did potassium hydroxide (KOH) preparations of the fluid reveal fungi. Coccidioidal peritonitis during CAPD appears to be a localized form of extrapulmonary coccidioidomycosis that has a relatively benign course once the peritoneal catheter is removed.     

Nontuberculous mycobacterial peritonitis during continuous ambulatory peritoneal dialysis: case report and review of diagnostic and therapeutic strategies

Nontuberculous mycobacteria (NTM) are responsible for an increasing proportion of mycobacterial disease. Peritonitis due to NTM is an unusual but treatable complication of continuous ambulatory peritoneal dialysis (CAPD). Its presentation is similar to that of typical bacterial peritonitis, but special culture techniques are required to avoid a delay in diagnosis. Successful treatment depends on early catheter removal, drainage of fluid collections, and appropriate use of antimicrobial agents. We report a case of Mycobacterium fortuitum peritonitis in a patient undergoing CAPD, and review all previously reported cases. Diagnostic and therapeutic strategies are summarized based on available literature.     

Vancomycin and ceftazidime in the treatment of CAPD peritonitis

102 episodes of continuous ambulatory peritoneal dialysis (CAPD) peritonitis were studied prospectively during a 288-day period at The Queen Elizabeth Hospital, Birmingham. Organisms were isolated from 76% of the episodes, with coagulase-negative staphylococci, being the most commonly encountered organism (55%). Initial treatment consisted of intraperitoneal vancomycin and ceftazidime with subsequent adjustment on the basis of antibiotic sensitivities. With this regimen, 83% of the positive cultures became negative by 72 h, 9.8% of cases relapsed and removal of the CAPD catheter was necessary in 8 patients (7.8%). Overall, 92% of cases were cured. No adverse drug reactions were seen. This combination of antibiotics appears effective and safe in the treatment of CAPD peritonitis.     

Transfer of autologous haemoglobin from the peritoneal cavity during peritoneal dialysis.

Transfer of autologous haemoglobin from the peritoneal cavity was evaluated retrospectively in 14 patients who received this marker intraperitoneally (group 1) during routine continuous ambulatory peritoneal dialysis (CAPD). Five additional patients were studied during acute peritonitis (group 2). A model for balance of both dialysate volume and amount of haemoglobin is developed to assess movement of the compound into lymph or adjacent tissues. Under the conditions of the study the transfer was slow (8 +/- 10 ml/h) in patients without peritonitis (group 1), and significantly faster (25 +/- 22 ml/h) in those with peritonitis (group 2). These clearance values are the upper limits for lymph flow.     

Epidemiology of CAPD-associated peritonitis caused by coagulase-negative staphylococci: comparison of strains isolated from hands, abdominal Tenckhoff catheter exit site and peritoneal fluid.

We identified twenty patients maintained on continuous ambulatory peritoneal dialysis who suffered repeated episodes of peritonitis caused by coagulase-negative staphylococci. We documented hand and exist-site coagulase-negative staphylococcus-associated peritonitis over a total period of 32 months, and compared hand and exit-site strains with strains isolated from dialysate fluid using three typing methods: biotyping using the API Staph kit plus antibiograms, immunoblotting using sera raised in rabbits to three standard strains of coagulase-negative staphylococci, and 35S-methionine-labelled coagulase-negative staphylococcal profiles separated on sodium dodecylsulphate polyacrylamide gel electrophoresis and visualised by autoradiography (radioPAGE). In 5 of 84 episodes, strains isolated from skin were indistinguishable by all three typing methods from the dialysate strain. In a further two episodes, hand or exit-site isolates were indistinguishable by all three typing methods from the dialysate strain isolated in the subsequent, but not the same, episode. Thus in the majority of episodes, no inference of hand or exit-site origin of dialysate infection could be drawn.     

Analysis of the causative pathogens in uncomplicated CAPD-associated peritonitis: duration of therapy, relapses, and prognosis

We analyzed the frequency with which certain bacteria caused uncomplicated peritonitis in an adult continuous ambulatory peritoneal dialysis (CAPD) program that continued patients on this modality of therapy despite frequent infections. All infections were treated with a commonly employed 10- to 14-day course of narrow spectrum intraperitoneal antibiotics. Although the distribution of bacterial pathogens was similar to previous reports (coagulase-negative staphylococci, 43%; Staphylococcus aureus, 13%), we observed no episodes of fungal peritonitis. Twenty percent of our infections were associated with either "no specimens obtained" or "no growth," a finding similar to the CAPD registry. When the data were available, two thirds of all infections were caused by the same pathogen (genus and species) as in the most immediately preceding infection. Twenty-two of 96 episodes of uncomplicated peritonitis occurred within three weeks of a preceding infection. In all 11 cases where organisms were isolated from both paired episodes, the infecting agent was the same as in the preceding infection and was a staphylococcus. This high rate of apparent relapse and the absence of fungal infections may relate to our treatment protocol and possible explanations are discussed. Lastly, the occurrence of coagulase-negative staphylococcal peritonitis is a harbinger of future episodes of peritonitis caused by a variety of organisms.     

Peritoneal ultrafiltration and fluid reabsorption during peritoneal dialysis

Peritoneal ultrafiltration and fluid reabsorption characteristics for 18 patients undergoing continuous ambulatory peritoneal dialysis (CAPD) were investigated in single dwell studies of 6 h duration with 21 of 3.86% glucose dialysis fluid. Dialysate volumes were determined in situ using radioiodinated serum albumin (RISA) as volume marker with a correction applied for the total elimination of RISA from the peritoneal cavity. The RISA elimination rate was calculated as 2.1 +/- 0.5 ml/min. The true dialysate volume after 360 min was on average 28% less than the apparent volume calculated without correction for the elimination of RISA. The mean maximum true volume plus sampling losses was 3255 ml at 240 min, corresponding to a mean net ultrafiltration volume of 762 ml between 3 min and 240 min. The mean net fluid reabsorption rate between 240 min and 360 min was 1.2 +/- 0.7 ml/min. This study of standard dialysate volume/time curves in clinically stable CAPD patients using hypertonic dialysis fluid shows that about 90% of the total net ultrafiltration is achieved during the first 90 min of the dwell. After an extended period of dialysate isovolaemia, usually lasting as long as between 120 min and 240 min, fluid reabsorption is observed in all patients.     

Predictors of the outcome following peritoneal dialysis-related bacterial-complicating peritonitis

Objective To investigate the risk factors predicting the outcome of peritoneal dialysis (PD)-related bacterial-complicating peritonitis. Methods In this retrospective study, all the episodes of PD-related bacterial peritonitis presenting during Jan 2009 to Dec 2013 in our center were reviewed. Clinical and laboratory parameters at the onset of peritonitis, including patient demographic information, age, gender, duration of PD, residual renal function, local and systemic inflammation state, daily exchange number, peritoneal glucose exposure and so on, were recorded. Patients episodes were divided into three groups according to the outcome: complete cure (complete resolution of peritonitis without relapse or recurrence or repeat), peritonitis-related catheter removal/death group, and relapse (relapse or recurrence or repeat) group. Results 187 CAPD patients with 27.15(11.15, 53.13) PD duration were enrolled in the study. Total of 347 episodes of bacterial peritonitis in these patients were analyzed, with 130 episodes of gram-positive bacterial infection, 71 episodes of gram-negative bacterial infection, 15 episodes of polymicrobial and 131 episodes of cultured negative. Compared to the complete cure group and the relapse group, gram negative bacterial infection was more prevalent in the peritonitis-related catheter removal/death group. Furthermore, patients in the peritonitis-related catheter removal/death group showed longer PD age (P﹤0.01) and higher serum hs-CRP (P﹤0.01). Compared to the complete cure group, the serum albumin concentration was lower in the peritonitis-related catheter removal/death group (P﹤0.01). Kt/V was significantly lower in the relapse group than that in the complete cure group (P﹤0.05). Logistic analysis indicated age, non gram positive bacterial infection and increased hs-CRP were independent predictors for peritonitis-related catheter removal or death. Conclusions Age, non gram positive bacterial infection and hs-CRP are risk factors predicting peritonitis-related catheter removal or death in CAPD patients.     

Rapid T-cell-based immunodiagnosis of tuberculous peritonitis in a peritoneal dialysis patient

Tuberculous peritonitis is a rare complication during peritoneal dialysis (PD). This report presents the case of a patient with clinical signs and symptoms indicative of bacterial peritonitis, but without culture growth of conventional bacteria or fungi. Cytokine flow cytometry after overnight stimulation of cells from peripheral blood and the peritoneal dialysate with Mycobacterium tuberculosis (MTB)-specific antigens revealed a 40-fold increase in MTB-specific CD4 + T cells expressing interferon-γ (IFN-γ) in peritoneal fluid compared with blood, which was indicative of active tuberculosis (TB). The presence of TB was later confirmed by polymerase chain reaction and growth of MTB in culture of the dialysate. The case illustrates the usefulness of MTB-specific immunodiagnosis for the rapid identification of peritoneal TB in PD patients.     

Clonal spread of staphylococci among patients with peritonitis associated with continuous ambulatory peritoneal dialysis

BACKGROUND: Peritonitis is the most important complication of continuous ambulatory peritoneal dialysis (CAPD). Coagulase-negative staphylococci (CNS) are the most common causes of peritonitis, only limited information is available regarding the distribution and epidemiology of different CNS species associated with CAPD peritonitis. METHODS: CNS isolated from dialysis effluent from CAPD patients with peritonitis was identified by species and further analyzed with pulsed-field gel electrophoresis (PFGE). RESULTS: A total of 216 microorganisms (206 bacteria and 10 Candida species) were isolated from 196 consecutive culture-positive CAPD samples obtained from 75 patients. One hundred and twenty-one (56%) isolates represented staphylococci. The four most frequently isolated staphylococcal species were Staphylococcus epidermidis (70 isolates), Staphylococcus aureus (31 isolates), Staphylococcus hemolyticus (10 isolates), and Staphylococcus hominis (4 isolates). PFGE analysis revealed the clonal spread among patients of three different clones of S. epidermidis and one clone of S. aureus among the investigated patients. Indistinguishable isolates of either S. epidermidis, S. hominis, or S. aureus were also isolated in repeated samples from several patients. CONCLUSION: PFGE is a useful method for the epidemiological evaluation of staphylococci-associated CAPD infections and should replace older and less accurate methods, such as antibiotic sensitivity patterns. We recommend that CNS isolates from patients with CAPD-associated peritonitis should be saved for future investigations and typing, which would aid in the management of this patient category.     

Down-regulation of CD43 molecule expression on intraperitoneal neutrophils in CAPD patients with peritonitis

To assess the release of proteases from neutrophils infiltrated into the peritoneal cavity in continuous ambulatory peritoneal dialysis (CAPD), we investigated the regulation of CD43, LAM-1 and Mac-1 expression on the neutrophil plasma membrane using FACS analysis in CAPD patients with peritonitis. Five CAPD patients with peritonitis and five CAPD patients without peritonitis were studied. CD43 expression was immunohistochemically determined in both groups of patients using flow cytometry, and comparisons were made between the two groups. Down-regulation of CD43 and LAM-1, and up-regulation of Mac-1 were demonstrated on neutrophils obtained from CAPD dialysate of peritonitis patients after 1-h dwell time. Further up-regulation of Mac-1 developed until a dwell time of 4 h. Immunoblot analysis for neutrophil lysate from dialysate showed the presence of the asialo form of CD43 molecules and their fragments, which may be produced by cleavage of the CD43 molecule at extracellular sites. The intraperitoneal neutrophils in dialysate from CAPD patients with peritonitis are continuously activated during dwell time, and proteases may be released from neutrophils into dialysate after only a short dwell time.     

Peritoneal fluid and solute transport: influence of treatment time, peritoneal dialysis modality, and peritonitis incidence

The integrity of the peritoneal membrane in peritoneal dialysis (PD) is of major importance for adequate dialysis and fluid balance. However, alterations in peritoneal fluid transport, such as ultrafiltration failure, often develop during long-term PD. To investigate peritoneal solute and fluid transport and to analyze the influence of treatment time, peritonitis incidence, and PD modality (continuous ambulatory PD [CAPD] or automated PD [APD]), a cross-sectional study with an extended peritoneal transport test that used dextran 70 in 2 L of glucose was performed in 23 nonselected chronic PD patients. Compared were long-term (>40 mo) with short-term PD patients (<40 mo), CAPD with APD patients, and those with a peritonitis incidence of >0.25/yr to those with an incidence of <0.25/yr. Dialysate/plasma (D/P) ratio and mass transfer area coefficient of creatinine, lymphatic absorption rate (LAR), transcapillary ultrafiltration, and effective ultrafiltration were measured. Long-term PD patients had higher D/P ratio of creatinine (73.5 +/- 2.3% versus 65.9 +/- 2.2%; P < 0.01) and higher LAR (243 +/- 69 ml/4 h versus 96 +/- 31 ml/4 h; P < 0.03), both resulting in lower effective ultrafiltration (242 +/- 35 ml/4 h versus 324 +/- 30 ml/4 h; P < 0.05). D/P ratio (r = 0.66) and LAR (r = 0.67) were positively correlated to PD duration. Patients on APD compared with those on CAPD and patients with a history of peritonitis compared with those without did not differ in terms of D/P ratio, mass transfer area coefficient, LAR, transcapillary ultrafiltration, and effective ultrafiltration. Lower ultrafiltration after long-term PD is both the result of increased small solute transport and increased lymphatic absorption. APD or CAPD modality and peritonitis incidence do not have a significant influence on small solute transport or fluid kinetics.