Prospective controlled trial of a Y-connector and disinfectant to prevent peritonitis in continuous ambulatory peritoneal dialysis

Long-term outcomes in children on chronic continuous ambulatory peritoneal dialysis: a retrospective cohort study from a developing country

BACKGROUND

Peritoneal dialysis (PD) is the preferred modality of dialysis among children with end-stage renal disease.

METHODS

To study the incidence of technique failure and survival among children with end-stage renal disease on continuous ambulatory peritoneal dialysis (CAPD), we included children younger than 18 years of age who commenced and continued PD for more than 3 months as their primary form of dialysis between 1st January 2005 and 31st December 2016. Kaplan-Meier survival analysis was applied to analyze the CAPD outcomes.

RESULTS

A total of 68 Tenckhoff (58 double cuffs, and ten single cuffs) catheters were inserted in 66 patients (mean age 12.3 ± 3.91 years) during the study period. Of the 66 children, 31 (47%) experienced 45 episodes of peritonitis. The total duration on CAPD was 107.58 years with a peritonitis rate of 0.42 episodes per year. Overall, the mean patient survival was 41 (95% confidence interval (CI) 29-54) months, with mean patient survival of 72% at 12 months, declining to 30% at 36 months and then remaining stable until the end of follow-up (106 months). The overall mean technique survival was 55 (95% CI 40-69) months, with mean technique survival of 69% at 12 months, declining to 44% at 36 months and then remaining stable until the end of follow-up (106 months).

CONCLUSION

CAPD is a viable option for end-stage renal disease in children from developing countries with a lack of access to automated PD and pediatric hemodialysis centers.

An international Delphi survey helped develop consensus-based core outcome domains for trials in peritoneal dialysis

Shared decision-making about clinical care options in end-stage kidney disease is limited by inconsistencies in the reporting of outcomes and the omission of patient-important outcomes in trials. Here we generated a consensus-based prioritized list of outcomes to be reported during trials in peritoneal dialysis (PD). In an international, online, three-round Delphi survey, patients/caregivers and health professionals rated the importance of outcomes using a 9-point Likert scale (with 7-9 indicating critical importance) and provided comments. Using a Best-Worst Scale (BWS), the relative importance of outcomes was estimated. Comments were analyzed thematically. In total, 873 participants (207 patients/caregivers and 666 health professionals) from 68 countries completed round one, 629 completed round two and 530 completed round three. The top outcomes were PD-related infection, membrane function, peritoneal dialysis failure, cardiovascular disease, death, catheter complications, and the ability to do usual activities. Compared with health professionals, patients/caregivers gave higher priority to six outcomes: blood pressure (mean difference, 0.4), fatigue (0.3), membrane function (0.3), impact on family/friends (0.1), peritoneal thickening (0.1) and usual activities (0.1). Four themes were identified that underpinned the reasons for ratings: contributing to treatment longevity, preserving quality of life, escalating morbidity, and irrelevant and futile information and treatment. Patients/caregivers and health professionals gave highest priority to clinical outcomes. In contrast to health professionals, patients/caregivers gave higher priority to lifestyle-related outcomes including the impact on family/friends and usual activities. Thus, prioritization will inform a core outcome set to improve the consistency and relevance of outcomes for trials in PD.

Prevention of Catheter Related Infections in Patients on CAPD

Catheter-related infections remain a serious problem for patients on peritoneal dialysis. Such infections can be reduced by careful patient selection and training, by the use of the best connection technology and screening and treating nasal carriage. To date, treatment is less than optimal and therefore, the primary goal should be prevention of catheter-related infections. Prevention is based on improving catheter design and implantation technique, while providing careful exit-site care. Regardless of how it is implemented, we must aggressively pursue the prevention of catheter-related infections by eradicating S.aureus exit-site carriage in PD patients. Based on its effectiveness in adult PD patients, its low rate of adverse effects, and its reasonable cost-effectiveness, application of mupirocin ointment at the exit-site is the current method of choice for preventing PD catheter infections caused byS. aureus. In addition to reducing S. aureus exit-site infections, mupirocin seems to reduce the rates of staphylococcal peritonitis and PD catheter loss. Whether the ointment should be applied in the nares, to the exit-site or both, and whether it should be used only in staphylococcal nasal carriers or all PD patients requires further study.

Survival in children requiring chronic renal replacement therapy

Survival in the pediatric end-stage renal disease (ESRD) population has improved substantially over recent decades. Nonetheless, mortality remains at least 30 times higher than that of healthy peers. Patient survival is multifactorial and dependent on various patient and treatment characteristics and degree of economic welfare of the country in which a patient is treated. In this educational review, we aim to delineate current evidence regarding mortality risk in the pediatric ESRD population and provide pediatric nephrologists with up-to-date information required to counsel affected families.

Antimicrobial agents for preventing peritonitis in peritoneal dialysis patients

BACKGROUND

Peritoneal dialysis (PD) is an important therapy for patients with end-stage kidney disease and is used in more than 200,000 such patients globally. However, its value is often limited by the development of infections such as peritonitis and exit-site and tunnel infections. Multiple strategies have been developed to reduce the risk of peritonitis including antibiotics, topical disinfectants to the exit site and antifungal agents. However, the effectiveness of these strategies has been variable and are based on a small number of randomised controlled trials (RCTs). The optimal preventive strategies to reduce the occurrence of peritonitis remain unclear.This is an update of a Cochrane review first published in 2004.

OBJECTIVES

To evaluate the benefits and harms of antimicrobial strategies used to prevent peritonitis in PD patients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant's Specialised Register to 4 October 2016 through contact with the Information Specialist using search terms relevant to this review. Studies contained in the Specialised Register are identified through search strategies specifically designed for CENTRAL, MEDLINE, and EMBASE; handsearching conference proceedings; and searching the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

RCTs or quasi-RCTs in patients receiving chronic PD, which evaluated any antimicrobial agents used systemically or locally to prevent peritonitis or exit-site/tunnel infection were included.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed risk of bias and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratio (RR) with 95% confidence intervals (CI).

MAIN RESULTS

Thirty-nine studies, randomising 4435 patients, were included. Twenty additional studies have been included in this update. The risk of bias domains were often unclear or high; risk of bias was judged to be low in 19 (49%) studies for random sequence generation, 12 (31%) studies for allocation concealment, 22 (56%) studies for incomplete outcome reporting, and in 12 (31%) studies for selective outcome reporting. Blinding of participants and personnel was considered to be at low risk of bias in 8 (21%) and 10 studies (26%) for blinding of outcome assessors. It should be noted that blinding of participants and personnel was not possible in many of the studies because of the nature of the intervention or control treatment.The use of oral or topical antibiotic compared with placebo/no treatment, had uncertain effects on the risk of exit-site/tunnel infection (3 studies, 191 patients, low quality evidence: RR 0.45, 95% CI 0.19 to 1.04) and the risk of peritonitis (5 studies, 395 patients, low quality evidence: RR 0.82, 95% CI 0.57 to 1.19).The use of nasal antibiotic compared with placebo/no treatment had uncertain effects on the risk of exit-site/tunnel infection (3 studies, 338 patients, low quality evidence: RR 1.34, 95% CI 0.62 to 2.87) and the risk of peritonitis (3 studies, 338 patients, low quality evidence: RR 0.94, 95% CI 0.67 to 1.31).Pre/perioperative intravenous vancomycin compared with no treatment may reduce the risk of early peritonitis (1 study, 177 patients, low quality evidence: RR 0.08, 95% CI 0.01 to 0.61) but has an uncertain effect on the risk of exit-site/tunnel infection (1 study, 177 patients, low quality evidence: RR 0.36, 95% CI 0.10 to 1.32).The use of topical disinfectant compared with standard care or other active treatment (antibiotic or other disinfectant) had uncertain effects on the risk of exit-site/tunnel infection (8 studies, 973 patients, low quality evidence, RR 1.00, 95% CI 0.75 to 1.33) and the risk of peritonitis (6 studies, 853 patients, low quality evidence: RR 0.83, 95% CI 0.65 to 1.06).Antifungal prophylaxis with oral nystatin/fluconazole compared with placebo/no treatment may reduce the risk of fungal peritonitis occurring after a patient has had an antibiotic course (2 studies, 817 patients, low quality evidence: RR 0.28, 95% CI 0.12 to 0.63).No intervention reduced the risk of catheter removal or replacement. Most of the available studies were small and of suboptimal quality. Only six studies enrolled 200 or more patients.

AUTHORS' CONCLUSIONS

In this update, we identified limited data from RCTs and quasi-RCTs which evaluated strategies to prevent peritonitis and exit-site/tunnel infections. This review demonstrates that pre/peri-operative intravenous vancomycin may reduce the risk of early peritonitis and that antifungal prophylaxis with oral nystatin or fluconazole reduces the risk of fungal peritonitis following an antibiotic course. However, no other antimicrobial interventions have proven efficacy. In particular, the use of nasal antibiotic to eradicate Staphylococcus aureus, had an uncertain effect on the risk of peritonitis and raises questions about the usefulness of this approach. Given the large number of patients on PD and the importance of peritonitis, the lack of adequately powered and high quality RCTs to inform decision making about strategies to prevent peritonitis is striking.

The Current State of Peritoneal Dialysis

Technical innovations in peritoneal dialysis (PD), now used widely for the long-term treatment of ESRD, have significantly reduced therapy-related complications, allowing patients to be maintained on PD for longer periods. Indeed, the survival rate for patients treated with PD is now equivalent to that with in-center hemodialysis. In parallel, changes in public policy have spurred an unprecedented expansion in the use of PD in many parts of the world. Meanwhile, our improved understanding of the molecular mechanisms involved in solute and water transport across the peritoneum and of the pathobiology of structural and functional changes in the peritoneum with long-term PD has provided new targets for improving efficiency and for intervention. As with hemodialysis, almost half of all deaths on PD occur because of cardiovascular events, and there is great interest in identifying modality-specific factors contributing to these events. Notably, tremendous progress has been made in developing interventions that substantially reduce the risk of PD-related peritonitis. Yet the gains have been unequal among individual centers, primarily because of unequal clinical application of knowledge gained from research. The work to date has further highlighted the areas in need of innovation as we continue to strive to improve the health and outcomes of patients treated with PD.

Early Peritonitis in a Large Peritoneal Dialysis Provider System in Colombia

♦ BACKGROUND: Peritonitis is the most important complication of peritoneal dialysis (PD), and early peritonitis rate is predictive of the subsequent course on PD. Our aim was to calculate the early peritonitis rate and to identify characteristics and predisposing factors in a large nationwide PD provider network in Colombia. ♦ METHODS: This was a historical observational cohort study of all adult patients starting PD between January 1, 2012, and December 31, 2013, in 49 renal facilities in the Renal Therapy Services in Colombia. We studied the peritonitis rate in the first 90 days of treatment, its causative micro-organisms, its predictors and its variation with time on PD and between individual facilities. ♦ RESULTS: A total of 3,525 patients initiated PD, with 176 episodes of peritonitis during 752 patient-years of follow-up for a rate of 0.23 episodes per patient year equivalent to 1 every 52 months. In 41 of 49 units, the rate was better than 1 per 33 months, and in 45, it was better than 1 per 24 months. Peritonitis rates did not differ with age, ethnicity, socioeconomic status, or PD modality. We identified high incidence risk periods at 2 to 5 weeks after initiation of PD and again at 10 to 12 weeks. ♦ CONCLUSION: An excellent peritonitis rate was achieved across a large nationwide network. This occurred in the context of high nationwide PD utilization and despite high rates of socioeconomic deprivation. We propose that a key factor in achieving this was a standardized approach to management of patients.

Peritoneal Dialysis as a First versus Second Option after Previous Haemodialysis: A Very Long-Term Assessment

For renal replacement therapy, overall survival is more important than the choice of currently available individual therapy. Objectives. To compare patients and technique survival on peritoneal dialysis as first treatment (PDF) versus after previous haemodialysis (HDPD) and other indicators of follow-up. Methods. We prospectively studied 110 incident patients, during the period from August 4, 1993, to June 30, 2012, for patients and technique survival (Kaplan-Meier) (log rank P < 0.05). Results. Groups: (A) PDF: 37 patients, 24 females, age: 52.2 ± 14.9 years old, time at risk: 2123 patient-months (p/m), mean: 57 ± 42 months; (B) HDPD: 73 patients, 42 females, age: 52.45 ± 14.7 years old, time in haemodialysis: 3569.2 (p/m), range: 3-216 months, mean: 49 ± 45 months, time at risk in PD: 3700 (p/m), mean: 51 ± 49 months. Patients' survival: (A) PDF: 100%, 76.6%, 65.6%, and 19.7%; (B) HDPD: 95.4%, 65.6%, 43%, and 43% at 12, 60, 120, and 144 months, respectively, P = 0.34.

TECHNIQUE

(A) PDF: 100%, 90%, 59.8%, and 24%; (B) HDPD: 94%, 75%, 32%, and 32% at 12, 60, 120, and 144 months, respectively, P = 0.40. Conclusions. Comparable patient and technique survival were observed. Peritoneal dialysis enables a greater extension of renal replacement therapy for patients with serious difficulties continuing with haemodialysis.

Risk factors for mortality in Chinese patients on continuous ambulatory peritoneal dialysis

OBJECTIVE

The intent of this study was to evaluate the clinical outcome and risk factors affecting mortality of the continuous ambulatory peritoneal dialysis (CAPD) patients in a single peritoneal dialysis (PD) center over a period of 10 years.

PATIENTS AND METHODS

We retrospectively analyzed patients on PD from June 2001 to June 2011. The clinical and biochemical data were collected from the medical records. Clinical variables included gender, age at the start of PD, smoking status, body mass index (BMI), cause of end-stage renal disease (ESRD), presence of diabetes mellitus and blood pressure. Biochemical variables included hemoglobin, urine volume, residual renal function (RRF), serum albumin, blood urea nitrogen (BUN), creatinine, total cholesterol, triglyceride, comorbidities, and outcomes. Survival curves were made by the Kaplan-Meier method. Univariate and multivariate analyses to identify mortality risk factors were performed using the Cox proportional hazard regression model.

RESULTS

A total of 421 patients were enrolled, 269 of whom were male (63.9%). The mean age at the start of PD was 57.9 ± 14.8 years. Chronic glomerulonephritis was the most common cause of ESRD (39.4%). Estimation of patient survival by Kaplan-Meier was 92.5%, 80.2%, 74.4%, and 55.7% at 1, 3, 5, and 10 years, respectively. Patient survival was associated with age (hazard ratio [HR]: 1.641 [1.027 - 2.622], p = 0.038), cardiovascular disease (HR: 1.731 [1.08 - 2.774], p = 0.023), hypertriglyceridemia (HR: 1.782 [1.11 - 2.858], p = 0.017) in the Cox proportional hazards model analysis. Estimation of technique survival by Kaplan-Meier was 86.7%, 68.8%, 55.7%, and 37.4% at 1, 3, 5, and 10 years, respectively. In the Cox proportional hazards model analysis, age (HR: 1.672 [1.176 - 2.377], p = 0.004) and hypertriglyceridemia (HR: 1.511 [1.050 - 2.174], p = 0.026) predicted technique failure.

CONCLUSION

The PD patients in our center exhibited comparable or even superior patient survival and technical survival rates, compared with reports from other centers in China and other countries.

Double bag or Y-set versus standard transfer systems for continuous ambulatory peritoneal dialysis in end-stage kidney disease

BACKGROUND

Peritonitis is the most frequent serious complication of continuous ambulatory peritoneal dialysis (CAPD). It has a major influence on the number of patients switching from CAPD to haemodialysis and has probably restricted the wider acceptance and uptake of CAPD as an alternative mode of dialysis.This is an update of a review first published in 2000.

OBJECTIVES

This systematic review sought to determine if modifications of the transfer set (Y-set or double bag systems) used in CAPD exchanges are associated with a reduction in peritonitis and an improvement in other relevant outcomes.

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register through contact with the Trials Search Co-ordinator. Studies contained in the Specialised Register are identified through search strategies specifically designed for CENTRAL, MEDLINE and EMBASE. Date of last search: 22 October 2013.

SELECTION CRITERIA

Randomised controlled trials (RCTs) or quasi-RCTs comparing double bag, Y-set and standard peritoneal dialysis (PD) exchange systems in patients with end-stage kidney disease.

DATA COLLECTION AND ANALYSIS

Data were abstracted by a single investigator onto a standard form and analysed by Review Manager. Analysis was by a random effects model and results were expressed as risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

Twelve eligible trials with a total of 991 randomised patients were identified. Despite the large total number of patients, few trials covered the same interventions, small numbers of patients were enrolled in each trial and the methodological quality was suboptimal. Y-set and twin-bag systems were superior to conventional spike systems (7 trials, 485 patients, RR 0.64, 95% CI 0.53 to 0.77) in preventing peritonitis in PD.

AUTHORS' CONCLUSIONS

Disconnect systems should be the preferred exchange systems in CAPD.

[Peritoneal dialysis from the beginnings up to today: which developments of the last decades were important?]

During the past years new developments in peritoneal dialysis (PD) technique have resulted in continuous improvement of patient outcome. The importance of salt and fluid balance, residual renal function and peritoneal glucose load are of increasing interest, whereas small solute clearances have lost importance. In patients with high peritoneal transport rates automated PD (APD) is indicated. However, APD can also be chosen as initial PD treatment since recent studies show comparable or even better survival as compared to continuous ambulatory PD patients. Alternative PD solutions improve peritoneal ultrafiltration (icodextrin), reduce peritoneal glucose load (amino acid solution, icodextrin) and protect the peritoneal membrane (solutions with low concentration of glucose degradation products). Infection risk can be reduced when using antibiotic creams, but resistances should be considered. Ongoing studies will clarify if non-antibiotic agents, e.g. medihoney, are effective in preventing PD-associated infections. Due to these improvements PD and hemodialysis have become equivalent treatments.

Prevention of peritoneal dialysis-related infections

Despite substantial advances in peritoneal dialysis (PD) as a renal replacement modality, PD-related infection remains an important cause of morbidity, technique failure, and mortality. This review describes the microbiology and outcomes of PD peritonitis and catheter infection, followed by a discussion of several strategies that may reduce the risk of PD-related infections. Strategies that are reviewed include use of antibiotics at the time of PD catheter insertion, selection of PD catheter design and insertion technique, patient training, PD connectology, exit site prophylaxis, periprocedural prophylaxis, fungal prophylaxis, and choice of PD solutions.

An International Perspective on Peritoneal Dialysis among Indigenous Patients

Objective

To review utilization rates, outcomes, and barriers to peritoneal dialysis (PD) in indigenous peoples from an international perspective.

Methods

Articles were obtained from Medline and EMBASE and from author name and reference searches. Data from census bureaus and renal registries in Australia, Canada, New Zealand, and the United States were used. Studies were included if they contained information on utilization of, outcomes of, or barriers to PD in indigenous populations.

Results

In 2007, of all prevalent PD patients, 7.0%, 5.1%, 28.2%, and 1.3% in Australia, Canada, New Zealand, and the United States respectively were of indigenous background. The proportions of prevalent renal replacement therapy patients on PD reflected the national rates—New Zealand being the highest at 0.29, and the United States the lowest at 0.05. Mortality was generally higher in indigenous than in non-indigenous PD patients. Variations in mortality study results likely reflect differences in the definitions of explanatory variables such as rurality and in the availability of local specialty care services. Technique failure and peritonitis rates were higher among indigenous than among non-indigenous patients.

Conclusions

The less favorable outcomes in indigenous PD patients across countries may, in part, be a manifestation of reduced access to resources. Understanding the effects of socio-economic, geographic, cultural, and language issues, and of health literacy discrepancies on various aspects of PD education, training, and outcomes can potentially identify ways in which outcomes might be improved among indigenous patients on PD.

Impact of C-reactive protein and pulse pressure evaluated at the start of peritoneal dialysis on cardiovascular events in the course of treatment with peritoneal dialysis

BACKGROUND

Despite a reduced number of infectious complications, cardiovascular (CV) mortality remains unchanged in peritoneal dialysis (PD) patients. The aim of this study was to evaluate the effects of high-sensitivity C-reactive protein (hs-CRP) and pulse pressure (PP) at the start of PD on the development of CV events (CVEs) in these patients.

METHODS

The study population was comprised of 291 patients that started PD between January 2003 and June 2008 and were treated for more than 6 months. Baseline clinical, biochemical, and echocardiographic data, indices of dialysis adequacy, and peritoneal transport rate were reviewed retrospectively. The clinical outcome was the occurrence of a CVE.

RESULTS

Mean duration of follow-up was 28 (range 6 - 70) months. A CVE was observed in 33 patients (11.3%). The 1-, 3-, and 5-year cumulative incidences of CVEs were 4.0%, 13.7%, and 27.5%, respectively. Although multiple variables were correlated with the prevalence of a CVE in the univariate analysis, hs-CRP, PP, and comorbidity remained significant after adjustment: hs-CRP: odds ratio (OR) 4.09 (1.53 - 10.95), p = 0.005; PP: OR 2.79 (1.26 - 6.17), p = 0.012. PP and hs-CRP, which were not intercorrelated in our data, combined adversely to increase the incidence of CVEs. The incidence of CVEs increased with the number of risk factors, which included high hs-CRP, high PP, and the presence of comorbidity (no risk factor, 0%; 1 risk factor, 1.5%; 2 risk factors, 30.8%; 3 risk factors, 53.9%).

CONCLUSIONS

Our study suggests that measurements of hs-CRP and PP at the start of PD may be helpful in predicting the development of CVEs in the course of treatment with PD.

Relationship between double-cuff versus single-cuff peritoneal dialysis catheters and risk of peritonitis

BACKGROUND

Peritonitis among peritoneal dialysis (PD) patients remains an important complication. To date, no catheter type has consistently been shown to reduce peritonitis risk. It has been hypothesized that double-cuff catheters might be superior to single-cuff catheters in preventing peritonitis caused by periluminal entry of organisms.

METHODS

Using data collected in the multicentre Canadian Baxter Peritonitis Organism Exit-Sites Tunnel Infections (POET) database between 1996 and 2005, the association between number of catheter cuffs and peritonitis was tested. Variables adjusted for in the negative binomial model included age, gender, race, diabetes, renal disease, transfer from haemodialysis, previous renal transplant, PD modality and swan neck versus straight catheter.

RESULTS

Data were available for 4247 incident patients with a total of 2555 peritonitis episodes, corresponding to a peritonitis rate of 0.364 per dialysis year at risk. After adjustment for covariates, double-cuff catheter use was associated with a trend towards a lower peritonitis rate ratio (RR) 0.90, 95% confidence interval (CI) 0.80-1.01, P = 0.08]. This trend was largely due to a decreased Staphylococcus aureus peritonitis rate in those with a double-cuff catheter (RR 0.46, 95% CI 0.33-0.64, P < 0.001). When stratified by era of PD initiation, the benefit of double-cuff catheters was seen only among those initiating PD before 2001.

CONCLUSION

Use of a double-cuff PD catheter is associated with a reduction in S. aureus peritonitis. Loss of the association between cuff number and peritonitis after the year 2000 may relate to changes in exit-site care that reduce the bacterial burden available for periluminal migration.

Risk Factors for Adverse Outcomes after Peritonitis-Related Technique Failure

Background

Peritonitis is the leading cause of technique failure in peritoneal dialysis (PD) patients. Some patients experience recurrent ascites, encapsulating peritoneal sclerosis (EPS), and even death after catheter removal. Little is known, however, about the risk factors for such complications.

Methods

The study subjects were 117 patients that had their PD catheter removed due to peritonitis between January 2000 and June 2006. Biochemical and clinical data were reviewed retrospectively. Serum C-reactive protein (CRP) and blood and effluent white blood cell counts (WBC) were measured at baseline and at 72 hours of peritonitis. Based on adverse outcomes, patients were classified into 4 groups: non-complication (NC; n = 73), recurrent ascites (A; n = 26), EPS (E; n = 10), and death directly related to peritonitis (D; n = 8).

Results

Age at PD catheter removal was significantly higher in D group compared to NC group (62.0 ± 10.6 vs 51.2 ± 11.5 years, p < 0.05). In addition, mean PD duration was significantly longer in E group compared to NC and A groups (130.5 ± 48.1 vs 58.8 ± 42.4 vs 74.8 ± 47.4 months, p < 0.01). Compared to baseline, effluent WBC was significantly decreased in NC group after 72 hours of peritonitis. In addition, serum CRP level was significantly decreased in NC and A groups, whereas it was significantly increased in D group. Multivariate analyses adjusted for age, PD duration, blood and effluent WBC, serum CRP, and micro-organisms revealed that serum CRP level at 72 hours predicted significantly the development of EPS [odds ratio (OR) 1.15, p < 0.05] and peritonitis-related death (OR 1.18, p < 0.01). In addition, PD duration (per 1 month increase: OR 1.03, p < 0.05) and age at PD catheter removal (per 1 year increase: OR 1.11, p < 0.05) were identified as significant determinants of EPS and peritonitis-related death respectively. Only effluent WBC at 72 hours was significantly associated with the development of ascites (OR 1.27, p < 0.05).

Conclusion

Older patients with long PD duration and those with persistently elevated serum CRP levels were likely to develop complications after peritonitis-related technique failure. Our study suggests that serial measurement of CRP may be helpful in predicting the development of complications after PD catheter removal.

Infections in patients with chronic kidney disease

There has been a notable lack of research activity regarding major infections in patients with advanced chronic kidney disease. To an outsider, this might seem unexpected, because uremia has long been considered a state of immune hyporesponsiveness and rates of major bacterial infection, like septicemia and pneumonia, are known to be orders of magnitude more likely in dialysis populations than in the general population. This article reviews recent literature on the topic, focusing predominantly on the clinical epidemiology of major bacterial infections in dialysis patients, the links between bacterial infections and cardiovascular disease, and randomized trials of interventions designed to prevent these infections.

Antimicrobial agents and catheter-related interventions to prevent peritonitis in peritoneal dialysis: Using evidence in the context of clinical practice

BACKGROUND

Peritonitis still represents a common and major complication of peritoneal dialysis. The broader adoption of several strategies, including antimicrobial and catheter related interventions, has been advocated to prevent or reduce the risk of peritonitis in peritoneal dialysis.

METHODS

In this article we start with the presentation of a clinical case where concern exists about the strategies for preventing peritoneal dialysis peritonitis. We then look at the available evidence in the form of systematic reviews of randomized trials and individual randomized trials of interventions to prevent peritonitis in peritoneal dialysis. A summary of the evidence is provided and then put in context with the clinical case scenario.

RESULTS

Nineteen eligible trials (1949 patients) of antimicrobial agents and 37 (2822 patients) of catheter related interventions to prevent peritonitis in peritoneal dialysis were identified. Nasal mupirocin compared with placebo significantly reduced the exit-site and tunnel infection rate (1 trial, 2716 patient months, RR 0.58, 95% CI 0.40 to 0.85) but not peritonitis rate (1 trial, 2716 patient months, RR 0.84, 95% CI 0.44 to 1.60). As for antimicrobial strategies, perioperative intravenous antibiotics compared with no treatment significantly reduced the risk of early peritonitis (4 trials, 335 patients, RR 0.35, 95% CI 0.15 to 0.80) but not exit site and tunnel infection (3 trials, 114 patients, RR 0.32, 95% CI 0.02 to 4.81). As for catheter related strategies, Y-set and twin-bag systems were superior to conventional spike systems (7 trials, 485 patients, RR 0.64, 95% CI 0.53 to 0.77) and no other catheter-related intervention was demonstrated to prevent peritonitis in PD.

CONCLUSIONS

Evidence exists to support the use of perioperative intravenous antibiotic prophylaxis at the time of catheter placement, the twin-bag and Y-set system, as well as prophylaxis with mupirocin in Staphylococcus aureus nasal carriers. Despite lack of evidence, several other agents are used and recommended in major international guidelines, which is reasonable but requires further investigation.

A comparison of peritonitis rates from the United States Renal Data System database: CAPD versus continuous cycling peritoneal dialysis patients

BACKGROUND

Previous comparisons of peritonitis rates between continuous ambulatory peritoneal dialysis (CAPD) and continuous cycling peritoneal dialysis (CCPD) have produced varying results.

METHODS

Using United States Renal Data System data, the authors evaluated peritonitis rates in 1994 through 1997 incident CAPD (n = 9,190) and CCPD (n = 2,785) Medicare patients. Patients were characterized during a 6-month entry period (months 4 through 9) and followed for a maximum of 2 years (months 10 through 33). Medicare claims data provided the date of the first peritonitis episode during the follow-up period. The time to first peritonitis after 9 months of PD was compared by the log-rank test, and then by Cox regression with adjustment for peritoneal dialysis modality, age, sex, race, primary end-stage renal disease (ESRD) diagnosis, number of entry-period hospital days, peritonitis during the entry period, hematocrit value, and congestive heart failure.

RESULTS

For CAPD and CCPD, the adjusted average months to first peritonitis after 9 months of PD were 17.1 and 16.1, respectively. The probabilities of remaining without a peritonitis episode after 1 year of follow-up were 0.53 and 0.50, respectively ( P = 0.008). The risk of peritonitis was lower for CAPD than for CCPD (relative risk, 0.939; 95% confidence interval, 0.883 to 0.998). Other significant risk factors included age <or=44 years, black race, diabetes as primary ESRD diagnosis, peritonitis during the entry period, greater than 4 entry-period hospital days, and congestive heart failure. Patients treated with recombinant human erythropoietin with a hematocrit value of >or=36% had lower risk of peritonitis.

CONCLUSION

Compared with CCPD, CAPD is associated with a slightly but significantly lower risk for development of a first peritonitis episode after 9 months of peritoneal dialysis therapy.

Comparison of peritoneal equilibration test with 99mTc-DTPA excretion in the assessment of peritoneal permeability

Assessment of peritoneal permeability is necessary for successful management of end-stage renal disease (ESRD) patients by continuous ambulatory peritoneal dialysis (CAPD). The objective of this study was to develop an alternative method of assessing the peritoneal permeability and to compare this method with the conventional method, the peritoneal equilibrium test, first described by Twardowski in 1987. Twenty patients undergoing regular CAPD were included in this study. Before starting the peritoneal dialysis, 370 MBq (10 mCi) technetium-99m diethylene triamine penta-acetic acid ((99m)Tc-DTPA) was injected intravenously. A standard dose of the same quantity was kept and used later for calculations. At the end of 4 h, a dialysate fluid sample (1 ml) was collected and the total dialysis effluent fluid volume was measured. Excretion of (99m)Tc-DTPA into the dialysate fluid as a percentage of the injected dose was calculated. Simultaneously, standard peritoneal equilibrium test values were recorded for comparison. Peritoneal excretion of (99m)Tc-DTPA ranged from 8% to 25% of the injected dose, depending on the peritoneal membrane permeability. When the results were compared with the conventional method, a good correlation (r=0.79) was found. This innovative radionuclide technique is a simple and convenient method to assess the peritoneal membrane permeability and can be used as an alternative to the peritoneal equilibrium test, which is very cumbersome and associated with many limitations.

Biofilms and infection in dialysis patients

Biofilm bacterial infections are implicated in most human bacterial infections and are also common in patients undergoing treatment with hemodialysis and peritoneal dialysis. Skin bacteria, which grow into microcolonies with biofilm formation in dialysis environments, are implicated in most of these infections. Dissemination of bacterial biofilms in hemodialysis patients induces bacteremia and endotoxemia. In peritoneal dialysis patients, biofilm causes peritonitis and catheter-related infections with consequent loss of catheters and technique failure. Effective strategies for the diagnosis, intervention, and prevention of biofilm-related infections in dialysis patients are described in this review.

Moncrief-Popovich catheter and implantation technique: the AV fistula of peritoneal dialysis

Despite the decrease in peritonitis rate from touch contamination caused by the use of disconnect systems, technique failure in peritoneal dialysis (PD) from pericatheter and exit-site infections in PD remains unchanged. This indicates a failure of current PD catheters to prevent bacterial transfer from exit site to the peritoneal cavity. In 1991, Moncrief and Popovich introduced a new catheter design and implantation technique to address this problem. The catheter is made of silastic, has a coiled tip with 2 cuffs, and an arcuate bend between the cuffs. This would prevent catheter malfunction and leakage of PD fluid. The implantation technique involves embedding of the external segment of the catheter in the subcutaneous tunnel at insertion. The catheter segment is kept embedded for 4 to 6 weeks before externalization. This procedure will allow time for tissue ingrowth on into the external cuff and catheter surfaces between the 2 cuffs, preventing bacterial colonization of the catheter surfaces from the exit wound and thereby reducing pericatheter infections. Thus, the new technique will establish a more effective bacteriologic barrier between the exit wound and the peritoneal cavity than the conventional catheters. Ten years after validation of the catheter design and implantation technique by Moncrief and Popovich, various clinical studies confirm that this new technique of catheter implantation increases catheter life expectancy and reduces pericatheter infections in PD. Like the arteriovenous fistula of haemodialysis, this new catheter remains embedded in subcutaneous tunnel, is exteriorized electively when patient needs to be started on dialysis, and reduces pericatheter and exit-site infections in PD. The new technique, therefore, is widely accepted as a simple, safe, and cost-effective procedure for quality care of PD patients around the world.

Evaluation of an antimicrobial-impregnated continuous ambulatory peritoneal dialysis catheter for infection control in rats

Infection is the most serious complication arising in long-term continuous ambulatory peritoneal dialysis (CAPD), specifically peritonitis and exit-site infection. The initial weeks after implantation is the crucial period during which bacterial colonization of the catheter results in maximal morbidity, with Staphylococcus aureus being the most virulent organism. We developed an antimicrobial-impregnated CAPD catheter by impregnating the cuff and tubing with chlorhexidine, silver sulfadiazine, and triclosan in a polymer matrix. The antimicrobial spectrum and duration were shown by measuring zones of inhibition to various bacteria and fungi over the course of 5 to 10 days. Activity also was assessed subsequent to soaking in trypticase soy broth containing 20% bovine serum over the course of 1, 3, and 7 days. Significant antimicrobial activity was shown against all organisms tested for, with particular efficacy against gram-positive bacteria. Catheters were implanted in rats followed by inoculation of the exit site with S aureus. Seven days postimplantation, 0% of the impregnated catheters were colonized intraperitoneally compared with 100% of the control catheters. Similarly, 12.5% of the impregnated catheters were colonized at the exit site, whereas 100% of the controls were colonized. Histologic analysis showed that this combination and concentration of antimicrobials did not retard healing or cause increased inflammation compared with control catheters after 3, 10, and 24 days postimplantation in noninoculated rats.

Do the Y-set and double-bag systems reduce the incidence of CAPD peritonitis? A systematic review of randomized controlled trials

BACKGROUND

Peritonitis is the most frequent serious complication of continuous ambulatory peritoneal dialysis (CAPD). It has a major influence on the number of patients switching from CAPD to haemodialysis and has probably restricted the wider acceptance and uptake of CAPD as an alternative mode of dialysis. This systematic review sought to determine if modifications of the transfer set (Y-set or double-bag systems) used in CAPD exchanges are associated with a reduction in peritonitis and an improvement in other relevant outcomes.

METHODS

Based on a comprehensive search strategy, we undertook a systematic review of randomized or quasi-randomized controlled trials comparing double-bag and/or Y-set CAPD exchange systems with standard systems, or comparing double-bag with Y-set systems, in patients with end-stage renal disease (ESRD) treated with CAPD. Only published data were used. Data were abstracted by a single investigator onto a standard form and subsequently entered into Review Manager 4.0.4. Its statistical package, Metaview 3.1, calculated an odds ratio (OR) for dichotomous data and a (weighted) mean difference for continuous data with 95% confidence intervals.

RESULTS

Twelve eligible trials with a total of 991 randomized patients were identified. In trials comparing either the Y-set or double-bag systems with the standard systems, significantly fewer patients (133/363 vs 158/263; OR 0.33, 95% CI 0.24-0.46) experienced peritonitis and the number of patient-months on CAPD per episode of peritonitis was consistently greater. When the double-bag systems were compared with the Y-set systems significantly fewer patients experienced peritonitis (44/154 vs 66/138; OR 0.44, 95% CI 0.27-0.71) and the number of patient-months on CAPD per episode of peritonitis was also greater.

CONCLUSIONS

Double-bag systems should be the preferred exchange systems in CAPD.

Double bag or Y-set versus standard transfer systems for continuous ambulatory peritoneal dialysis in end-stage renal disease

BACKGROUND

Peritonitis is the most frequent serious complication of continuous ambulatory peritoneal dialysis (CAPD). It has a major influence on the number of patients switching from CAPD to haemodialysis and has probably restricted the wider acceptance and uptake of CAPD as an alternative mode of dialysis.

OBJECTIVES

This systematic review sought to determine if modifications of the transfer set (Y-set or double bag systems) used in CAPD exchanges are associated with a reduction in peritonitis and an improvement in other relevant outcomes.

SEARCH STRATEGY

A broad search strategy was employed which attempted to identify all RCTs or quasi-RCTs relevant to the management of end-stage renal disease (ESRD). Five electronic databases were searched (Medline 1966-1999, EMBASE 1984-1999, CINAHL 1982-1996, BIOSIS 1985-1996 and the Cochrane Library), authors of included studies and relevant biomedical companies were contacted, reference lists of identified RCTs and relevant narrative reviews were screened and Kidney International 1980-1997 was hand searched.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials comparing double bag, Y-set and standard CAPD exchange systems in patients with ESRD.

DATA COLLECTION AND ANALYSIS

Data were abstracted by a single investigator onto a standard form and subsequently entered into Review Manager 4.0.4. Odds Ratio (OR) for dichotomous data and a (Weighted) Mean Difference (WMD) for continuous data were calculated with 95% confidence intervals (95% CI).

MAIN RESULTS

Twelve eligible trials with a total of 991 randomised patients were identified. In trials comparing either the Y-set or double bag systems with the standard systems significantly fewer patients (OR 0.33, 95% CI 0.24 to 0.46) experienced peritonitis and the number of patient-months on CAPD per episode of peritonitis were consistently greater. When the double bag systems were compared with the Y-set systems significantly fewer patients experienced peritonitis (OR 0.44, 95% CI 0.27 to 0.71) and the numbers of patient-months on CAPD/ episode of peritonitis were also greater.

REVIEWER'S CONCLUSIONS

Double bag systems should be the preferred exchange systems in CAPD.

Peritoneal dialysis. Prevention and control of infection

In spite of the reduction in peritonitis and catheter-related infection rates in patients undergoing peritoneal dialysis, these infections remain major sources of morbidity and transfer to haemodialysis. Touch contamination at the time of doing the exchanges is still a major cause of peritonitis and leads to Gram-positive organisms (coagulation-negative staphylococcus) being the most common pathogens. Newer exchange techniques have reduced this incidence but the more serious pathogens (Staphylococcal aureus, pseudomonas and fungi) remain a major problem. Treatment has to be immediate, and hence empirical, giving adequate cover for both Gram-positive and Gram-negative organisms. The use of vancomycin as an initial antibacterial has been discontinued because of the problem of vancomycin-resistant enterococcus. Recent guidelines advocate the use of a first generation cephalosporin combined with ceftazidime (if the urine output is >100 ml/day) or an aminoglycoside in anuric patients. Subsequent therapy changes are made upon bacterial isolation and sensitivities. Vancomycin is reserved for methicillin-resistant staphylococcus. Peritoneal catheter-related infections (exit site and tunnel) are predominantly caused by S. aureus and pseudomonal organisms and can be difficult to eradicate. Tunnel infections invariably involve the catheter dacron cuffs and therefore are more likely to lead to peritonitis; in this situation catheter removal is the treatment of choice. Treatment of exit-site infections is with oral antibacterials (penicillinase-resistant penicillins, cefalexin). Vancomycin is avoided if possible. The identification that nasal carriage of S. aureus predisposes to exit-site and tunnel infections has led to prophylactic regimens to combat this problem. Mupirocin applied at the exit site leads to a reduction in catheter-related infections and peritonitis.

Trends in patient and technique survival in peritoneal dialysis and strategies: how are we doing and how can we do better?

The best data on long term trends in patient and technique survival on dialysis come from North America. Mortality rates on both peritoneal (PD) and hemodialysis (HD) have fallen over the past one to two decades in both the US and Canada with the decline in the US being relatively greater in older and diabetic patients. There is some suggestion that this improvement may be proportionately greater in PD, relative to HD, patients in both the US and Canada. Overall, mortality rates on PD are similar to, or better than, those on HD in the early years of treatment, except in older US diabetic patients. In later years, patients on HD do relatively better than those on PD in the US but not in Canada. The biggest cause of mortality on dialysis is cardiovascular disease and the risk factors for this in the dialysis population generally, and particularly on PD, are reviewed, including newly appreciated ones such as hyperhomocysteinemia, high lipoprotein (a) levels and inflammation/malnutrition. Possible preventative and therapeutic strategies are also considered. Technique failure (TF) rates are high in PD but Canadian data suggest they have fallen over the past 20 years, primarily due to a reduction in cases due to peritonitis. TF rates due to inadequate dialysis have increased and an interpretation of this as well as an approach to reducing it are suggested.

Evidence-based medicine and health economics: a case study of end stage renal disease

This paper explores the potential for use of an economic evaluation framework alongside systematic reviews. Clinical issues in dialysis therapy for end stage renal disease are used as case studies. The effectiveness data required were obtained from a systematic review of randomized controlled trials. Resource use and cost data were obtained from three sources; the identified randomized controlled trials, a separate review of observational studies and primary data collection. The results of the case studies show that, although simple economic evaluations were possible, issues arose, such as how transferable results are between settings and how appropriate it is to focus on the average patient. The interface between economic evaluation and systematic reviews needs to be further developed in order to ensure that the best available evidence can be used to inform future policy and research.

Comparison of double-bag and Y-set disconnect systems in continuous ambulatory peritoneal dialysis: a randomized prospective multicenter study

We performed a multicenter, single-blinded, prospective randomized study on the use of a double-bag disconnect system (B) versus a Y-set disconnect system (Y). The peritonitis rate, exit site infection, clinical outcome, and patients' acceptance to the procedure were assessed. A total of 120 new end-stage renal failure patients of three regional hospitals were randomized: 60 each to the B and the Y systems. The results of 60 patients on the B system and 51 on the Y system were analyzable. They were followed up for a median of 16 months. Peritonitis rates for the B and the Y systems were 33.5 and 29.4 patient-months per episode, respectively. Exit site infection rates for the B and Y systems were 17.4 and 16.0 patient-months per episode, respectively. Four catheters were removed in each group. Patients on the B system were hospitalized for 2.1 days per patient per year related to peritonitis and exit site infection, and those on the Y system were hospitalized for 1.2 days. There was no significant difference between the B and Y systems in the incidences of peritonitis (all causes and those due to coagulase-negative staphylococci), exit site infection, and in hospitalization days. However, there was a higher percentage of gram-positive infections in the Y system (52%) than in the B system (32%) and a lower percentage of gram-negative infections in the Y system (16%) than in the B system (32%). Patients on the B system had a better acceptance of the procedure than patients on the Y system, as assessed by a six-item, 10-point questionnaire (total score, 43.1 +/- 10.2 v 37.6 +/- 9.4; P < 0.005 at 1 month; 44.6 +/- 9.1 v 39.8 +/- 8.6; P < 0.01 at 6 months). From this study, it is concluded that the B and Y systems are similar in the incidences of peritonitis and exit site infection, although the B system is better accepted by patients. This is probably the first multicenter randomized study comparing the double-bag and Y-set disconnect system using only new patients who had never used other systems of continuous ambulatory peritoneal dialysis.

Prevention of peritonitis with disconnect systems in CAPD: a randomized controlled trial. The Mexican Nephrology Collaborative Study Group

BACKGROUND

Recently, disconnect systems for CAPD that are associated with a reduced frequency of peritonitis have been introduced. Our objective was to compare the incidence of peritonitis using three current CAPD systems in a high-risk population with low educational and socioeconomic levels, and high prevalence of malnutrition.

METHODS

In a prospective controlled trial, 147 patients commencing CAPD were randomly assigned to one of three groups: 29 to the conventional, 57 to the Y-set, and 61 to the twin bag systems. The number of peritonitis episodes was registered, and patients were followed up for an average of 11.3 months.

RESULTS

The average peritonitis-free interval for the conventional group was 6.1 months, for the Y system was 12.0 months, and for the twin bag was 24.8 months (P < 0.001). By multivariate analysis, the only factor associated with peritonitis was the CAPD system. Peritonitis-related hospitalization was 5.3 +/- 2.0, 2.7 +/- 1.0, and 1.5 +/- 0.9 days/patient/year in the conventional, Y system, and twin bag groups, respectively. The cost per bag was similar for the conventional and Y system, but higher for the twin bag. However, the total costs of treatment (pesos/patient/year) were lower for twin bag (62,159 for the conventional, 70,275 for the Y system, and 54,387 for the twin bag), due to the lower peritonitis incidence and associated hospitalizations.

CONCLUSIONS

Y system and twin bag use was associated with a reduction of 50 and 75% peritonitis incidence, respectively, in patients on CAPD. The cost of the twin bag was actually lower, because of savings from a decreased usage of antibiotics and fewer hospitalizations.

Risk factors for peritonitis in long-term peritoneal dialysis: the Network 9 peritonitis and catheter survival studies. Academic Subcommittee of the Steering Committee of the Network 9 Peritonitis and Catheter Survival Studies

To determine factors involved in peritoneal dialysis-associated peritonitis and catheter loss, all point prevalent peritoneal dialysis patients in Health Care Finance Administration (HCFA) end-stage renal disease (ESRD) Network 9 were followed throughout 1991 for peritonitis events and throughout 1991 to 1992 for catheter survival. Data were collected by questionnaires compiled by the dialysis facility and validated by network staff. Peritonitis was reported 1,168 times in 729 of the 1,930 patients. By gamma-Poisson regression, a significantly increased risk for peritonitis was observed for patients with previous peritonitis, black race, and those dialyzing with standard connectors or cyclers compared with disconnect systems. Decreased risks were observed for patients with longer ESRD experience and when prophylactic antibiotics were administered before catheter insertion. Postinsertion leakage, diabetes, visual problems, previous or current immunosuppression, and physical activity were not risk factors. Infection of any kind caused the removal of 68% of the 414 catheters lost. Patients with downward-directed tunnels were less likely to experience concomitant exit site/tunnel infections associated with peritonitis. Peritonitis episodes with Staphylococcus epidermidis-like organisms were more likely to resolve with a single course of antibiotics. Perhaps because of their higher infection rate, blacks were more likely than whites to use a disconnect system. In general, the outcome of peritonitis in blacks was similar to that in whites, except that blacks were less likely to be hospitalized and were less likely to die.

Epidemiological perspective on infections in chronic dialysis patients

Infectious complications are a source of substantial morbidity and a common cause of death among dialysis patients. This article considers the magnitude and impact of the problem of infection among patients treated with hemodialysis (HD) and peritoneal dialysis (PD) using data from national registries and large cohort studies of patients with end-stage renal disease (ESRD). United States Renal Data System (USRDS) data indicate that in the United States for years 1991 to 1992, infection accounted for 12% of all deaths among HD patients and 15% of all deaths among PD patients. Septicemia was the underlying cause in 76% of these infectious deaths among HD patients, of which the vascular access, peritonitis, peripheral vascular disease, and other causes accounted for 12%, 5%, 24%, and 59% respectively. Among PD patients, septicemia accounted for 79% of infectious deaths. Of these deaths attributable to septicemia, peritonitis, peripheral vascular disease, and other causes were reported as the cause in 35%, 23%, and 41% respectively. Infection is also a major cause of morbidity in the dialysis population. Among HD patients, an average of 7.6 bacteremic episodes per 100 patient years (0.076 per year) has been described, of which 48% were associated with access infections. Among PD patients, studies have reported peritonitis rates ranging from 1 in 7.6 to 21.5 months (0.56 to 1.58 per patient year) and exit and/or tunnel infections occurring at a rate of 0.6 episodes per year. The known predictors of infectious complications among these populations are reviewed.

Bacterial peritonitis in continuous ambulatory peritoneal dialysis: effect on dialysis on host defense mechanisms

We have used an experimental model of continuous ambulatory peritoneal dialysis (CAPD) to investigate the effect of dialysis on host defense mechanisms in the peritoneal cavity. Laboratory rats undergoing regular dialysis were challenged with a single bolus of Staphylococcus epidermidis, Staphylococcus aureus, Candida albicans, and Pseudomonas aeruginosa. Intraperitoneal challenges with all four microbial strains underwent a rapid clearance during the first 4 hours, irrespective of whether the host was undergoing dialysis. Studies using S epidermidis showed that the rapid clearance was not mediated by the diaphragmatic stomata as might have been expected. Dialysis did, however, cause delays over the following 48 hours with all of the pathogens except C albicans. Bacterial clearance over a 10-day period was strain dependant, and microbial persistence was related to adhesion formation around the cannula. Again C albicans was an exception. Our conclusions are that dialysis does not affect the innate defense mechanisms involved in the early clearance of a bolus challenge to the peritoneal cavity but can cause delays in eradicating microorganisms that survive this phase. Because these experiments were carried out using a bolus inoculum, it may be necessary to reevaluate the effect of dialysis on host defenses in the peritoneal cavity under conditions in which the challenge more closely approximates a touch contamination event.

Host defences in continuous ambulatory peritoneal dialysis and the genesis of peritonitis

Continuous ambulatory peritoneal dialysis (CAPD) has come to be extensively used for the treatment of end-stage renal failure in children, and especially infants, such that now more than half of children on dialysis worldwide receive treatment by this means. Peritonitis, however, is commoner in children than in adults receiving treatment, and is a major source of morbidity and treatment failure in children started on CAPD. Only recently has the immunology of the normal peritoneum been studied extensively, with the need to assess the impact of the installation of large volumes of fluid into the peritoneal sac during dialysis. The main phagocytic defences of the peritoneum depend upon a unique set of macrophages which are present free in the peritoneal fluid but also in the submesothelium and in perivascular collections together with B lymphocytes in the submesothelial area. Both the number of macrophages per unit volume and the concentration of opsonic proteins, such as IgG, complement and fibronectin, are reduced to between only 1% and 5% when dialysis fluid is continuously present in the peritoneal sac. In addition, the fluids used for CAPD are toxic to both macrophages and to mesothelial cells. Thus minor degrees of contamination frequently lead to peritonitis and in addition the majority of patients have catheters inserted in their peritoneum which become colonised with organisms capable of producing exopolysaccharide (slime), which promotes adhesion of the organism to the plastic and protects them against phagocytic attack and the penetration of antibiotics. Thus the peritoneum is in a state of continual inflammation, as well as being a markedly more vulnerable site than the normal peritoneum to the entry of organisms. Whether clinical peritonitis appears in this state of chronic contamination probably depends on perturbation in the balance between host defences and the organism. Whilst Staphylococcus epidermidis is the commonest cause of peritonitis, Staphylococcus aureus and Gram-negative organisms are much more serious and more frequently lead either to temporary catheter removal or discontinuation of dialysis altogether. This review describes the peritoneal defences in relation to the genesis of peritonitis.