Biocompatibility of New Peritoneal Dialysis Solutions: What Can We Hope to Achieve?

Despite the bioincompatibility of the “old”, standard, high glucose, lactate-buffered peritoneal dialysis (PD) solutions, PD is itself a highly successful dialysis modality with patient survival equivalent to that of hemodialysis (HD) during the initial 3 – 5 years of dialysis therapy. Nevertheless, PD technique survival is often limited by infectious complications and alterations in the structure and function of the peritoneal membrane. These local changes also have a negative impact on patient survival owing to systemic effects such as those often seen in patients with high peritoneal transport rate and loss of ultrafiltration (UF) capacity.

Patient mortality remains unacceptably high in both HD and PD patients, with most premature deaths being associated with signs of malnutrition, inflammation, and atherosclerotic cardiovascular disease (MIA syndrome). These systemic signs are likely to be influenced by PD solutions both directly and indirectly (via changes in the peritoneal membrane). New, biocompatible PD solutions may have favorable local effects (viability and function of the peritoneal membrane) and systemic effects (for example, on MIA syndrome). Amino acid–based solution [Nutrineal (N): Baxter Healthcare Corporation, Deerfield, IL, U.S.A.] may improve nutritional status as well as peritoneal membrane viability. Bicarbonate/lactate–buffered solution [Physioneal (P): Baxter Healthcare Corporation] may ameliorate local and systemic effects of low pH, high lactate, and high glucose degradation products. Icodextrin-based solution [Extraneal (E): Baxter Healthcare SA, Castlebar, Ireland] may improve hypertension and cardiovascular problems associated with fluid overload and may extend time on therapy in patients with loss of UF capacity.

The positive effects of each of these new, biocompatible solutions have been demonstrated in several studies. It is likely that the combined use of N, P, and E solutions will produce favorable synergies in regard to both local effects (peritoneal viability) and systemic effects (less malnutrition, inflammation, and fluid overload). Solution combination is an exciting area for clinical study in the coming years. Furthermore, dialysis fluid additives such as hyaluronan, which protects and improves the function of the peritoneal membrane, may further improve PD solutions. The new, biocompatible PD solutions represent an entirely new era in the evolution of the PD therapy; they are likely to have markedly positive effects on both PD technique and PD patient survival in coming years.

Changes in Water Transport across the Peritoneum during Treatment with Continuous Ambulatory Peritoneal Dialysis in Selected Patients with and without Peritonitis

Background

The natural course of longitudinal changes in peritoneal permeability and membrane area has been studied mostly by performing single-dwell studies in selected patients during treatment with peritoneal dialysis.

Purpose

To evaluate the permeability characteristics of the peritoneal membrane by measuring drained ultrafiltration volume relative to initial glucose concentration in dialysis fluid from the start to the end of continuous ambulatory peritoneal dialysis (CAPD) treatment in a selected cohort of patients with and without peritonitis.

Design

A retrospective analysis of a group of patients whose peritoneal function was prospectively followed by recording drained ultrafiltration volume and glucose concentration in dialysis fluid for each dwell time, every day, during the time in CAPD treatment. Mean values from a 1-month period starting after the first 3 weeks of CAPD treatment were compared with the mean values from the last month of treatment. Approximately 11 500 exchanges were analyzed. Evaluations were done separately for short (day) and long (night) dwell times.

Patients and Statistics

Of 132 patients commencing CAPD treatment in the time period selected for inclusion, 51 had enough data to be included in this study. Of these, 29 patients experienced one or more episodes of successfully treated peritonitis. The selection of patients was not based upon patient characteristics, but upon criteria to satisfy predefined demands, such as number of measurements in each period, time since an episode of peritonitis, and time on CAPD treatment. Data were analyzed in three different groups: patients with episodes of peritonitis, patients without peritonitis, and both groups together. To assess changes between monthly mean at the start and at the end of CAPD, paired t-test was performed. Patients were also stratified into two groups according to low and high glucose in dialysis fluid at the start of CAPD (cutoff = 2 g/dL). Additionally, we used linear regression analyses to predict the level of drained ultrafiltration volume for a given level and change in glucose concentration. Mean treatment time for the entire group was 20 months (median 14.3 months), ranging from 6 to 69 months.

Results

No statistical differences in glucose concentrations were found between the periods compared. In the entire group there was an increase in ultrafiltration volume from the start to the end of CAPD treatment, for both day ( p = 0.009) and night ( p = 0.013) exchanges. Also, for patients without peritonitis, an increase appeared for day ( p = 0.046) and night exchanges ( p = 0.053). However, for the cohort with peritonitis, only an insignificant increase was indicated. Patient characteristics, diabetic patients, the need for glucose in dialysis fluid when commencing CAPD treatment, the number of episodes of peritonitis, and time on CAPD did not influence the change in ultrafiltration. Regression analyses showed higher ultrafiltration response to a given level and change in glucose concentration at the end of CAPD treatment compared to the start values, also for the cohort with peritonitis. The regression coefficient between these variables was also significantly changed for both day ( p < 0.0001) and night ( p = 0.027) exchanges.

Conclusion

A significant change in the regression coefficient between glucose in dialysis fluid and ultrafiltration volume reflects an increase in ultrafiltration response to a given level and change in glucose concentration during time on CAPD treatment. A parallel change after 5- and 9-hour dwells can be explained by a decrease in peritoneal surface area combined with a lesser decrease in peritoneal conductivity. However, changes in Starling forces across the peritoneal membrane are possible even in the absence of changes in peritoneal membrane characteristics.

Tamoxifen and bone morphogenic protein-7 modulate fibrosis and inflammation in the peritoneal fibrosis model developed in uremic rats

Background

Peritoneal fibrosis (PF) represents a long-term complication of peritoneal dialysis (PD), affecting peritoneal membrane (PM) integrity and function. Understanding the mechanisms underlying PF development in an uremic environment aiming alternative therapeutic strategies for treating this process is of great interest. The aim of this study was to analyze the effects of tamoxifen (TAM) and recombinant BMP7 (rBMP7) in an experimental model of PF developed in uremic rats.

Methods

To mimic the clinical situation of patients on long-term PD, a combo model, characterized by the combination of PF and CKD with severe uremia, was developed in Wistar rats. PF was induced by intraperitoneal (IP) injections of chlorhexidine gluconate (CG), and CKD was induced by an adenine-rich diet. Uremia was confirmed by severe hypertension, increased blood urea nitrogen (BUN> 120 mg/dL) and serum creatinine levels (> 2 mg/dL). Uremic rats with PF were treated with TAM (10 mg/Kg by gavage) or BMP7 (30 μg/Kg, IP). Animals were followed up for 30 days.

Results

CG administration in uremic rats induced a striking increase in PM thickness, neoangiogenesis, demonstrated by increased capillary density, and failure of ultrafiltration capacity. These morphological and functional changes were blocked by TAM or rBMP7 treatment. In parallel, TAM and rBMP7 significantly ameliorated the PM fibrotic response by reducing α-SMA, extracellular matrix proteins and TGF-ß expression. TAM or rBMP7 administration significantly inhibited peritoneal Smad3 expression in uremic rats with PF, prevented Smad3 phosphorylation, and induced a remarkable up-regulation of Smad7, an intracellular inhibitor of TGFβ/Smad signaling, contributing to a negative modulation of profibrotic genes. Both treatments were also effective in reducing local inflammation, possibly by upregulating IκB-α expression in the PM of uremic rats with PF. In vitro experiments using primary peritoneal fibroblasts activated by TGF-ß confirmed the capacity of TAM or rBMP7 in blocking inflammatory mediators, such as IL-1ß expression.

Conclusions

In conclusion, these findings indicate important roles of TGF-ß/Smad signaling in PF aggravated by uremia, providing data regarding potential therapeutic approaches with TAM or rBMP7 to block this process.

Electronic supplementary material

The online version of this article (10.1186/s10020-019-0110-5) contains supplementary material, which is available to authorized users.

Peritoneal Dialysis Vintage and Glucose Exposure but Not Peritonitis Episodes Drive Peritoneal Membrane Transformation During the First Years of PD

The impact of peritoneal dialysis (PD) associated peritonitis on peritoneal membrane integrity is incompletely understood. Children are particularly suited to address this question, since they are largely devoid of preexisting tissue damage and life-style related alterations. Within the International Peritoneal Biobank, 85 standardized parietal peritoneal tissue samples were obtained from 82 children on neutral pH PD fluids with low glucose degradation product (GDP) content. 37 patients had a history of peritonitis and 16 of the 37 had two or more episodes. Time interval between tissue sampling and the last peritonitis episode was 9 (4, 36) weeks. Tissue specimen underwent digital imaging and molecular analyses. Patients with and without peritonitis were on PD for 21.0 (12.0, 36.0) and 12.8 (7.3, 27.0) months (p = 0.053), respectively. They did not differ in anthropometric or histomorphometric parameters [mesothelial coverage, submesothelial fibrosis, blood, and lymphatic vascularization, leukocyte, macrophage and activated fibroblast counts, epithelial-mesenchymal transition (EMT), podoplanin positivity and vasculopathy]. VEGF and TGF-ß induced pSMAD abundance were similar. Similar findings were also obtained after matching for age and PD vintage and a subgroup analysis according to time since last peritonitis (<3, <6, >6 months). In patients with more than 24 months of PD vintage, submesothelial thickness, vessel number per mmm section length and ASMA fibroblast positivity were higher in patients with peritonitis history; only the difference in ASMA positivity persisted in multivariable analyses. While PD duration and EMT were independently associated with submesothelial thickness, and glucose exposure and EMT with peritoneal vessel density in the combined groups, submesothelial thickness was independently associated with EMT in the peritonitis free patients, and with duration of PD in patients with previous peritonitis. This detailed analysis of the peritoneal membrane in pediatric patients on PD with neutral pH, low GDP fluids, does not support the notion of a consistent long-term impact of peritonitis episodes on peritoneal membrane ultrastructure, on inflammatory and fibrotic cell activity and EMT. Peritoneal alterations are mainly driven by PD duration, dialytic glucose exposure, and associated EMT.

Peritoneal Membrane Preservation

Peritoneal dialysis (PD) is a successfully used method for renal replacement therapy. However, long-term PD may be associated with peritoneal fibrosis and ultrafiltration failure. The key factors linked to their appearance are repeated episodes of inflammation associated with peritonitis and long-term exposure to bioincompatible PD fluids. Different strategies have been proposed to preserve the peritoneal membrane. This article reviews the functional and structural alterations related to PD and strategies whereby we may prevent them to preserve the peritoneal membrane. The use of new, more biocompatible, PD solutions is promising, although further morphologic studies in patients using these solutions are needed. Blockade of the renin-angiotensin-aldosterone system appears to be efficacious and strongly should be considered. Other agents have been proven in experimental studies, but most of them have not yet been tested appropriately in human beings.

Treatment for peritoneal dialysis-associated peritonitis

BACKGROUND

Peritonitis is a common complication of peritoneal dialysis (PD) that is associated with significant morbidity including death, hospitalisation, and need to change from PD to haemodialysis. Treatment is aimed to reduce morbidity and recurrence. This is an update of a review first published in 2008.

OBJECTIVES

To evaluate the benefits and harms of treatments for PD-associated peritonitis.

SEARCH METHODS

For this review update we searched the Cochrane Renal Group's Specialised Register to March 2014 through contact with the Trials Search Co-ordinator 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, and handsearching conference proceedings.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs assessing the treatment of peritonitis in PD patients (adults and children). We included any study that evaluated: administration of an antibiotic by different routes (e.g. oral, intraperitoneal (IP), intravenous (IV)); dose of an antibiotic agent; different schedules of administration of antimicrobial agents; comparisons of different regimens of antimicrobial agents; any other intervention including fibrinolytic agents, peritoneal lavage and early catheter removal.

DATA COLLECTION AND ANALYSIS

Multiple authors independently extracted data on study risk of bias and outcomes. Statistical analyses were performed using the random effects model. We expressed summarised treatment estimates as a risk ratio (RR) with 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) with 95% CI for continuous outcomes.

MAIN RESULTS

We identified 42 eligible studies in 2433 participants: antimicrobial agents (36 studies); urokinase (4 studies), peritoneal lavage (1 study), and IP immunoglobulin (1 study). We did not identify any optimal antibiotic agent or combination of agents. IP glycopeptides (vancomycin or teicoplanin) had uncertain effects on primary treatment response, relapse rates, and need for catheter removal compared to first generation cephalosporins, although glycopeptide regimens were more likely to achieve a complete cure (3 studies, 370 episodes: RR 1.66, 95% CI 1.01 to 2.72). For relapsing or persistent peritonitis, simultaneous catheter removal and replacement was better than urokinase at reducing treatment failure rates (RR 2.35, 95% CI 1.13 to 4.91) although evidence was limited to a single small study. Continuous and intermittent IP antibiotic dosing schedules had similar treatment failure and relapse rates. IP antibiotics were superior to IV antibiotics in reducing treatment failure in one small study (RR 3.52, 95% CI 1.26 to 9.81). Longer duration treatment (21 days of IV vancomycin and IP gentamicin) had uncertain effects on risk of treatment relapse compared with 10 days treatment (1 study, 49 patients: RR 1.56, 95% CI 0.60 to 3.95) although may have increased ototoxicity.In general, review conclusions were based on a small number of studies with few events in which risk of bias was generally high; interventions were heterogeneous, and outcome definitions were often inconsistent. There were no RCTs evaluating optimal timing of catheter removal and data for automated PD were absent.

AUTHORS' CONCLUSIONS

Many of the studies evaluating treatment of PD-related peritonitis are small, out-dated, of poor quality, and had inconsistent definitions and dosing regimens. IP administration of antibiotics was superior to IV administration for treating PD-associated peritonitis and glycopeptides appear optimal for complete cure of peritonitis, although evidence for this finding was assessed as low quality. PD catheter removal may be the best treatment for relapsing or persistent peritonitis.Evidence was insufficient to identify the optimal agent, route or duration of antibiotics to treat peritonitis. No specific antibiotic appears to have superior efficacy for preventing treatment failure or relapse of peritonitis, but evidence is limited to few trials. The role of routine peritoneal lavage or urokinase is uncertain.

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.

Peritoneal dialysis fluid bioincompatibility and new vessel formation promote leukocyte-endothelium interactions in a chronic rat model for peritoneal dialysis

Peritoneal dialysis (PD)-induced peritonitis leads to dysfunction of the peritoneal membrane. During peritonitis, neutrophils are recruited to the inflammation site by rolling along the endothelium, adhesion, and transmigration through vessel walls. In a rat PD-model, long-term effects of PD-fluids (PDF) on leukocyte-endothelium interactions and neutrophil migration were studied under baseline and inflammatory conditions. Rats received daily conventional-lactate-buffered PDF (Dianeal), bicarbonate/lactate-buffered PDF (Physioneal) or bicarbonate/lactate buffer (Buffer) during five weeks. Untreated rats served as control. Baseline leukocyte rolling and N-formylmethionyl-leucyl-phenylalanine (fMLP) induced levels of transmigration in the mesentery were evaluated and quantified by intra-vital videomicroscopy and immunohistochemistry. Baseline leukocyte rolling was unaffected by buffer treatment, approximately 2-fold increased after Physioneal and 4-7-fold after Dianeal treatment. After starting fMLP superfusion, transmigrated leukocytes appeared outside the venules firstly after Dianeal treatment (15 minutes), thereafter in Physioneal and Buffer groups (20-22 minutes), and finally in control rats (>25 minutes). Newly formed vessels and total number of transmigrated neutrophils were highest in Dianeal-treated animals, followed by Physioneal and Buffer, and lowest in control rats and correlated for all groups to baseline leukocyte rolling (r = 0.78, P < 0.003). This study indicates that the start of inflammatory neutrophil transmigration is related to PDF bio(in)compatibility, whereas over time neutrophil transmigration is determined by the degree of neo-angiogenesis.

Impaired TGF-beta signalling enhances peritoneal inflammation induced by E. coli in rats

BACKGROUND

Peritonitis is a common and severe complication of peritoneal dialysis (PD). Although TGF-beta is a key mediator in peritoneal fibrosis with chronic PD, its role in acute peritoneal inflammation remains unclear.

METHODS

Potential role of TGF-beta signalling in acute peritonitis was investigated in a rat model by infecting peritoneum with E. coli and in primary culture of peritoneal mesothelial cells (PMC) by LPS.

RESULTS

We found that a single infection of E. coli caused an acute, but transient peritonitis by a significant increase in ascites white blood cells (WBC), peritoneal CD45+ leukocytes, upregulation of TNFalpha, activation of NF-kappaB/p65 and impaired peritoneal function (all P < 0.01). Interestingly, spontaneous recovery of acute peritonitis occurred with upregulation of TGF-beta1 and activation of Smad2/3, suggesting a protective role of TGF-beta signalling in acute peritonitis. This was demonstrated by the finding that blockade of the TGF-beta signalling pathway with gene transfer of Smad7 inactivated peritoneal Smad2/3 but worsened E. coli-induced, NF-kappaB-dependent peritoneal inflammation and peritoneal dysfunction (all P < 0.01). Furthermore, studies in vitro also found that impaired TGF-beta signalling by overexpressing Smad7 in PMC were able to overcome the inhibitory effect of TGF-beta on LPS-induced, NF-kappaB-mediated peritoneal inflammation.

CONCLUSION

Results from this study demonstrate that TGF-beta signalling is essential in protection against acute peritoneal inflammation induced by bacterial infection.

Concentration of adipokines in peritoneal effluent: a new marker of acute peritonitis in peritoneal dialysis patients?

BACKGROUND

An early and reliable diagnostic procedure for acute peritonitis in patients on peritoneal dialysis (PD) without typical clinical symptoms remains an important challenge in modern nephrology. During the first days of peritonitis, establishing the diagnosis based on peritoneal effluent pleocytosis and inflammatory markers [C-reactive protein (CRP) or interleukin-6] is not efficient in all cases. Increased peritoneal membrane permeability is a well-known consequence of peritonitis. Therefore, we evaluated the concentrations of selected circulating adipose tissue-derived proteins in the peritoneal effluent of PD patients with episodes of acute peritonitis.

MATERIAL AND METHODS

Concentrations of adiponectin and leptin, in both plasma and peritoneal effluent, were assessed in 24 adult PD patients with peritonitis episodes confirmed by clinical symptoms and/or microbiological tests, and in 23 PD patients without signs and symptoms of inflammation (control group).

RESULTS

In peritoneal effluent collected from patients with acute peritonitis (also without pleocytosis or increased CRP), both adiponectin and leptin concentrations were markedly elevated: adiponectin 744.1 (344.2 - 1144.1) ng/mL vs 4.8 (3.1 - 6.5) ng/mL; leptin 16.3 (9.4 - 23.1) ng/mL vs 5.1 (0.5 - 9.6) ng/mL. Receiver operating characteristic analyses revealed that peritoneal effluent adiponectin concentration >180 ng/mL has 100% sensitivity and 100% specificity, while peritoneal effluent leptin concentration >11.0 ng/mL has 58.3% sensitivity and 95.5% specificity for the diagnosis of acute peritonitis. The increases in adiponectin and leptin concentrations in peritoneal effluent were not consequences of changes in their plasma levels. A positive correlation between peritoneal effluent and plasma concentrations of adiponectin and leptin in patients with peritonitis was found.

CONCLUSION

Increased concentration of leptin and especially adiponectin in peritoneal effluent seems to be a valuable and new early marker of high peritoneal membrane permeability due to acute peritonitis.

Treatment for peritoneal dialysis-associated peritonitis

BACKGROUND

Peritonitis is a common complication of peritoneal dialysis (PD) and is associated with significant morbidity. Adequate treatment is essential to reduce morbidity and recurrence.

OBJECTIVES

To evaluate the benefits and harms of treatments for PD-associated peritonitis.

SEARCH STRATEGY

We searched the Cochrane Renal Group's specialised register, the Cochrane Central Register of Controlled Trials (CENTRAL, in The Cochrane Library), MEDLINE, EMBASE and reference lists without language restriction. Date of search: February 2005

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs assessing the treatment of peritonitis in peritoneal dialysis patients (adults and children) evaluating: administration of an antibiotic(s) by different routes (e.g. oral, intraperitoneal, intravenous); dose of an antibiotic agent(s); different schedules of administration of antimicrobial agents; comparisons of different regimens of antimicrobial agents; any other intervention including fibrinolytic agents, peritoneal lavage and early catheter removal were included.

DATA COLLECTION AND ANALYSIS

Two authors extracted data on study quality and outcomes. Statistical analyses were performed using the random effects model and the dichotomous results were expressed as relative risk (RR) with 95% confidence intervals (CI) and continuous outcomes as mean difference (WMD) with 95% CI.

MAIN RESULTS

We identified 36 studies (2089 patients): antimicrobial agents (30); urokinase (4), peritoneal lavage (1) intraperitoneal (IP) immunoglobulin (1). No superior antibiotic agent or combination of agents were identified. Primary response and relapse rates did not differ between IP glycopeptide-based regimens compared to first generation cephalosporin regimens, although glycopeptide regimens were more likely to achieve a complete cure (3 studies, 370 episodes: RR 1.66, 95% CI 1.01 to 3.58). For relapsing or persistent peritonitis, simultaneous catheter removal/replacement was superior to urokinase at reducing treatment failure rates (1 study, 37 patients: RR 2.35, 95% CI 1.13 to 4.91). Continuous IP and intermittent IP antibiotic dosing had similar treatment failure and relapse rates. IP antibiotics were superior to IV antibiotics in reducing treatment failure (1 study, 75 patients: RR 3.52, 95% CI 1.26 to 9.81). The methodological quality of most included studies was suboptimal and outcome definitions were often inconsistent. There were no RCTs regarding duration of antibiotics or timing of catheter removal.

AUTHORS' CONCLUSIONS

Based on one study, IP administration of antibiotics is superior to IV dosing for treating PD peritonitis. Intermittent and continuous dosing of antibiotics are equally efficacious. There is no role shown for routine peritoneal lavage or use of urokinase. No interventions were found to be associated with significant harm.

Treatment of peritoneal dialysis-associated peritonitis: a systematic review of randomized controlled trials

BACKGROUND

Peritonitis frequently complicates peritoneal dialysis. Appropriate treatment is essential to reduce adverse outcomes. Available trial evidence about peritoneal dialysis peritonitis treatment was evaluated.

SELECTION CRITERIA FOR STUDIES

The Cochrane CENTRAL Registry (2005 issue), MEDLINE (1966 to February 2006), EMBASE (1985 to February 2006), and reference lists were searched to identify randomized trials of treatments for patients with peritoneal dialysis peritonitis.

INTERVENTIONS

Trials of antibiotics (comparisons of routes, agents, and dosing regimens), fibrinolytic agents, peritoneal lavage, and intraperitoneal immunoglobulin.

OUTCOMES

Treatment failure, relapse, catheter removal, microbiological eradication, hospitalization, all-cause mortality, and adverse reactions.

RESULTS

36 eligible trials were identified: 30 trials (1,800 patients) of antibiotics; 4 trials (229 patients) of urokinase; 1 trial of peritoneal lavage (36 patients); and 1 trial of intraperitoneal immunoglobulin (24 patients). No superior antimicrobial class was identified. In particular, glycopeptides and first-generation cephalosporins were equivalent (3 trials, 387 patients; relative risk [RR], 1.84; 95% confidence interval [CI], 0.95 to 3.58). Simultaneous catheter removal/replacement was superior to urokinase at decreasing treatment failures (1 trial, 37 patients; RR, 2.35; 95% CI, 1.13 to 4.91). Continuous and intermittent intraperitoneal antibiotic dosing were equivalent regarding treatment failure (4 trials, 338 patients; RR, 0.69; 95% CI, 0.37 to 1.30) and relapse (4 trials, 324 patients; RR, 0.93; 95% CI, 0.63 to 1.39). One trial showed superiority of intraperitoneal antibiotics over intravenous therapy.

LIMITATIONS

The method quality of trials generally was suboptimal and outcome definitions were inconsistent. Small patient numbers led to inadequate power to show an effect. Interventions, such as optimal duration of antibiotic therapy, were not evaluated.

CONCLUSIONS

Trials did not identify superior antibiotic regimens. Intermittent and continuous antibiotic dosing are equivalent treatment strategies.

Dialysate CA125 levels in children on continuous peritoneal dialysis

This prospective study was conducted to assess dialysate cancer antigen 125 (dCA125) levels in pediatric peritoneal dialysis (PD) patients and to investigate whether it exhibits any alterations during or after recovery from peritonitis, and also to analyze the relationships between dCA125 and age, duration of PD treatment, peritonitis incidence, time passed since the last episode of peritonitis, PD prescription parameters, and peritoneal transport parameters. Forty-seven standardized 4-h peritoneal equilibration tests (PET) were performed in 38 children (mean age 11.6+/-4.7 years) on PD (duration 20.9+/-14.3 months). Thirty-two of the patients were in stable condition at the time of PET (stable group). Six patients were included in the study only during a peritonitis episode, and two of the stable patients were reevaluated during a peritonitis episode afterwards (peritonitis group). Seven out of a total of eight patients with acute peritonitis were reexamined after recovery (recovery group). CA125 levels were measured in 188 samples at 0-, 1-, 2-, and 4-h dwells. Peritoneal appearance rates (AR) were calculated. Mean dCA125 (4 h) and AR CA125 values were 5.6+/-5.3 U/ml [median 4.15 U/ml/4 h (range 0.5-25.9)] and 50.1+/-45.6 U/min/1.73 m2[median 37.91 U/ml/1.73 m2 (range 3.61-223.39)]. AR CA125 levels did not correlate with age, PD duration, peritonitis incidence, time passed since the last peritonitis episode, exchange volume used per m2 per day, or peritoneal transport properties in the stable patients' group. Although stable patients using hypertonic PD solutions (n=16) had slightly lower AR CA125 levels (p=0.04), multivariate analysis showed no influence of hypertonic dextrose solutions on mesothelial CA125 secretion (p=0.4). During acute peritonitis, CA125 concentrations showed a reversible threefold increase [AR CA125: stable 37.9 vs. peritonitis 101.2 U/ml/1.73 m2 (p=0.001)]. No difference could be found between the stable group and the recovery group. We conclude that changes in the peritoneal mesothelial cell mass cannot be assessed by determining CA125 in a cross-sectional way and that longitudinal determinations could be more valuable in the follow-up of patients.

Longitudinal relationship between solute transport and ultrafiltration capacity in peritoneal dialysis patients

BACKGROUND

Time on treatment is associated with a greater risk of impaired ultrafiltration (UF) in peritoneal dialysis (PD) patients. In addition to increasing solute transport, a potentially treatable cause of impaired ultrafiltration, cross-sectional studies suggest that there is also reduced osmotic conductance of the membrane. If this were the case then it would be expected that the UF capacity for a given rate of solute transport would change with time. The purpose of this analysis was to establish how solute transport and UF capacity change relative to one another with time on therapy.

METHODS

Membrane function, using a standard peritoneal equilibration test, was measured at least annually in a well-characterized, single-center observational cohort of PD patients between 1990 and 2003. Demography included age, gender, original cause of renal failure, body surface area (BSA), validated comorbidity score, residual urine volume and urea clearances, peritoneal urea clearances, and plasma albumin.

RESULTS

Data from 574 new PD patients were available for analysis. Independent demographic factors associated with higher solute transport at baseline were male gender and higher residual urine volume. Throughout time on therapy there was a negative relationship between solute transport and UF capacity and a significant increase and decrease in these parameters, respectively. During the first 12 months of treatment, the increase in solute transport was not associated with the expected fall in UF capacity, a phenomenon that was not explained by informative censoring, but was associated with an increased, albeit weak, correlation with BSA. In contrast, later in treatment there was a disproportionate fall in UF capacity, more accelerated in patients developing UF failure. Early exposure to higher intraperitoneal glucose concentrations, in the context of more comorbidity and relative lack of residual renal function, was associated with more rapid deterioration in membrane function.

CONCLUSION

Despite a causal link between solute transport and UF capacity of the membrane, due to the effect of the former on the osmotic gradient, there is evidence of their longitudinal dissociation. This implies a change in the structure-function relationship with time on treatment that can, to some extent, be predicted from clinical factors present within the first year of treatment. Dialysis-induced membrane injury must involve at least two processes, for example, increased vascular surface area contact with dialysate combined with changes in hydraulic conductance due to scarring of the vessels and interstitium.

Transperitoneal water transport before, during, and after episodes with infectious peritonitis in patients treated with CAPD

BACKGROUND

Peritonitis is considered to change peritoneal permeability and influences the long-term change in permeability during peritoneal dialysis. The objective of this study is to evaluate water transport across the peritoneum, expressed as drained ultrafiltration volume, before, during, and after episodes of peritonitis.

METHODS

A retrospective analysis of data from a group of patients was performed in which drained ultrafiltration volume and glucose concentration in dialysis fluid were recorded for each dwell time every day during time on continuous ambulatory peritoneal dialysis treatment as a part of the clinical routine performed. Days with peritonitis and average of daily measurements 1 month before and after each peritonitis episode were evaluated separately for day and night exchanges. In all, 64 episodes of peritonitis in 30 patients were included in this study. Approximately 15,000 exchanges were recorded. Paired t-test and repeated-measures analysis of variance were performed.

RESULTS

Compared with the average for the previous month, there was a significant decrease in ultrafiltration volume for day exchanges occurring 2 days before the appearance of other clinical symptoms of peritonitis (P = 0.029). For night exchanges, the decrease in ultrafiltration volume occurred 24 hours before diagnosis (P < 0.001). Ultrafiltration volume was at its minimum the day of diagnosis for both the day (P < 0.001) and night (P < 0.001) exchanges compared with average volume for the previous month. Ultrafiltration volumes remained low for 2 days after diagnosis during both the day (P = 0.009) and night (P = 0.017) exchanges. Relative to the previous month, glucose concentration on the day of clinical diagnosis of peritonitis did not differ significantly (P = 0.328 and P = 0.963 for day and night shifts, respectively). Overall, no significant changes in ultrafiltration volumes or glucose concentrations from the month before to the month after the peritonitis episode were found (P = 0.99 and P = 0.27 for measurements during the day, respectively).

CONCLUSION

Osmotic forced ultrafiltration decreased during infectious peritonitis, most significantly for a long dwell time, consistent with an increase in both functional peritoneal surface area and hydraulic conductivity. This finding appeared 2 days before other clinical symptoms and remained significantly low 2 days after diagnosis.

Dialysis therapies for end-stage renal disease

End-stage renal disease (ESRD) has various causes that may differ according to country and racial group. Whatever the cause, unless the water, salt, electrolytes, and waste products excreted by normal kidneys are removed, their accumulation will result in death. Removal of these products can be variably achieved by either hemodialysis or peritoneal dialysis. The principles and outcomes of these techniques are described, as are their complications. It is important that these two different methods of treatment are not regarded as competitive, but are integrated, together with renal transplantation where appropriate, into the management of patients with ESRD to optimize both outcome and quality of life.

Inflammatory cytokines, angiogenesis, and fibrosis in the rat peritoneum

Peritonitis, a common complication of peritoneal dialysis, is followed by acute changes in the function of the peritoneum. The role of inflammatory cytokines in these processes is not clearly identified. We used adenoviral-mediated gene transfer to transiently overexpress interleukin (IL)-1 beta (AdIL-1 beta) or tumor necrosis factor (TNF)-alpha (AdTNF-alpha) in the rat peritoneum then used a modified equilibrium test to study the histological and functional changes. Overexpression of IL-1 beta or TNF-alpha led to an acute inflammatory response. Both inflammatory cytokines induced an early expression of the angiogenic cytokine, vascular endothelial growth factor, along with increased expression of the profibrotic cytokine, transforming growth factor-beta1, along with fibronectin expression and collagen deposition in peritoneal tissues. Both inflammatory cytokines induced angiogenesis, increased solute permeability, and ultrafiltration dysfunction at earlier time points. Changes in structure and function seen in AdTNF-alpha-treated animals returned to normal by 21 days after infection, whereas AdIL-1 beta-treated animals had persistently increased vasculature with submesothelial thickening and fibrosis. This was associated with up-regulation TIMP-1. TNF-alpha or IL-1 beta both induce acute changes in the peritoneum that mimic those seen in peritoneal dialysis patients who experience an episode of peritonitis. These functional changes were associated with early angiogenesis that resolved rapidly after exposure to TNF-alpha. IL-1 beta exposure, however, led to a different response with sustained vascularization and fibrosis. IL-1 beta inhibition may be a therapeutic goal in acute peritonitis to prevent peritoneal damage.