Effect of biocompatible peritoneal dialysis solution on residual renal function: a systematic review of randomized controlled trials

Associations of neutral pH, low-GDP peritoneal dialysis solutions with patient survival, transfer to haemodialysis and peritonitis

BACKGROUND

Peritoneal dialysis (PD) solutions containing low levels of glucose degradation products (GDPs) are associated with attenuation of peritoneal membrane injury and vascular complications. However, clinical benefits associated with neutral-pH, low-GDP (N-pH/L-GDP) solutions remain unclear.

METHODS

Using data from the Australia and New Zealand Dialysis and Transplant Registry, we examined the associations between N-pH/L-GDP solutions and all-cause mortality, cause-specific mortality, transfer to haemodialysis (HD) for ≥30 days and PD peritonitis in adult incident PD patients in Australia and New Zealand between 1 January 2005 and 31 December 2020 using adjusted Cox regression analyses.

RESULTS

Of 12 814 incident PD patients, 2282 (18%) were on N-pH/L-GDP solutions. The proportion of patients on N-pH/L-GDP solutions each year increased from 11% in 2005 to 33% in 2017. During the study period, 5330 (42%) patients died, 4977 (39%) experienced transfer to HD and 5502 (43%) experienced PD peritonitis. Compared with the use of conventional solutions only, the use of any form of N-pH/L-GDP solution was associated with reduced risks of all-cause mortality {adjusted hazard ratio [aHR] 0.67 [95% confidence interval (CI) 0.61-0.74]}, cardiovascular mortality [aHR 0.65 (95% CI 0.56-0.77)], infection-related mortality [aHR 0.62 (95% CI 0.47-0.83)] and transfer to HD [aHR 0.79 (95% CI 0.72-0.86)] but an increased risk of PD peritonitis [aHR 1.16 (95% CI 1.07-1.26)].

CONCLUSIONS

Patients who received N-pH/L-GDP solutions had decreased risks of all-cause and cause-specific mortality despite an increased risk of PD peritonitis. Studies assessing the causal relationships are warranted to determine the clinical benefits of N-pH/L-GDP solutions.

Peritoneal dialysis fluids

There have been significant advances in the understanding of peritoneal dialysis (PD) in the last 40 years, and uptake of PD as a modality of kidney replacement therapy is increasing worldwide. PD fluids, therefore, remains the lifeline for patients on this treatment. Developing these fluids to be efficacious in solute clearance and ultrafiltration, with minimal adverse consequences to peritoneal membrane health and systemic effects is a key requirement. Since the first PD fluid produced in 1959, modifications to PD fluids have been made. Nonetheless, the search for that ideal PD fluid remains elusive. Understanding the components of PD fluids is a key aspect of optimizing the successful delivery of PD, allowing for individualized PD prescription. Glucose remains an integral component of PD fluids; however, its deleterious effects continue to be the impetus for the search of an alternative osmotic agent, and icodextrin remains the main alternative. More biocompatible PD fluids have been developed and have shown benefits in preserving residual kidney function. However, high cost and reduced accessibility remain deterrents to its widespread clinical use in many countries. Large-scale clinical trials are necessary and very much awaited to improve the narrow spectrum of PD fluids available for clinical use.

A New Peritoneal Dialysis Solution Containing L-Carnitine and Xylitol for Patients on Continuous Ambulatory Peritoneal Dialysis: First Clinical Experience

Peritoneal dialysis (PD) is a feasible and effective renal replacement therapy (RRT) thanks to the dialytic properties of the peritoneal membrane (PM). Preservation of PM integrity and transport function is the key to the success of PD therapy, particularly in the long term, since the prolonged exposure to unphysiological hypertonic glucose-based PD solutions in current use is detrimental to the PM, with progressive loss of peritoneal ultrafiltration capacity causing technique failure. Moreover, absorbing too much glucose intraperitoneally from the dialysate may give rise to a number of systemic metabolic effects. Here we report the preliminary results of the first clinical experience based on the use in continuous ambulatory PD (CAPD) patients of novel PD solutions obtained through partly replacing the glucose load with other osmotically active metabolites, such as L-carnitine and xylitol. Ten CAPD patients were treated for four weeks with the new solutions. There was good tolerance to the experimental PD solutions, and no adverse safety signals were observed. Parameters of dialysis efficiency including creatinine clearance and urea Kt/V proved to be stable as well as fluid status, diuresis, and total peritoneal ultrafiltration. The promising tolerance and local/systemic advantages of using L-carnitine and xylitol in the PD solution merit further research.

Current Opinion on Usage of L-Carnitine in End-Stage Renal Disease Patients on Peritoneal Dialysis

The advantages of peritoneal dialysis (PD) over hemodialysis (HD) are well-documented. Notwithstanding, only a small proportion of patients with end-stage renal disease (ESRD) are managed with PD. This may be related to the high glucose load that PD solutions in current use have on the patient. The effects of such excess glucose include the relatively early limitation of the ultrafiltration capacity of the peritoneal membrane, and the metabolic effects associated with hyperglycemia, e.g., decreased insulin sensitivity. This article describes the advantages that may be realized by the glucose-sparing effects of substituting part of the glucose load with other osmotically active metabolites, particularly L-carnitine. The latter is anticipated to have metabolic advantages of its own, especially as in PD patients, high plasma concentrations can be achieved in the absence of renal clearance. Besides its better biocompatibility, L-carnitine demonstrates anti-anemia action due to its effects on erythropoiesis, and positive effects on the longevity and deformability of erythrocytes. Observations from our trials on the use of carnitine-enriched PD solutions have demonstrated the effectiveness of L-carnitine as an efficient osmolyte in PD, and its favorable effect on the insulin sensitivity of the patients. The significance of these findings for future developments in the use of PD in the management of patients with ESRD is discussed.

Health-related quality of life in peritoneal dialysis patients: A narrative review

Health-related quality of life (HRQOL) is an important aspect of patients´ health that should be an integral part of the evaluation of patient-centered outcomes, not least because HRQOL associates with patients´ morbidity and mortality. This applies also to chronic kidney disease patients, including those dependent on renal replacement therapies, the type of which may influence patients´ perception of HRQOL. Several studies have addressed HRQOL in chronic kidney disease patients undergoing renal replacement therapies, especially transplanted patients and hemodialysis patients, while publications concerning peritoneal dialysis (PD) patients are scarcer. This review describes some of the methods used to assess HRQOL, factors influencing HRQOL in PD patients, HRQOL in PD vs hemodialysis, and the relation between HRQOL and patient outcomes. We conclude that assessment of HRQOL-often neglected at present-should be included as a standard measure of patient-centered outcomes and when monitoring the quality and effectiveness of renal care including PD treatment.

Low GDP Solution and Glucose-Sparing Strategies for Peritoneal Dialysis

Long-term exposure to a high glucose concentration in conventional peritoneal dialysis (PD) solution has a number of direct and indirect (via glucose degradation products [GDP]) detrimental effects on the peritoneal membrane, as well as systemic metabolism. Glucose- or GDP-sparing strategies often are hypothesized to confer clinical benefits to PD patients. Icodextrin (glucose polymer) solution improves peritoneal ultrafiltration and reduces the risk of fluid overload, but these beneficial effects are probably the result of better fluid removal rather than being glucose sparing. Although frequently used for glucose sparing, the role of amino acid-based solution in this regard has not been tested thoroughly. When glucose-free solutions are used in a combination regimen, published studies showed that glycemic control was improved significantly in diabetic PD patients, and there probably are beneficial effects on peritoneal function. However, the long-term effects of glucose-free solutions, used either alone or as a combination regimen, require further studies. On the other hand, neutral pH-low GDP fluids have been shown convincingly to preserve residual renal function and urine volume. The cost effectiveness of these solutions supports the regular use of neutral pH-low GDP solutions. Nevertheless, further studies are required to determine whether neutral pH-low GDP solutions exert beneficial effects on patient-level outcomes, such as peritonitis, technique survival, and patient survival.

Renal Association Clinical Practice Guideline on peritoneal dialysis in adults and children

These guidelines cover all aspects of the care of patients who are treated with peritoneal dialysis. This includes equipment and resources, preparation for peritoneal dialysis, and adequacy of dialysis (both in terms of removing waste products and fluid), preventing and treating infections. There is also a section on diagnosis and treatment of encapsulating peritoneal sclerosis, a rare but serious complication of peritoneal dialysis where fibrotic (scar) tissue forms around the intestine. The guidelines include recommendations for infants and children, for whom peritoneal dialysis is recommended over haemodialysis.Immediately after the introduction there is a statement of all the recommendations. These recommendations are written in a language that we think should be understandable by many patients, relatives, carers and other interested people. Consequently we have not reworded or restated them in this lay summary. They are graded 1 or 2 depending on the strength of the recommendation by the authors, and A-D depending on the quality of the evidence that the recommendation is based on.

Strategies for preventing peritoneal fibrosis in peritoneal dialysis patients: new insights based on peritoneal inflammation and angiogenesis

Peritoneal dialysis (PD) is an established form of renal replacement therapy. Long-term PD leads to morphologic and functional changes to the peritoneal membrane (PM), which is defined as peritoneal fibrosis, a known cause of loss of peritoneal ultrafiltration capacity. Inflammation and angiogenesis are key events during the pathogenesis of peritoneal fibrosis. This review discusses the pathophysiology of peritoneal fibrosis and recent research progress on key fibrogenic molecular mechanisms in peritoneal inflammation and angiogenesis, including Toll-like receptor ligand-mediated, NOD-like receptor protein 3/interleukin-1β, vascular endothelial growth factor, and angiopoietin-2/Tie2 signaling pathways. Furthermore, novel strategies targeting peritoneal inflammation and angiogenesis to preserve the PM are discussed in depth.

Predictors of Residual Renal Function Decline in Peritoneal Dialysis Patients: The balANZ Trial

Objective

Preservation of residual renal function (RRF) is associated with improved survival. The aim of the present study was to identify independent predictors of RRF and urine volume (UV) in incident peritoneal dialysis (PD) patients.

Methods

The study included incident PD patients who were balANZ trial participants. The primary and secondary outcomes were RRF and UV, respectively. Both outcomes were analyzed using mixed effects linear regression with demographic data in the first model and PD-related parameters included in a second model.

Results

The study included 161 patients (mean age 57.9 ± 14.1 years, 44% female, 33% diabetic, mean follow-up 19.5 ± 6.6 months). Residual renal function declined from 7.5 ± 2.9 mL/min/1.73 m2 at baseline to 3.3 ± 2.8 mL/min/1.73 m2 at 24 months. Better preservation of RRF was independently predicted by male gender, higher baseline RRF, higher time-varying systolic blood pressure (SBP), biocompatible (neutral pH, low glucose degradation product) PD solution, lower peritoneal ultrafiltration (UF) and lower dialysate glucose exposure. In particular, biocompatible solution resulted in 27% better RRF preservation. Each 1 L/day increase in UF was associated with 8% worse RRF preservation ( p = 0.007) and each 10 g/day increase in dialysate glucose exposure was associated with 4% worse RRF preservation ( p < 0.001). Residual renal function was not independently predicted by body mass index, diabetes mellitus, renin angiotensin system inhibitors, peritoneal solute transport rate, or PD modality. Similar results were observed for UV.

Conclusions

Common modifiable risk factors which were consistently associated with preserved RRF and residual UV were use of biocompatible PD solutions and achievement of higher SBP, lower peritoneal UF, and lower dialysate glucose exposure over time.

Effects of Conversion to a Bicarbonate/Lactate-Buffered, Neutral-pH, Low-GDP PD Regimen in Prevalent PD: A 2-Year Randomized Clinical Trial

♦ BACKGROUND: The use of pH-neutral peritoneal dialysis (PD) fluids low in glucose degradation products (GDP) may better preserve the peritoneal membrane and have fewer systemic effects. The effects of conversion from conventional to neutral-pH, low-GDP PD fluids in prevalent patients are unclear. Few studies on the role of neutral-pH, low-GDP PD have studied residual renal function, ultrafiltration, peritonitis incidence and technique failure, transport characteristics, and local and systemic markers of inflammation in prevalent PD patients. ♦ METHODS: In a multi-center open-label randomized clinical trial (RCT), we randomly assigned 40 of 78 stable continuous ambulatory PD (CAPD) and automated PD (APD) patients to treatment with bicarbonate/lactate, neutral-pH, low-GDP PD fluid (Physioneal; Baxter Healthcare Corporation, Deerfield, IL, USA) and compared them with 38 patients continuing their current standard lactate-buffered PD fluid (PDF) (Dianeal; Baxter Healthcare Corporation, Deerfield, IL, USA) during 2 years. Primary outcome was residual renal function (RRF) and ultrafiltration (UF) during peritoneal equilibration test (PET); peritonitis incidence was a secondary outcome. Furthermore, clinical parameters as well as several biomarkers in effluents and serum were measured. ♦ RESULTS: During follow-up, RRF did not differ between the groups. In the Physioneal group ultrafiltration (UF) during PET remained more or less stable (-20 mL [confidence interval (CI): -163.5 - 123.5 mL]; p = 0.7 over 24 months), whereas it declined in the Dianeal group (-243 mL [CI: -376.6 to -109.4 mL]; p < 0.0001 over 24 months), resulting in a difference of 233.7 mL [95% CI 41.0 - 425.5 mL]; p = 0.017 between the groups at 24 months. The peritonitis rate was lower in the Physioneal group: adjusted odds ratio (OR) 0.38 (0.15 - 0.97) p = 0.043. No differences were observed between the 2 groups in peritoneal adequacy or transport characteristics nor effluent markers of local inflammation (cancer antigen [CA]125, hyaluronan [HA], vascular endothelial growth factor [VEGF], macrophage chemo-attractant protein [MCP]-1, HA and transforming growth factor [TGF]β-1). ♦ CONCLUSION: In prevalent PD patients, our study did not find a difference in RRF after conversion from conventional to neutral-pH, low-GDP PD fluids, although there is a possibility that the study was underpowered to detect a difference. Decline in UF during standardized PET was lower after 2 years in the Physioneal group.

Peritoneal dialysis practice in Australia and New Zealand: A call to sustain the action

This paper updates a previous 'Call to Action' paper (Nephrology 2011; 16: 19-29) that reviewed key outcome data for Australian and New Zealand peritoneal dialysis patients and made recommendations to improve care. Since its publication, peritonitis rates have improved significantly, although they have plateaued more recently. Peritoneal dialysis patient and technique survival in Australian and New Zealand have also improved, with a reduction in the proportion of technique failures attributed to 'social reasons'. Despite these improvements, technique survival rates overall remain lower than in many other parts of the world. This update includes additional practical recommendations based on published evidence and emerging initiatives to further improve outcomes.

Newly Developed Neutralized pH Icodextrin Dialysis Fluid: Nonclinical Evaluation

A two-compartment system (NICOPELIQ; NICO, Terumo Co., Tokyo, Japan) has recently been developed to neutralize icodextrin peritoneal dialysis fluid (PDF). In this study, a nonclinical evaluation of NICO was carried out to evaluate biocompatibility as well as water transport ability. Glucose degradation products (GDPs) in the icodextrin PDFs were analyzed via high-performance liquid chromatography (HPLC). The cell viability of human peritoneal mesothelial cells derived from peritoneal dialysis effluent (PDE-HPMCs) was evaluated as well as the amount of lactate dehydrogenase (LDH) released after exposure to different PDFs (NICO and EXTRANEAL [EX, Baxter Healthcare Corp., Chicago, IL, USA]) and neutralized pH glucose PDF MIDPELIQ 250 (M250, Terumo). The water transport ability of NICO, EX, and M250 was tested using dialysis tube membranes with various pore sizes: 1, 2, 6-8, and 12-16 kDa. Although cell viability decreased by 30% after 30 min exposure to NICO, it was maintained for 6 h while a significant decrease was observed after 6 h exposure to EX. However, following adjustment of the pH to the same pre-exposure pH value, there was no significant difference in cell viability within the same pH group despite a doubling of the difference in the total amount of GDPs (44.6 ± 8.6 µM in NICO and 91.9 ± 9.5 µM in EX, respectively). In contrast, a significant decrease in cell viability was observed when the pH decreased to less than pH 6. Levels of released LDH, a cytotoxic marker, were within 5% after a 6-h exposure of NICO to PDE-HPMCs. There was no significant difference in water transport ability represented as overall osmotic gradients between NICO and EX. In conclusion, neutralization of icodextrin PDF is beneficial for maintaining cell viability and minimizing LDH release while water transport ability is comparable to the conventional icodextrin PDF.

Effect of peritoneal dialysis fluid containing osmo-metabolic agents on human endothelial cells

Background

The use of glucose as the only osmotic agent in peritoneal dialysis (PD) solutions (PDSs) is believed to exert local (peritoneal) and systemic detrimental actions, particularly in diabetic PD patients. To improve peritoneal biocompatibility, we have developed more biocompatible PDSs containing xylitol and carnitine along with significantly less amounts of glucose and have tested them in cultured Human Vein Endothelial Cells (HUVECs) obtained from the umbilical cords of healthy (C) and gestational diabetic (GD) mothers.

Methods

Primary C- and GD-HUVECs were treated for 72 hours with our PDSs (xylitol 0.7% and 1.5%, whereas carnitine and glucose were fixed at 0.02% and 0.5%, respectively) and two glucose-based PDSs (glucose 1.36% or 2.27%). We examined their effects on endothelial cell proliferation (cell count), viability (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide assay), intracellular nitro-oxidative stress (peroxynitrite levels), Vascular Cell Adhesion Molecule-1 and Intercellular Adhesion Molecule-1 membrane exposure (flow cytometry), and HUVEC-monocyte interactions (U937 adhesion assay).

Results

Compared to glucose-based PDSs, our in vitro studies demonstrated that the tested PDSs did not change the proliferative potential both in C- and GD-HUVECs. Moreover, our PDSs significantly improved endothelial cell viability, compared to glucose-based PDSs and basal condition. Notably, glucose-based PDSs significantly increased the intracellular peroxynitrite levels, Vascular Cell Adhesion Molecule-1 and Intercellular Adhesion Molecule-1 membrane exposure, and endothelial cell–monocyte interactions in both C- and GD-HUVECs, as compared with our experimental PDSs.

Conclusion

Present results show that in control and diabetic human endothelial cell models, xylitol–carnitine-based PDSs do not cause cytotoxicity, nitro-oxidative stress, and inflammation as caused by hypertonic glucose-based PDSs. Since xylitol and carnitine are also known to favorably affect glucose homeostasis, these findings suggest that our PDSs may represent a desirable hypertonic solution even for diabetic patients in PD.

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.

Hydration Status of Patients Dialyzed with Biocompatible Peritoneal Dialysis Fluids

♦

BACKGROUND

Biocompatible fluids for peritoneal dialysis (PD) have been introduced to improve dialysis and patient outcome in end-stage renal disease. However, their impact on hydration status (HS), residual renal function (RRF), and dialysis adequacy has been a matter of debate. The aim of the study was to evaluate the influence of a biocompatible dialysis fluid on the HS of prevalent PD patients. ♦

METHODS

The study population consisted of 18 prevalent PD subjects, treated with standard dialysis fluids. At baseline, 9 patients were switched to a biocompatible solution, low in glucose degradation products (GDPs) (Balance; Fresenius Medical Care, Bad Homburg, Germany). Hydration status was assessed through clinical evaluation, laboratory parameters, echocardiography, and bioimpedance spectroscopy over a 24-month observation period. ♦

RESULTS

During the study period, urine volume decreased similarly in both groups. At the end of the evaluation, there were also no differences in clinical (body weight, edema, blood pressure), laboratory (N-terminal pro-brain natriuretic peptide, NTproBNP), or echocardiography determinants of HS. However, dialysis ultrafiltration decreased in the low-GDP group and, at the end of the study, equaled 929 ± 404 mL, compared with 1,317 ± 363 mL in the standard-fluid subjects (p = 0.06). Hydration status assessed by bioimpedance spectroscopy was +3.64 ± 2.08 L in the low-GDP patients and +1.47 ± 1.61 L in the controls (p = 0.03). ♦

CONCLUSIONS

The use of a low-GDP biocompatible dialysis fluid was associated with a tendency to overhydration, probably due to diminished ultrafiltration in prevalent PD patients.

Injury-induced inflammation and inadequate HSP expression in mesothelial cells upon repeat exposure to dual-chamber bag peritoneal dialysis fluids

PURPOSE

Peritoneal dialysis fluids (PDFs) may induce inadequate heat-shock protein (HSP) expression and injury-related inflammation in exposed mesothelial cells. The aim of this study was to relate cellular injury to these cellular responses in mesothelial cells following repeated exposure to 3 commercial PDFs with different biocompatibility profiles.

METHODS

Primary cultures of human peritoneal mesothelial cells (HPMC) were exposed to a 1:2 mixture of cell culture medium and CAPD2 (single-chamber bag PDF; Fresenius, Bad Homburg, Germany), Physioneal (dual-chamber bag PDF; Baxter, Deerfield, IL, USA) or Balance (dual-chamber bag PDF, Fresenius) for up to 10 days exposure time (4 dwells). Supernatant was analyzed for LDH, IL-6, and IL-8, cells for HSP-72 expression, and protein content.

RESULTS

PDF exposure resulted in a biphasic pattern of cell damage switching from an earlier phase with increased injury by single-chamber PDF to a delayed phase with increased susceptibility to dual-chamber PDF. Sterile inflammation was related to LDH release over time and could be reproduced by exposure to necrotic cellular material. PDF exposure resulted in low HSP-72 expression in all tested PDFs.

CONCLUSIONS

Exposure to single-chamber as well as to dual-chamber bag PDFs induce increased vulnerability of mesothelial cells to repeated exposure of the same solution. These effects were delayed with dual-chamber PDFs. Injury-induced inflammation and impaired HSP expression upon PDF exposure might initiate a vicious cycle with progredient mesothelial cell damage upon repeated PDF exposure. Certainly, interventional studies and translation of these results into the in vivo system is needed.

Peritoneal Dialysis in Western Countries

BACKGROUND

Peritoneal dialysis (PD) for the treatment of end-stage renal failure was introduced in the 1960s. Nowadays it has evolved to an established therapy that is complementary to hemodialysis (HD), representing 11% of all patients treated worldwide with dialysis. Despite good clinical outcomes and similar results in patient survival between PD and HD, the penetration of PD is decreasing in the Western world.

SUMMARY

First the major events in the history of the development of PD are described. Then important insights into the physiology of peritoneal transport are discussed and linked to the changes in time observed in biopsies of the peritoneal membrane. Furthermore, the developments in peritoneal access, more biocompatible dialysate solutions, automated PD at home, the establishment of parameters for dialysis adequacy and strategies to prevent infectious complications are mentioned. Finally non-medical issues responsible for the declining penetration in the Western world are analyzed.

KEY MESSAGES

Only after introduction of the concept of continuous ambulatory PD by Moncrief and Popovich has this treatment evolved in time to a renal replacement therapy. Of all structures present in the peritoneal membrane, the capillary endothelium offers the rate-limiting hindrance for solute and water transport for the diffusive and convective transport of solutes and osmosis. The functional and anatomical changes in the peritoneal membrane in time can be monitored by the peritoneal equilibrium test. Peritonitis incidence decreased by introduction of the Y-set and prophylaxis using mupirocin on the exit site. The decrease in the proportion of patients treated with PD in the Western world can be explained by non-medical issues such as inadequate predialysis patient education, physician experience and training, ease of HD initiation, overcapacity of in-center HD, lack of adequate infrastructure for PD treatment, costs and reimbursement issues of the treatment.

FACTS FROM EAST AND WEST

(1) PD is cheaper than HD and provides a better quality of life worldwide, but its prevalence is significantly lower than that of HD in all countries, with the exception of Hong Kong. Allowing reimbursement of PD but not HD has permitted to increase the use of PD over HD in many Asian countries like Hong Kong, Vietnam, Taiwan, Thailand, as well as in New Zealand and Australia over the last years. In the Western world, however, HD is still promoted, and the proportion of patients treated with PD decreases. Japan remains an exception in Asia where PD penetration is very low. Lack of adequate education of practitioners and information of patients might as well be reasons for the low penetration of PD in both the East and West. (2) Patient survival of PD varies between and within countries but is globally similar to HD. (3) Peritonitis remains the main cause of morbidity in PD patients. South Asian countries face specific issues such as high tuberculosis and mycobacterial infections, which are rare in developed Asian and Western countries. The infection rate is affected by climatic and socio-economic factors and is higher in hot, humid and rural areas. (4) Nevertheless, the promotion of a PD-first policy might be beneficial particularly for remote populations in emerging countries where the end-stage renal disease rate is increasing dramatically.

Preserving the peritoneal membrane in long-term peritoneal dialysis patients

WHAT IS KNOWN AND OBJECTIVE

Peritoneal dialysis (PD) has been widely used by patients with end-stage renal disease. However, chronic exposure of the peritoneal membrane to bioincompatible PD solutions, and peritonitis and uraemia during long-term dialysis result in peritoneal membrane injury and thereby contribute to membrane changes, ultrafiltration (UF) failure, inadequate dialysis and technical failure. Therefore, preserving the peritoneal membrane is important to maintain the efficacy of PD. This article reviews the current literature on therapeutic agents for preserving the peritoneal membrane.

METHODS

A literature search of PubMed was conducted using the search terms peritoneal fibrosis, peritoneal sclerosis, membrane, integrity, preserve, therapy and peritoneal dialysis, but not including peritonitis. Published clinical trials, in vitro studies, experimental trials in animal models, meta-analyses and review articles were identified and reviewed for relevance.

RESULTS AND DISCUSSION

We focus on understanding how factors cause peritoneal membrane changes, the characteristics and mechanisms of peritoneal membrane changes in patients undergoing PD and the types of therapeutic agents for peritoneal membrane preservation. There have been many investigations into the preservation of the peritoneal membrane, including PD solution improvement, the inhibition of cytokine and growth factor expression using renin-angiotensin-aldosterone system (RAAS) blockade, glycosaminoglycans (GAGs), L-carnitine and taurine additives. In addition, there are potential future therapeutic agents that are still in experimental investigations.

WHAT IS NEW AND CONCLUSION

The efficacy of many of the therapeutic agents is uncertain because there are insufficient good-quality clinical studies. Overall membrane preservation and patient survival remain unproven in using more biocompatible PD solutions. With RAAS blockade, results are still inconclusive, as many of the clinical studies were retrospective. With GAGs, L-carnitine and taurine additives, there is no sufficiently long follow-up clinical study with a large sample size to support its efficacy. Therefore, better quality clinical studies within this area should be performed.

Effect of Neutral-pH, Low-Glucose Degradation Product Peritoneal Dialysis Solutions on Residual Renal Function, Urine Volume, and Ultrafiltration: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Neutral-pH, low-glucose degradation products solutions were developed in an attempt to lessen the adverse effects of conventional peritoneal dialysis solutions. A systematic review was performed evaluating the effect of these solutions on residual renal function, urine volume, peritoneal ultrafiltration, and peritoneal small-solute transport (dialysate to plasma creatinine ratio) over time.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Multiple electronic databases were searched from January of 1995 to January of 2013. Randomized trials reporting on any of four prespecified outcomes were selected by consensus among multiple reviewers.

RESULTS

Eleven trials of 643 patients were included. Trials were generally of poor quality. The meta-analysis was performed using a random effects model. The use of neutral-pH, low-glucose degradation products solutions resulted in better preserved residual renal function at various study durations, including >1 year (combined analysis: 11 studies; 643 patients; standardized mean difference =0.17 ml/min; 95% confidence interval, 0.01 to 0.32), and greater urine volumes (eight studies; 598 patients; mean difference =128 ml/d; 95% confidence interval, 58 to 198). There was no significant difference in peritoneal ultrafiltration (seven studies; 571 patients; mean difference =-110; 95% confidence interval, -312 to 91) or dialysate to plasma creatinine ratio (six studies; 432 patients; mean difference =0.03; 95% confidence interval, 0.00 to 0.06).

CONCLUSIONS

The use of neutral-pH, low-glucose degradation products solutions results in better preservation of residual renal function and greater urine volumes. The effect on residual renal function occurred early and persisted beyond 12 months. Additional studies are required to evaluate the use of neutral-pH, low-glucose degradation products solutions on hard clinical outcomes.