"Biocompatible" Neutral pH Low-GDP Peritoneal Dialysis Solutions: Much Ado About Nothing?

Dyslipidemia in Peritoneal Dialysis: Implications for Peritoneal Membrane Function and Patient Outcomes

Dyslipidemia is a common metabolic complication in patients undergoing peritoneal dialysis (PD) and has traditionally been viewed primarily in terms of cardiovascular risk. Current guidelines do not recommend initiating lipid-lowering therapy in dialysis patients due to insufficient evidence of its benefits on cardiovascular mortality. However, the impact of dyslipidemia in PD patients may extend beyond cardiovascular concerns, influencing PD-related outcomes such as the peritoneal ultrafiltration rate, residual kidney function, PD technique survival, and overall mortality. This review challenges the traditional perspective by discussing dyslipidemia's potential role in PD-related complications, which may account for the observed link between dyslipidemia and increased all-cause mortality in PD patients. It explores the pathophysiology of dyslipidemia in PD, the molecular mechanisms linking dyslipidemia to peritoneal membrane dysfunction, and summarizes clinical evidence supporting this hypothesis. In addition, this paper examines the potential for therapeutic strategies to manage dyslipidemia to improve peritoneal membrane function and patient outcomes. The review calls for future research to investigate dyslipidemia as a potential contributor to peritoneal membrane dysfunction and to develop targeted interventions for PD patients.

Rationale and Design of PURE: A Randomized Controlled Trial to Evaluate Peritoneal Ultrafiltration with PolyCore™ in Refractory Congestive Heart Failure

INTRODUCTION

Peritoneal ultrafiltration (PUF) has been proposed as an additional therapeutic option for refractory congestive heart failure (RCHF) patients. Despite promising observational studies and/or case report results, limited clinical trial data exist, and so far, PUF solutions remain only indicated for chronic kidney diseases. In this article, we described a multicenter, randomized, controlled, unblinded, adaptive design clinical trial, about to start, investigating the effects of PolyCore™, an innovative PUF solution, in the treatment of RCHF patients.

METHODS

The Peritoneal Ultrafiltration in Cardiorenal Syndrome (PURE) study is a phase II, multicenter, randomized, controlled, unblinded, adaptive design clinical trial that aims to evaluate the safety and efficacy of PUF, using PolyCore™ as the investigational solution, in the treatment of RCHF patients who present with prominent right ventricular failure due to afterload mismatch, functional tricuspid regurgitation and enlarged cava vein consequent to intravascular fluid overload. Approximately 84 patients will be randomized 1:1 either to continue with their prescribed guideline-directed medical therapy or to add the PUF treatment on top of it. The primary objective is to evaluate if PUF treatment has an impact on the composite endpoint of the patient's mortality or worsening of the patient's condition such as hospitalization for cardiovascular causes, increasing the initial daily dose of loop diuretic or worsening of renal function. Statistical analysis for the primary endpoint will be standard survival analysis to estimate the failure rate at month 7 for each group via Kaplan-Meier curves. Sensitivity analysis and various secondary analyses, including a multiple events analysis, will be conducted to evaluate the robustness of the primary endpoint results. Safety will be evaluated for up to 12 months.

CONCLUSION

The PURE study was designed to evaluate the safety and efficacy of peritoneal ultrafiltration with PolyCore™ on top of guideline-directed medical therapy in patients with RCHF, assuming a combined clinical endpoint of mortality or worsening patients' condition. If successful, the treatment should allow for an improvement of the RCHF symptoms, decreasing hospitalization rate of patients.

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.

Insulin resistance in cardiovascular disease, uremia, and peritoneal dialysis

Diabetic nephropathy is highly correlated with the occurrence of other complications of type 1 diabetes (T1D) and type 2 diabetes (T2D) mellitus; for example, hypertension with cardiovascular disease (CVD) being the most frequent cause of death in patients with end-stage renal disease and undergoing renal dialysis. Hyperglycemia and insulin resistance (IR) are responsible for the micro- and macrovascular complications of diabetes through different mechanisms. In particular, IR plays a key role in the etiology of atherosclerosis in both diabetic and non-diabetic patients. IR - exacerbated by organ-level selectivity - is more important than glycemic control per se in determining cardiovascular outcomes. This may be exacerbated by the fact that IR is organ and pathway specific due to the only selective loss of sensitivity to insulin action of specific pathways/processes. Therefore, it is counterintuitive that the use of peritoneal dialysis (PD) in (frequently) diabetic renal disease patients should involve their exposure to high daily doses of glucose peritoneally. In view of the controversy about the causal association between glucose load and CVD in PD patients, we discuss the role that selective IR may play in the progression of CVD in diabetic renal end-stage patients. In discussing these associations, we propose that reducing glucose exposure in PD solutions may be beneficial especially if coupled with strategies that address IR directly, and the avoidance of excessive use of insulin treatment in T2D.

A Novel Formulation of Glucose-Sparing Peritoneal Dialysis Solutions with l-Carnitine Improves Biocompatibility on Human Mesothelial Cells

The main reason why peritoneal dialysis (PD) still has limited use in the management of patients with end-stage renal disease (ESRD) lies in the fact that the currently used glucose-based PD solutions are not completely biocompatible and determine, over time, the degeneration of the peritoneal membrane (PM) and consequent loss of ultrafiltration (UF). Here we evaluated the biocompatibility of a novel formulation of dialytic solutions, in which a substantial amount of glucose is replaced by two osmometabolic agents, xylitol and l-carnitine. The effect of this novel formulation on cell viability, the integrity of the mesothelial barrier and secretion of pro-inflammatory cytokines was evaluated on human mesothelial cells grown on cell culture inserts and exposed to the PD solution only at the apical side, mimicking the condition of a PD dwell. The results were compared to those obtained after exposure to a panel of dialytic solutions commonly used in clinical practice. We report here compelling evidence that this novel formulation shows better performance in terms of higher cell viability, better preservation of the integrity of the mesothelial layer and reduced release of pro-inflammatory cytokines. This new formulation could represent a step forward towards obtaining PD solutions with high biocompatibility.

Stability of Meropenem and Piperacillin/Tazobactam with Heparin in Various Peritoneal Dialysis Solutions

BACKGROUND

Infections caused by ceftazidime-resistant Pseudomonas and extended-spectrum beta-lactamase (ESBL)-producing gram-negative bacteria are increasing worldwide. Meropenem and piperacillin/tazobactam (PIP/TZB) are recommended for the treatment of peritoneal dialysis-associated peritonitis (PDAP) caused by ceftazidime-resistant Pseudomonas and other resistant gram-negative bacteria. Patients may also receive intraperitoneal heparin to prevent occlusion of their catheters. However, the stability of meropenem or PIP/TZB, in combination with heparin, in different types of peritoneal dialysis (PD) solutions used in clinical practice is currently unknown. Therefore, we investigated the stability of meropenem and PIP/TZB, each in combination with heparin, in different PD solutions.

METHODS

A total of 15 PD bags (3 bags for each type of PD solution) containing meropenem and heparin and 24 PD bags (3 bags for each type of PD solution) containing PIP/TZB and heparin were prepared and stored at 4°C for 168 hours. The same bags were stored at 25°C for 3 hours followed by 10 hours at 37°C. An aliquot withdrawn before storage and at defined time points was analyzed for the concentration of meropenem, PIP, TZB, and heparin using high-performance liquid chromatography. Samples were also analysed for particle content, pH and color change, and the anticoagulant activity of heparin.

RESULTS

Meropenem and heparin retained more than 90% of their initial concentration in 4 out of 5 types of PD solutions when stored at 4°C for 168 hours, followed by storage at 25°C for 3 hours and then at 37°C for 10 hours. Piperacillin/tazobactam and heparin were found to be stable in all 8 types of PD solutions when stored under the same conditions. Heparin retained more than 98% of its initial anticoagulant activity throughout the study period. No evidence of particle formation, color change, or pH change was observed at any time under the storage conditions employed in the study.

CONCLUSIONS

This study provides clinically important information on the stability of meropenem and PIP/TZB, each in combination with heparin, in different PD solutions. The use of meropenem-heparin admixed in pH-neutral PD solutions for the treatment of PDAP should be avoided, given the observed suboptimal stability of meropenem.