Physiology of peritoneal dialysis; pathophysiology in long-term patients.

The microvascular wall of peritoneal tissues is the main barrier in solute and water transport in the initial phase of peritoneal dialysis (PD). Small solute transport is mainly by diffusion through inter-endothelial pores, as is hydrostatic fluid transport with dissolved solutes. Water is also transported through the intra-endothelial water channel aquaporin-1(AQP-1) by a glucose-induced crystalloid osmotic gradient (free water transport).

Peritoneal Protein Loss With Time in Peritoneal Dialysis.

Longitudinal evolution of peritoneal protein loss (PPL), a reflection of hydrostatic pressure-driven leak of plasma proteins through the large-pore pathway, is not clear. Time on PD causes loss of mesothelial cells, vasculopathy, and increased thickness of the submesothelial fibrous layer. Are these structural changes associated with progressive increase of PPL, in a parallel with the rise in the D/P creatinine? The aim of the present study was to identify longitudinal changes of PPL over time.

Glucose-induced pseudohypoxia and advanced glycosylation end products explain peritoneal damage in long-term peritoneal dialysis.

Long-term peritoneal dialysis is associated with the development of peritoneal membrane alterations, both in morphology and function. Impaired ultrafiltration (UF) is the most important functional change, and peritoneal fibrosis is the major morphological alteration. Both are caused by the continuous exposure to dialysis solutions that are different from plasma water with regard to the buffer substance and the extremely high-glucose concentrations.

Low immunoglobulin G concentrations are not associated with an increased risk of peritoneal dialysis-related peritonitis.

Background: Peritonitis is a common and severe complication of peritoneal dialysis (PD) and is associated with high morbidity and sometimes also with mortality. Identification of risk factors, as well as protective mechanisms for peritonitis, is important to reduce peritonitis-induced morbidity. According to the current literature, IgG concentrations might be associated with peritonitis in PD-treated patients.

Corrigendum: Aging of the Peritoneal Dialysis Membrane.

[This corrects the article DOI: 10.3389/fphys.2022.

Aging of the Peritoneal Dialysis Membrane.

Long-term peritoneal dialysis as currently performed, causes structural and functional alterations of the peritoneal dialysis membrane. This decay is brought about by the continuous exposure to commercially available glucose-based dialysis solutions. This review summarizes our knowledge on the peritoneum in the initial phase of PD, during the first 2 years and the alterations in function and morphology in long-term PD patients.

Relative Contributions of Pseudohypoxia and Inflammation to Peritoneal Alterations with Long-Term Peritoneal Dialysis Patients.

Long-term peritoneal dialysis is associated with alterations in peritoneal function, like the development of high small solute transfer rates and impaired ultrafiltration. Also, morphologic changes can develop, the most prominent being loss of mesothelium, vasculopathy, and interstitial fibrosis. Current research suggests peritoneal inflammation as the driving force for these alterations.

Assessment of the size selectivity of peritoneal permeability by the restriction coefficient to protein transport.

Transport of serum proteins from the circulation to peritoneal dialysate in peritoneal dialysis patients mainly focused on total protein. Individual proteins have hardly been studied. We determined serum and effluent concentrations of four individual proteins with a wide molecular weight range routinely in the standardised peritoneal permeability analysis performed yearly in all participating patients.

Promoter Variant, Water Transport, and Outcomes in Peritoneal Dialysis.

Background: Variability in ultrafiltration influences prescriptions and outcomes in patients with kidney failure who are treated with peritoneal dialysis. Variants in , the gene that encodes the archetypal water channel aquaporin-1, may contribute to that variability.

Methods: We gathered clinical and genetic data from 1851 patients treated with peritoneal dialysis in seven cohorts to determine whether variants were associated with peritoneal ultrafiltration and with a risk of the composite of death or technique failure (i.

Acquired Decline in Ultrafiltration in Peritoneal Dialysis: The Role of Glucose.

Ultrafiltration is essential in peritoneal dialysis (PD) for maintenance of euvolemia, making ultrafiltration insufficiency-preferably called ultrafiltration failure-an important complication. The mechanisms of ultrafiltration and ultrafiltration failure are more complex than generally assumed, especially after long-term treatment. Initially, ultrafiltration failure is mainly explained by a large number of perfused peritoneal microvessels, leading to a rapid decline of the crystalloid osmotic gradient, thereby decreasing aquaporin-mediated free water transport.

Do low GDP neutral pH solutions prevent or retard peritoneal membrane alterations in long-term peritoneal dialysis?

Several studies have been published in the last decade on the effects of low glucose degradation product (GDP) neutral pH (L-GDP/N-pH) dialysis solutions on peritoneal morphology and function during the long-term PD treatment. Compared to conventional solutions, the impact of these solutions on the morphological and functional alterations of the peritoneal membrane is discussed, including those of effluent proteins that reflect the status of peritoneal tissues. Long-term PD with conventional solutions is associated with the loss of mesothelium, submesothelial and interstitial fibrosis, vasculopathy, and deposition of advanced glycosylation end products (AGEs).

Overhydration May Be the Missing Link between Peritoneal Protein Clearance and Mortality.

Introduction: Peritoneal protein loss (PPL) has been associated with mortality. Inflammation was assumed a putative cause with malnutrition as a consequence. Hydrostatic convection is a major drive for microvascular protein transport, but most studies in peritoneal dialysis (PD) patients overlooked this mechanism.

Comparison of Longitudinal Membrane Function in Peritoneal Dialysis Patients According to Dialysis Fluid Biocompatibility.

Introduction: Preservation of peritoneal function is essential in long-term peritoneal dialysis. Biocompatible dialysis solutions might prevent or postpone the membrane alteration resulting in ultrafiltration failure and consecutive morbidity and mortality.

Methods: We conducted an observational cohort study in which we made a longitudinal comparison between the course of peritoneal solute and fluid transport during treatment with conventional and biocompatible solutions.

Peritoneal dialysis induces alterations in the transcriptome of peritoneal cells before detectible peritoneal functional changes.

Long-term peritoneal dialysis (PD) is associated with functional and structural alterations of the peritoneal membrane. Inflammation may be the key moment, and, consequently, fibrosis may be the end result of chronic inflammatory reaction. The objective of the present study was to identify genes involved in peritoneal alterations during PD by comparing the transcriptome of peritoneal cells in patients with short- and long-term PD.

Long-term peritoneal dialysis treatment provokes activation of genes related to adaptive immunity.

Permanent irritation of the peritoneum during peritoneal dialysis (PD) treatment leads to local chronic inflammation and subsequently activation of processes driving fibrogenesis in the long-term. The aim of the study was to compare the peritoneal effluent transcriptome of 20 patients treated less and 13 patients treated more than 2 years using microarray analysis. An increased expression of genes associated with an immune response was observed in long-term treated patients with well preserved peritoneal function, when compared to patients treated less than 2 years.

Development and Validation of Residual Kidney Function Estimating Equations in Dialysis Patients.

Rationale & Objective: Measurement of residual kidney function is recommended for the adjustment of the dialysis prescription, but timed urine collections are difficult and prone to errors. Equations to calculate residual kidney function from serum concentrations of endogenous filtration markers and demographic parameters would simplify monitoring of residual kidney function. However, few equations to estimate residual kidney function using serum concentrations of small solutes and low-molecular-weight proteins have been developed and externally validated.

Relationships Between Peritoneal Protein Clearance and Parameters of Fluid Status Agree with Clinical Observations in Other Diseases that Venous Congestion Increases Microvascular Protein Escape.

Background: Peritoneal effluent from peritoneal dialysis (PD) patients contains proteins, mainly transported from the circulation through large pores in the venular part of the peritoneal microvessels. Hydrostatic convection is the major driver for peritoneal protein transport, although in PD there is additional diffusion. Consequently, venous pressure may have a role in peritoneal protein transport.

Ultrafiltration Failure Is a Reflection of Peritoneal Alterations in Patients Treated With Peritoneal Dialysis.

Ultrafiltration (UF) failure is a common and important complication of peritoneal dialysis (PD), especially in long-term patients without residual urine production, because it often causes overhydration, which is an important cause of death in this population. The current review provides an overview of the pathways of peritoneal fluid transport, followed by the mechanisms and causes of UF failure. The egression of circulating fluid to the tissue compartment and its subsequent re-uptake by the colloid osmotic pressure are markedly influenced by PD, because the dialysis solutions contain glucose as a low molecular weight agent causing removal of fluid from the circulation by crystalloid osmosis.

Early Detection of Imminent Encapsulating Peritoneal Sclerosis: Free Water Transport, Selected Effluent Proteins, or Both?

Background: No diagnostic tool or methodology is currently available for early detection of imminent encapsulating peritoneal sclerosis (EPS). The objective of this study was to investigate the predictive value of free water transport (FWT) and construct a panel of peritoneal effluent proteins for EPS alone or in combination with FWT. These parameters could be incorporated in the follow-up of peritoneal dialysis (PD) patients.

Peritoneal vasculopathy in the pathophysiology of long-term ultrafiltration failure: A hypothesis based on clinical observations .

Ultrafiltration failure in long-term peritoneal dialysis patients is a well-known and important, but poorly-explained complication of the treatment. Transcapillary ultrafiltration consists mainly of small-pore fluid transport and partly of free-water transport. The former is to a large extent dependent on the hydrostatic pressure gradient and on the number of perfused peritoneal microvessels.

Patient-reported outcomes (PROs) argue against the limited use of peritoneal dialysis in end-stage renal disease .

Aim: Approximately 40% of dialysis patients are durably treated with peritoneal dialysis (PD) in our teaching hospital. Patients' perspectives were studied by patient-reported outcome measurements (PROMs) to find possible explanations for why the generally-reported decline in the use of PD hardly occurred in our facility.

Materials And Methods: All 75 prevalent adult dialysis patients hemodialysis (HD) duration 27, PD 16 months) were included.

Prediction models for the mortality risk in chronic dialysis patients: a systematic review and independent external validation study.

Objective: In medicine, many more prediction models have been developed than are implemented or used in clinical practice. These models cannot be recommended for clinical use before external validity is established. Though various models to predict mortality in dialysis patients have been published, very few have been validated and none are used in routine clinical practice.

The truth on current peritoneal dialysis: state of the art.

The share of peritoneal dialysis (PD) in the spectrum of chronic dialysis has decreased markedly in the Netherlands in the last 15 years. Consequently, the knowledge of nephrologists and nursing staff on PD has declined leading to a negative spiral in which loss of experience resulted in loss of enthusiasm to offer PD to patients and also in less interest in the new PD developments. All these changes took place while the results of PD improved and patient survival was at least similar to that on haemodialysis.