Clinical guideline on adequacy and prescription of peritoneal dialysis

In recent years, the meaning of adequacy in peritoneal dialysis has changed. We have witnessed a transition from an exclusive achievement of specific objectives -namely solute clearances and ultrafiltration- to a more holistic approach more focused to on the quality of life of these patients. The purpose of this document is to provide recommendations, updated and oriented to social and health environment, for the adequacy and prescription of peritoneal dialysis. The document has been divided into three main sections: adequacy, residual kidney function and prescription of continuous ambulatory peritoneal dialysis and automated peritoneal dialysis. Recently, a guide on the same topic has been published by a Committee of Experts of the International Society of Peritoneal Dialysis (ISPD 2020). In consideration of the contributions of the group of experts and the quasi-simultaneity of the two projects, references are made to this guide in the relevant sections. We have used a systematic methodology (GRADE), which specifies the level of evidence and the strength of the proposed suggestions and recommendations, facilitating future updates of the document.

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.

Serum globulin is a novel predictor of mortality in patients undergoing peritoneal dialysis

Serum globulin, which is composed mainly of immunoglobulins and acute phase proteins, can be considered as reflecting the inflammatory state. We conducted the present study to investigate the role of globulin in mortality risk in patients undergoing peritoneal dialysis (PD). The study participants were categorized by the median globulin value (2.8 g/dL) as the high globulin group (≥ 2.8 g/dL), and low globulin group (< 2.8 g/dL). Serum globulin is calculated by the equation: (serum total protein-serum albumin). The area under the curve (AUC) by the receiver operating characteristics curve analysis was calculated to compare the mortality prediction capacity of globulin with that of ferritin, and WBC counts. Among the 554 patients, 265 (47.83%) were men, the mean age was 52.91 ± 15.54 years and the body mass index was 23.44 ± 3.88 kg/m². Multivariate Cox models showed the high globulin group had higher mortality risks of all-cause and cardiovascular disease (CVD), compared with the low globulin group with adjusted HRs of 2.06 (95% CI 1.39-3.05) and 1.94 (95% CI 1.18-3.16), respectively. The AUC of univariate and multivariate models for all-cause mortality resulted in higher AUC values for globulin than for ferritin and white blood cell (WBC) counts. In patients undergoing PD, the serum globulin can serve as a novel and independent determinant of predicting overall and CVD- associated mortality.

Incremental peritoneal dialysis is a safe and feasible prescription in incident patients with preserved residual kidney function

BACKGROUND

Incremental peritoneal dialysis (PD) is recommended as a component of high-quality care by the international society for PD; however, its feasibility and clinical outcomes have not been widely reported. The aim of this study is to describe our experience with incremental PD.

METHODS

This was a retrospective cohort study of incident PD patients at Eastern Health between 2015 and 2019. Patients who stopped PD within 30 days were excluded. Incremental PD was defined in CAPD as using <8 L/day of exchange volume and in automated PD as dialysing without a last fill. Dialysis modality accorded with patient and physician preferences.

RESULTS

The 96 patients were included in this study; 54 with incremental PD. Compared to full-dose PD, incremental PD patients were more likely to be female, had less comorbid diabetes (28% vs. 52%) and higher residual kidney function (RKF) (Kt/V 2.0 ± 0.7 vs. 1.4 ± 0.7). Age, BMI and starting eGFR did not differ between groups. Incremental PD exposed patients to lower exchange volumes (4.4 ± 2.1 vs. 8.5 ± 1.1 L/day), glucose load (46 ± 41 g/day vs. 119 ± 46) and was associated with a longer peritonitis-free survival. PD technique survival, rates of peritonitis or hospitalization were comparable between groups. Predictors for longer incremental PD use included older age and higher starting eGFR.

CONCLUSIONS

Incremental PD is a feasible, goal-directed initial prescription in patients with RKF with comparable peritonitis rates and technique survival. Validation of this prescription in prospective studies is warranted.

Peritoneal dialysis has optimal intradialytic hemodynamics and preserves residual renal function: Why isn't it better than hemodialysis?

Rates of cardiovascular mortality are disproportionately high in patients with end stage kidney disease receiving dialysis. However, it is now generally accepted that patient survival is broadly equivalent between the two most frequently used forms of dialysis, in-center hemodialysis (HD) and peritoneal dialysis (PD). This equivalent patient survival is notable when considering how specific aspects of HD have been shown to contribute to morbidity and mortality. These include more rapid loss of residual renal function (RRF), HD-induced myocardial and cerebral ischemia, and risk factors associated with the intermittent delivery of HD. Potential mechanisms specific to PD that may drive cardiovascular disease include the metabolic consequences of excessive absorption of glucose and glucose degradation products (GDPs), inadequate volume control, and high rates of hypokalemia. The aim of this review is to compare and contrast the different drivers of adverse outcomes between the dialysis modalities, as greater understanding of this may help in patient-centered decision-making when considering options for renal replacement therapy.

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.

Food-derived 1,2-dicarbonyl compounds and their role in diseases

Reactive 1,2-dicarbonyl compounds (DCs) are generated from carbohydrates during food processing and storage and under physiological conditions. In the recent decades, much knowledge has been gained concerning the chemical formation pathways and the role of DCs in food and physiological systems. DCs are formed mainly by dehydration and redox reactions and have a strong impact on the palatability of food, because they participate in aroma and color formation. However, they are precursors of advanced glycation end products (AGEs), and cytotoxic effects of several DCs have been reported. The most abundant DCs in food are 3-deoxyglucosone, 3-deoxygalactosone, and glucosone, predominating over methylglyoxal, glyoxal, and 3,4-dideoxyglucosone-3-ene. The availability for absorption of individual DCs is influenced by the release from the food matrix during digestion and by their reactivity towards constituents of intestinal fluids. Some recent works suggest formation of DCs from dietary sugars after their absorption, and others indicate that certain food constituents may scavenge endogenously formed DCs. First works on the interplay between dietary DCs and diseases reveal an ambiguous role of the compounds. Cancer-promoting but also anticancer effects were ascribed to methylglyoxal. Further work is still needed to elucidate the reactions of DCs during intestinal digestion and pathophysiological effects of dietary DCs at doses taken up with food and in "real" food matrices in disease states such as diabetes, uremia, and cancer.

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.

Recommendations for pathological diagnosis on biopsy samples from peritoneal dialysis patients

Peritoneal dialysis (PD) has been established as an essential renal replacement therapy for patients with end stage renal disease during the past half century. Histological evaluation of the peritoneal membrane has contributed to the pathophysiological understanding of PD-related peritoneal injury such as peritonitis, fibrosis, and encapsulating peritoneal sclerosis (EPS). Hyalinizing peritoneal sclerosis (HPS), also known as simple sclerosis, is observed in almost all of PD patients. HPS is morphologically characterized by fibrosis of the submesothelial interstitium and hyalinizing vascular wall, particularly of the post-capillary venule (PCV). Two histological factors, the thickness of submesothelial compact zone (SMC) and the lumen/vessel ratio (L/V) at the PCV, have been used for the quantitative evaluation of HPS. The measuring system on SMC thickness and L/V ratio is easy and useful for evaluating the severity of HPS. On the other hand, EPS is characterized by unique encapsulation of the intestines by an "encapsulating membrane". This newly formed membranous structure covers the visceral peritoneum of the intestines, which contains fibrin deposition, angiogenesis, and proliferation of fibroblast-like cells and other inflammatory cells. This review will cover the common understandings of PD-related peritoneal alterations and provide a basic platform for clinical applications and future studies in this field.

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.

Advances in Understanding and Management of Residual Renal Function in Patients with Chronic Kidney Disease

BACKGROUND

Residual renal function (RRF), defined as the ability of native kidneys to eliminate water and uremic toxins, is closely correlated with mortality and morbidity rates among patients receiving either peritoneal dialysis (PD) or hemodialysis (HD) via continuous clearance of middle-sized molecules and protein-bound solutes. Therefore, preserving RRF is considered to be one of the primary goals in managing patients with end-stage renal disease (ESRD).

SUMMARY AND KEY MESSAGES

In this article, we provide a review on the understanding and management of RRF in patients on dialysis. RRF may be estimated and measured by calculating the mean 24-hour urine creatinine level and urea clearance. Currently, several middle-sized molecules are reported but rarely used in practice. Many risk factors such as original renal diseases, dietary intake, and nephrotoxic agents impair RRF. Targeting such factors may halt the decline in RRF and offer better outcomes for patients on PD or HD. Except for in PD patients, RRF is a powerful predictor of survival in HD patients. RRF requires more clinical and research attention in the care of patients with ESRD on dialysis.

Chemistry and clinical relevance of carbohydrate degradation in drugs

Carbohydrate degradation products are formed during heat sterilization in drugs containing (poly-)glucose as osmotic agents. Given this situation, peritoneal dialysis fluids (PDFs) and infusion fluids are of particular clinical relevance, because these drugs deliver process contaminants either over a longer period or directly into the circulation of patients who are critically ill. For the development of suitable mitigation strategies, it is important to understand the reaction mechanisms of carbohydrate degradation during sterilization and how the resulting products interact with physiological targets at the molecular level. Furthermore, reliable, comprehensive, and highly sensitive quantification methods are required for product control and toxicological evaluation.

Comparing Changes in Plasma and Skin Autofluorescence in Low-Flux versus High-Flux Hemodialysis

Background

Tissue advanced glycation end products (AGE) are increased in hemodialysis (HD) patients, especially those with cardiovascular complications. Skin autofluorescence (skin-AF) can noninvasively estimate the accumulation of AGE in tissue. The aim was to clarify whether HD using a high-flux (HF) dialyzer favors plasma- or skin-AF removal compared to low-flux (LF) dialysis.

Material and methods

28 patients were treated with either an HF-HD or LF-HD but otherwise unchanged conditions in a cross-over design. A glucose containing dialysate was used. Skin-AF was measured noninvasively with an AGE reader before and after HD. Fluorescence (370 nm/465 nm) of plasma (p-AF) was determined as total and nonprotein-bound fractions. Correction for hemoconcentrations were made using the change in serum albumin. Paired and nonpaired statistical analyses were used.

Results

Skin-AF was unchanged after LF- and HF-dialysis. Total, free, and protein- bound p-AF was reduced after a single LF-HD by 21%, 28%, and 17%, respectively ( P<.001). After HF HD total and free p-AF was reduced by 5% and 15%, respectively ( P<.001), while protein bound values were unchanged. The LF-HD resulted in a more pronounced reduction of p-AF than did HF HD ( P<.001). Serum albumin correlated inversely with p-AF in HF-HD.

Conclusions

In the dialysis settings used there was no significant change in skin AF after dialysis, with LF or with HF dialysis. Although only limited reduction in plasma fluorescence was observed, this was more pronounced when performing LF dialysis. These data are not in overwhelming support of the use of HF dialysis in the setting used in this study.