Ultrapure dialysis water obtained with additional ultrafilter may reduce inflammation in patients on hemodialysis

Alleviation of Oxidative Stress during Hemodialysis Sessions by Hemodialysis Membrane Innovation: A Multidisciplinary Perspective

Oxidative stress is prevalent in end-stage kidney disease patients receiving chronic hemodialysis and is associated with heavy cardiovascular disease burdens and increased mortality risks. Hemoincompatible hemodialysis membranes per se contribute to the activation of oxidative reactions and the generation of oxygen free radicals. Since the early 1990s, vitamin E-coated membranes have been extensively used in hemodialysis patients to reduce oxidative stress during hemodialysis sessions. However, the beneficial effects of vitamin E-coated membranes versus unmodified synthetic membranes on long-term patient-centered outcomes, such as survival, quality of life, and prevalence of cardiovascular diseases, remain controversial. Accordingly, novel antioxidant hemodialysis membranes were prepared to replace the use of vitamin E-coated membranes despite the translational research on these membranes unfortunately coming to a standstill. In this review, we first summarize the state-of-the-art on the use of vitamin E-coated membranes in hemodialysis patients to highlight their strengths and limitations. Then, we discuss the latest advances in fabricating antioxidant hemodialysis membranes and provide perspectives to bridge knowledge gaps between laboratorial investigations and clinical practice in fabricating antioxidant hemodialysis membranes.

Quality of dialysis water and dialysate in hemodialysis centers: highlight for occurrence of non-fermenting gram-negative bacilli

AIMS

To evaluate the physicochemical and microbiological quality of dialysis water and dialysate samples from hemodialysis centers.

METHODS AND RESULTS

Samples were fortnightly collected from three hemodialysis centers in Bauru City, Brazil, between July/2017 and June/2018, at the stages of post-reverse osmosis, reuse and dialysate. Analyses included determination of conductivity, fluoride, nitrate and sulfate; test for total coliform bacteria; count of heterotrophic bacteria; count and identification of non-fermenting gram-negative bacilli (NFGNB); drug susceptibility test; biofilm formation capacity, and genetic similarity among some isolated NFGNB. Of the analyzed samples, only 4/72 (5.6%) had conductivity values ≥ 10 mS/cm, 4/216 (1.9%) presented total coliforms, and 1/216 (0.5%) had heterotrophic bacteria count > 100 CFU/mL. NFGNB were isolated from 99/216 (45.8%) samples, and the major identified microorganisms included Herbaspirillum aquaticum/huttiense, Brevundimonas aurantiaca, Cupriavidus metallidurans, Pseudomonas aeruginosa and Ralstonia insidiosa. Isolates of P. aeruginosa and Burkholderia cepacia complex were sensitive to most antimicrobials and, together with isolates of Ralstonia insidiosa and Ralstonia pickettii, showed strong biofilm formation capacity. Some isolates expressed the same electrophoretic profile on pulsed-field gel electrophoresis, indicating persistence of bacterial clones in the systems over time.

CONCLUSIONS

NFGNB were observed in several dialysis water and dialysate samples from all investigated centers, which may represent a risk to the health of patients.

SIGNIFICANCE AND IMPACT OF THE STUDY

Regular inclusion of actions for NFGNB control and monitoring in hemodialysis fluids are suggested for greater safety of the dialytic process.

Survival with low- and high-flux dialysis

Background

Besides advances in haemodialysis (HD), mortality rates are still high. The effect of the different types of HD membranes on survival is still a controversial issue. The aim of this COSMOS (Current management Of Secondary hyperparathyroidism: a Multicentre Observational Study) analysis was to survey, in HD patients, the relationship between the use of conventional low- or high-flux membranes and all-cause and cardiovascular mortality.

Methods

COSMOS is a multicentre, open-cohort, 3-year prospective study, designed to evaluate mineral and bone disorders in the European HD population. The present analysis included 5138 HD patients from 20 European countries, 3502 randomly selected at baseline (68.2%), plus 1636 new patients with <1 year on HD (31.8%) recruited to replace patients who died, were transplanted, switched to peritoneal dialysis or lost to follow-up by other reasons. Cox-regression analysis with time-dependent variables, propensity score matching and the use of an instrumental variable (facility-level analysis) were used.

Results

After adjustments using three different multivariate models, patients treated with high-flux membranes showed a lower all-cause and cardiovascular mortality risks {hazard ratio (HR) = 0.76 [95% confidence interval (CI) 0.61-0.96] and HR = 0.61 (95% CI 0.42-0.87), respectively}, that remained significant after matching by propensity score for all-cause mortality (HR = 0.69, 95% CI 0.52-0.93). However, a facility-level analysis showed no association between the case-mix-adjusted facility percentage of patients dialysed with high-flux membranes and all-cause and cardiovascular mortality.

Conclusions

High-flux dialysis was associated with a lower relative risk of all-cause and cardiovascular mortality. However, dialysis facilities using these dialysis membranes to a greater extent did not show better survival.

Immunological Effects of a Single Hemodialysis Treatment

Immune disorders, involving both innate and adaptive response, are common in patients with end-stage renal disease under chronic hemodialysis. Endogenous and exogenous factors, such as uremic toxins and the extracorporeal treatment itself, alter the immune balance, leading to chronic inflammation and higher risk of cardiovascular events. Several studies have previously described the immune effects of chronic hemodialysis and the possibility to modulate inflammation through more biocompatible dialyzers and innovative techniques. On the other hand, very limited data are available on the possible immunological effects of a single hemodialysis treatment. In spite of the lacking information about the immunological reactivity related to a single session, there is evidence to indicate that mediators of innate and adaptive response, above all complement cascade and T cells, are implicated in immune system modulation during hemodialysis treatment. Expanding our understanding of these modulations represents a necessary basis to develop pro-tolerogenic strategies in specific conditions, like hemodialysis in septic patients or the last session prior to kidney transplant in candidates for receiving a graft.

Positron Emission Tomography Can Support the Diagnosis of Dialysis-Related Amyloidosis

BACKGROUND

The improvements in dialysis have not eliminated long-term problems, including dialysis-related amyloidosis (DRA), caused by Beta-2 microglobulin deposition. Several types of scintigraphy have been tested to detect DRA, none entered the clinical practice. Aim of the study was to assess the potential of PET-FDG scan in the diagnosis of DRA.

METHODS

Forty-six dialysis patients with at least one PET scan (72 scans) were selected out 162 patients treated in 2016-2018. Subjective global assessment (SGA), malnutrition inflammation score (A), Charlson Comorbidity Index (CCI), were assessed at time of scan; 218 age-matched cases with normal kidney function were selected as controls. PET scans were read in duplicate. Carpal tunnel syndrome was considered a proxy for DRA. A composite "amyloid score" score considered each dialysis year = 1 point; carpal tunnel-DRA = 5 points per site. Logistic regression, ROC curves and a prediction model were built.

RESULTS

The prevalence of positive PET was 43.5% in dialysis, 5% in controls (p < 0.0001). PET was positive in 14/15 (93.3%) scans in patients with carpal tunnel. PET sensitivity for detecting DRA was 95% (specificity 64%). Carpal tunnel was related to dialysis vintage and MIS. A positive PET scan was significantly associated with dialysis vintage, MIS and amyloid score. A prediction model to explain PET positivity combined clinical score and MIS, allowing for an AUC of 0.906 (CI: 0.813-0.962; p < 0.001).

CONCLUSIONS

PET-FDG may identify DRA, and may be useful in detecting cases in which inflammation favours B2M deposition. This finding, needing large-scale confirmation, could open new perspectives in the study of DRA.