Removal of large middle molecules via haemodialysis with medium cut-off membranes at lower blood flow rates: an observational prospective study

Most recently developed polyester polymer alloy dialyzer: A new medium cut-off membrane?

BACKGROUND

New versions of the polyester polymer alloy (PEPA) membrane have appeared over the years, with increases in both the pore size and the amount of polyvinylpyrrolidone (PVP) to optimize hydrophilicity performance. This study aimed to assess the efficacy of the most recently developed PEPA dialyzer, the FDY series, in hemodialysis (HD) modality in terms of uremic toxin removal and albumin loss and to compare it with that of several high-flux dialyzers currently used in HD and post-dilution hemodiafiltration (HDF) treatments.

METHODS

A prospective study was carried out in 21 patients. All patients underwent six dialysis sessions with the same routine dialysis parameters; only the dialyzer and/or the dialysis modality varied: FX80 in HD, FDY 180 in HD, Clearum HS17 in HDF, Elisio 19H in HDF, Vitapes 180 in HDF, and FX80 in post-dilution HDF. The reduction ratios (RR) of urea, creatinine, ß2-microglobulin, myoglobin, κFLC, prolactin, α1-microglobulin, α1-acid glycoprotein, λFLC, and albumin were compared intraindividually. Dialysate albumin loss was also measured.

RESULTS

Both membranes FDY and FX80 are high-flux dialyzers and are applied here in high-flux HD. The average RR of β2-microglobulin was slightly lower in the two HD treatments than in the HDF treatments. Comparison of dialysis treatments revealed that the PEPA FDY dialyzer in the HD modality was more effective than the FX80 dialyzer in high-flux HD and was as effective as post-dilution HDF, especially in terms of myoglobin, κFLC, prolactin, α1-microglobulin, and λFLC RRs. The FDY treatments obtained similar albumin RR in blood and slightly higher dialysate albumin loss, although the values were clinically acceptable.

CONCLUSIONS

The most recently developed PEPA dialyzers in the HD modality were as effective as all treatments in the HDF modality and were clearly superior to high-flux helixone HD treatment. These results confirm that this dialyzer should be categorized within the medium cut-off (MCO) membrane classification.

Hemodiafiltration versus Hemodialysis in End-Stage Kidney Disease: A Systematic Review and Meta-Analysis

Rationale & Objective

The use of hemodiafiltration (HDF) as a kidney replacement therapy (KRT) in patients with end-stage kidney disease (ESKD) has sparked a debate regarding its advantages over conventional hemodialysis (HD). The present study aims to shed light on this controversy by comparing mortality rates and cause-specific deaths between ESKD patients receiving HDF and those undergoing HD.

Study Design

Systematic review and meta-analysis of randomized controlled trials (RCTs). The search was conducted using PubMed, EMBASE, and Cochrane Central on July 1, 2023.

Setting & Participants

Adult patients with ESKD on regular KRT.

Exposure

Studies with participants undergoing HDF.

Outcomes

Primary outcomes were all-cause mortality, cardiovascular (CV) mortality, deaths related to infections, and kidney transplant. We also evaluated the endpoints for deaths related to malignancy, myocardial infarction, stroke, arrhythmias, and sudden death.

Analytical Approach

We included RCTs evaluating HDF versus HD. Crossover trials and studies with overlapping populations were excluded. Two authors independently extracted the data following predefined search criteria and quality assessment. The risk of bias was assessed with Cochrane's RoB2 tool.

Results

We included 5 RCTs with 4,143 patients, of which 2,078 (50.1%) underwent HDF, whereas 2,065 (49.8%) were receiving HD. Overall, HDF was associated with a lower risk of all-cause mortality (risk ratio [RR], 0.81; 95% confidence interval [CI], 0.73-0.91; P < 0.001; I2 = 7%) and a lower risk of CV-related deaths (RR, 0.75; 95% CI, 0.61-0.92; P = 0.007; I2 = 0%). The incidence of infection-related deaths was also significantly different between therapies (RR, 0.69; 95% CI, 0.50-0.95; P = 0.02; I2 = 26%).

Limitations

In individual studies, the HDF groups achieved varying levels of convection volume.

Conclusions

Compared with those undergoing HD, patients receiving HDF experienced a reduction in all-cause mortality, CV mortality, and infection-related mortality. These results provide compelling evidence supporting the use of HDF as a beneficial intervention in ESKD patients undergoing KRT.

Registration

Registered at PROSPERO: CRD42023438362.

Medium cut-off dialyzer for middle molecular uremic toxins in AKI and chronic dialysis

Uremic toxins accumulate in patients affected by renal failure and can deposit in different organs, including the kidneys and heart. Given their physicochemical characteristics, uremic toxins can contribute to organ dysfunction due to several pathobiological actions at cellular and molecular levels. Several uremic compounds have been described in serum and plasma from patients with acute kidney injury (AKI) and kidney failure; they are usually classified based on their molecular size and protein-binding properties. In this scenario, new dialytic approaches have been proposed in the last few years with the aim of improving uremic toxin removal. Recent studies which focused on the use of medium cut-off membranes in patients on chronic hemodialysis have shown a discrete ability to remove β2-microglobulin and other middle molecules, such as kappa and lambda free light chains, complement factor D and α1-microglobulin. However, current evidence is mainly based on the impact on short-term outcomes and, consequently, longer observational studies are necessary to confirm the efficacy and safety of the medium cut-off dialyzer. Here we present the state-of-the-art on the clinical application of medium cut-off membranes in AKI and chronic dialysis patients.

Trial design of the MOTheR HDx study: a multicenter, open-label, prospective, randomized study to explore the morbidity and mortality in patients dialyzed with the Theranova HDx in comparison with online hemodiafiltration

Background

Dialysis patients have been maintaining a high rate of cardiovascular morbidity and mortality. For this reason, it is to introduce necessary new technical advances in clinical practice. There is a relation between toxins retention and inflammation, mortality and morbidity. Medium cut-off (MCO) membranes are a new generation of membranes that allow the removal of a greater number of medium-sized molecules compared with high-flux hemodialysis (HF-HD), but retaining albumin. MCO membranes have an increased permeability and the presence of internal filtration. Because of these special properties, MCO generated a new concept of therapy called expanded HD (HDx). Until now, online hemodiafiltration (OL-HDF) has demonstrated its superiority, in terms of survival, compared with HF-HD. However, the comparison between OL-HDF and HDx remains an unsolved question.

Methods

The MOTheR HDx study trial (NCT03714386) is an open-label, multicenter, prospective, 1:1 randomized, parallel-group trial designed to evaluate the efficacy and safety of HDx compared with OL-HDF in patients treated for dialysis in Spain for up to 36 months. The main endpoint is to determinate whether HDx is non inferior to OL-HDF at reducing the combined outcome of all-cause death and stroke (ischemic or hemorrhagic), acute coronary syndrome (angina and myocardial infarction), peripheral arterial disease (amputation or revascularization) and ischemic colitis (mesenteric thrombosis).

Results

The trial has already started.

Comparison of the medium cutoff dialyzer and postdilution hemodiafiltration on the removal of small and middle molecule uremic toxins

BACKGROUND

The medium cutoff (MCO) dialyzer increases the removal of several middle molecules more effectively than high-flux hemodialysis (HD). However, comparative data addressing the efficacy and safety of MCO dialyzers vs. postdilution hemodiafiltration (HDF) in Korean patients are lacking.

METHODS

Nine patients with chronic HD were included in this pre-post study. Patients underwent HD with an MCO dialyzer for 4 weeks, followed by a 2-week washout period using a high-flux dialyzer to minimize carryover effects, and then turned over to postdilution HDF for 4 weeks. Reduction ratios and differences in the uremic toxins before and after dialysis were calculated from the MCO dialysis, postdilution HDF, and high-flux HD. In the in vitro study, EA.hy926 cells were incubated with dialyzed serum.

RESULTS

Compared to postdilution HDF, the MCO dialyzer achieved significantly higher reduction ratios for larger middle molecules (myoglobin, kappa free light chain [κFLC], and lambda FLC [λFLC]). Similarly, the differences in myoglobin, κFLC, and λFLC concentrations before and after the last dialysis session were significantly greater in MCO dialysis than in postdilution HDF. The expression of Bax and nuclear factor κB was decreased in the serum after dialysis with the MCO dialyzer than with HDF.

CONCLUSION

Compared with high-volume postdilution HDF, MCO dialysis did not provide greater removal of molecules below 12,000 Da, whereas it was superior in the removal of larger uremic middle molecule toxins in patients with kidney failure. Moreover, these results may be expected to have an anti-apoptotic effect on the human endothelium.

Medium Cut-Off versus Low-Flux Dialyzers in Hemodialysis Patients with COVID-19: Clinical Outcomes and Reduction in Interleukin-6

INTRODUCTION

The coronavirus disease 2019 (COVID-19) pandemic has caused extensive morbidity and mortality worldwide. Hemodialysis (HD) patients are both vulnerable to COVID-19 infection and tend to suffer greater disease severity and mortality. This retrospective study aimed to compare medium cut-off (MCO) and low-flux (LF) membrane dialyzers in terms of interleukin-6 (IL-6) reduction, change in inflammatory state, intradialytic complications, and mortality in chronic HD patients with COVID-19.

METHOD

HD patients with a confirmed COVID-19 infection were admitted to the hospital for 10-14 days and underwent HD at the COVID-HD unit. Choice of dialyzer membrane used (MCO vs. LF) depended on the primary nephrologist(s). We collected data on demographics, baseline characteristics, laboratory results, diagnosis, treatments, HD prescription, hemodynamic status during HD, and mortality at 14 and 28 days after.

RESULTS

IL-6 reduction ratio (RR) in the MCO group was 9.7 (interquartile range, 71.1) percent, which was significantly higher than that of the LF group (RR, -45.7 [interquartile range, 70.2] percent). The incidence rate of intradialytic hypotension in the MCO group was 3.846 events per 100 dialysis hours (95% confidence interval [CI], 1.954-6.856), which was significantly lower than that of the LF group (9.057; 95% CI, 5.592-13.170). Overall, mortality was not significantly different between the two groups.

CONCLUSION

The MCO membrane was more effective in removing IL-6 and was better tolerated than the LF membrane. Large, randomized controlled trials are required to confirm the relative benefits of the MCO membrane, especially mortality. However, due to the COVID-19 pandemic, our results suggest that the MCO membrane may be beneficial in chronic HD patients with COVID-19.

Clinical performance comparison of two medium cut-off dialyzers

INTRODUCTION

Medium-cut-off (MCO) dialyzers may beneficially impact outcomes in patients on hemodialysis.

METHODS

In a randomized, controlled trial in maintenance hemodialysis patients, the new Nipro ELISIO-17HX MCO dialyzer was compared to the Baxter Theranova 400 filter regarding middle molecule removal. Furthermore, the suitability of two assays for free lambda-light chain (λFLC) detection (Freelite vs. N-Latex) was verified.

RESULTS

ELISIO-HX achieved slightly lower reduction ratios for β₂ -microglobulin (71.8 ± 6.0 vs. 75.3 ± 5.8%; p = 0.001), myoglobin (54.7 ± 8.6 vs. 64.9 ± 8.7%; p < 0.001), and kappa-FLC (62.1 ± 8.8 vs. 56.3 ± 7.7%; p = 0.021). λFLC reduction ratios were more conclusive with the Freelite assay and not different between ELISIO-HX and Theranova (28.4 ± 3.9 vs. 38.7 ± 13.4%; p = 0.069). The albumin loss of Theranova was considerably higher (2.14 ± 0.45 vs. 0.77 ± 0.25 g; p = 0.001) and the Global Removal Score_{Loss alb} largely inferior (30.6 ± 7.4 vs. 82.4 ± 29.2%/g; p = 0.006) to ELISIO-HX.

CONCLUSIONS

The new ELISIO-HX expands the choice of dialyzers for MCO hemodialysis.

Hemodiafiltration: Technical and Medical Insights

Despite the significant medical and technical improvements in the field of dialytic renal replacement modalities, morbidity and mortality are excessively high among patients with end-stage kidney disease, and most interventional studies yielded disappointing results. Hemodiafiltration, a dialysis method that was implemented in clinics many years ago and that combines the two main principles of hemodialysis and hemofiltration-diffusion and convection-has had a positive impact on mortality rates, especially when delivered in a high-volume mode as a surrogate for a high convective dose. The achievement of high substitution volumes during dialysis treatments does not only depend on patient characteristics but also on the dialyzer (membrane) and the adequately equipped hemodiafiltration machine. The present review article summarizes the technical aspects of online hemodiafiltration and discusses present and ongoing clinical studies with regards to hard clinical and patient-reported outcomes.

The Medium Cut-Off Membrane Does Not Lower Protein-Bound Uremic Toxins

The accumulation of protein-bound uremic toxins (PBUT) is associated with increased cardiovascular outcomes in patients on dialysis. However, the efficacy of PBUT removal for a medium-cutoff (MCO) membrane has not been clarified. This study was designed to assess the efficacy of PBUT clearance according to dialysis modalities. In this prospective and cross-over study, we enrolled 22 patients who received maintenance hemodiafiltration (HDF) thrice weekly from three dialysis centers. The dialysis removal of uremic toxins, including urea, beta 2-microglobulin (B2MG), lambda free light chain (λ-FLC), indoxyl sulfate (IS), and p-cresyl sulfate (pCS), was measured in the 22 patients on high-flux HD (HF-HD), post-dilution online HDF (post-OL-HDF), and MCO-HD over 3 weeks. The average convection volume in post-OL-HDF was 21.4 ± 1.8 L per session. The reduction rate (RR) of B2MG was higher in post-OL-HDF than in MCO-HD and HF-HD. The RR of λ-FLC was the highest in MCO-HD, followed by post-OL-HDF and HF-HD. The dialysate albumin was highest in MCO-HD, followed by post-OL-HDF and HF-HD. Post-dialysis plasma levels of IS and pCS were not statistically different across dialysis modalities. The total solute removal and dialytic clearance of IS and pCS were not significantly different. The clearance of IS and pCS did not differ between the HF-HD, post-OL-HDF, and MCO-HD groups.

Effects of Medium Cut-Off Polyarylethersulfone and Polyvinylpyrrolidone Blend Membrane Dialyzers in Hemodialysis Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

The use of medium cut-off (MCO) polyarylethersulfone and polyvinylpyrrolidone blend membrane is an emerging mode in hemodialysis. Recent studies have shown that MCO membranes exhibit a middle high molecular weight uremic toxin clearance superior to standard high flux hemodialysis. We conducted a systematic literature review and meta-analysis of randomized controlled trials to investigate whether MCO membranes efficiently increase the reduction ratio of middle molecules, and to explore the potential clinical applications of MCO membranes. We selected articles that compared beta 2-microglobulin (β2M), kappa free light chain (κFLC), lambda free light chain (λFLC), interleukin-6 (IL-6), and albumin levels among patients undergoing hemodialysis. Five randomized studies with 328 patients were included. The meta-analysis demonstrated a significantly higher reduction ratio of serum β2M (p < 0.0001), κFLC (p < 0.0001), and λFLC (p = 0.02) in the MCO group. No significant difference was found in serum IL-6 levels after hemodialysis. Albumin loss was observed in the MCO group (p = 0.04). In conclusion, this meta-analysis study demonstrated the MCO membranes’ superior ability to clear β2M, κFLC, and λFLC. Serum albumin loss is an issue and should be monitored. Further studies are expected to identify whether MCO membranes could significantly improve clinical outcomes and overall survival.

Clinical Safety of Expanded Hemodialysis Compared with Hemodialysis Using High-Flux Dialyzer during a Three-Year Cohort

Expanded hemodialysis (HD) equipped with a medium cut-off (MCO) membrane provides superior removal of larger middle molecules. However, there is still little research on the long-term benefits of expanded HD. Over a three-year period, this observational study evaluated the efficacy and safety profile of expanded HD for inflammatory cytokines, including IL-6. We conducted a prospective cohort study to investigate the inflammatory cytokine changes and a retrospective observational cohort study to investigate long-term clinical efficacy and safety over a three-year period. We categorized the patients according to dialyzer used: MCO and high-flux (HF) dialyzer. The inflammatory cytokines, including IFN-γ, IL-1β, IL-6, and TNF-α, were measured annually. The concentrations and changes of the four cytokines over time did not differ between the HF group (n = 15) and MCO group (n = 27). In both prospective and retrospective (HF group, n = 38; MCO group, n = 76) cohorts, there were no significant differences in either death, cardiovascular events, infections, or hospitalizations. Furthermore, the temporal changes in laboratory values, including serum albumin and erythropoietin prescriptions, did not differ significantly between the two groups in either the prospective or retrospective cohorts. In conclusion, clinical efficacy and safety outcomes, as well as inflammatory cytokines, did not differ with expanded HD compared with HF dialysis during a three-year treatment course, although the level of inflammatory cytokine was stable.

Efficacy and safety of expanded hemodialysis in hemodialysis patients: a meta-analysis and systematic review

Background

Expanded hemodialysis (HDx) is a new dialysis modality, but a systematic review of the clinical effects of using HDx is lacking. This systematic review and meta-analysis aimed to assess the efficacy and safety of HDx for hemodialysis (HD) patients.

Methods

PubMed, the Cochrane library, and EMBASE databases were systematically searched for prospective interventional studies comparing the efficacy and safety of HDx with those of high flux HD or HDF in HD patients.

Results

Eighteen trials including a total of 853 HD patients were enrolled. HDx increased the reduction ratio (RR) of β2-microglobulin (SMD 6.28%, 95% CI 0.83, 1.73, p = .02), κFLC (SMD 15.86%, 95% CI 6.96, 24.76, p = .0005), and λFLC (SMD 22.42%, 95% CI, 17.95, 26.88, p < .0001) compared with high flux HD. The RR of β2-microglobulin in the HDx group was lower than that in the HDF group (SMD −3.53%, 95% CI −1.16, −1.9, p < .0001). HDx increased the RRs of κFLC (SMD 1.34%, 95% CI 0.52, 2.16, p = .001) and λFLC (SMD 7.28%, 95% CI 1.08, 13.48, p = .02) compared to HDF. There was no significant difference in albumin loss into the dialysate between the HDx and HDF groups (SMD 0.35 g/session, 95% CI −2.38, 3.09, p = .8).

Conclusions

This meta-analysis indicated that compared with high-flux HD and HDF, HDx can increase the clearance of medium and large-molecular-weight uremic toxins. And it does not increase the loss of albumin compared with HDF.

Hemodiafiltration (HDF) versus expanded hemodialysis (HDx)

Medium cutoff (MCO) membranes have resulted in a novel dialyzer class designed to improve membrane permeability and have been postulated as an alternative to online hemodiafiltration since MCO membranes may achieve similar solute clearances. These membranes have been incorporated into clinical practice, and the term expanded HD (HDx) has been proposed to differentiate from high-flux hemodialysis. Efficacy, safety, and quality of life comparison of HDF versus HDx have been reviewed in this article.

Clinical Outcomes With Medium Cut-Off Versus High-Flux Hemodialysis Membranes: A Systematic Review and Meta-Analysis

BACKGROUND

A novel medium cut-off (MCO) dialyzer (Theranova, Baxter Healthcare, Deerfield, IL, USA) enhances large middle molecule clearance while retaining selectivity for molecules >45 000 Da.

OBJECTIVE

We undertook a systematic review and meta-analysis evaluating clinical outcomes with MCO vs high-flux membranes.

METHODS

We searched MEDLINE, EMBASE, CINAHL, Cochrane Library, and Web of Science through July 2020, and gray literature sources from 2017. We included randomized (RS) and nonrandomized studies (NRS) comparing MCO and high-flux membranes in adults receiving maintenance hemodialysis. Pairs of reviewers performed study selection, data extraction, and risk of bias assessment in duplicate. We conducted random-effects pairwise meta-analyses to pool results across studies and used the Grading of Recommendations Assessment, Development and Evaluation approach to assess evidence certainty.

RESULTS

We identified 22 eligible studies (6 RS, 16 NRS; N = 1811 patients; patient-years = 1546). The MCO dialyzer improved (estimate; 95% confidence interval [CI]; certainty rating) quality of life (mean difference [MD] = 16.7/100 points; 6.9 to 26.4; moderate), Kidney Disease Quality of Life Instrument (KDQOL) subscales-burden (MD = 4.0; 1.1 to 6.9; moderate) and effects (MD = 5.4; 3.2 to 7.6; moderate), pruritus (MD = -4.4; -7.1 to -1.7; moderate), recovery time (MD = -420 minutes; -541 to -299; high), and restless legs syndrome (odds ratio = 0.39; 0.29 to 0.53; moderate). There was little to no difference in all-cause mortality (risk difference = -0.4%; -2.8 to 2.1; moderate) and serious adverse events (rate ratio = 0.63; 0.38 to 1.04; low). MCO dialysis reduced hospitalization (rate ratio = 0.48; 0.27 to 0.84; low), infection (rate ratio = 0.38; 0.17 to 0.85; moderate), hospitalization days (MD = -1.5 days; 95% CI, -2.22 to -0.78; moderate), erythropoiesis resistance index (MD = -2.92 U/kg/week/g/L; 95% CI, -4.25 to -1.6; moderate) and cumulative iron use over 12 weeks (MD = -293 mg; 95% CI, -368 to -218; moderate). We found with low certainty that MCO dialysis had little to no effect on KDQOL symptoms/problem list, pain, and physical health and moderate certainty that MCO dialysis likely has no effect on the KDQOL mental health composite.

CONCLUSIONS

We found with predominantly moderate certainty that the MCO dialyzer improves several patient-important outcomes with no apparent risks or harms. More definitive studies are needed to better quantify the effects of MCO membranes on mortality, hospitalization, and other rare events.

Effects of Medium Cut-Off Versus High-Flux Hemodialysis Membranes on Biomarkers: A Systematic Review and Meta-Analysis

BACKGROUND

Medium cut-off (MCO) membranes enhance large middle-molecule clearance while selectively retaining molecules >45 000 Da.

OBJECTIVES

We undertook a systematic review and meta-analysis comparing the effects of MCO versus high-flux membranes on biomarkers.

METHODS

We searched MEDLINE, Embase, CINAHL, Cochrane Library, and Web of Science from January 2015 to July 2020, and gray literature sources from 2017. We included randomized (RS) and nonrandomized studies (NRS) comparing MCO and high-flux membranes in adults (>18 years) receiving maintenance hemodialysis. We performed study selection, data extraction, and quality appraisals in duplicate and used the Grading of Recommendations Assessment, Development, and Evaluation framework. Outcomes included solute removal (plasma clearance or dialysate quantitation), reduction ratios, and predialysis serum concentrations for a range of prespecified large middle molecules.

RESULTS

We identified 26 eligible studies (10 RS and 16 NRS; N = 1883 patients; patient-years = 1366.3). The mean difference (MD) for albumin removal was 2.31 g per session (95% confidence interval [CI], 2.79 to 1.83; high certainty), with a reduction in predialysis albumin of -0.12 g/dl (95% CI, -0.16 to -0.07; I 2 = 0%; high certainty) in the first 24 weeks, returning to normal (MD = -0.02 g/dl, 95% CI, -0.07 to -0.03; I 2 = 56%; high certainty) after 24 weeks. We also found with high certainty that MCO dialysis resulted in a large increase (standardized mean difference [SMD]> 2.0 for all) in β2-microglobulin, κ- and λ-free light chains, and myoglobin removal, resulting in moderate (SMD > 0.5) to large (SMD > 0.8) reductions in predialysis concentrations for all of these solutes. Medium cut-off dialysis increased the reduction ratio for tumor necrosis factor-alpha (TNF-α) by 7.7% (95% CI, 4.7 to 10.6; moderate certainty), and reduced predialysis TNF-α by SMD -0.48 (95% CI, -0.91 to -0.04; moderate certainty). We found with moderate certainty that MCO dialysis had little to no effect on predialysis interleukin-6 (IL-6) plasma concentrations. Medium cut-off dialysis reduced mRNA expression of TNF-α and IL-6 in peripheral leukocytes by MD -15% (95% CI, -19.6 to -10.4; moderate certainty) and -8.8% (95% CI, -10.2 to -7.4; moderate certainty), respectively.

CONCLUSION

Medium cut-off dialysis increases the clearance of a wide range of large middle molecules and likely reduces inflammatory mediators with a concomitant transient reduction in serum albumin concentration. The net effect of MCO dialysis on large middle molecules could translate into important clinical effects.

Hemodiálisis extendida frente a convencional o hemodiafiltración en línea. Estudio comparativo de necesidad de heparina y coagulación del sistema

Introducción: La reciente aparición de membranas de corte medio ofrece una alternativa para la eliminación de moléculas medianas y nueva terapia dialítica, la hemodiálisis expandida. Estas membranas se caracterizan por un mayor tamaño de poro que podría afectar a la eliminación de la heparina utilizada durante las sesiones de hemodiálisis. Objetivo: Determinar si existen diferencias en la necesidad de heparina y el estado de coagulación del sistema y dializador según técnica dialítica empleada. Material y Método: Estudio cuasiexperimental en pacientes en hemodiálisis con dos periodos de estudio, en el primero, el paciente realizó hemodiálisis convencional o hemodiafiltración y en el segundo, hemodiálisis expandida con membranas de corte medio. Resultados: El dializador quedó parcialmente coagulado en el 10,3% de las sesiones de hemodiálisis expandida frente al 19,1% de las sesiones de hemodiálisis y el 11,4% de hemodiafiltración (p=0,011). Conclusiones: La hemodiálisis expandida ofrece mejor estado de coagulación final del sistema y dializador que otras membranas.

Characterization of the cylindrical electrospun nanofibrous polysulfone membrane for hemodialysis with modelling approach

Electrospun nanofibrous membrane (ENM) is a membrane fabricated using electrospinning technique which has considerable characteristics such as high porosity, nanometer pore size, and simple process. Although ENMs are being evaluated in various medical applications, the effectiveness for hemodialysis (HD) has not been evaluated carefully. Thus, in this study, the cylindrical electrospun nanofibrous polysulfone (CENP) membrane was fabricated and its performance in the dialysis adequacy in HD patients was evaluated.The CENP membrane was fabricated in a tabular shape. The physical characteristics of the membrane are examined using scanning electron microscope (SEM) images and the permporometry technique. Then, its efficiency in urea and creatinine removal from the blood serum of 21 HD patients was evaluated at a low blood flow rate (BFR) of 200 ml min^-1 and dialysate fluid rate (DFR) of 300 ml min^-1. Afterwards, the results were modeled and optimized using artificial neural network (ANN) and genetic algorithm (GA), respectively. Finally, sensitive analysis was performed via Spearman's rank correlation coefficient. The highest dialysis adequacy was observed in membranes with an inner diameter of 3 mm. The CENP membrane belongs to the super high-flux membrane and it could be replaced with existing commercial hollow fiber membranes.

Expanded Haemodialysis as a Current Strategy to Remove Uremic Toxins

Chronic kidney disease (CKD) is characterized by the retention of solutes named uremic toxins, which strongly associate with high morbidity and mortality. Mounting evidence suggests that targeting uremic toxins and/or their pathways may decrease the risk of cardiovascular disease in CKD patients. Dialysis therapies have been developed to improve removal of uremic toxins. Advances in our understanding of uremic retention solutes as well as improvements in dialysis membranes and techniques (HDx, Expanded Hemodialysis) will offer the opportunity to ameliorate clinical symptoms and outcomes, facilitate personalized and targeted dialysis treatment, and improve quality of life, morbidity and mortality.

Effect of a medium cut-off dialyzer on protein-bound uremic toxins and mineral metabolism markers in patients on hemodialysis

INTRODUCTION

Hemodialysis (HD) with medium cut-off (MCO) dialyzers may expand molecular clearance, predominantly larger middle molecules (molecular weight 25-60 kDa). However, the impact of MCO dialyzers on long-term clearance of various other components of the uremic milieu is unknown. The tRial Evaluating Mid cut-Off Value membrane clearance of Albumin and Light chains in HemoDialysis patients (REMOVAL-HD) provided an opportunity to assess the effect of MCO dialyzers on protein-bound uremic toxins and novel markers of mineral metabolism.

METHODS

This exploratory sub-study of REMOVAL-HD evaluated changes in protein-bound solutes (total and free indoxyl sulfate [IS] and p-cresyl sulfate [PCS]) and mineral metabolism markers (intact fibroblast growth factor-23 [iFGF23], fetuin-A and endogenous calciprotein particles [CPP-1 and CPP-2]). Mid-week, pre-HD serum samples were collected at baseline and after 12 and 24 weeks of MCO use in stable adult patients. Change from baseline to Week 12 and 24 was estimated using linear mixed effects models.

FINDINGS

Eighty-nine participants were studied (mean age 67 ± 15 years, 38% female, 51% diabetic, median urine output 200 ml/24 h). Serum iFGF23 was reduced at Week 12 compared to baseline (-26.8% [95%CI -39.7, -11.1], p = 0.001), which was sustained at Week 24 (-21.7% [95%CI -35.7, -4.5], p = 0.012). There was no significant change in serum IS, PCS, fetuin-A, CPP-1, or CPP-2.

DISCUSSION

The use of a MCO dialyzer over 24 weeks was associated with a sustained reduction in FGF23, while other measured components of the uremic milieu were not significantly altered. Further studies are required to determine whether FGF23 reduction is associated with improved patient outcomes.

Changes in plasma sclerostin level associated with use of a medium cut-off dialyzer in end-stage renal disease

Background

Larger middle molecules are important substances associated with cardiovascular complications in end- stage renal disease. Unfortunately, larger middle molecules are not reliably removed by a high -flux dialyzer. A medium cut-off (MCO) membrane could effectively remove larger middle molecules. This study aimed to identify the long-term effect of the MCO membrane for changes of larger middle molecules.

Methods

Thirty-four patients were prospectively analyzed for 12 months. The enrolled patients were divided into control and MCO groups. We measured the plasma levels of growth differentiation factor 15, sclerostin, and fibroblast growth factor 23 in larger middle molecules and those of biomarkers including small solutes. Single-pool Kt/V (spKt/V) and reduction ratios also were evaluated.

Results

Plasma sclerostin did not increase significantly in patients using the MCO dialyzer (135.294 [–637.726 to 908.314], p = 0.715). And there was a significant difference in change of plasma sclerostin level between the two groups (–1,646.916 [–3,015.150 to –278.682], p = 0.033). Furthermore, a negative association between calcium and sclerostin was not observed in the MCO group (r = –0.142, p = 0.587). Solute clearance of larger middle molecules in the MCO group was significantly higher. Moreover, spKt/V values for patients in the MCO group were significantly increased without albumin loss. Values are presented as mean (95% confidence interval [CI]) or adjusted mean (95% CI).

Conclusion

The MCO dialyzer can increase dialytic adequacy and suppress the increase in plasma sclerostin level without significant albumin loss in patients with end-stage renal disease.

Slipping Through the Pores: Hypoalbuminemia and Albumin Loss During Hemodialysis

Hypoalbuminemia results when compensatory mechanisms are unable to keep pace with derangements in catabolism/loss and/or decreased synthesis of albumin. Across many disease states, including chronic kidney disease (CKD), hypoalbuminemia is a well-established, independent risk factor for adverse outcomes, including mortality. In the setting of CKD, reduced serum albumin concentrations are often a manifestation of protein-energy wasting, a state of metabolic and nutritional alterations resulting in reduced protein and energy stores. The progression of CKD to kidney failure and the initiation of maintenance hemodialysis (HD) further predisposes an already at-risk population toward hypoalbuminemia such that approximately 60% of HD patients have albumin concentrations <4.0 g/dl. Albumin loss into the dialysate through the dialyzer appears to be a potentially modifiable cause of hypoalbuminemia in some patients. A group of newer dialyzers for maintenance HD-sometimes termed protein-leaking or medium cut-off membranes-aim to improve clearance of middle molecules (vs high flux dialyzers) but are associated with increased albumin losses. In this article, we will examine the impact of dialyzer selection on albumin losses during conventional HD, including the clinical relevance of such losses on serum albumin levels. Data on the clinical relevance of albumin losses during dialysis and current gaps in the evidence base are also discussed.

Medium Cut-Off Dialysis Membranes: Can They Have Impact on Outcome of COVID-19 Hemodialysis Patients?

Introduction

Severe acute respiratory syndrome coronavirus-2 may lead to high levels of expression of inflammatory cytokines. Medium cut-off (MCO) membranes may make greater clearances for large-middle molecules (including cytokines) than low-flux (LF) membranes. In this study, we aimed to evaluate the impact of MCO membranes on outcome of COVID-19 patients on hemodialysis (HD).

Methods

Sixty COVID-19 HD patients were included in this study. The patients were categorized into 2 groups regarding type of HD membranes. Clinical data were taken from medical records.

Results

Initial crp and ferritin levels, which are surragates of cytokine storm and severity of disease in COVID-19, were significantly higher in MCO membrane group compared to LF group (p = 0.037 and 0.000, respectively). Although there were more patients with severe disease in MCO group, there were no significant differences regarding need for intensive care unit and death.

Conclusion

It may be an option to use MCO membranes in HD patients with COVID-19 in order to reduce cytokine levels and prevent cytokine storm.

Removal of middle molecules with medium cutoff dialyzer in patients on short frequent hemodialysis

INTRODUCTION

Medium cutoff (MCO) membranes for hemodialysis (HD) remove more effectively large middle molecules than high-flux (HF) membranes. In patients on in-center short frequent HD regimen (5 sessions per week, 2 hours and 30 minutes per session) the effect of MCO on middle weight uremic toxins has not been elucidated.

METHODS

This retrospective study included 15 patients previously performing short frequent HD with HF dialyzer (HF-HD), that were switched to short frequent HD with MCO dialyzer (MCO-HD) for 2 months, and returned to HF-HD. The primary endpoint was the predialysis concentration of α1-acid glycoprotein during the different study phases. Secondary endpoints were predialysis concentration of other middle molecules, albumin, and assessment of the quality of life using the 36-item short-form health survey (SF-36).

FINDINGS

During MCO-HD phase there was a reduction in mean ± SD α1-acid glycoprotein concentration (98.71 ± 25.2 vs. 88.6 ± 24.6 mg/dL, P = 0.107), followed by an increment 2 months after returning to HF-HD (89.18 ± 26.12 vs. 97.33 ± 31.29 mg/dL, P = 0.002); however, only the second variation was statistically significant. MCO-HD provided lower median predialysis concentration of prolactin (16 [10.2-25.6] vs. 14.1 [11.7-34.8] ng/mL, P = 0.036). Single-pool Kt/V, standard Kt/V, predialysis β2-microglobulin, myoglobin, and SF-36 questionnaire remained stable during the first two phases (pre-MCO and MCO). β2-Microglobulin increased in the post-MCO phase (20.02 ± 8.14 vs. 21.27 ± 7.64 μg/mL, P = 0.000). Mean predialysis concentration of albumin reduced significantly from pre-MCO vs. MCO phases (39.9 ± 3.7 vs. 38.3 ± 3.3 g/L, P = 0.020) and rebounded significantly from MCO vs. post-MCO phases (38.7 ± 3.1 vs. 41.3 ± 3.0 g/L, P = 0.007).

DISCUSSION

In this retrospective analysis, short frequent MCO-HD promotes a reduction in prolactin, a middle weight uremic toxin, and trends toward a reduction in α1-acid glycoprotein. No patients developed hypoalbuminemia. These findings are encouraging and deserve investigation in prospective studies.

Comparison of Hemodialysis Using a Medium Cutoff Dialyzer versus Hemodiafiltration: A Controlled Cross-Over Study

Purpose

Conventional hemodialysis (HD) treatment has an acceptable removal of small uremic molecules, but so-called "middle molecules" in the range of 0.5-60 kDa are poorly cleared with HD compared to a native kidney, which may contribute to morbidity in the dialysis population. Hemodiafiltration (HDF) has a better removal of middle molecules compared to HD but is technically demanding and requires well-functioning dialysis access. The newly introduced medium cutoff (MCO) filters have been developed to enhance middle molecule clearance in HD-mode. The aim of this study was to compare reduction ratios (RRs) of molecules with different molecular weights (0.06-150 kDa) during dialysis with MCO dialyzer (used in HD-mode) compared to online-hemodiafiltration (ol-HDF) treatment with a conventional high-flux dialyzer.

Patients and Methods

This is a prospective controlled single-center cross-over study, including 16 patients in Malmö, Sweden. All patients had ongoing post-dilution ol-HDF treatment before the study. The study compared reduction ratios of small-, middle-, and large-sized molecules during a single 4h dialysis treatment with post-dilution ol-HDF (Polyflux 210H) to a 4h dialysis treatment with MCO dialyzer (Theranova 500) in HD-mode. Between treatments, the patients had a washout period of at least two weeks of their ordinary HDF treatment to reach their ordinary steady state.

Results

ol-HDF had significantly higher RR for cystatin C (13 kDa), compared to MCO (RR 68.1 vs 65.8, p=0.003), during a 4h dialysis treatment (mean convection volume of 24.5 L for HDF, and mean Q_b of 324 mL/min for HDF and 323 mL/min for MCO). There was no significant difference in the RR for other middle molecules, or for smaller or larger molecules.

Conclusion

Overall, the RRs were comparable for ol-HDF and MCO-HD. There was a slightly higher RR of cystatin C (a small middle molecule) for HDF compared to MCO but no difference in other measured molecules.

High-volume online haemodiafiltration treatment and outcome of end-stage renal disease patients: more than one mode

The reduction of the dismally high mortality of current end-stage renal disease patients maintained on conventional standard haemodialysis (HD) remains an unmet medical need. Online haemodiafiltration (HDF) modes with various sites of fluid substitution (post-, pre-, mixed- and mid-dilution) are increasingly used worldwide as promising alternatives to conventional HD. Large scale cohort studies, post hoc analyses of randomized trials, and individual participant meta-analyses suggest that post-dilution and pre-dilution, especially with high substitution volumes, improve outcomes compared with conventional standard HD. However, there is no definitive proof of a survival advantage of HDF over standard HD. The different modes of high-volume HDF should be considered a therapeutic platform allowing to personalize and tailor routine HDF treatment. The selection of the HDF mode should be made according to individual patient characteristics. Utilizing high retention onset membranes, expanded haemodialysis (HDx) can achieve the same solute removal performance as HDF. Subgroups of high-volume OL-HDF patients could benefit from HDx. Ongoing and future trials should provide definitive proof for the superiority of high-volume OL-HDF over conventional HD or HDx to give guidance for the most favourable mode of dialytic therapy for clinical use.