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Background: A novel class of membranes, medium cut-off (MCO) membranes, has recently been designed to achieve interesting removal capacities for middle and large middle molecules in hemodialysis (HD) treatments. The few studies published to date have reported contradictory results regarding middle-sized molecules when comparing MCO dialyzers versus dialyzers used in online hemodiafiltration (OL-HDF). Methods: A prospective, single-center study was carried out in 22 patients. Each patient underwent 9 dialysis sessions with routine dialysis parameters, one with an MCO dialyzer in HD and the other 8 with different dialyzers in OL-HDF. The removal ratio (RR) of urea, creatinine, β2-microglobulin, myoglobin, prolactin, α1-microglobulin, α1-acid glycoprotein, and albumin was intraindividually compared. Albumin loss in dialysate was measured. We propose a global removal score ([ureaRR + β2-microglobulinRR + myoglobinRR + prolactinRR + α1-microglobulinRR + α1-acid glycoproteinRR]/6 – albuminRR) as a new tool for measuring dialyzer effectiveness. Results: No significant differences in the RRs of small and middle molecular range molecules were observed between the MCO vs. OL-HDF dialyzers (range 60–80%). Lower RRs were found for α1-microglobulin and α1-acid glycoprotein without significant differences. The albumin RR was < 11% and dialysate albumin loss was < 3.5 g in all situations without significant differences. The global removal score was 54.9 ± 4.8% with the MCO dialyzer without significant differences. Conclusions: Removal of a wide range of molecular weights, calculated with the proposed global removal score, was almost equal with the MCO dialyzer in HD treatment compared with 8 high-flux dialyzers in high-volume OL-HDF without relevant changes in albumin loss. The global removal score could be a new tool to evaluate the effectiveness of dialyzers and/or different treatment modalities.

Anemia is a common complication in chronic kidney disease (CKD), and is associated with a reduced quality of life, and an increased morbidity and mortality. The mechanisms involved in anemia associated to CKD are diverse and complex. They include a decrease in endogenous erythropoietin (EPO) production, absolute and/or functional iron deficiency, and inflammation with increased hepcidin levels, among others. Patients are most commonly managed with oral or intravenous iron supplements and with erythropoiesis stimulating agents (ESA). However, these treatments have associated risks, and sometimes are insufficiently effective. Nonetheless, in the last years, there have been some remarkable advances in the treatment of CKD-related anemia, which have raised great expectations. On the one hand, a novel family of drugs has been developed: the hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs). These agents induce, among other effects, an increase in the production of endogenous EPO, improve iron availability and reduce hepcidin levels. Some of them have already received marketing authorization. On the other hand, recent clinical trials have elucidated important aspects of iron supplementation, which may change the treatment targets in the future. This article reviews the current knowledge of the pathophysiology CKD-related anemia, current and future therapies, the trends in patient management and the unmet goals.

Most high-flux dialyzers can be used in both hemodialysis (HD) and online hemodiafiltration (OL-HDF). However, some of these dialyzers have higher permeability and should not be prescribed for OL-HDF to avoid high albumin losses. The aim of this study was to compare the safety and efficacy of a currently used dialyzer in HD and OL-HDF with those of several other high permeability dialyzers which should only be used in HD. A prospective, single-center study was carried out in 21 patients. Each patient underwent 5 dialysis sessions with routine dialysis parameters: 2 sessions with Helixone (HD and postdilution OL-HDF) and 1 session each with steam sterilized polyphenylene, polymethylmethacrylate (PMMA), and medium cutoff (MCO) dialyzers in HD treatment. The removal ratios (RR) of urea, creatinine, ß 2 -microglobulin, myoglobin, prolactin, α 1 -microglobulin, α 1 -acid glycoprotein, and albumin were compared intraindividually. A proportional part of the dialysate was collected to quantify the loss of various solutes, including albumin. Urea and creatinine RRs with the Helixone-HDF and MCO dialyzers were higher than with the other 3 dialyzers in HD. The β 2 -microglobulin, myoglobin and prolactin RRs with Helixone-HDF treatment were significantly higher than those obtained with all 4 dialyzers in HD treatment. The β 2 -microglobulin value obtained with the MCO dialyzer was also higher than that obtained with the other 3 dialyzers in HD treatment. The myoglobin RR with MCO was higher than those obtained with Helixone and PMMA in HD treatment. The prolactin RR with Helixone-HD was significantly lower than those obtained in the other 4 study sessions. The α 1 -microglobulin and α 1 -acid glycoprotein RRs with Helixone-HDF were significantly higher than those obtained with Helixone and PMMA in HD treatment. The albumin loss varied from 0.54 g with Helixone-HD to 3.3 g with polyphenylene. The global removal score values ((Urea RR + β 2 -microglobulin RR + myoglobin RR + prolactin RR + α 1 -microglobulin RR + α 1 -acid glycoprotein RR -albumin RR )/6) were 43.7% with Helixone-HD, 47.7% with PMMA, 54% with polyphenylene, 54.8% with MCO and 59.6% with Helixone-HDF, with How to cite this article: Maduell F, Rodas L, Broseta JJ, et al. High-permeability alternatives to current dialyzers performing both high-flux hemodialysis and postdilution online hemodiafiltration.

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<b><i>Introduction:</i></b> COVID-19 is a highly contagious disease that has easily spread worldwide. Outpatient maintenance hemodialysis seems to entail an increased risk of contagion, and previous reports inform of increased mortality among this population. <b><i>Methods:</i></b> We retrospectively analyzed clinical and laboratory parameters, outcomes, and management once discharged of CKD-5D patients infected with SARS-CoV-2 from our health area. <b><i>Results:</i></b> Out of the 429 CKD-5D population, 36 were diagnosed with SARS-CoV-2 infection (8%): 34 on in-center hemodialysis and 2 on peritoneal dialysis. Five were asymptomatic. The most common symptom was fever (70%), followed by dyspnea and cough. History of cardiovascular disease and elevation of LDH and C-reactive protein during admission were associated with higher mortality. Thirteen patients died (36%), 8 patients were admitted to an ICU, and survival was low (38%) among the latter. The mean time to death was 12 days. Most discharged patients got negative rRT-PCR in nasopharyngeal swabs within 26 days of diagnosis. However, there is a portion of cured patients that continue to have positive results even more than 2 months after the initial presentation. <b><i>Conclusions:</i></b> Patients on dialysis have an increased mortality risk if infected with SARS-CoV-2. Preventive measures have proven useful. Thus, proper ones, such as universal screening of the population and isolation when required, need to be generalized. Better de-isolation criteria are necessary to ensure an appropriate use of public health resources.

Introduction Given the increased COVID-19 observed in kidney transplant recipients (KTRs) and haemodialysis patients, several studies have tried to establish the efficacy of mRNA vaccines in these populations by evaluating their humoral and cellular responses. However, there is currently no information on clinical protection (deaths and hospitalizations), a gap that this study aims to fill. Methods Observational prospective study involving 1,336 KTRs and haemodialysis patients from three dialysis units affiliated to Hospital Clínic of Barcelona, Spain, vaccinated with two doses of mRNA-1273 (Moderna) or BNT162b2 (Pfizer-BioNTech) SARS-CoV-2 mRNA vaccines. The outcomes measured were SARS-CoV-2 infection diagnosed by a positive RT-PCR fourteen days after the second vaccine dose, hospital admissions derived from infection, and a severe COVID-19 composite outcome, defined as either ICU admission, invasive and non-invasive mechanical ventilation, or death. Results Six per cent (18/302) of patients on haemodialysis were infected, of whom four required hospital admission (1.3%), only one (0.3%) had severe COVID-19, and none of them died. In contrast, 4.3% (44/1034) of KTRs were infected, and presented more hospital admissions (26 patients, 2.5%), severe COVID-19 (11 patients, 1.1%) or death (4 patients, 0.4%). KTRs had a significantly higher risk of hospital admission than HD patients, and this risk increased with age and male sex (HR 3.37 and 4.74, respectively). Conclusions The study highlights the need for booster doses in KTRs. In contrast, the haemodialysis population appears to have an adequate clinical response to vaccination, at least up to four months from its administration. Graphical abstract

Blood flow (Qb) is one of the dialysis parameters most strongly influencing the performance of dialysis modalities. However, few studies have compared different dialysis modalities in patients with low Qb. We conducted a prospective, single‐center study in 21 patients. Each patient underwent four dialysis sessions with routine dialysis parameters: high‐flux hemodialysis (HD), predilution hemodiafiltration (pre‐HDF), expanded HD (HDx), and postdilution HDF (post‐HDF). The removal ratios (RR) of urea, creatinine, ß2‐microglobulin, myoglobin, prolactin, α1‐microglobulin, free kappa and lambda immunoglobulin light chains (ķFLC and λFLC), α1‐acid glycoprotein, and albumin were compared intraindividually. A proportional part of the dialysate was collected to quantify albumin loss. There were no differences in urea and creatinine RRs. The β2‐microglobulin RR was higher in pre‐HDF and post‐HDF. Myoglobin and prolactin RRs were higher with HDx and post‐HDF. The α1‐microglobulin and α1‐acid glycoprotein RRs were significantly higher with post‐HDF than with other treatments, and RRs obtained with HDx were higher than obtained with HD and pre‐HDF. Free ķFLC and λFLC RRs showed the following results in ascending order: HD, pre‐HDF, HDx, and post‐HDF, most of them with statistical significance. Albumin loss varied from 0.45 g with HD to 3.5 g with post‐HDF. The global removal score values were 41.0 ± 4.8% with HD, 44.0 ± 5.2% with pre‐HDF, 49.5 ± 4.6% with HDx, and 54.8 ± 5.3% with post‐HDF, with significant differences between all treatment modalities. In conclusion, this study confirms the superiority of post‐HDF over high‐flux HD, pre‐HDF, and HDx in patients with low Qb. HDx was the closest alternative to post‐HDF and was clearly superior to HD and pre‐HDF. Finally, pre‐HDF was also superior to HD. With this Qb, there was a higher risk of underdialysis, both diffusive and convective, especially in patients with a session duration of less than 5 h.