Comparison of High-Flux, Super High-Flux, Medium Cut-Off Hemodialysis and Online Hemodiafiltration on the Removal of Uremic Toxins.

INTRODUCTION: Online hemodiafiltration (OL-HDF) and hemodialysis (HD) using high-performance membranes such as adsorptive, medium cut-off (MCO), and super high-flux (SHF) dialyzers have been implemented to enhance the removal of middle molecules (MM). The aim of this study was to compare the efficacy of different dialysis strategies and dialyzers on small solutes and MM reduction ratio (RR) and mass removal. METHODS: We performed a prospective study in 8 HD patients. Each patient underwent 9 dialysis sessions: seven sessions on HD using either Theranova 500™, Elisio 21H™, Renak PS-2.0W™, Filtryzer BK-2.1F™, Vie 21X™, TS-2.1UL™ or FDY 210-GW™ dialyzers and two sessions on OL-HDF using Elisio 21H™ or Renak PS-2.0W™ dialyzers. RESULTS: Urea mass removal and RR were similar between all dialysis strategies. The lowest beta2-microglobulin RR was achieved with Filtryzer BK-2.1F™ HD (p < 0.05). Compared to Elisio 21H™ HD, Renak PS-2.0W™ OL-HDF produced higher beta2-microglobulin mass removal (181 ± 46 vs. 317 ± 161 mg, p < 0.05). Theranova 500™ HD, Vie 21X™ HD, FDY 210-GW™ HD, Elisio 21H™ OL-HDF, and Renak PS-2.0W™ OL-HDF induced higher RR for kappa and lambda FLC, as compared to Elisio 21H™ HD and Filtryzer BK-2.1F™ HD (p < 0.05). Renak PS-2.0W™ OL-HDF achieved higher kappa FLC mass removal compared to Elisio 21H™ HD (563 ± 515 vs. 141 ± 47 mg, p < 0.01) and to Renak PS-2.0W™ HD (563 ± 515 vs. 153 ± 25 mg, p < 0.05). Albumin loss varied from 0.02 ± 0.05 to 7.6 ± 3.8 g/session with Elisio 21H™ HD and Renak PS-2.0W™ OL-HDF, respectively. Compared to all other strategies, Renak PS-2.0W™ OL-HDF induced a significantly higher albumin loss (p < 0.05). CONCLUSION: This study confirms that albumin loss and removal of MM are similar using conventional Elisio 21H™ OL-HDF, MCO-HD, and SHF type V dialyzers. Although Renak PS-2.0W™ OL-HDF provides high performance for MM depuration, this protein-permeable dialyzer should not be used in OL-HDF because of excessive albumin loss.

Idiopathic nephrotic syndrome relapse following COVID-19 vaccination: a series of 25 cases.

Background: Several cases of idiopathic nephrotic syndrome (INS) relapse following the administration of coronavirus disease 2019 (COVID-19) vaccines have recently been reported, raising questions about the potential relationship between the immune response to COVID-19 vaccination and INS pathogenesis. Methods: We performed a retrospective multicentre survey describing the clinical and biological characteristics of patients presenting a relapse of INS after COVID-19 vaccination, with an assessment of outcome under treatment. Results: We identified 25 patients (16 men and 9 women) presenting a relapse within 1 month of a COVID-19 vaccine injection. The glomerular disease was of childhood onset in half of the patients and most patients (21/25) had received at least one immunosuppressive drug in addition to steroids for frequently relapsing or steroid-dependent nephrotic syndrome (NS). All patients were in a stable condition at the time of injection and 11 had no specific treatment. In five patients, the last relapse was reported >5 years before vaccine injection. The Pfizer-BioNTech (BNT162b2) vaccine was used in 80% of the patients. In 18 cases, INS relapse occurred after the first injection, a mean of 17.5 days after vaccination. A second injection was nevertheless administered in 14 of these patients. Five relapses occurred after administration of the second dose and two relapses after the administration of the third dose. All but one of the patients received steroids as first-line treatment, with an additional immunosuppressive agent in nine cases. During follow-up, complete remission was achieved in 21 patients, within 1 month in 17 cases. Only one patient had not achieved at least partial remission after 3 months of follow-up. Conclusions: This case series suggests that, in rare patients, COVID-19 vaccination may trigger INS relapse that is generally easy to control. These findings should encourage physicians to persuade their patients to complete the COVID-19 vaccination schedule.

Comparison of the injection of low-molecular weight heparin in the arterial vs. venous blood line for preventing extracorporeal circuit clotting during hemodialysis.

Low-molecular weight heparins (LMWH) are widely used for preventing clotting during hemodialysis (HD). Although injection in the venous blood line is recommended to avoid initial loss of LMWH through the dialyzer, LMWH is still frequently administered in the arterial blood line at the start of dialysis. This study aimed to compare the safety and efficacy of the same enoxaparin dose administered through the venous blood line or arterial blood line. We also evaluated antifactor Xa (aXa) activity according to the injection route and dialysis modalities: high-flux (HF) HD, medium cut-off (MCO) HD, and online hemodiafiltration (OL-HDF). Forty-three patients were studied over 18 consecutive dialysis sessions using a fixed enoxaparin dose (20 or 40 mg), first administered through the arterial blood line bolus and then through the venous blood line for another 18 sessions. Compared to arterial blood line administration, venous blood line bolus resulted in a significant increase in median post-dialysis aXa activity: 0.16 (0.1-0.6) IU/ml versus 0.31 (0.1-1.3) IU/ml, respectively, p = 0.006. After arterial blood line bolus of 40 mg enoxaparin, median post-dialysis aXa activity was significantly lower with OL-HDF compared to HF-HD: 0.14 (0.1-0.35) versus 0.32 (0.15-0.49), p = 0.02. A trend for lower clotting within lines and bubble trap using venous blood line bolus was observed. In conclusion, venous blood line enoxaparin injection is safe in OL-HDF patients. However, in HF-HD and MCO-HD, venous blood line injection of 40 mg enoxaparin may increase overdosing risk. Thus, aXa activity should be monitored in HF-HD and MCO-HD patients at risk of bleeding and/or on vitamin K antagonists and careful surveillance is required when administering a 40 mg enoxaparin dose through the venous blood line route.