Depurative capacity toward medium molecules of the dialyzer Toray NV-U Hydrolink™: A new hydrophilic membrane to perform online hemodiafiltration.

Introduction: New dialysis membranes with new properties are being developed to improve efficacy and tolerance. The hemocompatibility of a polymeric biomaterial is influenced by the layer of water at the blood membrane interface. The new dialyzer TORAY NV-U has a membrane Hydrolink™, designed to suppress platelet adhesion and to improve the hemocompatibility. Until now, there is no experience in online hemodiafiltration (OL-HDF).The objective of the present study is to evaluate the efficacy of this new membrane in OL-HDF therapy compared to another membrane commonly used. Other objectives are to evaluate the inflammatory response, hemodynamic tolerance, and the anticoagulation regimes.

Methods: This is a prospective pilot study performed in five anuric patients receiving OL-HDF. For 1 month patients were kept with their usual dialyzer FX1000 (FMC). Subsequently, the dialyzer was changed to TORAY NV-U (Hydrolink) for 1 month. In the last dialysis session of each dialyzer, blood tests were performed to evaluate inflammation and depurative capacity.

Results: We did not find differences in medium size removal molecules and convective volume: FX1000: 31 ± 9 l per session and Hydrolink™ 30 ± 8 l;  = 0.7); β2microglobulin reduction ratio (RR) FX1000 FMC 83 ± 3%; Hydrolink™ 79 ± 4;  = 0.14; Myoglobin RR FX1000 FMC 72 ± 7%; Hydrolink™ 76 ± 4;  = 0.28. We did not find differences in inflammation parameters: serum IL6 with FX1000 6.0 ± 4.2 pg/mL; Hydrolink™ 7.6 ± 5.0 pg/mL;  = 0.3.During all sessions with the two dialyzers there was adequate plasmatic filling, reaching 85 % filling. All patients had "good" dialyzer status in all dialysis sessions with TORAY NV-U, while the dialyzer status with FX1000 was "good" in 20% of the sessions, "medium" in 30%, and "dirty" in the remaining 50% dialysis sessions.

Conclusions: The new dialyzer Hydrolink™, TORAY NV-U is not inferior to perform OL-HDF compared to dialyzers usually used for this therapy, and could allow decrease heparin doses. Further studies with a bigger sample size and longer follow-up will answer if Hydrolink improves inflammation and assess a better hemodynamic tolerance.