INTRODUCTION Activation of the complement system and leukocytes by blood-membrane interactions may further promote arteriosclerosis typically present in patients on lipoprotein apheresis. As clinical data on the hemocompatibility of lipoprotein apheresis are scarce, a controlled clinical study comparing two different types of plasma separation and fractionation membranes used in double filtration lipoprotein apheresis was urgently needed, as its outcome may
influence clinical decision-making. METHODS In a prospective, randomized, crossover controlled trial, eight patients on double filtration lipoprotein apheresis were subjected to one treatment with recent polyethersulfone (PES) plasma separation and fractionation membranes and one control treatment using a set of ethylene-vinyl alcohol copolymer (EVAL) membranes. White blood cell (WBC) and platelet (PC) counts, complement factor C5a and thrombin-anti-thrombin III (TAT) concentrations were determined in samples drawn at defined times from different sites of the extracorporeal blood and plasma circuit. RESULTS With a nadir at 25 min, WBC in EVAL decreased to 33.5 ± 10.7 % of baseline compared to 63.8 ± 22.0 % at 20 min in PES (P < 0.001). The maximum C5a levels in venous blood re-entering the patients were measured at 30 min, being 30.0 ± 11.2 µg/L with EVAL and 12.3 ± 9.0 µg/L with PES (P < 0.05). The highest C5a concentrations were found in plasma after the plasma filters (EVAL 56.1 ± 22.0 µg/L at 15 min vs. PES 23.3 ± 15.2 µg/L at 10 min; P < 0.001). PC did not significantly decrease over time with both membrane types, while TAT levels did not rise until the end of the treatment without differences between membranes. Regarding lipoprotein(a) and LDL cholesterol removal, both membrane sets performed equally. CONCLUSION Compared to EVAL, PES membranes cause less leukocyte and complement system activation, the classical parameters of hemocompatibility of extracorporeal treatment procedures, at identical treatment efficacy. Better hemocompatibility may avoid inflammation-promoting effects through blood-material interactions in patients requiring double-filtration lipoprotein apheresis.
