Elimination of recombinant hirudin by modified ultrafiltration during simulated cardiopulmonary bypass: Assessment of different filter systems

Recombinant hirudin (r-hirudin) is being used increasingly in patients with heparin-induced thrombocytopenia type II. Renal failure has been demonstrated to prolong the half-life of r-hirudin and to cause bleeding in patients who have undergone cardiopulmonary bypass (CPB). We assessed the ability of different filter systems for modified ultrafiltration to eliminate r-hirudin in vitro using simulated CPB. r-Hirudin concentration was measured (chromogenic laboratory standard plus ecarin clotting time) before and after filtration, and its elimination was calculated using both controlled system flow and arterial inflow (separate pump). Four hemofilters (Renoflow II, Baxter; Arylane H4, Cobe; Ultraflux AV 600, Fresenius; and BCS 110 Plus, Iostra) and two plasmapheresis filter systems (ASAHI Plasmaflow OP, Diamed; and PF 2000 N, Gambro) were assessed (5 filters of each brand = 30 filters) in a closed in vitro CPB system applying conditions usually occurring during CPB. Ten plasmapheresis filters showed a greater ability than 20 hemofilters to eliminate r-hirudin (60%-70% vs 15%-42%) within the shortest time (80 vs 180 s). Among the four hemofilter systems, the Arylane H4 filter provided the most effective (42%) r-hirudin elimination. Elimination of r-hirudin was markedly improved using plasmapheresis systems, compared with hemofilter systems. Our findings may be relevant to patients with impaired renal function, who have been administered r-hirudin during CPB.