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 demonstra ted to prolong the half-life of r-hirudin and to cause bleeding in patients who have undergone cardiopulmonary bypass (CPB). We assessed the ability o f different filter systems for modified ultrafiltration to eliminate r-hiru din in vitro using simulated CPB. r-Hirudin concentration was measured (chr omogenic laboratory standard plus ecarin clotting time) before and after fi ltration, and its elimination was calculated using both controlled system f low and arterial inflow (separate pump). Four hemofilters (Renoflow II, Bax ter; Arylane H4, Cobe; Ultraflux AV 600, Fresenius; and BCS 110 Plus, lostr a) and two plasmapheresis filter systems (ASAHI Plasmaflow OF, 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 C PB. Ten plasmapheresis filters showed a greater ability than 20 hemofilters to eliminate r-hirudin (60%-70% vs 15%-42%) within the shortest time (80 v s 180 s). Among the four hemofilter systems, the Arylane H4 filter provided the most effective (42%) r-hirudin elimination. Elimination of r-hirudin w as markedly improved using plasmapheresis systems, compared with hemofilter systems. Our findings may be relevant to patients with impaired renal func tion, who have been administered r-hirudin during CPB.