Complement activation by extracorporeal circulation: effects of precoating a membrane oxygenator circuit with human...

In an in vitro study of extracorporeal circulation (ECC), uncoated oxygenators (UC), oxygenators precoated with whole human blood (CN) and oxygenators precoated with blood and then rinsed with Ringer's acetate (CR) all significantly (p less than 0.001) activated the initial and terminal parts of the complement cascade. After 60 min C3 activation had increased by 692% (UC), 750% (CN) and 393% (CR), and terminal complement complex (TCC) concentrations by 194% (UC), 215% (CN) and 273% (CR). C3 activation was significantly (p less than 0.05) less in the CR than in the other groups. There was no statistical intergroup difference in increase of TCC concentration. Complement activation was accompanied by a significant drop in neutrophil counts, which was uninfluenced by coating or rinsing. The observed dissociation of the complement cascade shows that assessment of activation products from both parts is necessary for evaluation of total complement activation. The study suggests that protein precoating may improve biocompatibility of ECC.