Influence of low-dose aprotinin on the inflammatory reaction due to cardiopulmonary bypass in children

Background. The serine protease inhibitor aprotinin inhibits trypsin, kallikrein, and plasmin and enhances the complement hemolytic activity of the first complement component C1. We tested whether low-dose aprotinin influences the inflammatory reaction related to cardiopulmonary bypass. Methods. In an open, randomized study, 25 children undergoing cardiac operations were investigated prospectively. The treated group comprised 11 patients receiving low-dose aprotinin (20,000 kIU/kg [2.8 mg/kg]), and the control group included 14 patients. Complement activation, cytokine production, and leukocyte stimulation were analyzed before, during, and after cardiopulmonary bypass. Results. In all children, significant C3 conversion and C5a generation, interleukin-6 synthesis, and myeloperoxidase, eosinophil cationic protein, and histamine liberation occurred in relation to cardiopulmonary bypass. This was not influenced by aprotinin treatment. In contrast, neutrophil kinetic studies at the end of cardiopulmonary bypass showed a significantly lower increase in the aprotinin as compared with the control group. Conclusions. Our results suggest that low-dose aprotinin has little influence on the inflammatory reaction induced by cardiopulmonary bypass. Aprotinin affects neutrophil mobilization but not white blood cell degranulation related to cardiopulmonary bypass, and has no influence on complement activation and interleukin-6 synthesis.