Complement activation and use of a cell saver in cardiopulmonary bypass. Complement activation was evaluated in ten patients undergoing cardiopulmonary bypass (CPB) and intraoperative blood salvage with a cell saver (CS) to assess the inflammatory response related to the CS. The washed red blood cell concentrate was reinfused after protamine injection. Plasma C3a was measured by radioimmunoassay preoperatively, 5 min before CPB, at 5, 60, and 90 min during CPB, 5 min after protamine infusion, at the end of surgery, and after 24 hr. In addition, a clinical score based on renal, pulmonary, neurologic, and myocardial postoperative evolution was given (0-8) to every patient. Results were compared with the C3a changes and clinical scores obtained from 26 routine (no CS) cardiac surgical patients. Results showed maximal C3a generation after protamine and no further activation in cases of CS concentrate reinfusion, which ranged from 400 ml to 2,000 ml. No difference in clinical score was observed between the CS (1 +/- 1) and control (0.85 +/- 0.6) groups. The authors conclude that the CS does not enhance complement activation resulting from extracorporeal circulation and can be safely used as a blood saving strategy in cardiac surgery. 