Cefamandole kinetics during cardiopulmonary bypass

The kinetics of cefamandole during cardiac surgery was studied in 16 adult patients given a single intravenous infusion of 20 mg/kg at the time of anesthesia induction. Five normal volunteers who received the same dose served as controls. Cardiopulmonary bypass (CPB) was found to signficantly increase the half-life (t 1/2) of cefamandole. The mean t 1/2 during CPB (113.2 min) was longer than the terminal t 1/2 in normal volunteers (52.0 min; p less than 0.005). Throughout CPB (maximum, 3,7 hr), cefamandole plasma levels were maintained above the minimum inhibitory concentration for those organisms most likely to cause postoperative infections. We conclude that if 20 mg/kg of cefamandole is given within an hour of the beginning of cardiovascular surgery, a supplemental dose is not needed until the patient has been on CPB for at least four hours.