Clinical effects of different protamine doses after cardiopulmonary bypass.

The optimal dose of protamine needed to reverse the anticoagulant effect of heparin after cardiopulmonary bypass is still not known. In this retrospective cohort study, we investigated 3 different dose regimes in 300 patients undergoing coronary artery bypass grafting. Group A patients (n = 100) were given protamine in the ratio of 1.3 mg to 1 mg heparin, group B patients (n = 100) were given 0.75 mg protamine to 1 mg heparin, and group C patients (n = 100) were given protamine in fractionated doses of 1 mg + 0.15 mg + 0.15 mg to 1 mg heparin. The groups were comparable in all major clinical and operative variables. The heparin dose was almost identical in the groups. The rate of red cell transfusion was significantly higher in group B than in the other groups. A similar but nonsignificant trend was observed in the incidence of resternotomy for postoperative bleeding, mediastinal drainage, and postoperative hemoglobin loss. The study demonstrates that a single bolus dose of 1.3 mg protamine to 1 mg heparin is safe and efficient for neutralizing heparin after cardiopulmonary bypass.