Protamine Overdose and Its Impact on Coagulation, Bleeding, and Transfusions After Cardiopulmonary Bypass

We assessed the effects of protamine overdosing on thrombelastometry, bleeding, and transfusions in patients after cardiopulmonary bypass (CPB).In group 1 (n = 15), representing the clinical standard, the protamine dose was based on the initial heparin dose, and group 2 (n = 15) received protamine based on the heparin concentration measured after CPB. Primary end points were thromboelastometric parameters. Secondary end points were perioperative blood loss and utilization of blood products.During CPB, heparin concentrations decreased by 40%, resulting in overdosing of protamine in group 1. Thromboelastometry revealed longer clotting time (CT) in group 1 (P values < .05). Four patients in group 1 but none in group 2 had excessive prolonged CT values (>360 seconds) and concomitant microvascular bleeding, requiring substantial replacement of coagulation factors.Heparin dose-based protamine management leads to protamine overdosing with inhibition of the coagulation process. Protamine management guided by heparin concentration avoids these complications.