Protamine Overdose and Its Impact on Coagulation, Bleeding, and Transfusions After Cardiopulmonary Bypass: Results of a Randomized Double-Blind Controlled Pilot Study

We assessed the effects of protamine overdosing on thrombelastometry, bleeding, and transfusions in patients after cardiopulmonary bypass (CPB). Methods: 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. Results: 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. Conclusions: Heparin dose-based protamine management leads to protamine overdosing with inhibition of the coagulation process. Protamine management guided by heparin concentration avoids these complications.