Use of activated coagulation time to monitor heparin during cardiac surgery.

Activated coagulation time (ACT) for protamine reversal was monitored in 28 consecutive patients (Group 1) and a standard heparin-protamine protocol was used for an earlier series of 28 patients (Group 2). Although Group 1 received a significantly higher total heparin dose than Group 2 (p less than 0.01), the protamine dose for reversal was significantly less for the ACT group than for the controls (p less than 0.0005). The mean ratio of protamine to total heparin was 1 : 1 (range, 0.33 to 1.44) for the ACT group and 2 : 1 (range, 1.42 to 2.59) for the controls. There were no significant differences between the two groups in operative and postoperative blood loss, transfusion requirements, hematocrit, and partial thromboplastin time. This study shows that the ACT test did not reduce postoperative bleeding significantly when compared with our standard protocol. It also indicates that there is wide individual sensitivity to heparin and that significantly less protamine is required for reversal.