Use of the activated coagulation time in intraoperative heparin reversal for cardiopulmonary operations.

Activated clotting time (ACT) was used in 300 consecutive patients undergoing cardiac operations to determine the adequacy of heparin reversal. Mean ACT prior to protamine sulfate administration was 9 minutes 40 seconds. A return to normal value (less than 2 min 10 sec) occurred in three-fourths of our patients following administration of 1.5 mg of protamine sulfate for each 100 units of heparin. Additional protamine sulfate was administered in 50 mg doses to those having abnormal ACT until normal clotting was obtained. Normal values for ACT usually coincided with clotting in the operative field. ACT proved to be a reliable guide to protamine sulfate administration.