Control of heparinization by activated clotting time during bypass with improved postoperative hemostasis.

Heparin and protamine dosages monitored during open-heart operations by activated clotting time (ACT) have been reported to be superior to dosage schedules based on body weight or body surface area. To evaluate the automated ACT, 114 consecutive open-heart operations performed between October, 1974, and December, 1975, were studied. Fifty-eight operations prior to April, 1975, using a standard heparin-protamine protocol (Group I) were compared with 56 operations from April to December, 1975, monitored with an automated ACT (Group II). The two groups were similar with respect to surgical procedures, pump time, and perfusion techniques. The protamine/heparin ratio was 25% less in Group II compared with Group I, and the 12-hour postoperative blood loss was 48% less in Group II. The automated ACT is a reliable, rapid, and simple test that has resulted in improved hemostasis following cardiac operation.