Impact of low-dose heparin on accurate anticoagulation during cardiopulmonary bypass and postoperative blood loss in cardiac surgery

Activated clotting time (ACT) is most commonly measured for monitoring the anticoagulation effect of heparin during cardiopulmonary bypass (CPB). The aim of this study was to compare the standard heparin dose (300 IU/kg) with lower doses to achieve ACT of 480 sec during CPB.
Methods: In this prospective, randomized, double-blind clinical trial, 120 patients (40/group) who underwent first-time elective coronary artery bypass grafting were randomized into 3 groups A, B, and C receiving an initial heparin dose of 200, 250, and 300 IU/kg. Extra incremental heparin (50 IU/kg) was added if required to achieve a target ACT of 480 sec before initiating CPB. Postoperative blood loss was measured from the time of heparin reversal until the chest drains were removed 48 h after operation in the intensive care unit.
Results: The study groups were similar in demographic data. Target ACT was achieved in 32.5%, 50%, and 65% of the patients in groups A, B, and C — respectively — after the initial dose of heparin (P=0.051). The postoperative mean blood loss in the 2 groups of B and C (13.14±1.07 and 12.5±0.79 mL/kg, respectively) was lower than that in group A (15.97±1.31 mL/kg) (P=0.58). However, this difference between the 3 groups was not statically significant. The mean total dose of heparin in groups A and B was lower than that in group C (P=0.002).
Conclusions: The patients receiving lower doses of heparin to achieve the target ACT did not have lower postoperative blood loss. An initial heparin dose of 300 IU/kg was most often sufficient to reach the target ACT with the lowest incremental dose of heparin.