Monitoring Anticoagulation During Aprotinin Utilization

The literature reviewed discussed the varying practices of anticoagulation measurement in those open heart patients receiving aprotinin. All references have reported an increase in celite ACTs (C-ACTs) in heparinized patients who were treated with aprotinin. Two authors attributed this effect to aprotinin's ability to enhance heparin's anticoagulation and therefore permit a decrease in the heparin dose. Other authorities proved that during aprotinin administration the C-ACTs were artificially prolonged and that the C-ACT should either be maintained at 750 seconds or greater, or not be used at all. An alternative is the kaolin ACT (K-ACT), which is not affected by aprotinin except at serum levels above 500 KIU/ml. An additional method of measurement is the high dose thrombin time (HITT), a test that is not affected by variables that alter the C and K-ACTs but is inaccurate at low heparin levels. There appears to be no ideal method to provide an accurate anticoagulation measurement when considering aprotinin's effect on the hemostatic system. Based on these data, the anticoagulation protocol remains an institutional decision in determining which measurement method will render cardiopulmonary bypass safe and effective when aprotinin is used.