Changing systems for measuring activated clotting times: Impact on the clinical practice of heparin anticoagulation during cardiac surgery

The activated clotting time (ACT) is a standard monitor for heparin anticoagulation during cardiopulmonary bypass (CPB). This study determines the effect of upgrading our ACT system on our clinical practice with regards to the conduct and safety of heparin anticoagulation during cardiopulmonary bypass. We compared the intraoperative heparin doses required for all adult cardiac surgery patients ( n=1240) and postoperative bleeding for a subset of primary aortocoronary bypass (CABG) surgery procedures ( n=285) from cohorts before and after the change in ACT systems. The heparin dose needed to exceed our target ACT of 480 sec for the duration of CPB was higher (45 000 vs. 40 000 units; p