Weight Based Heparin Dosage with Activated Clotting Time Monitoring Leads to Adequate and Safe Anticoagulation in Non-Cardiac Arterial Procedures

Background: Unfractionated heparin has an unpredictable effect in an individual patient. The activated clotting time (ACT) can be used to measure the effect of heparin in the individual patient and guide additional heparin dosages. Previous cohort studies showed that a standardized bolus of 5,000 IU during noncardiac arterial procedures (NCAP) does not lead to an adequate ACT in the vast majority of patients. The aim of this study was to investigate whether an initial heparin dose of 100 IU/kg leads to an adequate but safe ACT, from 200 to 300 s. Methods: In this multicenter prospective study, 186 patients undergoing NCAP were enrolled and received an initial heparin dose of 100 IU/kg. Target ACT was set at ≥250 s initially; during the course of the study the target ACT was lowered to ≥200 s. After the initial heparin dose, additional heparin dosages were administered depending on the ACT values following a heparin dose protocol. ACT measurements and complications were monitored. Results: The mean baseline ACT was 134 ± 17 s. The mean ACT 5 minutes after the initial heparin dose was 227 ± 37 s. After the initial dose of heparin, 78 and 46% of patients reached an ACT of 200 and 250 s, respectively. Seven patients (4%) reached an ACT of 300 s or more. Ninety-four patients (51%) received at least one additional dose of heparin. After one additional dose of heparin, 91% of patients reached an ACT of 200 s and 13 patients (7%) reached an ACT of 300 s or more. Arterial thromboembolic complications occurred in 4.3% and bleeding complications occurred in 9.7%. Conclusions: A bolus of 100 IU/kg of heparin during NCAP results in adequate coagulation in most patients. ACT measurements enable accurate additional dosing, ensuring the individual patient tailored and safe coagulation. Key words: anticoagulants; heparin; blood coagulation tests; vascular surgical procedures; peripheral vascular diseas