SHOCK6: Assessment of anticoagulation status with thrombin time during bivalirudin infusion in patients on extracorporeal life support

Abstract

The purpose of this study was to evaluate the use of thrombin time (TT) to inform adjustments in anticoagulation strategies for the maintenance of extracorporeal life support (ECLS) circuit patency in patients receiving bivalirudin. Previous studies show the average life span of a circuit is 264 hours. Our single center, retrospective study included 13 adult patients on ECLS receiving bivalirudin who obtained TT to assess the degree of anticoagulation. The primary outcome was the number of oxygenator changes associated with circuit thrombosis. Secondary outcomes were major and minor bleeding, survival to ECLS decannulation and hospital discharge, time on ECLS, and venous thromboembolism (VTE). There were a total of 4 oxygenator changes among 3 out of the 13 patients included in the study. The median time on circuit was 354 hours (216 to 480) before a circuit change was required. Major bleeding occurred in 4 patients and minor bleeding occurred in 8 patients. There were 10 patients who survived to ECLS decannulation and 9 patients survived to discharge. Time on ECLS ranged from 144 to 1032 hours. VTE occurred in 3 patients. Among the 195 TT collected while aPTT was therapeutic for 8 patients, 30% of dose adjustments occurred within the next aPTT check or 24 hours. The use of TT was prompted primarily due to increased fibrin deposits on circuit despite therapeutic aPTT. We observed that the use of TT was associated with longer duration on circuit before an oxygenator change was required. The utility of TT to guide adjustments to anticoagulation strategies for bivalirudin in ECLS warrants further investigation.