Satisfactory outcome with low activated clotting time in extracorporeal membrane oxygenation

Optimal anticoagulation is critical for successful extracorporeal membrane oxygenation (ECMO) to counterbalance the activation of the coagulation system initiated by the blood-biosurface reaction and mechanical stresses. Systemic anticoagulation is achieved mainly with unfractionated heparin (UFH). Activated clotting time (ACT) is a widely used laboratory parameter to monitor anticoagulation. The therapeutic range of ACT is 180-220 s. We investigated the effect of a lower target ACT (<150 s) during ECMO on safety and outcomes and compared it with those of a conventional target ACT (180- 200 s). In this single-center, retrospective study, we reviewed 72 adult patients treated with ECMO from March 2017 to October 2019. We included 43 patients after applying the exclusion criteria and divided them into the low ACT group (<150 s, n =14, 32.6%) and conventional ACT group (>= 150 s, n = 29, 67.4%). There was no difference in the successful weaning from ECMO support (50% vs. 62.1%, p = 0.452) and discharge (50% vs. 41.4%, p = 0.594) rates between the groups. One patient in the conventional ACT group had intracranial hemorrhage. There was one thromboembolic complication case with an intra-circuit thrombus. To date, anticoagulation remains a challenge during ECMO. Our results suggest that a lower target ACT does not necessarily increase the thromboembolic risk during ECMO management. Clinicians may consider anticoagulation with lower ACT target for some patients with careful assessment and close monitoring. Further prospective trials are warranted to validate these results.