ID:111 FC-D04-3 Anticoagulation practices during V-V ECMO at TPCH- a retrospective cohort study

Background: The flow of blood across an artificial surface during Venovenous Extracorporeal Membrane Oxygenation (VV ECMO) generates a complex interplay between haemolysis, thrombosis, and consumptive coagulopathy. Anticoagulation is recommended, with unfractionated heparin commonly used. However, evidence supporting an ideal anticoagulation strategy is lacking, and both bleeding and circuit thromboses remain significant complications of VV ECMO. The aim of this study was to examine anticoagulation practices during VV ECMO support in a Quaternary Cardiothoracic and ECMO centre. Methods: Adult (>18yo) patients receiving VV ECMO between 2012-2024 receiving VV ECMO were identified and their electronic medical records reviewed. Data collected included patient demographics, laboratory and ECMO values relevant to anticoagulation practice. Complications were identified by keyword search of the records. Results: Sixty-three patients received VV ECMO during the study period. The percentage patients discharged from ICU post VV-ECMO support increased over the study period, without notable changes in patient demographics. Over the study period, downward trends were observed in: ECMO blood flow rates, Activated Partial Thromboplastin Times (APTTs), incidence of circuit thromboses, bleeding events, and blood transfusions. APTT and Anti-Xa levels correlated poorly with heparin dosing, although Anti-Xa numbers were limited. Anti-Xa better correlated with bleeding complications. Conclusion: The observed downward trends in ECMO blood flow rates and anticoagulation targets were not associated with an increase in thrombotic complications. Additionally, there was a decreasing trend in bleeding complications and blood transfusion requirements. Determining the efficacy and safety of a lower anticoagulation dosing target for VV ECMO will require further prospective trials.