(1003) Characterization of Warfarin Use in Patients on ECMO

Introduction: Extracorporeal membrane oxygenation (ECMO) requires anticoagulation, commonly unfractionated heparin, bivalirudin, or argatroban. No literature exists regarding the use of warfarin during ECMO and our objective was to characterize its use in this population.

Methods: This was a retrospective study of adult patients who received ECMO and more than one dose of concomitant warfarin from 1/1/2014-4/30/24. Characteristics collected were age, gender, dialysis, INR goal, INR values, IV anticoagulation, warfarin administered, ECMO type, ECMO duration, and Intensive Care Unit (ICU) and hospital length of stay (LOS). Thrombotic events were defined as any thrombosis documented in patient care notes (including oxygenator thrombosis). Bleeding events were defined as any blood product administration. All data was summarized using counts, percentages and medians, ranges.

Results: 9 patients were included. Median age was 61 (53-72) and 8 (88.9%) were male. Hospital LOS was 43 days (15-49), ICU LOS was 22 days (6-41), and ECMO duration was 9 days (2-14). All patients were on venovenous ECMO at the time of warfarin administration and 3 required dialysis. All patients received concomitant IV anticoagulation (55.6% bivalirudin, 44.4% heparin). Most patients had a goal INR of 2-3 (88.8%), but one had a goal of 2.5-3.5. The number of warfarin doses administered was 3 (2-6) and starting dose was 3mg (0.5-3). Daily warfarin dose for the duration of therapy was 1mg (0.5-3). 7 patients (77.8%) achieved a therapeutic INR and the warfarin dose on the immediate day prior was 3mg (0.5-3). 5 patients (55.6%) had at least one supratherapeutic INR and the warfarin dose on the immediate day prior was 2.5 mg (1-3). 4 patients (44.4%) received blood products with one also requiring vitamin K due to INR values greater than 8. All those who received blood products had achieved a therapeutic INR and 3 had a supratherapeutic INR. Only one patient (11.1%) experienced thrombosis, which occurred in the oxygenator with a therapeutic INR.

Conclusions: This was the first characterization of warfarin therapy during ECMO, but use was uncommon as only 9 patients were included over 10 years. Conservative warfarin dosing is warranted in this population as no patients received more than 3mg/day and 44.4% required blood products during therapy.