The investigators will randomly assign 34 adult patients requiring ECMO to receive bivalirudin or unfractionated heparin in a 1:1 fashion. There will be 17 patients in each group for a total of 34 patients.~Unfractionated heparin binds to antithrombin thereby causing an anticoagulant effect while bivalirudin binds directly to thrombin. Use of unfractionated heparin in this population is problematic due to reliance on adequate levels of circulating antithrombin, complex pharmacokinetics, and variable clearance. Bivalirudin avoids many of these difficulties.
This study will evaluate heparin as compared to bivalirudin for systemic anticoagulation in adult patients that require extracorporeal membrane oxygenation (ECMO). Half of the participants will receive heparin and half will receive bivalirudin.