RecruitingPhase 1Drug trialHydrogen's Feasibility and Safety as a Therapy in ECPRThe purpose of this project is to test the feasibility and safety of inhaled hydrogen gas (H2) administration as a rescue therapy during cardiac arrest requiring extracorporeal cardiopulmonary resuscitation (ECPR, i.e. mechanical circulatory support). Under exemption from informed consent, patients undergoing refractory cardiac arrest in the cardiac ICU at a participating center will be randomized to standard therapy with or without the administration of 2% hydrogen in gases administered via the ventilator and ECMO membrane for 72 hours.