Project Summary/Abstract Background. The purpose of the proposed research 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). Among patients with congenital heart disease (CHD) receiving ECPR, 52% either die or suffer severe neurologic impairment. Diatomic hydrogen (H2) chemically reduces toxic oxygen mediators that directly damage cellular structures, and has been shown to improve neurologic and renal function in a number of preclinical ischemic injury models. Recently, we have demonstrated that inhalation of 2.4% H2 for up to 72 hours is safe in healthy adults. However, H2 has never been applied to the ECPR population. Study design. We propose an early-phase, two-site, randomized trial of H2 in ECPR patients entitled the ‘Hydrogen FAST Trial’ (Hydrogen’s Feasibility And Safety as a Therapeutic agent). Key Inclusion criteria are (1) patients with CHD (broadly defined, including myocarditis, channelopathies, transplant rejection), (2) experiencing a cardiac arrest >5 minutes and receiving ongoing CPR, and (3) a decision made to resuscitate using ECPR. The trial will be led by MPIs John Kheir, MD and Lynn Sleeper, ScD, who have a strong collaborative history in this area and complementary expertise in critical care, translational research, and clinical trials. Furthermore, the trial design has received favorable feedback from the FDA. During the R61 Phase: (1) Regulatory (IRB and FDA) approvals will be obtained, including exception from informed consent (EFIC) requirements. This is necessary because the emergent nature of ECPR and time- sensitivity of H2 preclude traditional informed consent. Instead, non-opt-out patients will be randomized and enrolled emergently, with subsequent traditional informed consent. (2) Investigational product (IP) manufacturing, storage, and administration logistics will be established. (3) Endpoint adjudication processes and DSMB infrastructure will be established. (4) Study roll-out and clinical staff education will be completed, followed by a 3-patient vanguard phase (Phase 0) trial. During the R33 Phase, 53 patients with CHD will be randomly assigned in a 3:2 (32/21) ratio to either usual care plus 2.4% H2 gas following ECPR for 72 hours or to usual care from two sites. Primary endpoints include measures of feasibility and safety (rate of treatment-associated severe adverse events, adjudicated by an independent committee blinded to treatment group). Secondary endpoints will include functional status, brain biomarkers and cranial images obtained using a new point-of-care MRI device. Impact. The experienced team and infrastructure in place for this trial will ensure the successful completion of R31 and R466 milestones. If H2 therapy is shown to be feasible and safe, this work will provide a foundation for H2 administration in the critical care environment, and subsequent testing in cardiac arrest, stroke, myocardial infarction, and other disorders in which ischemia-reperfusion injury plays a role.

Project Narrative The goal of this project is to examine the feasibility and safety of administering hydrogen gas to patients suffering from cardiac arrest treated with emergency heart-lung bypass. Oxygen deprivation to the brain results in severe brain injury or death in more than 50% of these patients, and hydrogen may be a therapy to directly interrupt the culpable mechanisms of brain injury. If feasible and safe, hydrogen administration may improve outcomes in cardiac arrest, stroke, myocardial infarction, organ transplant, and sepsis, all pathologies in which ischemia-reperfusion injury plays a central role.