Our overarching goal is to advance understanding of mitochondrial mechanisms of carbon monoxide (CO) poisoning to develop diagnostics, therapeutics, and clinical trials. CO poisoning remains a major cause of death and disability, affecting 50,000 people per year in the United States alone. Patients removed from fires or following exposure to car and home generator exhaust are placed on 100% oxygen and transferred to a facility with a hyperbaric oxygen (HBO) delivery system. Despite the availability of HBO therapy centers in most major cities, inherent delays in access to and initiation of therapy greatly limit efficacy. In fact, even with HBO oxygen therapy a substantial number of surviving patients exhibit permanent neurocognitive impairments. This highlights an urgent need for alternative therapy. In the present proposal, we propose to study novel antidotal therapies for CO poisoning, based on our in vivo preliminary data that the use of a succinate prodrug relieves partial CIV inhibition caused by CO poisoning. Another existing gap is the lack of effective biomarkers to gauge severity, prognosis, and response to treatment. While a carboxyhemoglobin level is readily available at most institutions, its use is limited only to confirm exposure with no predictive value. The three main objectives our proposal seeks to address are: (1) extent of mitochondrial involvement for diagnostics and therapies; (2) limitations of current biomarkers to gauge severity of disease and treatment response; (3) lack of treatment strategies that target mitochondrial dysfunction to mitigate long-term neurologic and cardiac disability. Specifically for this A1 submission, we recently developed a novel survival swine model for CO poisoning with clinically relevant outcome metrics that include behavioral, imaging, and biomolecular measures. We also have obtained additional noninvasive optical data that also correlate with tissue respiration data. Another important feature of this proposal is the evaluation of a new treatment strategy involving a mitochondrial prodrug with the potential to shift existing treatment paradigm. We will also leverage our biomedical optics technology measuring cerebral blood flow, oxygenation, COHb and redox states of CIV in real time which will allow us to further elucidate the mechanisms of CO combined with repeat measures using two clinically relevant exposure duration with varying doses as well as prolonged low dose CO exposure. Aim 1 • To investigate the mitochondrial mechanisms that contribute to the neurologic and cardiac injury with the use of blood cell as a liquid biomarker in both acute AND early chronic CO poisoning. Aim 2 • Randomized, blinded pre-clinical intervention trial in swine models of CO poisoning to compare an engineered succinate prodrug to standard therapy of hyperbaric oxygen (HBO).