One vs. Three Hyperbaric Oxygen Treatments for Acute Carbon Monoxide Poisoning

Inclusion Criteria: * Symptomatic CO poisoning (headache, nausea, vomiting, dizziness, fatigue, muscle aches, slowed mentation, confusion, or loss of consciousness). * Carboxyhemoglobin (COHb) levels \> 10% or confirmation of poisoning with ambient levels \> 50 ppm in a patient with symptoms compatible with CO poisoning and no other reasonable explanation for their signs and symptoms. * Less than 24 hours from removal from the source of CO exposure and study enrollment. * Accidental poisoning Exclusion Criteria: * Pregnancy * Age \< 18 years or \> 79 years * Complication during first hyperbaric oxygen session precluding subsequent hyperbaric oxygen. * Intentional CO poisoning * Unable to obtain informed consent * Moribund patient * Concomitant smoke inhalation with cyanide poisoning * Bleomycin use within two weeks of study enrollment * Intracardiac defibrillator that cannot be deactivated * Non-English speaking * Unlikely to return at 6 weeks * History of central nervous system (CNS) disease (i.e., Alzheimer's, Parkinson's, dementia, demyelinating disease (MS), etc.) * History of prior brain injury (i.e., stroke, traumatic brain injury) * Presence of chronic debilitating disease likely to result in death within 12 months (i.e., kidney failure on dialysis, heart failure) * Subject has a significant medical condition or conditions that would interfere with the treatment, safety, or compliance with the protocol. * Intubated subjects * Subjects requiring greater than 50% oxyg…