Carbon monoxide poisoning is a protean disease characterized by hypoxic injury, metabolic poisoning of cells, reperfusion injury mediated by damage to the inside lining of blood vessels, brain lipid peroxidation, and other pathologic processes. Hyperbaric oxygen therapy is beneficial when delivered hyperacutely, but the dose is less certain when there is delay to treatment. Dr. Harch has presented information at the UHMS meeting showing the benefit of low-pressure HBOT and SPECT brain imaging in the treatment of chronic persistent or delayed neuropsychiatric sequelae of CO poisoning (26). In addition, he has successfully used SPECT brain imaging in acute CO poisoning to help track the patient's progress. Below is an example of such a case.