Two cases of CO poisoning with delayed sequelae improved after long term hyperbaric oxygen (HBO) therapy

We reported two cases of CO poisoning with late sequelae improved after long term HBO therapy. Case 1, exposed to CO by automobile exhaust gas for suicide, immediately regained consciousness by oxygen. Twenty-five days later, disorientation, gait disturbance and urinary incontinence appeared. HBO therapy was done 77 times. Case 2 was exposed to CO by automobile gas by accident. Next day disturbance of consciousness disappeared after oxygen inhalation and additional HBO therapy was done 7 times. Twenty-three days later the patient became akinetic and mutistic. HBO therapy was done 80 times. Symptoms and signs of both cases improved and they returned to their daily work. EEG and CT findings of both patients improved. MRI and SPECT findings of case 1 also improved. Improvement of SPECT findings reflects recovery of brain function. Delayed release of CO from cytochrome oxidase might be associated with the appearance of late symptoms. Long term HBO therapy may be effective for delayed sequelae of CO poisoning and possibly for their prevention