Non-comatose patients with acute carbon monoxide poisoning: hyperbaric or normobaric oxygenation?

Twenty-six non-comatose patients with acute carbon monoxide (CO) poisoning were randomized into two groups. Both groups were treated as soon as possible and for 2 h, the first group by 100% normobaric oxygen (NBO) and the second by 100% hyperbaric oxygen. At the end of this period, patients treated by HBO had a significant improvement of their clinical and biological conditions compared with patients treated with NBO. Both groups then received the same NBO therapy for 10 h. At the end of this second period, carboxyhemoglobin level was normal in both groups. However, patients treated with NBO showed some clinical impairments, and 3 wk after onset had significantly more electroencephalogram abnormalities and a reduced cerebral blood flow reactivity to acetazolamide. We conclude that HBO reduces the time of initial recovery and the number of delayed functional abnormalities in non-comatose patients with acute CO poisoning. A practical scheme for the use of NBO and HBO in such patients is proposed.