Effects of mode of inhalation of carbon monoxide and of normobaric oxygen administration on carbon monoxide elimination from the blood.

1. The half-life of carbon monoxide (CO) in blood was studied retrospectively in 26 fire victims and in 19 cases of CO poisoning. Normobaric oxygen therapy was administered via mechanical ventilation in 19 fire victims, and by facial mask to the rest of the casualties. 2. Arterial pH was significantly lower (P < 0.05) and PaO2 significantly greater (P < 0.01) in the mechanically ventilated fire victims compared to the spontaneously breathing fire victims. 3. The blood CO half-lives were 91 +/- 38 min for the 26 fire victims and 87 +/- 40 min for the 19 pure CO intoxications. 4. The blood CO half-lives were 92 +/- 40 min for the 19 mechanically ventilated fire victims and 87 +/- 37 min for the 26 spontaneously breathing subjects. 5. We conclude that the elimination of CO from blood was a slow process with no significant effects on the blood CO half-life of either the cause of the CO poisoning or the mode of normobaric oxygen therapy. These data suggest that enhancement of the elimination of carbon monoxide by normobaric oxygen in both pure CO poisoning and fire victims is more difficult to achieve and more complex than has previously been reported.