Carbon monoxide poisoning: interpretation of randomized clinical trials and unresolved treatment issues.

Since hyperbaric oxygen therapy (HBO2) appeared as a treatment for CO poisoning in 1960, whether and when to use it for CO poisoning have often been debated. HBO2 has been advocated to treat severe CO poisoning to limit delayed and permanent neurologic sequelae. Initially, inferences about efficacy were based on clinical experience and uncontrolled studies, but since1989, six prospective clinical trials have been reported comparing HBO2 and normobaric O2 administration to treat patients with acute CO poisoning. Of the six trials, four found better clinical outcomes among patients receiving HBO2 while two have shown no treatment effect. The most recent and best-designed randomized controlled clinical trial, performed in Salt Lake City, supports the efficacy of HBO2 in severe acute CO poisoning in accordance with scientific rationale and clinical experience. However, a number of important issues remain for future investigation, which could be addressed in a large multi-center trial. Such a trial should attempt to determine the optimal number of HBO2 treatments and the maximum treatment delay from CO poisoning for HBO2 to provide efficacy in patients with specific risk factors for a poor outcome.