What Researchers Did
Researchers reviewed all the available randomized controlled trials comparing hyperbaric oxygen (HBO) to normal oxygen treatment for people poisoned by carbon monoxide, to see whether HBO better prevents brain and nerve problems afterward.
What They Found
This systematic review of eight randomized controlled trials found no statistically significant difference between HBO and normobaric oxygen (NBO) in preventing neurological sequelae after carbon monoxide poisoning. At one-month follow-up, sequelae were present in 242 of 761 patients (36.1%) treated with NBO, compared with 259 of 718 patients (31.8%) treated with HBO. Restricting the analysis to the highest-quality trials or to trials enrolling patients regardless of severity did not change this lack of statistical significance. The reviewers also found evidence of bias inflating HBO's apparent benefit in two positive trials, while methodological problems in negative trials (low follow-up rates, unusual control interventions, and inclusion of less severely poisoned patients) may have caused them to miss a real benefit, if one exists.
What This Means for Canadian Patients
For patients with carbon monoxide poisoning, this review found conflicting and uncertain evidence about whether HBO provides a meaningful benefit over standard oxygen therapy in preventing neurological sequelae. The authors state that firm guidelines on using HBO for CO poisoning cannot be established based on the current trial evidence.
Canadian Relevance
No direct Canadian connection identified.
Study Limitations
The included trials varied widely in quality and poisoning severity, two had no usable data and were excluded, two were published only as abstracts, and the review's authors identified specific biases that may have inflated HBO's benefit in some trials while other methodological issues may have caused negative trials to miss a genuine effect.