Introduction: Although hyperbaric oxygen therapy (HBO) is broadly used for carbon monoxide (CO) poisoning, its efficacy and practical modalities remain controversial.
Objectives: To assess HBO in patients poisoned with CO.
Design: Two prospective randomized trial on two parallel groups.
Setting: Critical Care Unit, Raymond Poincaré Hospital, Garches, France.
Subjects: Three hundred eighty-five patients with acute domestic CO poisoning.
Intervention: Patients with transient loss of consciousness (trial A, n = 179) were randomized to either 6 h of normobaric oxygen therapy (NBO; arm A0, n = 86) or 4 h of NBO plus one HBO session (arm A1, n = 93). Patients with initial coma (trial B, n = 206) were randomized to either 4 h of NBO plus one HBO session (arm B1, n = 101) or 4 h of NBO plus two 2 HBO sessions (arm B2, n = 105).
Primary endpoint: Proportion of patients with complete recovery at 1 month.
Results: In trial A, there was no evidence for a difference in 1-month complete recovery rates with and without HBO [58% compared to 61%; unadjusted odds ratio, 0.90 (95% CI, 0.47-1.71)]. In trial B, complete recovery rates were significantly lower with two than with one HBO session [47% compared to 68%; unadjusted odds ratio, 0.42 (CI, 0.23-0.79)].
Conclusion: In patients with transient loss of consciousness, there was no evidence of superiority of HBO over NBO. In comatose patients, two HBO sessions were associated with worse outcomes than one HBO session.