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Hyperbaric oxygen therapy for acute domestic carbon monoxide poisoning: two randomized controlled trials

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Although hyperbaric oxygen therapy (HBO) is broadly used for carbon monoxide (CO) poisoning, its efficacy and practical modalities remain controversial.


To assess HBO in patients poisoned with CO.


Two prospective randomized trial on two parallel groups.


Critical Care Unit, Raymond Poincaré Hospital, Garches, France.


Three hundred eighty-five patients with acute domestic CO poisoning.


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.


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)].


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.

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The study was supported by the Assistance Publique des Hôpitaux de Paris. The sponsor had no role in the study design, data collection, analysis, decision to publish, or preparation of the manuscript. Registration numbers were NCT01100515 for trial A and NCT01099995 for trial B. The authors are grateful to the physicians and nursing staff of Raymond Poincaré Teaching Hospital and to Paris area emergency departments for their valuable contribution.

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Correspondence to Djillali Annane.

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The full trial protocol can be obtained by direct contact with the corresponding author.

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Annane, D., Chadda, K., Gajdos, P. et al. Hyperbaric oxygen therapy for acute domestic carbon monoxide poisoning: two randomized controlled trials. Intensive Care Med 37, 486–492 (2011).

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