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<< Diagnosis And Management Of Carbon Monoxide Poisoning In The Emergency Department

Controversies And Cutting Edge

There have been multiple RCTs comparing hyperbaric and normobaric oxygen for prevention of late neurological complications in CO poisoning.12,40-43 These trials have been of varying quality, and the outcomes have been mixed. A double-blinded RCT of 191 patients found a significantly higher rate of neuropsychological test abnormalities among the patients treated with HBO at completion of treatment and no difference at 1-month follow-up.43 Another double-blinded study measured the incidence of cognitive sequelae at 6 weeks in 152 patients randomized to hyperbaric versus normobaric 100% oxygen and room-air treatments. The study was halted early when interim data analysis detected less-frequent cognitive defects in the HBO group (25%) than in the NBO group (46%).40 Both of these studies have been criticized for their methodologies. In the first study, only 46% of patients presented to 1-month follow-up. In addition, it is not clear how cognitive differences at completion of treatment relate to long-term function, which is the primary outcome of interest to patients and physicians. In the second study, the 2 groups had significant differences in baseline cerebellar dysfunction (4% vs 15%) as well as different lengths of exposure to CO at baseline (13 +/- 41 hours vs 22 +/- 64 hours), favoring the group randomized to hyperbaric treatment.

A Cochrane review of 6 RCTs of HBO for CO poisoning did not find sufficient evidence to establish that the administration of HBO reduced the incidence of delayed neurological sequelae. Further, the Cochrane group found that “design or analysis flaws were evident in all trials.”32

The ACEP 2008 policy statement on the subject came to the conclusion that HBO therapy is a treatment option but that “its use cannot be mandated.”7 The Undersea and Hyperbaric Medical Society lists CO poisoning in its indications for the use of HBO but does not give criteria for its consideration.44

Hyperbaric oxygen therapy continues to be widely recommended for cases of severe poisoning, given the presence of some RCT data demonstrating a benefit and that the natural course of severe CO poisoning leads to high morbidity and mortality without treatment. At facilities that do not have a hyperbaric chamber, the clinician must make a risk-versus-benefit decision regarding transfer to another facility.

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Last Modified: 11/23/2017
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