Carbon Monoxide Poisoning Sir

Sir, The recent review of carbon monoxide poisoning by Balzan et al' provided helpful advice about this sometimes difficult diagnosis. We would, however, hesitate to follow the recommendations made about the treatment of CO poisoning. Their assessment of the benefit of hyperbaric oxygen (HBO) does not appear to be based on the presented evidence and the potential complications of transporting critically ill patients to HBO facilities do not receive the attention they merit. The authors cite one randomised trial assessing HBO in patients who were not pregnant.2 The indications they propose for HBO include two (impaired consciousness and cardiovascular instability) that were the exclusion criteria in this trial. Case series are also cited.3'4 We do not believe these provide sufficient information to allow clinically useful comparison between different treatments. Their role is to generate rather than to test hypotheses. We conclude with the observation of Thom et al (our italics)2; "Questions that should be addressed include whether treating patients [with hyperbaric oxygen] more than 6 hours after poisoning is effective and whether the benefits outweigh the costs of transportation and treatment."