Carbon monoxide poisoning

Abstract

Carbon monoxide (CO) poisoning is diagnosed in 1 in 100,000 people per year in the UK, more commonly in winter and in more deprived areas. Toxicity occurs mainly through the formation of carboxyhaemoglobin (COHb), causing ischaemia of vital organs. Features are non-specific and include headache, gastrointestinal upset, dizziness, weakness, convulsions, coma, chest pain and dyspnoea. Neuropsychiatric features can appear up to 40 days after the initial exposure. The diagnosis can be missed unless a history of exposure to sources of CO is elicited or a CO alarm triggered. There may be a history of others (including pets) with a similar illness in a particular location (e.g. home, office) and an improvement in symptoms when away from that location. A COHb concentration >5% in non-smokers, and >10% in smokers, indicates CO poisoning. COHb concentration >30% indicates severe poisoning, although lower concentrations do not rule out severe CO poisoning. Patients should be treated with high-flow oxygen, which usually results in rapid improvement. Complications, including myocardial infarction and stroke-like features, should be managed conventionally. The source of CO should be identified and eliminated. Patients and families should be educated to prevent CO poisoning in the community.