Carbon Monoxide Poisoning

Key points

• • Carbon monoxide is a colourless, odourless gas made by the incomplete burning of fuel, from car exhaust, faulty heaters and fires.
• • It binds haemoglobin far more strongly than oxygen does, forming carboxyhaemoglobin, so the blood cannot carry enough oxygen to the tissues.
• • Because it also stops the remaining oxygen being released to the tissues, the body is starved of oxygen even though the blood is loaded with the gas.
• • Early effects are headache, dizziness and confusion, which can pass unnoticed, so it is a common cause of accidental and suicidal death.
• • A classic but unreliable sign is a cherry-red colour of the skin, lips and (at autopsy) the blood and internal organs.
• • Exposure is supported by measuring the carboxyhaemoglobin level in the blood, which can fall after oxygen treatment but can still be measured even after death.