The Chief Medical Officer and Chief Nursing Office November 2013 letter to general practitioners in England has brought together the most up-to-date information on CO poisoning.
The letter updates the CMO/CNO letter of November 2010. It describes the signs and symptoms which should be looked for; explains the investigations which may be necessary to establish whether CO poisoning has occurred; describes how cases should be managed; sets out the main sources of CO in the home; and gives sources of further advice and information.
A copy of a diagnostic tool developed by the Health Protection Agency (now Public Health England), Department of Health, Royal College of General Practitioners and College of Emergency Medicine is attached to the letter.
Recognising the symptoms of CO poisoning is not easy. The most common - headache, nausea and vomiting, tiredness - are also symptoms of a number of other conditions such as food poisoning, flu, migraine or depression.
Patients who present with these symptoms should be asked key questions to identify whether CO poisoning may be the cause.
Tests to check for CO poisoning include measuring the levels of the gas in expired air and the levels of carboxyhaemoglobin in venous blood.