Acute carbon monoxide poisoning

Carbon monoxide (CO) is responsible for around 3,000 cases of poisoning a year in France. Worldwide, the mortality rate is estimated at 4.6 cases per million inhabitants. The diagnosis of acute CO poisoning necessarily involves a history compatible with exposure, symptoms (except in pregnant women) and ideally a high carboxyhaemoglobinemia (COHb) level when the sampling is performed early after removal of the source (threshold > 3% in non-smokers and > 6% in smokers in France, or > 10% in most international literature). Non-invasive measurements, such as transcutaneous and exhaled CO levels, are too imprecise to be useful in clinical practice, particularly for ruling out CO poisoning with certainty. Indications for hyperbaric oxygen therapy are based solely on clinical signs of severity. In other cases, normobaric oxygen therapy is generally recommended for 12 h, or a minimum of 6 h if symptoms have fully resolved. Poisoning must be reported to either the regional health agency or the poison control center. In the days or weeks following acute poisoning, a condition known as 'post-interval syndrome' (delayed neurological sequelae) may appear. The main risk factor for this syndrome is the severity of the initial neurological symptoms. Medical follow-up is therefore essential to detect this syndrome. Finally, social assistance is sometimes necessary to ensure a patient can safely return home.