Carbon monoxide poisoning

Carbon monoxide poisoning can cause hypoxia, cell damage, and death. Approximately one third of severe poisonings are fatal.

Carbon monoxide is an odourless, colourless gas. Poisoning can occur following exposure from fire or non-fire sources.

Early symptoms are non-specific and include headache, dizziness, and nausea.

Increasing exposure results in cardiovascular effects such as myocardial ischaemia, infarction, dysrhythmias, and cardiac arrest.

Neurological symptoms include acute stroke-like symptoms, altered mental status, confusion, coma, and syncope.

Make a clinical diagnosis based on the history and symptoms. Use a blood gas analysis to confirm the diagnosis based on the carboxyhaemoglobin level.

High-flow oxygen therapy and supportive therapy are the key treatments for carbon monoxide poisoning. Consult senior colleagues when deciding whether to refer a patient for hyperbaric oxygen treatment.

Complications of hyperbaric treatment include seizures related to oxygen toxicity, barotraumas, and pulmonary oedema.

Carbon monoxide poisoning can occur following exposure to a variety of sources. The increased affinity of carbon monoxide with haemoglobin results in tissue hypoxia and impairment of cellular respiration, and direct effects of carbon monoxide toxicity at the cellular level. The symptoms of carbon monoxide poisoning can be acute or chronic, depending on dose and duration of the exposure. They are mostly non-specific, and vary from headache, nausea, and dizziness to severe cardiovascular and neurological symptoms. People who are most at risk of adverse outcomes after carbon monoxide poisoning are those with coronary heart disease, vascular disease, asthma, or anaemia; pregnant women and their fetuses; children; and older people.[1]UK Health Security Agency. Carbon monoxide: health effects, incident management and toxicology. May 2022 [internet publication]. https://www.gov.uk/government/publications/carbon-monoxide-properties-incident-management-and-toxicology [2]Queensland Ambulance Service. Clinical practice guidelines: toxicology and toxinology/carbon monoxide. Feb 2021 [internet publication]. https://www.ambulance.qld.gov.au/docs/clinical/cpg/CPG_Carbon%20monoxide.pdf ​​ About one third of severe poisonings are fatal.[3]Varon J, Marik PE. Carbon monoxide poisoning. Internet J Emerg Intensive Care Med. 1997;1(2).[4]Tomaszewski C. Carbon monoxide poisoning: early awareness and intervention can save lives. Postgrad Med. 1999 Jan;105(1):39-40, 43-8, 50. http://www.ncbi.nlm.nih.gov/pubmed/9924492?tool=bestpractice.com