Clinical presentation

Carbon monoxide poisoning can cause tissue hypoxia in any organ. Depending on the source of carbon monoxide and where the exposure occurs, multiple patients may present simultaneously with vague symptoms of headache, flu-like symptoms, weakness, confusion and unexplained loss of consciousness. If faulty heaters are the cause of carbon monoxide poisoning, symptoms may have been present for several days or weeks.

The central nervous system is the most susceptible to hypoxia and effects include:

• loss of consciousness or coma, respiratory depression, seizures
• headache, confusion, dizziness, nausea, weakness
• focal neurological signs, including cerebellar abnormalities
• mild to severe cognitive impairment, including memory deficits (eg short-term memory loss) and reduced mathematical ability
• parkinsonism, speech abnormalities
• depressed mood.

Co-ingestion of sedative drugs or alcohol increases the risk of altered conscious state associated with carbon monoxide poisoning.

Neurological effects of severe carbon monoxide poisoning can take weeks or months to manifest, and may be persistent.

Cardiovascular effects of hypoxia include:

• tachycardia, hypotension, hypertension
• myocardial ischaemia and infarction, arrhythmias.

Metabolic effects of hypoxia include lactic acidosis, rhabdomyolysis and hyperglycaemia.