Carbon monoxide poisoning

Carbon monoxide has high affinity for haemoglobin and myoglobin resulting in a left-shift of the oxygen dissociation curve and tissue hypoxia. There are approximately 50 per year deaths from accidental carbon monoxide poisoning in the UK

Questions may hint at badly maintained housing e.g. student houses

Features of carbon monoxide toxicity

• headache: 90% of cases
• nausea and vomiting: 50%
• vertigo: 50%
• confusion: 30%
• subjective weakness: 20%
• severe toxicity: 'pink' skin and mucosae, hyperpyrexia, arrhythmias, extrapyramidal features, coma, death

Typical carboxyhaemoglobin levels

• < 3% non-smokers
• < 10% smokers
• 10 - 30% symptomatic: headache, vomiting
• > 30% severe toxicity

Management

• 100% oxygen
• hyperbaric oxygen

Indications for hyperbaric oxygen*

• loss of consciousness at any point
• neurological signs other than headache
• myocardial ischaemia or arrhythmia
• pregnancy

*as stated in the 2008 Department of Health publication 'Recognising Carbon Monoxide Poisoning'