Carbon monoxide poisoning kills 50 people and seriously injures nearly 200 in the UK each year.

Suspect this in patients who have issues with their boiler/heating at home, especially the elderly.

Pathophysiology

• carbon monoxide binds readily to haemoglobin, forming carboxyhaemoglobin → reduced oxygen-carrying capacity
• in carbon monoxide poisoning the oxygen saturation of haemoglobin decreases leading to an early plateau in the oxygen dissociation curve

PC

It can present in a non-specific manner:

• Headache (90% of cases, most common feature)
• Nausea and vomiting (50%)
• Vertigo (50%)
• Confusion (30%)
• Subjective weakness (20%)

Severe toxicity: Cherry red skin, hyperpyrexia, arrhythmias, extrapyramidal features, coma, death

Examination:

• Tachycardia
• 100% oxygen saturations on pulse oximetry (because it only measures saturation of non-affected haemoglobin molecules)