OSCE — Carbon Monoxide Poisoning

Brief (to candidate)

You will assess a patient with a presentation consistent with Carbon Monoxide Poisoning.
You have 8 minutes to take a focused history, outline examination, investigations, and management including red flags.

Clinical context

Carbon monoxide (CO) poisoning is a leading cause of unintentional poisoning deaths worldwide — a colourless, odourless, tasteless gas produced by incomplete combustion of carbonaceous fuels. The clinical syndrome arises because CO binds haemoglobin with an affinity approximately 240 times that of oxygen, forming carboxyhaemoglobin (COHb) that both reduces oxygen-carrying capacity and shifts the oxyhaemoglobin dissociation curve leftward (impairing oxygen unloading at tissue). Additional injury occurs through direct mitochondrial poisoning (cytochrome c oxidase / cytochrome aa3 inhibition), oxidative stress from neutrophil priming, and lipid peroxidation of myelin-rich white matter that prod

Candidate tasks

1. Clarify onset, severity, associated features, and red-flag symptoms.
2. State focused examination priorities.
3. List first-line investigations and any named score/criteria.
4. Give immediate resuscitation steps.
5. Outline definitive management with doses/routes where standard.
6. Name complications and disposition (ward / HDU / theatre / discharge safety-net).
7. Mention one special-population modifier (pregnancy, child, elderly, CKD).

Examiner checklist

Model outline

Lead with the working diagnosis and life threats. Resuscitate before definitive tests when unstable. Use guideline-standard therapy with named agents and doses. Document escalation criteria and follow-up. A safe candidate is specific, structured, and never delays critical care for non-urgent imaging.