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Smoke inhalation with carbon monoxide poisoning — RCPSC EM MCQ

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HardEnvironmental emergenciesSmoke inhalation with carbon monoxide poisoningRCPSC EM

A 42-year-old man is found confused after a house fire. He is agitated, tachycardic and has soot around his mouth but oxygen saturation reads 100% on pulse oximetry. Lactate is 9 mmol/L and venous blood gas shows metabolic acidosis. What is the most appropriate investigation?

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Correct answer: C — Co-oximetry carboxyhaemoglobin level with consideration of cyanide toxicity testing where available

Pulse oximetry can be falsely normal in carbon monoxide poisoning. Co-oximetry confirms carboxyhaemoglobin; severe lactic acidosis after smoke inhalation also raises concern for cyanide toxicity.

Reference: Canadian poison centre guidance; Wilderness and environmental emergency medicine