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Drowning with hypoxaemia — RCPSC EM MCQ

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HardEnvironmental emergenciesDrowning with hypoxaemiaRCPSC EM

Several family members develop headache and nausea after using a generator in an enclosed garage. One briefly fainted. Pulse oximetry reads 100%, and the first carboxyhaemoglobin level is 24%. What is the immediate treatment?

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Correct answer: E — Start high-flow 100% oxygen and consult for hyperbaric assessment

The best answer is “Start high-flow 100% oxygen and consult for hyperbaric assessment”. Pulse oximetry cannot distinguish oxyhaemoglobin from carboxyhaemoglobin and is falsely reassuring in CO poisoning. Give high-flow oxygen immediately and assess serious features, including syncope and neurologic or cardiac involvement, with hyperbaric-centre consultation when indicated. Methylene blue treats methemoglobinemia, not CO toxicity.

Reference: Emergency Care BC: Carbon Monoxide Toxicity—Diagnosis and Treatment: https://emergencycarebc.ca/clinical_resource/clinical-summary/carbon-monoxide-toxicity-treatment/