A man collapses at home and is found with a cherry-pink complexion and headache next to a faulty gas boiler. His pulse oximeter reads 99 percent on air. What is the correct interpretation and treatment?
Answer and explanation
Correct answer: D. Carbon monoxide poisoning: the oximeter is unreliable
- Step 1: Carboxyhaemoglobin is read by standard oximeters as oxyhaemoglobin, giving a falsely normal saturation. Step 2. Treatment is the highest concentration of oxygen possible, which shortens carboxyhaemoglobin half-life, and arterial or venous co-oximetry confirms the level. Answer: Carbon monoxide poisoning: the oximeter is unreliable. Why not the others: A 99 percent reading cannot be trusted here. Cyanide would not give a falsely normal oximeter reading in the exposure described and treatment differs. Methaemoglobinaemia gives a reading drifting toward 85 percent.
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