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Salicylate poisoning — SCE Acute Medicine MCQ

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HardToxicology and OverdoseSalicylate poisoningSCE Acute Medicine

A 26-year-old man is assessed on the acute medical unit. He has tinnitus, vomiting, fever and tachypnoea after aspirin ingestion. ABG shows alkalosis with low bicarbonate and raised anion gap. Initial assessment includes relevant observations, bedside tests and urgent blood results. What is the most likely underlying cause/mechanism?

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Correct answer: A — Mixed respiratory alkalosis and high anion gap metabolic acidosis

Mixed respiratory alkalosis and high anion gap metabolic acidosis is the best answer because salicylate poisoning produces respiratory centre stimulation plus metabolic acidosis. Histamine-mediated vasodilatation and bronchoconstriction is plausible, but it is less appropriate for the physiology or timing described in this stem. The other distractors either fit a neighbouring presentation, delay definitive treatment, or miss the key immediate risk. Clinical pearl: Worsening acidosis increases CNS salicylate penetration and toxicity.

Reference: Toxbase; BNF