skip to main content

Salicylate poisoning with mixed acid-base disorder — SCE Acute Medicine MCQ

Instant feedback + full explanation. One question, done properly.

HardClinical pharmacology and poisoningSalicylate poisoning with mixed acid-base disorderSCE Acute Medicine

A 20-year-old man presents after taking a large amount of aspirin. He is vomiting, tachypnoeic and confused. ABG shows pH 7.48, PaCO2 2.7 kPa, bicarbonate 15 mmol/L and lactate 3.2 mmol/L; salicylate concentration is high and rising. What is the most likely acid-base disturbance?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: C — Mixed respiratory alkalosis and metabolic acidosis

Salicylate poisoning classically produces early respiratory alkalosis from direct respiratory-centre stimulation plus metabolic acidosis from uncoupled oxidative phosphorylation and organic acids. The high pH does not mean the patient is safe because bicarbonate is low and toxicity can worsen. Severe features require urinary alkalinisation and possible haemodialysis discussion.

Reference: TOXBASE salicylate poisoning