OSCE — Salicylate (Aspirin) Overdose

Brief (to candidate)

You will assess a patient with a presentation consistent with Salicylate (Aspirin) Overdose.
You have 8 minutes to take a focused history, outline examination, investigations, and management including red flags.^[2][3]

Clinical context

Salicylate (aspirin) overdose produces a characteristically MIXED acid-base disorder through three mechanisms: direct stimulation of the medullary respiratory centre (hyperventilation, primary respiratory alkalosis), uncoupling of oxidative phosphorylation in mitochondria (hyperthermia, increased oxygen consumption, lactate), and disturbance of the Krebs cycle (ketoacids and organic acids), together producing a high anion-gap metabolic acidosis. The classic adult blood gas is therefore primary respiratory alkalosis PLUS high anion-gap metabolic acidosis with tinnitus. Early features include tinnitus, deafness, nausea, vomiting, hyperpnoea, fever, sweating; severe poisoning causes agitation,^[1][2]

Candidate tasks

1. Clarify onset, severity, associated features, and red-flag symptoms.^[1][2]
2. State focused examination priorities.
3. List first-line investigations and any named score/criteria.
4. Give immediate resuscitation steps.
5. Outline definitive management with doses/routes where standard.
6. Name complications and disposition (ward / HDU / theatre / discharge safety-net).
7. Mention one special-population modifier (pregnancy, child, elderly, CKD).

Examiner checklist

| Domain | Pass behaviours |^[2][3] |---|---| | Definition | Correct working diagnosis language | | Assessment | Focused, prioritised, red flags sought | | Investigations | Appropriate first-line + interpretation | | Emergency care | ABC / time-critical actions first | | Definitive care | Specific drugs/procedures, not generic phrases | | Safety | Mixed respiratory alkalosis + high anion-gap metabolic acidosis with tinnitus - | | Safety | Salicylate over 7.2 mmol/L (100 mg/dL) 1D or 6.5 mmol/L (90 mg/dL) 2D (lower with impaired kidney function), or severe acidaemia pH at or under 7.20, | | Safety | Non-cardiogenic pulmonary oedema in salicylate overdose - severe poisoning; dial | | Communication | Clear plan and safety-netting |

Model outline

Lead with the working diagnosis and life threats. Resuscitate before definitive tests when unstable. Use guideline-standard therapy with named agents and doses. Document escalation criteria and follow-up. A safe candidate is specific, structured, and never delays critical care for non-urgent imaging.^[1][2]

References4ShowHide

1. [1]Juurlink DN, Gosselin S, Kielstein JT, et al. Extracorporeal Treatment for Salicylate Poisoning: Systematic Review and Recommendations From the EXTRIP Workgroup Ann Emerg Med, 2015.PMID 25986310
2. [2]Proudfoot AT, Krenzelok EP, Vale JA. Position Paper on urine alkalinization J Toxicol Clin Toxicol, 2004.PMID 15083932
3. [3]Temple AR. Acute and chronic effects of aspirin toxicity and their treatment Arch Intern Med, 1981.PMID 7469627
4. [4]McCabe DJ, Lupu AL, Cienki JJ. The association of hemodialysis and survival in intubated salicylate-poisoned patients Am J Emerg Med, 2017.PMID 28438446