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Salicylate poisoning
Salicylate poisoning begins with respiratory alkalosis (stimulation of the respiratory centre) and progresses to a high anion gap metabolic acidosis; treatment is fluids, urine alkalinisation with sodium bicarbonate, potassium correction, and dialysis in severe cases.
Why it matters in the exam
The classic question describes a patient with tinnitus, vomiting, rapid breathing and a blood gas showing metabolic acidosis and respiratory alkalosis together. A common distractor is early intubation — ventilation that does not match the patient's own hyperventilation worsens the acidosis and drives salicylate into the brain.
Treatment targets and dialysis indications are also tested: a urine pH target of 7.5–8.0, normal potassium (hypokalaemia prevents urine alkalinisation), and dialysis when the level is above 100 mg/dL (7.2 mmol/L), above 90 mg/dL (6.5 mmol/L) with poor kidney function, with altered consciousness, new hypoxaemia, or a pH of 7.20 or less.
Chronic poisoning in older people sometimes shows as confusion, fever and non-cardiogenic pulmonary oedema, and is mistaken for sepsis or dementia; its dialysis thresholds are lower. The blood level can keep rising for many hours after ingestion because of tablet clumps or coated preparations, so it is measured every two hours until it is clearly falling. Glucose is given to a patient with altered consciousness, because brain glucose can be low even when blood glucose is normal.
Key points
- Respiratory alkalosis followed by a high anion gap acidosis.
- Repeat levels every two hours — absorption can continue.
- Sodium bicarbonate to a urine pH of 7.5–8.0 and potassium correction.
- Dialysis: level above 100 mg/dL, or above 90 with poor kidneys, altered consciousness, hypoxaemia or a pH of 7.20 or less.
- Beware of intubation — if unavoidable, keep the hyperventilation.
Summary table
| Stage or situation | Finding | Meaning | Action |
|---|---|---|---|
| Early | Respiratory alkalosis, tinnitus, vomiting | Stimulation of the respiratory centre | Fluids, activated charcoal, repeat level |
| Advanced | High anion gap metabolic acidosis | Disturbed cellular metabolism | Sodium bicarbonate, urine pH target 7.5–8.0 |
| Hypokalaemia | Low potassium | Prevents urine alkalinisation | Correct potassium |
| Severe poisoning | Altered consciousness, pulmonary oedema, fever | Salicylate in the brain | Haemodialysis |
| High level | Above 100 mg/dL (7.2 mmol/L), or above 90 (6.5 mmol/L) with poor kidneys | Dialysis threshold | Haemodialysis |
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Sources
- Goldfrank's Toxicologic Emergencies, 11th edition (2019) — Salicylates
- EXTRIP workgroup, Extracorporeal treatment for salicylate poisoning (Annals of Emergency Medicine), 2015 — Recommendations
- Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 9th edition (2020) — Aspirin and nonsteroidal agents
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.