SAQ 192 – Toxicology – aspirin overdose risk assessment
Model Answer
Question 8. aspirin overdose risk assessment.
a. Dose-related risk
| Dose range | Clinical effects | Acid-base disturbance |
|---|---|---|
| <150 mg/kg | Minimal symptoms. | Nil. |
| 150-300 mg/kg | Hyperpnoea, tinnitus, reduced hearing, agitation, nausea, or vomiting. | Respiratory alkalosis. |
| >300 mg/kg | Altered mental state or seizure. | High-anion-gap metabolic acidosis. |
| >500 mg/kg | Potentially lethal toxicity. | Acidaemia. |
b. Serum salicylate levels
- Levels correlate poorly with clinical severity.
- Serial levels every 2-4 hours help detect ongoing or delayed absorption.
- Very high levels may support dialysis.
- Lower levels can still be concerning in chronic poisoning or older patients.
- A rising level after charcoal may indicate repeated charcoal dosing.
c. Decontamination
- Activated charcoal is effective and may be used for doses above 150 mg/kg, including delayed administration.
- For doses above 300 mg/kg, give via nasogastric tube after airway protection; repeat if levels rise.
d. Enhanced elimination
- Use urinary alkalinisation for symptomatic poisoning.
- Haemodialysis is indicated when alkalinisation is not feasible, levels rise despite treatment, or severe toxicity is present.
- Early decontamination and urinary alkalinisation reduce the need for haemodialysis.
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