MRCP revision battle 34.5: Salicylate overdose

Patients who have taken a salicylate overdose are potentially more interesting than those who have taken a paracetamol overdose as salicylate poisoning actually has early clinical features you can look out for,  such as:

• sweating
• tinnitus
• dizziness
• pyrexia
• hyperventilation

A blood gas should show a mixed respiratory alkalosis and metabolic acidosis, and potentially a low potassium.


The sweating and pyrexia are due to uncoupling of oxidative phosphorylation.




The effects of salicylate are dose related:

• 150mg/kg: mild
• 250mg/kg: moderate
• >500mg/kg: severe

Later features of salicylate poisoning include:

• renal failure
• hypo or hyperglycaemia
• seizures
• acidosis

Treatment:

• activated charcoal if within 1 hr
• correct acidosis with 1.26% sodium bicarb
• haemodialysis if:
• conc >700mg/l
• metabolic acidosis resistant to treatment
• acute renal failure
• pulmonary oedema
• seizures
• urinary alkalinization is rarely used and is contra-indicated in cerebral or pulmonary oedema

Lets move on to consider use of haemodialysis in overdoses in general...