Salicylate overdose

Question 1

What are 6 features of aspirin (salicylate) poisoning?

Answer 1

1. Hyperventilation
2. Tinnitus
3. Deafness
4. Vasodilatation
5. Sweating
6. Coma - very severe poisoning

Question 2

Where must aspirin overdose be treated and why?

Answer 2

in hospital: plasma salicylate, pH and electrolytes can be measured

Question 3

Why may salicylate concentration require repeated measurement?

Answer 3

absorption of aspirin may be slow so plasma-salicylate concentration may continue to rise for several hours

Question 4

Why is clinical and biochemical assessment very important in additon to measurement of salicyalte levels in aspirin overdose?

Answer 4

plasma-salicylate concentration may not correlate with clinical severity, especially in young and elderly

Question 5

What dosage of aspirin is considered to be more clinically severe?

Answer 5

plasma salicylate concentration of >500mg/L (3.6 mmol/L) unless evidence of metabolic acidosis

Question 6

When should activated charcoal be given for salicyalte poisoning?

Answer 6

within 1h of ingesting >125mg/kg of aspirin

Question 7

What is the typical ABG finding in salicylate poisoning?

Answer 7

initial respiratory alkalosis - stimulates respiratory centres in brain, followed by metabolic acidosis by uncoupling oxidative phosphorylation

Question 8

What are 4 possible aspects of management of salicylate poisoning?

Answer 8

1. Replace fluid losses
2. Measure plasma potassium concentration
3. IV sodium bicarbonate may be given (if potassium in normal range)
4. Haemodialysis if severe

Question 9

Why must plasma potassium levels be measured before giving sodium bicarbonate in salicylate poisoning?

Answer 9

hypokalaemia may complicate alkalinisation of the urine; goal of sodium bicarbonate excretion is to enhance urinary salicylate excretion