Aspirin Overdose

Question 1

Define Aspirin Overdose

Answer 1

Overdose of Aspirin, causing toxicity

10-20g causes moderate to severe toxicity in adults

Question 2

Aetiology of Aspirin overdose

Answer 2

May be due to deliberate self-harm, suicidal intent, or by accident e.g. in children

Question 3

Aspirin overdose early symptoms

Answer 3

Flushed, fever hyperthermia
Sweating
Hyperventilation
Tinnitus, deafness
Dizziness

Question 4

Later symptoms of aspirin overdose

Answer 4

Resp. depression and signs of pulmonary oedema
Low GCS: Lethargy, confusion, drowsiness, coma
Convulsions/seizures

Question 5

Signs of aspirin overdose

Answer 5

Fever
Tachypnoea
Tachycardia
Epigastric tenderness

Question 6

Investigations for aspirin overdose

Answer 6

Salicylate levels: >500 (>750 = severe)

ECG - flattened T waves (hypokalaemia)

ABG: resp. alkalosis -> metabolic acidosis
U+Es: hypokalaemia if vomiting
LFTs: raised ALT/AST
Clotting screen: prolonged PT

Question 7

Management of an aspirin overdose

Answer 7

Fluid resus and electrolyte correction
<12 h after ingestion - gastric lavage to empty stomach + oral activated charcoal

Moderate: urine alkalinization with IV NaHCO3/sodium bicarb (+ IV potassium chloride)

Severe: consider haemodialysis

Question 8

Pathophysiology of and aspirin overdose

Answer 8

Aspirin stimulates the CNS resp. centre -> Increased RR
Hyperventilation -> resp. alkalosis
Compensation by increasing urinary bicarb and potassium excretion -> dehydration and hypokalaemia
Loss of bicarb + uncoupling of mitochondrial oxidative phosphorylation (salicyclic acid) and build up of lactic acid -> met. acidosis