Aspirin overdose Flashcards
Define
- Excessive ingestion of aspirin causing toxicity
* Acute ingestion of greater than150mg/kg or 6.5g can cause moderate-severe toxicity in adults
What are the risk factors?
- It can be a result of deliberate self-harm, suicidal intent or by accident
- Children aged 3 years or younger and adults older than 70 more at risk
What’s the pathophysiology?
o Increases respiratory rate and depth by stimulating the respiratory centre in the brainstem
o This hyperventilation –> respiratory alkalosis (in the early stage)
o The body compensates by increasing urinary bicarbonate and K+ excretion
o This leads to dehydration and hypokalaemia
o Loss of bicarbonate, uncoupling of mitochondrial oxidative phosphorylation and the build up of lactic acid can lead to metabolic acidosis
o In SEVERE cases, CNS depression and respiratory failure can occur
Epidemiology
• One of the MOST COMMON drug overdoses
What are the presenting symptoms?
• Early Symptoms o Flushed o Fever o Sweating o Hyperventilation o Dizziness o Tinnitus o Deafness o GI symptoms – nausea, vomiting, haematemesis, epigastric pain • Later Symptoms o Lethargy o Confusion o Convulsions o Drowsiness o Respiratory depression o Coma
What are the signs?
- Fever
- Tachycardia
- Hyperventilation
- Epigastric tenderness
What are the appropriate investigations?
• Bloods
o Salicylate levels (positive or negative)
o FBC – WBC may be elevated
o Blood glucose – hyer or hypoglycaemia
o U&Es - check for hypokalaemia, hypocalcaemia
o Serum ketones – positive particularly in children
o LFTs - high AST/ALT
o Clotting screen - high PT
o Other drug levels (e.g. paracetamol)
o ABG - may show mixed metabolic acidosis and respiratory alkalosis
o Chest x-ray – pulmonary oedema may be present
• ECG
o Signs of hypokalaemia - flattened/inverted T waves, U waves, prolonged PR interval, ST depression
o Sinus tachycardia
