Aspirin Poisoning

Introduction

Poisons are chemical or physical agents that produce adverse responses in biological systems.
Poisoning on the other hand is the ingestion by, or exposure of a patient to excessive doses of a medicine or other substances that may cause harm.
Aspirin toxic doses are associated with increased sensitivity of the respiratory center, incomplete oxidative phosphorylation and increased rate of metabolism

Clinical features of aspirin poisoning

Initial manifestations
(The initial manifestations of aspirin poisoning occur 3-6 hours after an overdose greater than 150mg/kg)

  • Vomiting
  • Sweating
  • Tachycardia
  • Hyperventilation
  • Tinnitus
  • Fever
  • Lethargy
  • Confusion
  • Respiratory alkalosis
  • Impaired renal function
  • Increased anion gap
  • Metabolic acidosis may result

Severe poisoning:

  • Coma
  • Respiratory depression.
  • Seizures
  • Cardiovascular collapse
  • Cerebral and pulmonary oedema

Investigations

  • FBC, ESR
  • Electrolytes, Urea and Creatinine
  • Random Blood Glucose
  • Liver function tests including prothrombin time
  • Blood aspirin levels

Treatment for aspirin poisoning

Treatment objectives

The treatment objectives of aspirin poisoning are:

  1. To prevent or reduce damage to organs
  2. To restore normal metabolic functions

Non-drug treatment

  • Gastric lavage and whole bowel irrigation

Drug treatment

  1. Activated charcoal can be used up to 12 – 24 hours after ingestion (see
    Paracetamol poisoning)
  2. Intravenous infusion of sodium chloride 0.9% (preferably with glucose)
  3. Correct dehydration and ensure good urine output (saline diuresis)
  4. Supplemental oxygen
  5. Supplemental glucose
  6. Intravenous vitamin K 10 mg daily for coagulopathy
  7. Intravenous NaHCO, to alkalinize urine
  8. Correct other electrolyte derangements
  9. Haemodialysis for severe salicylate poisoning

Indications for haemodialysis.

  1. Severe clinical toxicity
  2. Aspirin (acetylsalicylic acid) levels > 7 mmol/L (100 mg/dL) a rapidly rising plasma salicylate level even if not up to 7 mmol/L is an indication forbdialysis
  3. Failure of other treatment modalities
  4. Renal failure
  5. Heart failure
  6. Seizures
  7. Severe acidosis