What is the treatment for an aspirin (acetylsalicylic acid) overdose?

Treatment of Aspirin Overdose

Aspirin overdose requires immediate supportive care with intravenous bicarbonate therapy to achieve urinary alkalinization (pH 7.5-8.0), and hemodialysis should be initiated without delay for patients with altered mental status, severe acidemia (pH ≤7.20), salicylate levels >7.2 mmol/L (100 mg/dL), or clinical deterioration despite standard therapy. 1, 2

Immediate Supportive Care

The foundation of treatment includes:

• Airway management and fluid resuscitation with correction of electrolyte abnormalities 2
• Volume repletion is critical as salicylate toxicity causes significant fluid losses 1
• Gastrointestinal decontamination with activated charcoal should be administered early (within 1-2 hours of ingestion) if the patient can safely receive it 1, 3
  • Activated charcoal decreases peak salicylate concentrations significantly (by approximately 9.4 mg/L/g of aspirin ingested) 3
  • Multiple doses may be considered, especially in massive ingestions or when bezoar formation is suspected 3, 4

Bicarbonate Therapy: The Cornerstone of Medical Management

Intravenous sodium bicarbonate is essential and serves dual critical functions:

• Creates alkalemia (systemic alkalosis) which minimizes salicylate passage into the central nervous system 1, 2
• Produces alkaluria which reduces renal tubular reabsorption and promotes renal excretion of salicylate 1, 2

Target urinary pH: 7.5-8.0 1, 2

Administration protocol:

• Continue bicarbonate infusion until clinical symptoms resolve AND the patient is clinically stable 2
• Bicarbonate enhances elimination, reducing the apparent elimination half-life from approximately 13.4 hours to 9.3 hours 3
• Monitor for fluid overload as a potential complication of prolonged therapy 2

Absolute Indications for Hemodialysis

Hemodialysis must be initiated immediately for any of the following: 1, 2

• Altered mental status (regardless of salicylate level or pH)
• Severe acidemia with pH ≤7.20 (mandates immediate hemodialysis regardless of salicylate level)
• Salicylate concentration >7.2 mmol/L (100 mg/dL)
• New hypoxemia requiring supplemental oxygen
• Acute respiratory distress syndrome (ARDS) or cerebral edema
• Failure to respond to standard therapy (bicarbonate and supportive care)
• Fluid overload precluding bicarbonate administration
• Renal failure with impaired clearance

Additional considerations for hemodialysis:

• Salicylate levels >6.5 mmol/L (90 mg/dL) with impaired kidney function 2
• Chronic poisoning with levels >3.6-4.2 mmol/L (50-60 mg/dL) 1

Intermittent hemodialysis is the preferred extracorporeal modality 1, 2

• Hemoperfusion is an acceptable alternative if hemodialysis is unavailable 2
• Continue bicarbonate therapy between dialysis sessions until salicylate levels remain consistently below toxic thresholds 2

Critical Monitoring Parameters

Serial measurements are essential:

• Salicylate concentrations every 2-4 hours until steadily decreasing according to expected half-life 4
  • Clinical status is MORE important than absolute salicylate level for treatment decisions 1
• Arterial blood gases to track acid-base status 2, 5
  • Classic presentation: mixed respiratory alkalosis and high anion gap metabolic acidosis 2
  • Isolated respiratory alkalosis may indicate critical CNS penetration and impending deterioration 2
• Serum electrolytes (particularly potassium, as hypokalemia impairs urinary alkalinization) 5
• Mental status (any change warrants immediate hemodialysis) 1, 2

Critical Pitfalls to Avoid

Never suppress compensatory hyperventilation in salicylate toxicity 2

• If intubation becomes necessary, maintain aggressive hyperventilation to prevent catastrophic acidemia 2
• Acidemia promotes CNS salicylate accumulation and can be rapidly fatal 2

Beware of delayed toxicity:

• Salicylate concentrations can increase to toxic levels up to 35 hours after ingestion due to pylorospasm or bezoar formation 4, 6
• Initial undetectable levels do NOT exclude significant toxicity 4, 6
• Rebound toxicity is more likely with extended-release formulations 2

Special consideration for rectal administration:

• Rectal aspirin overdoses have delayed absorption properties 7
• Remove as much aspirin from the rectum as possible 7
• Consider activated charcoal enemas in addition to oral administration 7

Involvement of Toxicology Expertise

Consult a clinical toxicologist or regional poison center immediately 1

• Salicylate poisoning is a medical emergency that is easily underestimated 1
• Expert guidance is essential for optimal management of these complex patients 1