Paediatric Aspirin Toxicity
Lesson Objectives
By the end of this lesson, learners should be able to:
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Describe the pharmacology of aspirin and its clinical uses in children.
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Explain the pathophysiology of aspirin toxicity, including metabolic effects.
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Recognize the spectrum of clinical features from early to life-threatening toxicity.
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Identify appropriate investigations to confirm toxicity and assess severity.
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Apply stepwise management, including decontamination, fluid therapy, alkalinization, and adjunct therapy.
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Understand indications for haemodialysis and critical care referral.
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Monitor and manage complications such as electrolyte disturbances, hypoglycaemia, and renal failure.
Description
Aspirin (acetylsalicylic acid) is widely used as an analgesic, antipyretic, and anti-inflammatory agent. Toxicity occurs when plasma salicylate levels rise beyond the therapeutic window, causing multi-system derangements including metabolic acidosis, respiratory alkalosis, dehydration, and organ dysfunction.
Pathophysiology of toxicity:
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Aspirin uncouples oxidative phosphorylation, increasing metabolic rate.
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Causes direct stimulation of the respiratory center → respiratory alkalosis.
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Accumulation of salicylate anions → metabolic acidosis.
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Electrolyte loss due to vomiting and osmotic diuresis → hypokalemia, dehydration.
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Severe toxicity may result in rhabdomyolysis, renal failure, cerebral edema, and respiratory failure.
Clinical Features
| Stage | Symptoms / Signs |
|---|---|
| Early / Mild | Tinnitus, nausea, vomiting, fever, tachypnea, dehydration, double vision, mild confusion |
| Moderate | Persistent vomiting, lethargy, irritability, diaphoresis, tachycardia, pallor, hyperventilation, mild metabolic acidosis |
| Severe / Life-threatening | Coma, seizures, bizarre behavior, unsteady gait, hypotension, shock, rhabdomyolysis (dark urine), acute renal failure, respiratory failure |
Investigations
| Test | Purpose / Findings |
|---|---|
| Plasma salicylate concentration | Confirms toxicity; guides severity and treatment. |
| Electrolytes, renal function, liver function | Monitor for hypokalemia, acidosis, dehydration, renal injury. |
| Blood glucose | Hypoglycemia is common; monitor every 6 hours. |
| Arterial blood gases | Detect metabolic acidosis, compensatory respiratory alkalosis. |
| Urinalysis | Assess for ketones, rhabdomyolysis (myoglobinuria). |
| ECG | Monitor for arrhythmias due to electrolyte imbalances. |
Toxic dose threshold: Generally >150 mg/kg acutely ingested.
Stepwise Management
| Parameter | Mild Toxicity | Moderate Toxicity | Severe Toxicity |
|---|---|---|---|
| Plasma salicylate | <350 mg/L | >350 mg/L | >700 mg/L |
| Fluids | Oral fluids; correct dehydration | IV fluids two-thirds maintenance; correct dehydration | IV fluids two-thirds maintenance; correct dehydration |
| Sodium bicarbonate | No | 1 mEq/kg IV bolus then continuous infusion of 100–150 mEq in 1 L 5% dextrose at 2× maintenance | 1 mEq/kg IV bolus then continuous infusion of 100–150 mEq in 1 L 5% dextrose at 2× maintenance; monitor urine pH >7.5 |
| Activated charcoal | No | 1 g/kg (max 50 g) orally or via NG tube within 4 hours | 1 g/kg (max 50 g) orally or via NG tube within 4 hours |
| Haemodialysis | No | No | Yes — indicated for severe toxicity, renal failure, or refractory acidosis |
Other supportive measures:
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Potassium supplementation: 20–40 mEq/L in IV fluids to prevent hypokalemia.
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Glucose monitoring: Every 6 hours to detect hypoglycemia.
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Monitor vital signs: Respiratory rate, blood pressure, oxygen saturation, pulse.
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Observation for neurological deterioration (confusion, seizures, coma).
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Frequent ABG analysis to assess acid-base status and adjust sodium bicarbonate infusion.
Complications to anticipate:
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Cerebral edema
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Respiratory failure
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Renal failure
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Electrolyte disturbances
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Hypoglycemia
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Rhabdomyolysis
Key Points Summary
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Aspirin toxicity is a multi-system emergency requiring early recognition.
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Clinical spectrum ranges from tinnitus and nausea to coma and multi-organ failure.
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Activated charcoal is most effective within 4 hours of ingestion.
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IV sodium bicarbonate corrects acidosis and promotes urinary excretion of salicylates.
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Haemodialysis is life-saving in severe or refractory cases.
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Continuous monitoring and supportive care are essential for survival.