Salicylate/Aspirin Overdose

Snapshot

• A 20-year-old man presents to the emergency room after an intentional overdose of aspirin. He reports ingesting an unknown amount of aspirin about 30 minutes prior to presentation with the intention of committing suicide. However, he changed his mind and asked to be saved. He reports some nausea, vomiting, and ringing in his ears. He is started on intravenous hydration and given activated charcoal.  

Introduction (Salicylate/Aspirin Overdose)

• Clinical definition
  • a constellation of symptoms resulting from toxicity or overdose from salicylates, most commonly aspirin
• Epidemiology
  • demographics
    • patients taking chronic pain medications
• Etiology
  • intentional overdose
  • accidental overdose
• Pathogenesis
  • salicylates have multiple effects on the body
    • hyperventilation and early respiratory alkalosis 
      • aspirin directly stimulates the respiratory centers in the brainstem
    • later metabolic acidosis, resulting in mixed metabolic acidosis-respiratory alkalosis
      • aspirin uncouples oxidative phosphorylation, which impairs the Krebs cycle
        • this results in a lactic acidosis
    • tinnitus
      • aspirin is toxic to cranial nerve VIII
    • acute respiratory distress syndrome
      • aspirin is also toxic to the lungs
    • renal insufficiency
      • aspirin is toxic to the renal tubules
    • increased bleeding time
      • aspirin inhibits platelet aggregation
• Prognosis
  • depends on the severity of toxicity
• severe cases may be fatal

Presentation

• Symptoms
  • tinnitus
  • nausea
  • vomiting
  • fever
  • lethargy
  • seizure or coma (in cases of severe poisoning)
• Physical exam
  • tachypnea
  • tachycardia
• hyperthermia

Studies

• Labs
  • arterial blood gas to evaluate for acidosis or alkalosis
  • serum salicylate level
    • to confirm the diagnosis
    • measure every 3 hours as toxicity can be delayed
  • chemistry panel with liver function tests
    • to assess renal and hepatic function
• Making the diagnosis
  • based on clinical presentation and laboratory studies
• especially if patients present with tinnitus, anion gap metabolic acidosis, and elevated serum salicylate levels

Differential

• Acetaminophen overdose
  • distinguishing factors
    • hepatic failure
    • no tinnitus or acid-base derangement
• the antidote is N-acetylcysteine

Treatment

• Conservative
  • supportive care
    • indication
      • for all patients
    • modalities
      • intravenous hydration
• Medical
  • activated charcoal
    • indications
      • for patients with known salicylate ingestion within the past hour
      • to block absorption
  • sodium bicarbonate
    • indications
      • for patients in whom supportive care is not sufficient, or if patients are not good candidates for activated charcoal
      • alkalinize urine to increase excretion of salicylates
      • alkalinize serum to decrease central nervous system toxicity
• Non-operative
  • dialysis
    • indication
• for severe cases (salicylate concentration > 100 mg/dL) or if clinical features are severe

Treatment for salicylate overdose typically involves the following steps:

1. Activated charcoal administration: In cases where the overdose is recent (within the last hour or so), activated charcoal may be given to help prevent further absorption of the salicylate into the body. Activated charcoal works by binding to the medication in the digestive system, reducing its absorption.
2. Supportive care: The person’s vital signs, such as heart rate, blood pressure, and breathing, will be closely monitored. If necessary, intravenous fluids may be administered to maintain hydration and electrolyte balance.
3. Correction of acid-base imbalance: Salicylate overdose can cause metabolic acidosis, which means there is an excess of acid in the body. Treatment may involve the administration of sodium bicarbonate intravenously to correct the acid-base balance.
4. Enhanced elimination: In some cases, measures may be taken to enhance the elimination of salicylate from the body. This can include techniques such as hemodialysis or hemoperfusion, which involve filtering the blood to remove the medication.

Complications

• Renal failure

Symptoms and Signs of Salicylate/Aspirin Overdose

Salicylate poisoning, which can occur from an overdose of aspirin or other salicylate-containing medications, can present with various symptoms and signs. The severity and onset of these symptoms can vary depending on the dose ingested, the individual’s age and health, and the time elapsed since the ingestion. Here are some common symptoms and signs of salicylate poisoning:

1. Tinnitus (ringing in the ears): Tinnitus is a common early symptom of salicylate poisoning and can range from mild to severe.
2. Hyperventilation (rapid breathing): Increased breathing rate and depth of breathing may occur as the body tries to compensate for the metabolic acidosis caused by salicylate overdose.
3. Nausea and vomiting: Gastrointestinal symptoms, such as nausea and vomiting, are common in salicylate poisoning.
4. Dizziness and confusion: As salicylate levels rise, it can affect the central nervous system, leading to dizziness, confusion, and altered mental status.
5. Sweating and fever: Salicylates can cause an increase in body temperature and profuse sweating.
6. Dehydration: Salicylate poisoning can lead to dehydration due to fluid loss from vomiting, increased respiratory rate, and sweating.
7. Rapid heart rate: Tachycardia, or a fast heart rate, is a possible manifestation of salicylate overdose.
8. Hypoglycemia (low blood sugar): In severe cases, salicylate poisoning can cause hypoglycemia, which may lead to symptoms like weakness, confusion, and seizures.
9. Respiratory distress: In some cases, salicylate overdose can result in respiratory distress, including shortness of breath and difficulty breathing.
10. Seizures: Seizures can occur in severe cases of salicylate poisoning.

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