What is the management of a tricyclic antidepressant (TCA) overdose?

Management of Tricyclic Antidepressant (TCA) Overdose

Sodium bicarbonate administration is the cornerstone of treatment for TCA overdose with QRS prolongation, ventricular arrhythmias, or hypotension, and should be administered promptly along with supportive care to reduce mortality. 1, 2

Initial Assessment and Stabilization

• Airway and Breathing:

  • Early endotracheal intubation for severe toxicity or altered mental status 2
  • Avoid respiratory acidosis in intubated patients as it worsens toxicity 1

• Circulation:

  • Continuous cardiac monitoring for at least 6 hours post-ingestion 2
  • Obtain ECG immediately - look for:
    • QRS prolongation >100 ms (critical finding requiring intervention)
    • Terminal 40 ms right axis deviation in lead aVR (sensitive marker for TCA toxicity)
    • Brugada-like ECG pattern 2

• Decontamination:

  • Activated charcoal 30-50g orally/via NG tube if patient presents within 1-2 hours of ingestion and has intact airway 3
  • Do not induce emesis 4

Specific Interventions

Sodium Bicarbonate Therapy

• Indications: QRS >100 ms, ventricular arrhythmias, hypotension, or acidosis 2, 3
• Administration: 1-2 mEq/kg IV bolus, repeated as needed 2, 3
• Target: Maintain arterial pH 7.45-7.55 2
• Caution: Monitor for hypokalemia and avoid extreme hypernatremia (serum sodium not to exceed 150-155 mEq/L) 1, 2

Management of Hypotension

• Administer 5-10 mL/kg boluses of normal saline 2
• If hypotension persists despite fluid resuscitation:
  • Epinephrine or norepinephrine are preferred vasopressors (more effective than dopamine) 2
  • Dobutamine may also be considered 1

Management of Arrhythmias

• Sodium bicarbonate is first-line for wide-complex tachycardia 1
• Lidocaine is second-line therapy for persistent ventricular arrhythmias 1, 2
• Avoid Class IA, IC, or III antiarrhythmics (may worsen cardiac toxicity) 2

Management of Seizures

• Benzodiazepines are first-line treatment 4
• Avoid flumazenil (contraindicated in TCA overdose) 4

Refractory Cases

• Consider intravenous lipid emulsion (ILE) if other therapies fail, though evidence is limited 1, 2
• Extracorporeal membrane oxygenation (VA-ECMO) for cardiac arrest or refractory shock 1, 2
• Mechanical circulatory support for cardiogenic shock refractory to other treatments 1

Monitoring Parameters

• Continuous cardiac monitoring
• Serial ECGs to monitor QRS duration
• Electrolytes, particularly potassium (risk of hypokalemia with bicarbonate therapy)
• Arterial blood gases to monitor pH
• Mental status and seizure activity
• Vital signs including temperature (risk of hyperthermia)

Disposition

• All symptomatic patients require admission to a monitored setting 4
• Patients with QRS >100 ms require ICU admission 3
• Asymptomatic patients with unintentional ingestions may not need referral to emergency department if more than 6 hours have passed since ingestion 4

TCA overdose is potentially lethal but responds well to prompt recognition and appropriate management with sodium bicarbonate as the mainstay of therapy for cardiac toxicity.