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

Management of Tricyclic Antidepressant (TCA) Overdose

Sodium bicarbonate administration is the first-line treatment for TCA overdose with cardiac toxicity, administered as 1-2 mEq/kg IV bolus and repeated as needed to maintain arterial pH 7.45-7.55 for QRS prolongation >100 ms. 1, 2

Initial Assessment and Stabilization

• Establish and maintain airway, provide adequate oxygenation and ventilation, and consider early intubation for respiratory depression 2
• Initiate cardiac monitoring immediately for early detection of arrhythmias, particularly focusing on QRS duration 2
• Obtain ECG or rhythm strip during initial assessment - QRS duration >100 msec indicates severe toxicity requiring immediate intervention 1, 3
• Contact regional poison center for expert guidance in management 4

Specific Management of Cardiac Toxicity

• For QRS prolongation >100 ms or cardiac arrhythmias:

  • Administer sodium bicarbonate 1-2 mEq/kg IV bolus 1, 5
  • Repeat doses as needed to maintain arterial pH 7.45-7.55 2
  • Monitor serum sodium (target <150-155 mEq/L) and pH (target <7.50-7.55) to avoid iatrogenic harm 1
  • Consider continuous sodium bicarbonate infusion after initial boluses, though evidence for superiority over repeated boluses is unsettled 1

• For wide-complex tachycardia refractory to sodium bicarbonate:

  • Consider lidocaine as a second-line therapy (Class Ib antiarrhythmic) 1
  • Avoid Class IA, IC, and III antiarrhythmics as they may worsen cardiac toxicity 2
  • Phenytoin may be considered as an alternative second-line therapy 1

Management of Hypotension

• Administer IV fluid boluses (10 mL/kg) of normal saline for initial management 2
• For persistent hypotension despite fluid resuscitation, continue sodium bicarbonate therapy 1, 5
• For refractory shock, consider venoarterial extracorporeal membrane oxygenation (VA-ECMO) 1, 2

Seizure Management

• Administer benzodiazepines for TCA-associated seizures 3
• Avoid flumazenil in patients with suspected TCA overdose as it may precipitate seizures 4, 3
• Avoid physostigmine as it may cause asystole in TCA overdose patients 6

Gastrointestinal Decontamination

• Activated charcoal (30-50g) may be administered for recent ingestions if no contraindications exist 3, 5
• Do not induce emesis 3
• Do not delay other treatments to administer activated charcoal 3

Advanced Management for Refractory Cases

• For life-threatening toxicity refractory to standard therapy:
  • Consider intravenous lipid emulsion (ILE) therapy as a last resort, not as first-line therapy 1
  • Consider VA-ECMO for refractory cardiogenic shock 1

Monitoring and Supportive Care

• Monitor serum potassium levels as hypokalemia may develop during sodium bicarbonate therapy 1
• Maintain normal body temperature, as hyperthermia can worsen toxicity 2
• Continue cardiac monitoring until QRS normalizes and patient is asymptomatic for at least 6 hours 3

Common Pitfalls to Avoid

• Failing to recognize the urgency of QRS prolongation >100 ms as an indicator of severe toxicity 1, 3
• Delaying sodium bicarbonate administration in patients with cardiac toxicity 5
• Using physostigmine for anticholinergic effects of TCAs, which can precipitate asystole 6
• Underestimating the potential for rapid clinical deterioration - patients may initially appear stable then quickly deteriorate 7, 8
• Failing to consider possible co-ingestions, especially with benzodiazepines or opioids 2