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

Management of Tricyclic Antidepressant Overdose

Immediate administration of sodium bicarbonate (1-2 mEq/kg IV) is the cornerstone of management for tricyclic antidepressant overdose with cardiac toxicity, especially when QRS duration exceeds 100 ms. 1

Initial Assessment and Stabilization

• Establish and maintain airway, provide adequate oxygenation and ventilation; intubation may be necessary for respiratory depression 1, 2
• Obtain ECG immediately to assess for QRS prolongation (>100 ms), PR interval prolongation, and right axis deviation, which are markers of severe toxicity 3, 4
• Initiate cardiac monitoring for early detection of arrhythmias 1
• Secure IV access for medication administration 2

Gastrointestinal Decontamination

• Administer activated charcoal (30-50g) orally or via nasogastric tube if presentation is within 1-2 hours of ingestion and airway is protected 3, 5
• Avoid inducing emesis due to risk of rapid deterioration and seizures 2, 5

Specific Management of Cardiac Toxicity

• For QRS prolongation >100 ms, administer sodium bicarbonate 1-2 mEq/kg IV bolus, repeated as needed to maintain arterial pH 7.45-7.55 1
• Continue sodium bicarbonate as an infusion (150 mEq NaHCO₃ per liter of D5W) after initial boluses to maintain alkalosis 1, 6
• Monitor serum pH and electrolytes during sodium bicarbonate therapy 5, 6
• Avoid Class IA (quinidine, procainamide), Class IC (flecainide, propafenone), and Class III (amiodarone, sotalol) antiarrhythmics as they may worsen cardiac toxicity 1, 6

Management of Hypotension

• Administer IV fluid boluses (10 mL/kg) of normal saline for initial management 1, 3
• If hypotension persists despite fluid resuscitation, epinephrine and norepinephrine are more effective than dopamine 1, 5
• Consider venoarterial extracorporeal membrane oxygenation (VA-ECMO) for refractory shock unresponsive to high-dose vasopressors 1

Management of Seizures

• Administer benzodiazepines (diazepam or lorazepam) as first-line treatment for seizures 5, 4
• If seizures are refractory to benzodiazepines, consider barbiturates or propofol 5
• Muscular paralysis and mechanical ventilation may be required if seizures cannot be controlled with anticonvulsants 5

Monitoring and Supportive Care

• Continue cardiac monitoring for at least 24-48 hours after clinical recovery, as delayed arrhythmias may occur 2, 4
• Monitor for hypoxia, acidosis, and hypokalemia and correct aggressively 5, 6
• Maintain normal body temperature, as hyperthermia can worsen toxicity 1, 6

Special Considerations

• A QRS interval >100 ms is a better predictor of serious complications than serum tricyclic levels 3, 4
• Tricyclic antidepressants are sodium channel blockers, similar to Class Ia antiarrhythmics, and treatment principles are similar 1, 6
• Consider possible co-ingestions, especially with benzodiazepines or opioids, which may require specific antidotes 7

Common Pitfalls to Avoid

• Delaying sodium bicarbonate administration in patients with QRS prolongation 3, 6
• Using physostigmine routinely - it should be reserved for severe cases with life-threatening anticholinergic effects and has significant risks 5, 4
• Failing to recognize that sinus tachycardia with QRS prolongation may be difficult to distinguish from ventricular tachycardia 6
• Underestimating the severity of overdose - even patients who initially appear stable can rapidly deteriorate 2, 4