What is the treatment for a Tricyclic Antidepressant (TCA) overdose?

Treatment of Tricyclic Antidepressant (TCA) Overdose

Administer sodium bicarbonate 1-2 mEq/kg IV bolus immediately for any patient with QRS prolongation >100 ms or life-threatening cardiotoxicity from TCA overdose. 1, 2

Initial Assessment and Stabilization

Airway and Breathing:

• Establish and maintain airway patency as the first priority 2
• Consider early endotracheal intubation for respiratory depression or altered mental status 2
• Provide bag-mask ventilation if needed before intubation 3

Cardiac Monitoring:

• Obtain an ECG or rhythm strip immediately during initial assessment 2, 4
• A QRS duration >100 ms indicates severe toxicity requiring immediate sodium bicarbonate administration 1, 2, 4
• Terminal rightward axis deviation in lead aVR is an early warning sign of impending ventricular dysrhythmias 1

Specific Management of Cardiac Toxicity

Sodium Bicarbonate (First-Line Therapy):

• Administer 1-2 mEq/kg IV bolus for QRS >100 ms, cardiac arrhythmias, or hypotension 1, 2, 5
• Repeat doses as needed to maintain arterial pH 7.45-7.55 1, 2
• Monitor serum sodium (target <150-155 mEq/L) and pH (target <7.50-7.55) to avoid iatrogenic complications 2
• Monitor serum potassium as hypokalemia may develop during therapy 2

Antiarrhythmic Considerations:

• Avoid Class IA, Class IC, and Class III antiarrhythmics as they worsen cardiac toxicity 2
• Consider lidocaine (Class Ib) as second-line therapy for wide-complex tachycardia refractory to sodium bicarbonate 2

Management of Hypotension

Fluid Resuscitation:

• Administer IV fluid boluses of 10 mL/kg normal saline for initial hypotension management 2
• Continue sodium bicarbonate therapy for persistent hypotension despite fluid resuscitation 2

Refractory Shock:

• Consider venoarterial extracorporeal membrane oxygenation (VA-ECMO) for refractory shock unresponsive to high-dose vasopressors 1, 2

Gastrointestinal Decontamination

• Administer activated charcoal 30-50 g orally or by nasogastric tube if patient presents within 1-2 hours of ingestion and airway is protected 4, 5
• Do not induce emesis 4
• Do not delay transportation or critical interventions to administer activated charcoal 4

Seizure Management

• Administer benzodiazepines (diazepam or midazolam) for TCA-induced seizures 1, 4
• Do not administer flumazenil in TCA overdose as it can precipitate seizures 3, 4

Advanced Management for Refractory Cases

Intravenous Lipid Emulsion (ILE):

• Consider ILE therapy as a last resort for life-threatening toxicity refractory to standard therapy 2

Magnesium Sulfate:

• Magnesium may be beneficial for ventricular arrhythmias refractory to standard treatments, though evidence is limited 6, 7
• Magnesium is not a replacement for sodium bicarbonate, which remains first-line therapy 6

Monitoring and Disposition

Observation Period:

• Asymptomatic patients who remain symptom-free for 6 hours after ingestion are unlikely to develop toxicity and may not require emergency department referral 4
• All symptomatic patients (weak, drowsy, dizzy, tremulous, palpitations) require immediate emergency department referral 4
• The greatest number of adverse cardiac symptoms occur within the first 24 hours after overdose 8

Dose-Based Referral Thresholds:

• Refer to emergency department for ingestions >5 mg/kg for most TCAs 4
• Lower thresholds apply for desipramine, nortriptyline, and trimipramine (>2.5 mg/kg) and protriptyline (>1 mg/kg) 4

Critical Pitfalls to Avoid

• Never assume a walking, talking patient is stable—TCA toxicity can cause rapid deterioration and death 9
• Do not use Class IA, IC, or III antiarrhythmics, which exacerbate sodium channel blockade 2
• Do not administer flumazenil, as it precipitates seizures in TCA overdose 3, 4
• Maintain normal body temperature, as hyperthermia worsens toxicity 2
• Consider co-ingestions, especially with other psychopharmaceutical agents, which may alter management 4