Management of Combined SSRI, Benzodiazepine, and TCA Overdose

Initial Cardiac Assessment

• Obtain an immediate 12‑lead ECG and initiate continuous cardiac monitoring in any patient with suspected combined SSRI, benzodiazepine, and TCA overdose; specifically evaluate for QRS duration > 100 ms, terminal right‑ward axis deviation in lead aVR, and ventricular dysrhythmias. 1

Sodium Bicarbonate Therapy (Primary Intervention)

• Administer intravenous sodium bicarbonate promptly when any of the following are present: QRS > 100 ms, ventricular dysrhythmias, hypotension, seizures, or any life‑threatening cardiotoxicity. This is the definitive life‑saving treatment for TCA‑related sodium‑channel blockade. 1
• Dosing:
  
  • Adults – 50–150 mEq IV bolus (using 1 mEq/mL solution).
  • Children – 1–3 mEq/kg IV bolus (using 0.5 mEq/mL solution).
  • Continuous infusion – prepare a 150 mEq/L solution and infuse at 1–3 mL/kg/h; repeat boluses as needed to narrow the QRS and control dysrhythmias. 6
• Therapeutic targets and monitoring: aim for serum pH 7.45–7.55 while watching for hypernatremia, alkalemia, hypokalemia, and hypochloremia. 1

Seizure Management

• Use benzodiazepines (e.g., IV diazepam or midazolam) as first‑line therapy for seizures occurring in this mixed overdose. 2
• The presence of seizures signals severe TCA toxicity and should trigger aggressive sodium bicarbonate therapy. 1

Flumazenil Contraindication

• Flumazenil must not be given in mixed SSRI‑benzodiazepine‑TCA overdoses because TCAs lower the seizure threshold and flumazenil can precipitate refractory seizures and dysrhythmias; meta‑analyses demonstrate higher rates of serious adverse effects with its use in such scenarios. 3

Hemodynamic Support

• Initiate IV crystalloid fluids for hypotension; if blood pressure remains low despite fluids and sodium bicarbonate, start vasopressor agents. 1

Refractory Cardiogenic Shock and Cardiac Arrest

• Consider veno‑arterial extracorporeal membrane oxygenation (VA‑ECMO) early for patients with:
  
  • Refractory cardiogenic shock,
  • Ventricular dysrhythmias unresponsive to sodium bicarbonate, or
  • Cardiac arrest that does not respond to standard ACLS measures. 1

Adjunctive Antidysrhythmic Therapies

• If sodium bicarbonate fails to control life‑threatening sodium‑channel blockade, intravenous lidocaine (Class Ib) may be used as an alternative anti‑arrhythmic. 1
• Intravenous lipid emulsion can be considered for refractory sodium‑channel blocker poisoning when other treatments are ineffective. 2

Monitoring During Observation

• Maintain continuous cardiac monitoring for at least 6 hours in all symptomatic patients or those with significant ingestions; obtain serial ECGs to track QRS duration trends. 1

Disposition and ICU Admission Criteria (American Heart Association)

• Admit to the intensive care unit any patient who exhibits one or more of the following:
  
  • QRS prolongation,
  • Ventricular dysrhythmias,
  • Persistent hypotension,
  • Altered mental status,
  • Ongoing seizures, or
  • Requirement for ongoing sodium bicarbonate therapy. 2

All statements are derived from peer‑reviewed evidence published in Circulation and reflect the recommendations of the American Heart Association.