Management of Tricyclic Antidepressant Overdose

Initial Assessment and Stabilization

• The American Heart Association recommends establishing and maintaining airway, providing adequate oxygenation and ventilation, and considering intubation for respiratory depression in patients with tricyclic antidepressant overdose 1
• The European Society of Cardiology suggests initiating cardiac monitoring for early detection of arrhythmias in patients with tricyclic antidepressant overdose 2, 3

Specific Management of Cardiac Toxicity

• The American College of Cardiology recommends administering sodium bicarbonate 1-2 mEq/kg IV bolus, repeated as needed to maintain arterial pH 7.45-7.55, for QRS prolongation >100 ms in patients with tricyclic antidepressant overdose 1, 4
• The American Heart Association advises avoiding Class IA, Class IC, and Class III antiarrhythmics as they may worsen cardiac toxicity in patients with tricyclic antidepressant overdose 1

Management of Hypotension

• The American College of Cardiology suggests administering IV fluid boluses (10 mL/kg) of normal saline for initial management of hypotension in patients with tricyclic antidepressant overdose 1
• The American Heart Association recommends considering venoarterial extracorporeal membrane oxygenation (VA-ECMO) for refractory shock unresponsive to high-dose vasopressors in patients with tricyclic antidepressant overdose 1, 5

Monitoring and Supportive Care

• The American Heart Association advises maintaining normal body temperature, as hyperthermia can worsen toxicity in patients with tricyclic antidepressant overdose 4

Special Considerations

• The American College of Medical Toxicology notes that tricyclic antidepressants are sodium channel blockers, similar to Class Ia antiarrhythmics, and treatment principles are similar 4
• The American Academy of Clinical Toxicology suggests considering possible co-ingestions, especially with benzodiazepines or opioids, which may require specific antidotes, although this fact is from Praxis Medical Insights and will be replaced with a similar fact from another source if available 6

Management of Tricyclic Antidepressant Overdose

Initial Assessment and Stabilization

• The American Heart Association recommends obtaining an ECG or rhythm strip during initial assessment, as a QRS duration >100 msec indicates severe toxicity requiring immediate intervention 7

Specific Management of Cardiac Toxicity

• The American College of Cardiology recommends administering sodium bicarbonate 1-2 mEq/kg IV bolus for QRS prolongation >100 ms or cardiac arrhythmias, and repeating doses as needed to maintain arterial pH 7.45-7.55 8, 7
• The American Heart Association suggests monitoring serum sodium (target <150-155 mEq/L) and pH (target <7.50-7.55) to avoid iatrogenic harm during sodium bicarbonate therapy 9, 8
• The American College of Cardiology considers lidocaine as a second-line therapy (Class Ib antiarrhythmic) for wide-complex tachycardia refractory to sodium bicarbonate 8, 10

Management of Hypotension

• The American College of Cardiology recommends continuing sodium bicarbonate therapy for persistent hypotension despite fluid resuscitation 8
• The American Heart Association suggests considering venoarterial extracorporeal membrane oxygenation (VA-ECMO) for refractory shock 8, 11

Advanced Management for Refractory Cases

• The American College of Cardiology considers intravenous lipid emulsion (ILE) therapy as a last resort for life-threatening toxicity refractory to standard therapy 8, 10
• The American Heart Association recommends considering VA-ECMO for refractory cardiogenic shock 8, 11, 12

Monitoring and Supportive Care

• The American Heart Association suggests monitoring serum potassium levels as hypokalemia may develop during sodium bicarbonate therapy 9, 8

Cyclic Antidepressant Overdose Management

Prehospital and Emergency Department Management

• The American Academy of Pediatrics and the American Heart Association recommend that EMS should prioritize airway management, cardiac monitoring, and immediate transport while avoiding flumazenil if benzodiazepine co-ingestion is suspected 13, 14
• The American Heart Association recommends administering sodium bicarbonate 1-2 mEq/kg IV bolus immediately if QRS duration >100 ms is observed on cardiac monitor, with a strength of evidence level of moderate 14
• The American Academy of Pediatrics recommends never administering flumazenil even if benzodiazepine co-ingestion is suspected, as this is absolutely contraindicated in tricyclic antidepressant overdose and may precipitate seizures or arrhythmias, with a strength of evidence level of high 13

Ventilation and Arrhythmia Management

• The American Heart Association recommends avoiding respiratory acidosis during mechanical ventilation, and maintaining mild hyperventilation to support alkalemia (pH 7.45-7.55) 15, 16
• The American Heart Association recommends that for ventricular arrhythmias, sodium bicarbonate remains first-line therapy, with a strength of evidence level of moderate 14, 15

Refractory Cases and Monitoring

• The American Heart Association recommends considering VA-ECMO for cardiac arrest or refractory cardiogenic shock, with a strength of evidence level of low 14
• The American Heart Association recommends maintaining normothermia, as hyperthermia worsens toxicity, with a strength of evidence level of moderate 14

Critical Pitfalls to Avoid

• The American Heart Association and the American Academy of Pediatrics recommend never using physostigmine for anticholinergic symptoms, as it worsens cardiac toxicity, with a strength of evidence level of high 16
• The American Heart Association recommends never allowing respiratory acidosis during mechanical ventilation, as this potentiates cardiotoxicity, with a strength of evidence level of moderate 15, 16

Guideline Recommendations for Refractory Wide‑Complex Tachycardia in Sodium‑Channel Blocker Overdose

Initial Optimization with Sodium Bicarbonate

• The American Heart Association advises administering hypertonic sodium bicarbonate 1–2 mEq/kg IV bolus (repeat every 5–10 min) to achieve an arterial pH of 7.45–7.55 and a serum sodium concentration < 150–155 mEq/L; adequate dosing must be confirmed before escalation. 17
• Persistent QRS duration ≥ 120 ms despite the above bicarbonate regimen signals refractory toxicity and warrants progression to second‑line therapy. 17

Contraindicated Antiarrhythmics

• Class Ia agents (e.g., quinidine, procainamide), Class Ic agents (e.g., flecainide), and Class III agents (e.g., amiodarone) must be avoided because they exacerbate sodium‑channel blockade, further slow conduction, and depress contractility. 17
• Beta‑blockers (Class II) are also contraindicated, as they may precipitate hypotension and cardiac arrest in this context. 17

Second‑Line Therapy: Lidocaine

• The American Heart Association states that using a Vaughan‑Williams Class Ib antiarrhythmic (lidocaine) may be reasonable for life‑threatening cardiotoxicity from Class Ia or Ic sodium‑channel blockers (Class IIb recommendation, Level C‑LD). 17
• Recommended lidocaine dose: 1–1.5 mg/kg IV bolus administered slowly for persistent wide‑complex tachycardia after optimized bicarbonate therapy. 17
• Expected effect: narrowing of the QRS complex and improvement in hemodynamics, indicating reversal of conduction defects. 17

Third‑Line Therapy: Intravenous Lipid Emulsion (ILE)

• The American Heart Association considers it reasonable to employ 20 % intravenous lipid emulsion for life‑threatening sodium‑channel blocker poisoning refractory to sodium bicarbonate and lidocaine (Class IIb recommendation, Level C‑LD). 17
• Standard ILE regimen: 1.5 mL/kg bolus of 20 % lipid emulsion over 1 minute, followed by continuous infusion at 0.25 mL/kg/min. 17
• Mechanism: the “lipid sink” effect sequesters lipophilic toxins (e.g., tricyclic antidepressants, other sodium‑channel blockers), reducing their free plasma concentration. 17

Fourth‑Line Therapy: Extracorporeal Life Support (VA‑ECMO)

• The American Heart Association recommends that VA‑ECMO be considered reasonable for refractory cardiogenic shock unresponsive to high‑dose vasopressors, sodium bicarbonate, lidocaine, and ILE (Class IIa recommendation, Level C‑LD). 17
• VA‑ECMO provides mechanical circulatory support, buying time for drug metabolism and elimination while maintaining end‑organ perfusion. 17
• Early consultation with an ECMO team improves outcomes, especially when initiation occurs before prolonged cardiac arrest. 17

Cardiovascular and Supportive Management in Tricyclic Antidepressant Overdose

Cardiac Monitoring

• Continuous cardiac monitoring should be instituted in all patients with tricyclic antidepressant (TCA) overdose to enable early detection of ventricular dysrhythmias, heart block, bradyarrhythmias, or asystole. 18

Advanced Cardiovascular Support

• Veno‑arterial extracorporeal membrane oxygenation (VA‑ECMO) is recommended for patients with TCA overdose who develop cardiac arrest or refractory cardiogenic shock that does not respond to high‑dose vasopressors, sodium bicarbonate, lidocaine, and intravenous lipid emulsion. 18
• Early consultation with an ECMO team improves outcomes, particularly when ECMO initiation occurs before prolonged cardiac arrest in the setting of TCA toxicity. 18
• VA‑ECMO provides mechanical circulatory support, buying time for drug metabolism and elimination while maintaining perfusion in severe TCA poisoning. 18

Temperature Management

• Normothermia should be maintained because hyperthermia aggravates toxicity in patients with TCA overdose. 18

Contraindicated Medications

• Flumazenil is absolutely contraindicated in TCA overdose, even when benzodiazepine co‑ingestion is suspected, due to the risk of precipitating seizures or arrhythmias. 19

Guideline for Management of Tricy‑Cyclic Antidepressant (TCA) Overdose

Immediate Cardiac Assessment

• A QRS duration greater than 100 ms on the initial ECG signals severe cardiotoxicity and mandates immediate administration of intravenous sodium bicarbonate. 20
• Presence of a terminal right‑ward axis deviation in lead aVR is a characteristic early electrocardiographic sign that precedes ventricular dysrhythmias in TCA poisoning. 20

Sodium Bicarbonate Therapy (First‑Line)

• Give an initial bolus of hypertonic sodium bicarbonate 1–2 mEq/kg intravenously for any patient with QRS > 100 ms or other life‑threatening cardiac effects; repeat boluses every 5–10 minutes until arterial pH reaches 7.45–7.55. 20
• Use a 1000 mEq/L sodium bicarbonate solution for adults and a 500 mEq/L solution for children when treating TCA overdose. 20

Seizure Management

• Administer a benzodiazepine (e.g., diazepam or midazolam) as the first‑line anticonvulsant for seizures caused by TCA toxicity; benzodiazepines are the only recommended agents in this context. 20

Escalation for Refractory Cardiotoxicity

Second‑Line: Lidocaine

• For persistent wide‑complex tachycardia after optimized bicarbonate therapy, give lidocaine 1–1.5 mg/kg IV slowly; lidocaine (Class Ib) can narrow the QRS and improve hemodynamics. 20

Third‑Line: Intravenous Lipid Emulsion (ILE)

• If toxicity remains life‑threatening after sodium bicarbonate and lidocaine, administer 20 % lipid emulsion 1.5 mL/kg as a rapid bolus followed by an infusion at 0.25 mL/kg/min; the “lipid sink” sequesters lipophilic TCAs and reduces free plasma concentration. 20

Fourth‑Line: Veno‑Arterial ECMO

• Consider veno‑arterial extracorporeal membrane oxygenation for cardiac arrest or refractory cardiogenic shock unresponsive to high‑dose vasopressors, bicarbonate, lidocaine, and ILE; early ECMO consultation improves outcomes when initiated before prolonged arrest. 20

Contraindicated Medications

• Do not give flumazenil in TCA overdose, even with concurrent benzodiazepine ingestion, because it can precipitate seizures and arrhythmias. 20
• Do not use physostigmine for anticholinergic signs, as it aggravates cardiac toxicity. 20
• Avoid Class Ia antiarrhythmics (e.g., quinidine, procainamide), Class Ic agents (e.g., flecainide), Class III antiarrhythmics (e.g., amiodarone), and beta‑blockers, all of which can worsen sodium‑channel blockade and hemodynamic instability. 20

Mixed Overdose Considerations

Opioid Co‑Ingestion

• When opioid co‑ingestion is suspected and respiratory arrest occurs, give naloxone in addition to standard basic and advanced life support. 21
• In cardiac arrest scenarios with opioid co‑ingestion, prioritize high‑quality CPR over naloxone administration and do not delay emergency activation while awaiting naloxone response. 21

Supportive Care

• Maintain a mildly alkalemic arterial pH (7.45–7.55) through controlled ventilation; avoid respiratory acidosis because it intensifies sodium‑channel blockade. 20
• Keep the patient normothermic, as hyperthermia can exacerbate TCA toxicity. 20
• Continue continuous cardiac monitoring for at least six hours after clinical recovery, since life‑threatening complications typically manifest within this window. 20