Guideline sources The following summarized guidelines for the evaluation and management of tricyclic antidepressant overdose are prepared by our editorial team based on guidelines from the Guidelines in Emergency Medicine Network (GEMNet 2011). 1 1 1 1 2 3 Definition TCA overdose is de ned as ingestion of TCA at above the recommended therapeutic dose. 1 Epidemiology TCA overdose may be accidental or intentional, including as part of suicide attempts. 1 Pathophysiology The incidence of TCA overdose is estimated at 3.8 per 100,000 person-years. 2 Disease course TCAs block alpha-adrenergic receptors and have anticholinergic effects, leading to tachycardia, hypotension, cardiac conduction abnormalities, and arrhythmias. TCAs also exert a number of effects on the CNS, which may lead to drowsiness, coma, respiratory depression, seizures, and delirium. 1 Prognosis and risk of recurrence https://web.pathway.md/diseases/recfGDOrcXMFsa9K3 1/4 6/24/23, 4:19 PM Tricyclic antidepressant overdose Pathway og os s a d s o ecu e ce Hospital admission and intensive care support are required in several patients. Fatality rates of up to 6% have been reported in patients with severe overdose. 3 Guidelines 1. Diagnostic investigations Electrocardiogram: obtain an ECG in all patients presenting to hospital following TCA overdose. B Show 2 more Blood gas analysis: Obtain a blood gas as part of the initial assessment and monitoring of patients with TCA overdose. B Consider using venous sampling for blood gas analysis as an acceptable alternative to arterial sampling, unless hypoxia or hypoventilation are suspected. A 2. Respiratory support Airway protection: Perform endotracheal intubation in patients with severely altered mental status (e.g. GCS 8) using rapid sequence induction. B Consider performing endotracheal intubation in patients with other features suggestive of airway compromise, hypoventilation or refractory seizures. A 3. Medical management Gastric decontamination: consider using activated charcoal in patients with TCA overdose who present within 1 hour of ingestion and have an intact or secured airway. The potential risk of aspiration should be strongly considered before use. A Show 2 more Management of agitation: consider using benzodiazepines to control agitation following TCA overdose. A Management of seizures: Use benzodiazepines to control seizures following TCA overdose. B Avoid using phenytoin in patients with TCA overdose. D Management of hypotension: administer a bolus of intravenous uids as rst-line therapy to treat hypotension induced by TCA overdose. B Show 4 more https://web.pathway.md/diseases/recfGDOrcXMFsa9K3 2/4 6/24/23, 4:19 PM Tricyclic antidepressant overdose Pathway Management of dysrhythmias: Administer sodium bicarbonate in patients with dysrhythmias associated with TCA overdose, with initial doses as follows: for life-threatening toxicity, sodium bicarbonate 8.4% (50-100 mL IV) for more stable patients, sodium bicarbonate 1.26% (500 mL IV). B Show 4 more 4. Follow-up and surveillance Discharge from hospital: consider discharging asymptomatic patients with no signs of instability and no significant electrocardiographic changes at 6 hours after ingestion following TCA overdose. A Likelihood Ratios Pertinent positives The following findings increase the probability of ventricular arrhythmia in patients with TCA overdose. 3 Finding LR+ Value Increased R/S ratio in lead aVR (> 0.7) 15.7 Increased serum TCA levels 1.8 Prolonged QTc interval (> 430 ms) 1.8 Increased QRS duration (> 100 ms) 1.5 Pertinent negatives The following findings decrease the probability of ventricular arrhythmia in patients with TCA overdose. 3 Finding LR- Value QTc interval not prolonged ( 430 ms) 0.4 serum TCA levels not increased 0.4 QRS duration not increased ( 100 ms) 0.5 R/S ratio in lead aVR not increased ( 0.7) 0.5 References 1. Richard Body, Tom Bartram, Fawad Azam et al. Guidelines in Emergency Medicine Network GEMNet): guideline for the management of tricyclic antidepressant overdose. Emerg Med J. 2011 Apr;28 4 347 68. Open 2. Anselm Wong, David McD Taylor, Karen Ashby et al. Changing epidemiology of intentional antidepressant drug overdose in Victoria, Australia. 2010 Aug;44 8 759 64.2010 Aug;44 8 759 64. Open https://web.pathway.md/diseases/recfGDOrcXMFsa9K3 3/4 6/24/23, 4:19 PM Tricyclic antidepressant overdose Pathway 3. Florian Eyer, Jochen Stenzel, Tibor Schuster et al. Risk assessment of severe tricyclic antidepressant overdose. 2009 Aug;28 8 511 9.2009 Aug;28 8 511 9. Open 4. Bailey B, Buckley NA, Amre DK. A meta-analysis of prognostic indicators to predict seizures, arrhythmias or death after tricyclic antidepressant overdose. J Toxicol Clin Toxicol. 2004;42 6 877 88. Open 5. Ashish R Panchal, Jason A Bartos, Jos G Caba as et al. Part 3 Adult Basic and Advanced Life Support: 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2020 Oct 20;142 16_suppl_2 S366 S468. Open https://web.pathway.md/diseases/recfGDOrcXMFsa9K3 4/4