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Diagnosis and Management of Tricyclic Antidepressant Ingestion Patrick George Minges and Robert W. Shaffer

Introduction Tricyclic antidepressant (TCA) overdoses have become less common over the last 20 years as their overall use has decreased with the advent of safer and more effective antidepressants. Despite their declining popularity in the management of depression, they continue to be used clinically for conditions including the management of neuropathic and chronic pain, cyclic vomiting, nocturnal enuresis, OCD and ADHD. These medications continue to be a leading cause of mortality from intentional ingestions, and account for nearly half of all antidepressant-related deaths [1]. Common tricyclic antidepressants in use today include amitriptyline, nortriptyline, imipramine, desipramine and doxepin. The management of tricyclic antidepressant poisonings can be quite challenging. Since they exert their toxicity through several different mechanisms an understanding of their pharmacology is imperative. TCAs all have inherent anticholinergic effects that may cause tachycardia,

P.G. Minges Department of Emergency Medicine, University of Michigan Hospitals, Ann Arbor, MI, USA R.W. Shaffer (*) Department of Emergency Medicine, University of Michigan Health System, Ann Arbor, MI, USA e-mail: [email protected]

altered mental status and seizures. They can cause profound hypotension through alpha-­adrenergic blockade as well as catecholamine depletion through reuptake inhibition. Finally, they block fast sodium channels in the cardiac conduction system leading to myocardial depression and ventricular arrhythmias [2]. Successful treatment of patients poisoned by tricyclic antidepressants hinges on prompt diagnosis and recognition of the classic EKG findings associated with their toxicity. GI decontamination should be considered when patients present within the first 1–2 h following an overdose. Serum alkalinization with sodium bicarbonate is considered the first-line treatment when signs of cardiotoxicity develop. Patients with refractory hypotension may require vasopressor support.

Case Presentation A 32 year old female with a history notable for depression, migraine headaches, and chronic pelvic pain arrived to the emergency department 90 min after ingesting approximately sixty 75 mg tablets of amitriptyline. On arrival, she was noted to be agitated and confused. Her presenting vital signs included the following: BP 96/62, P 122, RR18, T37.8, O2 sat (RA) 99 %, GCS 13. An EKG showed sinus tachycardia with normal intervals and normal axis. Blood glucose was normal, and serum lactate was 3.7. Serum and urine tox screening was negative. Shortly after

© Springer International Publishing Switzerland 2017 R.C. Hyzy (ed.), Evidence-Based Critical Care, DOI 10.1007/978-3-319-43341-7_6

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arrival, the patient had a generalized tonic-clonic seizure that was successfully aborted with 2 mg IV Ativan. She was subsequently intubated for airway protection, and 50 g of activated charcoal was