A 64-year-old woman is brought to the emergency department after her husband found her obtunded at home. He found open bottles of her usual medications of sertraline, diphenhydramine, amitriptyline, and lorazepam at her bedside. Her husband does not know how many pills from each bottle may be missing. He reports that the patient appeared more depressed recently and had been expressing increased hopelessness. She has not seen any of her doctors in the past couple of months. The patient has a long-standing history of depression, lower back pain, and insomnia but no other medical problems. She has no known history of cardiac problems or stroke. The patient does not use tobacco, alcohol or illicit drugs. In the emergency department, she is sedated but intermittently arousable.
Temperature is 37.2 C (99 F), blood pressure is 95/45 mm Hg, and pulse is 106/min. Oxygen saturation is 94% on room air. The pupils are mildly dilated. Heart sounds are normal. The lungs are clear. She moves all extremities on command but has hyperreflexia of both lower extremities and exhibits frequent myoclonic jerks. She appears confused.
Which of the following is the most appropriate next step in management of this patient?

Question

A 64-year-old woman is brought to the emergency department after her husband found her obtunded at home.  He found open bottles of her usual medications of sertraline, diphenhydramine, amitriptyline, and lorazepam at her bedside.  Her husband does not know how many pills from each bottle may be missing.  He reports that the patient appeared more depressed recently and had been expressing increased hopelessness.  She has not seen any of her doctors in the past couple of months.  The patient has a long-standing history of depression, lower back pain, and insomnia but no other medical problems.  She has no known history of cardiac problems or stroke.  The patient does not use tobacco, alcohol or illicit drugs.  In the emergency department, she is sedated but intermittently arousable.
Temperature is 37.2 C (99 F), blood pressure is 95/45 mm Hg, and pulse is 106/min.  Oxygen saturation is 94% on room air.  The pupils are mildly dilated.  Heart sounds are normal.  The lungs are clear.  She moves all extremities on command but has hyperreflexia of both lower extremities and exhibits frequent myoclonic jerks.  She appears confused.
Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

The primary concern in this patient is the possibility of cardiac toxicity due to possible tricyclic antidepressant (TCA) and diphenhydramine overdose. A wide complex tachycardia or a QRS duration of >100 msec indicates potential cardiac toxicity, requiring intravenous sodium bicarbonate even in the absence of acidosis as it predicts a higher risk of arrhythmia, which may be fatal. Sodium bicarbonate is administered incrementally up to a pH of 7.45-7.55 until the QRS complex duration normalizes. TCA overdose can manifest with respiratory depression, hypotension, tachycardia, sedation, seizures, coma, and death. Anticholinergic toxicity caused by amitriptyline and/or diphenhydramine could additionally result in hyperthermia, flushing, mydriasis, delirium, and urinary retention. Sertraline overdose may lead to serotonin syndrome (characterized by hyperreflexia, seizures, fever, autonomic instability, and mental status changes) but it does not commonly affect cardiac conduction. Lorazepam overdose may cause delirium, sedation, and respiratory depression and may require intubation. (Choice A) Cyproheptadine is a serotonin antagonist used to treat serotonin syndrome. Although this patient may have overdosed with sertraline as well, the immediate concern is her cardiac status given the possibility of TCA and/or diphenhydramine overdose. (Choice B) Flumazenil should not be administered as it can lower the seizure threshold if the patient has overdosed on a TCA and a benzodiazepine (or if the patient is benzodiazepine dependent and at risk for withdrawal). (Choice C) PR interval durations frequently increase in TCA overdose but do not predict the risk for arrhythmia as well as QRS duration does. (Choice E) Serum levels of amitriptyline or other medications do not correlate well with cardiac toxicity and do not play a role in acute management. Educational objective: Tricyclic antidepressant overdose manifests with respiratory depression, hypotension, tachycardia, sedation, seizures, coma, and death. A wide complex tachycardia or a QRS duration of >100 msec is an indication for intravenous sodium bicarbonate even in the absence of acidosis as it predicts a higher risk of arrhythmia, which may be fatal. __________ References: A literature review of the use of sodium bicarbonate for the treatment of QRS widening. (http://www.ncbi.nlm.nih.gov/pubmed/26159649)

A 64-Year-Old Woman Is Brought to the Emergency Department After