A 55-year-old man is brought to the emergency department due to altered mental status. The patient's wife came home from work and found him confused. He was fine that morning before she left the house. The patient has a medical history of chronic migraines and major depression; he has been out of work for a few months due to the pain. The wife reports her husband has tried "every migraine medication there is," but she does not know which one he is currently taking. Blood pressure is 80/60 mm Hg, and pulse is 125/min. The patient is drowsy and does not answer questions or follow commands. The oral membranes are dry. There is reddening around the face and neck. ECG reveals sinus tachycardia with a QRS duration of 120 msec and frequent premature ventricular beats. Initial laboratory studies are ordered, and intravenous hydration is started. Which of the following is the best next step in management?

Question

A 55-year-old man is brought to the emergency department due to altered mental status.  The patient's wife came home from work and found him confused.  He was fine that morning before she left the house.  The patient has a medical history of chronic migraines and major depression; he has been out of work for a few months due to the pain.  The wife reports her husband has tried "every migraine medication there is," but she does not know which one he is currently taking.  Blood pressure is 80/60 mm Hg, and pulse is 125/min.  The patient is drowsy and does not answer questions or follow commands.  The oral membranes are dry.  There is reddening around the face and neck.  ECG reveals sinus tachycardia with a QRS duration of 120 msec and frequent premature ventricular beats.  Initial laboratory studies are ordered, and intravenous hydration is started.  Which of the following is the best next step in management?

Quizplus · Accepted Answer

11ec25c8_d1de_a9ac_bc81_f3ad77c7fa42_MD0003_00 This patient with chronic pain has altered mental status, hypotension, signs of anticholinergic toxicity (eg, facial flushing, dry mouth), and a prolonged QRS interval. These clinical features suggest tricyclic antidepressant (TCA) poisoning; TCAs are frequently prescribed for migraine prophylaxis. TCAs exert their antidepressant effects by inhibiting presynaptic neurotransmitter reuptake; however, they interact with multiple other receptors, leading to the characteristic manifestations of TCA overdose. In addition, TCAs can block cardiac fast sodium channels, resulting in conduction abnormalities (QRS and QT interval prolongation), which can lead to fatal arrhythmias (eg, ventricular tachycardia, ventricular fibrillation). TCA overdose Management of TCA poisoning includes supportive care, telemonitoring, intravenous fluids, and benzodiazepines if seizure occurs. In addition, when the QRS interval >100 msec (as in this patient), intravenous sodium bicarbonate should be given to shorten the QRS interval and reduce the risk of fatal arrhythmias (Choice F). Sodium bicarbonate alkalinizes the plasma, which favors the nonionized (neutral) form of the drug and makes it less accessible to bind to sodium channels. It also increases the extracellular sodium concentration, which helps overcome the sodium channel blockade induced by TCAs. (Choice A) Amiodarone is an antiarrhythmic medication used to treat ventricular fibrillation, ventricular tachycardia, and wide-complex tachycardias. Although it is not well studied in TCA overdose, amiodarone can cause QTc interval prolongation and is not recommended. (Choice B) Atropine is indicated for organophosphate toxicity, which also presents with altered mental status typically after exposure to agricultural pesticides. However, signs of cholinergic excess (eg, salivation, urination, diarrhea, bradycardia) would be expected, and QRS interval widening is not typical. (Choice C) Calcium chloride is indicated for treatment of severe hyperkalemia (in addition to insulin with glucose and beta agonists). It also is indicated for calcium channel blocker (CCB) overdose; CCBs are often used to prevent migraines. Hyperkalemia causes arrhythmias and QRS interval widening but typically produces other ECG findings (eg, peaked T waves). CCB overdose frequently causes hypotension and atrioventricular blocks. However, neither hyperkalemia nor CCB overdose would cause anticholinergic symptoms. peaked T waves (Choice D) Hemodialysis is used in overdoses to increase the elimination of certain substances (eg salicylates, lithium). However, TCAs have a large volume of distribution, and enhanced elimination has not been shown to be effective. Educational objective: Tricyclic antidepressant overdose can present with CNS, cardiac, and anticholinergic findings. Sodium bicarbonate is used to treat cardiac toxicity, which is characterized by prolonged QRS duration (>100 msec) and ventricular arrhythmias (eg, ventricular tachycardia, ventricular fibrillation). References: Management of the cardiovascular complications of tricyclic antidepressant poisoning: role of sodium bicarbonate. (http://www.ncbi.nlm.nih.gov/pubmed/16390221) Rapid diagnosis and treatment of severe tricyclic antidepressant toxicity (http://www.ncbi.nlm.nih.gov/pubmed/26468220)

A 55-Year-Old Man Is Brought to the Emergency Department Due