A 27-year-old woman presents to the emergency department with altered mental status. Her boyfriend found her at home next to a suicide note and brought her into the emergency department. According to her boyfriend, the patient has a medical history of bipolar disorder for which she takes lithium, as well as chronic lower back pain for which she sees a pain specialist. Her temperature is 100.5°F (38.1°C), blood pressure is 102/78 mmHg, pulse is 127/min, respirations are 19/min, and oxygen saturation is 99% on room air. An ECG is performed as seen in Figure A. Which of the following findings is also likely to be present at some point in this patient’s course?
Miosis
Diaphoresis
Urinary retention
Wheezing
Urinary retention
This patient is presenting after a suicide attempt with an unknown overdose and is confused, febrile, tachycardic, and has QRS widening on ECG. This combination of symptoms is highly concerning for a tricyclic antidepressant (TCA) overdose which can cause an anticholinergic toxidrome and urinary retention.

Tricyclic antidepressants (TCAs) were once a mainstay in the treatment of depression before the advent of selective serotonin reuptake inhibitors (SSRIs) and serotonin–norepinephrine reuptake inhibitors (SNRIs). They are sometimes still used for depression and neuropathic pain. In overdose, TCAs block sodium channels in the heart and cause a pathognomonic QRS widening. Sodium bicarbonate should be administered until the QRS duration normalizes. TCAs also have anticholinergic properties and can cause an anticholinergic toxidrome including delirium, confusion, constipation, decreased bowel sounds, urinary retention, dry, warm, and flushed skin, and fever. Although physostigmine is typically the antidote of choice for an anticholinergic toxidrome, it is avoided in TCA toxicity due to the theoretical concern for inducing a cardiac arrest.

Urquhart et al. studied the utility of tricyclic antidepressants in the treatment of chronic lower back pain. They found no significant difference in pain reduction compared to placebo. They recommend further study of the potential benefits of TCAs, independent of sleep improvement, for the treatment of lower back pain.

Figure/Illustration A is an ECG demonstrating QRS widening (note how long the red lines are which demarcate the QRS duration) which is highly concerning for TCA overdose.

Incorrect Answers:
Answer A: Diaphoresis, tachycardia, increased bowel sounds, and agitation would be seen in a sympathomimetic toxidrome from drugs like cocaine or amphetamines. Rather, dry, flushed skin would be seen in an anticholinergic toxidrome.

Answer B: Jaundice, nausea, vomiting, and abdominal pain would be seen in acetaminophen overdose which can cause fulminant liver failure. It is also possible that patients may initially be asymptomatic in acetaminophen overdose, and a high level of suspicion must be maintained for this diagnosis. A serum acetaminophen level should be drawn in any patient suspected of overdose.

Answer C: Miosis, bradypnea, decreased bowel sounds, and somnolence would be seen in an opioid toxidrome. Rather, dilated and minimally responsive pupils would be seen in an anticholinergic toxidrome.

Answer D: Wheezing, bronchorrhea, urinary incontinence, fecal incontinence, confusion, and drooling would be seen in a cholinergic toxidrome from agents such as organophosphates or nerve gases like sarin. None of these symptoms are seen in this patient.

Bullet Summary:
A tricyclic antidepressant overdose can cause QRS widening on ECG as well as an anticholinergic toxidrome (dry, flushed skin, constipation, decreased bowel sounds, urinary retention, and altered mental status).