A 24-year-old woman is found on her bedroom floor beside an empty prescription bottle, her skin cool and damp and her speech thick. Her pulse is 132, blood pressure 86/54, and the monitor shows a broad-complex tachycardia with an abnormal terminal QRS appearance. Her roommate says she was “fine an hour ago” and may have taken several different medications. The next choice—what to give before the rhythm deteriorates—is still yours.

— What’s your move? Read on.

Before you read
  • When is sodium bicarbonate indicated, and what is the treatment endpoint?
  • Which toxic syndromes require active cooling, benzodiazepines, or cyproheptadine?

When to Think of It

Suspect antidepressant poisoning with unexplained altered mental status, seizures, hyperthermia, clonus, anticholinergic findings, hypotension, or QRS/QTc prolongation. High-risk agents include tricyclic antidepressants (TCAs), bupropion, venlafaxine, MAO inhibitors, and citalopram/escitalopram.

Sick or Not Sick

Sick vs. not sick: the critical call is whether there is sodium-channel cardiotoxicity or impending airway/seizure collapse. A QRS ≥100 ms, ventricular dysrhythmia, hypotension, seizure, severe acidosis, or altered mental status makes this a resuscitation—not an observation—patient.

The First Fifteen Minutes

  • Place on cardiac monitor, obtain IV/IO access, bedside glucose, temperature, and serial ECGs; call Poison Control/toxicology early.
  • If hypoglycemic: dextrose 25 g IV (50 mL D50) in an adult, because neuroglycopenia is rapidly reversible; use dextrose 10% 250 mL IV when peripheral extravasation risk or severe hyperosmolarity is a concern.
  • If QRS ≥100 ms, hypotension, ventricular dysrhythmia, or suspected TCA cardiotoxicity: sodium bicarbonate 1–2 mEq/kg IV bolus, repeat every 3–5 minutes until QRS narrows and perfusion improves; then 150 mEq in 1 L D5W IV infusion, titrated to pH about 7.50–7.55. Sodium loading narrows the QRS and alkalinization reduces sodium-channel binding. Check potassium and pH frequently; avoid severe alkalemia and hypokalemia.
  • For seizure, severe agitation, or serotonin-mediated neuromuscular activity: lorazepam 2–4 mg IV, repeat every 5–10 minutes as needed; benzodiazepines suppress neuronal and muscular hyperactivity without worsening sodium-channel blockade.
  • If hyperthermic: immediate undressing, mist-and-fan or evaporative cooling, and cooled IV crystalloid; do not use antipyretics, which do not correct toxin-mediated heat production.
  • If serotonin syndrome remains severe despite sedation and supportive care: cyproheptadine 12 mg PO/NG, then 2 mg every 2 hours until response, followed by 8 mg every 6 hours; evidence and dosing vary, so confirm with a toxicology reference. It is adjunctive—not a substitute for sedation and cooling.
  • If a potentially lethal ingestion occurred within approximately 1 hour and the airway is protected: activated charcoal 50 g PO/NG once; avoid it with vomiting, ileus, or an unprotected airway.
  • For persistent hypotension after crystalloid: norepinephrine 0.05–0.1 mcg/kg/min IV infusion, titrated to perfusion; it restores vascular tone while definitive toxicologic therapy continues.

Definitive Care & Disposition

Continue serial ECGs, electrolytes, glucose, blood gas, creatine kinase, renal function, and temperature monitoring. Treat ventricular dysrhythmia with more bicarbonate and toxicology guidance; avoid class IA/IC antiarrhythmics and generally avoid flumazenil. Sustained-release or large bupropion/venlafaxine ingestions may require prolonged observation because seizures and cardiotoxicity can be delayed. Admit symptomatic patients, those with ECG abnormalities, seizures, hypotension, or intentional overdose to a monitored or ICU setting; asymptomatic patients require a toxicology-guided observation period, commonly at least 6 hours for immediate-release and longer for extended-release products.

How This One Kills

The lethal error is treating a widened QRS or hypotension as a routine dysrhythmia with standard antiarrhythmics while missing sodium-channel blockade; refractory ventricular arrhythmia and cardiovascular collapse follow.
The Differential — What Else Looks Like This
  • Opioid poisoning — pinpoint pupils and hypoventilation with a narrow QRS; confusing it with antidepressant toxicity delays ventilation and naloxone.
  • Serotonin syndrome — clonus, hyperreflexia, and rapid onset after serotonergic exposure; missing it leads to uncontrolled hyperthermia and rhabdomyolysis.
  • Neuroleptic malignant syndrome — lead-pipe rigidity and slower evolution after dopamine blockade; treating it as serotonin syndrome may miss the need to stop antipsychotics and manage prolonged rigidity.
  • Sepsis or intracranial catastrophe — fever or altered mental status without a toxicologic history; anchoring on overdose can delay source control or neuroimaging.

The Second-Day Story

Older adults may present with falls, delirium, urinary retention, or unexplained hypotension rather than a reported overdose. A partially treated seizure may leave only metabolic acidosis, elevated CK, or a changing ECG. Obtain collateral medication information, inspect pill bottles, repeat ECGs, and treat the physiologic abnormality—especially QRS widening—even when the history is unreliable.
Back to Our Patient
Back to the 24-year-old with cool skin, hypotension, and a broad-complex tachycardia: she has a high-risk antidepressant overdose with sodium-channel cardiotoxicity until proven otherwise. Recognize the altered mental status, shock, and widened QRS; risk-stratify her as critically ill; protect the airway if consciousness worsens, give sodium bicarbonate 1–2 mEq/kg IV, repeat to QRS narrowing and improved blood pressure, and treat any seizure with lorazepam. She requires toxicology consultation, serial ECGs and electrolytes, vasopressor support if needed, and ICU admission—not discharge after an initially reassuring pill count.
Patient Presentation to Attending
How you’d present this patient on the floor — tight, pertinent positives and negatives, no rambling
“This is a 24-year-old woman found with an empty antidepressant bottle, presenting with altered mental status, hypotension at 86/54, tachycardia at 132, and a broad-complex tachycardia with QRS prolongation. She has cool, diaphoretic skin and no reported trauma, fever, or focal neurologic deficit, although the ingestion history is incomplete. Her glucose and temperature are being checked, and we have IV access, continuous monitoring, and Poison Control involved. I am most concerned for sodium-channel cardiotoxicity from a TCA or another antidepressant overdose with imminent seizure and ventricular dysrhythmia risk. I will give IV sodium bicarbonate, repeat ECGs and blood gases, use benzodiazepines for seizure or severe agitation, support blood pressure with norepinephrine if needed, and admit her to the ICU.”

Study Directive

  • Draw the sodium-channel blockade treatment pathway from memory: ECG → bicarbonate bolus → repeat ECG/pH → infusion/vasopressor/toxicology escalation.
  • Practice interpreting three toxicology ECGs, specifically QRS width, terminal R wave in aVR, QTc, and rhythm.
  • Memorize adult doses for bicarbonate, benzodiazepines, activated charcoal, norepinephrine, and magnesium.
  • Review your institutional protocol for TCA, serotonin syndrome, and extended-release antidepressant observation periods.
  • Work through one simulated case involving a seizure followed by QRS widening and verbalize the first 15 minutes aloud.