CPEN CPEN Toxicology and Poisoning Emergencies 5 — Questions and Answers
Question 1: A 10-year-old with known depression is brought in after ingesting her parent's tricyclic antidepressant (TCA). Which ECG finding is MOST concerning for life-threatening cardiotoxicity?
- Sinus bradycardia
- QRS duration greater than 100 ms (Correct answer)
- Prolonged QTc interval only
- First-degree AV block
Correct answer: QRS duration greater than 100 ms
QRS widening greater than 100 ms in TCA overdose indicates significant sodium channel blockade and predicts a high risk of ventricular dysrhythmias and cardiovascular collapse.
Question 2: Sodium bicarbonate is administered for a pediatric TCA overdose with wide-complex dysrhythmia. What is the PRIMARY mechanism by which it helps?
- It increases urinary excretion of the TCA
- Alkalinization reverses sodium channel blockade and increases protein binding of the drug (Correct answer)
- It chelates the TCA molecule directly
- It stimulates beta-adrenergic receptors
Correct answer: Alkalinization reverses sodium channel blockade and increases protein binding of the drug
Sodium bicarbonate alkalinizes the serum, which increases protein binding of TCAs and partially reverses sodium channel blockade, reducing QRS widening and dysrhythmia risk.
Question 3: A 4-year-old ingested a grandparent's clonidine tablet and is now bradycardic and difficult to arouse. Which opioid antagonist may be trialed for clonidine toxicity despite clonidine not being an opioid?
- Flumazenil
- Naloxone (Correct answer)
- Physostigmine
- Cyproheptadine
Correct answer: Naloxone
Naloxone is often trialed in clonidine toxicity because clonidine's CNS depression may involve endogenous opioid pathways, and some patients show partial reversal of sedation.
Question 4: A 7-year-old is found unresponsive with a respiratory rate of 6 breaths/min, pinpoint pupils, and slow heart rate. Which intervention is MOST immediately indicated?
- Activated charcoal administration
- Naloxone administration and ventilatory support (Correct answer)
- Sodium bicarbonate infusion
- Flumazenil administration
Correct answer: Naloxone administration and ventilatory support
The classic opioid toxidrome (CNS depression, respiratory depression, miosis) requires immediate naloxone and ventilatory support to reverse life-threatening respiratory depression.
Question 5: A 6-year-old ingested a sulfonylurea medication. After initial treatment with dextrose, hypoglycemia recurs. Which agent is MOST appropriate to prevent recurrent hypoglycemia in sulfonylurea overdose?
- Glucagon IM injection
- Octreotide (Correct answer)
- Continuous high-dose dextrose infusion alone
- Insulin drip
Correct answer: Octreotide
Octreotide inhibits pancreatic insulin secretion and is preferred over repeated dextrose boluses for sulfonylurea-induced hypoglycemia because dextrose alone stimulates further insulin release.
Question 6: A teenager presents with confusion, tachycardia, dry skin, urinary retention, and mydriasis after ingesting diphenhydramine. Which mnemonic BEST describes this toxidrome?
- SLUDGE
- Mad as a hatter, dry as a bone, red as a beet, blind as a bat, hot as a hare (Correct answer)
- DUMBELS
- Fight or flight
Correct answer: Mad as a hatter, dry as a bone, red as a beet, blind as a bat, hot as a hare
The anticholinergic toxidrome is classically described by the mnemonic 'Mad as a hatter, dry as a bone, red as a beet, blind as a bat, hot as a hare,' reflecting delirium, anhidrosis, flushing, mydriasis, and hyperthermia.
Question 7: A 2-year-old presents after ingesting a dishwasher detergent pod with oral burns, drooling, and refusal to swallow. Which action is CONTRAINDICATED in managing this caustic ingestion?
- IV access and pain management
- Induction of vomiting with syrup of ipecac (Correct answer)
- NPO status pending endoscopic evaluation
- Airway assessment and intubation if needed
Correct answer: Induction of vomiting with syrup of ipecac
Inducing vomiting after caustic ingestion is strictly contraindicated because it re-exposes the esophageal and oropharyngeal mucosa to the caustic agent, worsening burns and increasing perforation risk.
CPEN CPEN Toxicology and Poisoning Emergencies 5
A 10-year-old with known depression is brought in after ingesting her parent's tricyclic antidepressant (TCA).
Which ECG finding is MOST concerning for life-threatening cardiotoxicity?