AEMCA Toxicology and Substance Abuse 2 — Questions and Answers
Question 1: Which antidote is used to reverse benzodiazepine overdose?
- Naloxone
- N-acetylcysteine
- Flumazenil (Correct answer)
- Physostigmine
Correct answer: Flumazenil
Flumazenil is a competitive benzodiazepine receptor antagonist that reverses CNS and respiratory depression caused by benzodiazepine overdose.
Question 2: Carbon monoxide (CO) poisoning is best treated prehospitally with:
- 21% oxygen via nasal cannula at 2 L/min
- 100% oxygen via non-rebreather mask (Correct answer)
- Activated charcoal administration
- Sodium bicarbonate IV
Correct answer: 100% oxygen via non-rebreather mask
100% high-flow oxygen reduces the half-life of carboxyhemoglobin from approximately 4–5 hours to about 60–90 minutes by competing with CO for hemoglobin binding.
Question 3: A patient with an unknown ingestion has a high anion gap metabolic acidosis, visual disturbances, and elevated osmol gap. Which toxic ingestion is most likely?
- Cocaine
- Methanol (Correct answer)
- Opioids
- Benzodiazepines
Correct answer: Methanol
Methanol is metabolized to formic acid, causing severe high anion gap metabolic acidosis and optic nerve toxicity that can lead to blindness.
Question 4: Within what time frame after ingestion is activated charcoal most effective for most overdoses?
- Within 15 minutes only
- Within 1 hour of ingestion (Correct answer)
- Within 4 hours of ingestion
- Time does not affect charcoal efficacy
Correct answer: Within 1 hour of ingestion
Activated charcoal is most effective when given within 1 hour of ingestion to adsorb toxic substances in the GI tract before systemic absorption occurs.
Question 5: A patient presents with hyperthermia, muscle rigidity, altered mental status, and autonomic instability after starting a new antipsychotic medication. What is the most likely diagnosis?
- Serotonin syndrome
- Neuroleptic malignant syndrome (NMS) (Correct answer)
- Cocaine toxicity
- Anticholinergic toxidrome
Correct answer: Neuroleptic malignant syndrome (NMS)
Neuroleptic malignant syndrome is a life-threatening reaction to antipsychotic (neuroleptic) drugs characterized by hyperthermia, muscle rigidity, altered mental status, and autonomic dysfunction developing over days.
Question 6: Which of the following findings is most consistent with the anticholinergic toxidrome?
- Miosis (pinpoint pupils)
- Bradycardia and hypotension
- Dry, flushed skin and urinary retention (Correct answer)
- Excessive salivation and bronchospasm
Correct answer: Dry, flushed skin and urinary retention
Anticholinergic toxidrome causes dry flushed skin, mydriasis, tachycardia, hyperthermia, and urinary retention — recalled by 'hot as a hare, dry as a bone, red as a beet, blind as a bat, mad as a hatter.'
Question 7: What acid-base disturbance pattern is classically associated with aspirin (salicylate) overdose?
- Respiratory alkalosis progressing to metabolic acidosis (Correct answer)
- Opioid-like respiratory acidosis only
- Pure metabolic alkalosis
- Immediate metabolic acidosis without respiratory change
Correct answer: Respiratory alkalosis progressing to metabolic acidosis
Salicylates initially stimulate the respiratory center causing respiratory alkalosis (hyperventilation), then toxicity progresses to uncoupled oxidative phosphorylation and metabolic acidosis.
AEMCA Toxicology and Substance Abuse 2
Which antidote is used to reverse benzodiazepine overdose?