CPR Toxicological Emergencies and Overdose Management 2 — Questions and Answers
Question 1: Which antidote is used for acetaminophen (Tylenol) overdose to prevent hepatotoxicity?
- Fomepizole
- N-acetylcysteine (NAC) (Correct answer)
- Deferoxamine
- Dimercaprol
Correct answer: N-acetylcysteine (NAC)
N-acetylcysteine replenishes glutathione stores and detoxifies NAPQI, the hepatotoxic acetaminophen metabolite, preventing liver failure when administered within the treatment window.
Question 2: A patient is found unresponsive in a closed garage with altered mental status, severe headache, and cherry-red skin. What poisoning is most likely?
- Cyanide poisoning
- Hydrogen sulfide
- Carbon monoxide (Correct answer)
- Methemoglobin-forming agent
Correct answer: Carbon monoxide
Carbon monoxide binds hemoglobin with approximately 200 times the affinity of oxygen, causing tissue hypoxia; the classic cherry-red skin finding is caused by carboxyhemoglobin.
Question 3: What is the treatment for hemodynamically unstable beta-blocker overdose refractory to initial resuscitation measures?
- Amiodarone infusion
- High-dose insulin euglycemic therapy and calcium (Correct answer)
- Adenosine IV
- Magnesium sulfate IV
Correct answer: High-dose insulin euglycemic therapy and calcium
High-dose insulin euglycemic therapy improves cardiac contractility in beta-blocker overdose by providing an alternative metabolic substrate; calcium supports hemodynamics by partially overcoming blockade.
Question 4: Which benzodiazepine reversal agent must be used with extreme caution in patients with chronic benzodiazepine use or seizure history?
- Naloxone
- Flumazenil (Correct answer)
- Physostigmine
- Protamine sulfate
Correct answer: Flumazenil
Flumazenil can precipitate severe withdrawal seizures in benzodiazepine-dependent patients and in those whose epilepsy is controlled by benzodiazepines, making it potentially life-threatening in these populations.
Question 5: A patient ingested methanol and presents with visual disturbances and high anion-gap metabolic acidosis. What is the antidote?
- Thiamine IV
- Sodium bicarbonate only
- Fomepizole (4-MP) (Correct answer)
- Pyridoxine IV
Correct answer: Fomepizole (4-MP)
Fomepizole inhibits alcohol dehydrogenase, preventing conversion of methanol to formic acid, the toxic metabolite responsible for metabolic acidosis and optic nerve damage.
Question 6: For severe calcium channel blocker overdose with cardiogenic shock unresponsive to vasopressors and calcium, which advanced therapy is recommended?
- Digoxin loading
- Intravenous lipid emulsion therapy (Correct answer)
- Dopamine at low dose only
- Adenosine IV push
Correct answer: Intravenous lipid emulsion therapy
Intravenous lipid emulsion creates a 'lipid sink' in the bloodstream that sequesters lipophilic calcium channel blockers and may also provide cardiac energy substrate, improving hemodynamics in refractory toxicity.
Question 7: A patient collapsed at a house fire presents with unconsciousness, severe lactic acidosis, and cardiovascular collapse from suspected cyanide poisoning. What is the preferred antidote?
- Hydroxocobalamin (Cyanokit) (Correct answer)
- N-acetylcysteine
- Sodium thiosulfate alone
- Naloxone
Correct answer: Hydroxocobalamin (Cyanokit)
Hydroxocobalamin directly binds cyanide to form nontoxic cyanocobalamin and is the preferred agent in fire victims because, unlike nitrites, it does not worsen concurrent carbon monoxide-induced hypoxia.
CPR Toxicological Emergencies and Overdose Management 2
Which antidote is used for acetaminophen (Tylenol) overdose to prevent hepatotoxicity?