FACEM Toxicology and Poisoning 1 — Questions and Answers
Question 1: A 25-year-old presents 4 hours after ingesting 15g of acetaminophen. What is the most appropriate initial management step?
- Administer N-acetylcysteine (NAC) immediately without further workup
- Give activated charcoal and observe
- Obtain a serum acetaminophen level and plot it on the Rumack-Matthew nomogram (Correct answer)
- Initiate hemodialysis
Correct answer: Obtain a serum acetaminophen level and plot it on the Rumack-Matthew nomogram
The Rumack-Matthew nomogram requires a serum acetaminophen level drawn at 4 hours or later post-ingestion to accurately stratify risk and determine whether NAC is indicated.
Question 2: A patient presents with QRS widening to 160ms after tricyclic antidepressant (TCA) overdose. What is the most appropriate immediate treatment?
- Lidocaine 1mg/kg IV push
- Sodium bicarbonate 1–2 mEq/kg IV bolus (Correct answer)
- Magnesium sulfate 2g IV over 10 minutes
- Amiodarone 300mg IV
Correct answer: Sodium bicarbonate 1–2 mEq/kg IV bolus
Sodium bicarbonate alkalinizes the serum and provides a sodium load that reverses TCA-induced fast sodium channel blockade, narrowing the QRS and reducing arrhythmia risk.
Question 3: A farm worker presents with excessive secretions, miosis, bradycardia, urinary incontinence, and muscle fasciculations. Which antidote should be administered first?
- Pralidoxime (2-PAM) 1–2g IV
- Atropine 2–4mg IV, titrated until secretions dry (Correct answer)
- Physostigmine 2mg IV
- Diazepam 5mg IV for fasciculations
Correct answer: Atropine 2–4mg IV, titrated until secretions dry
Atropine is the first-line antidote for organophosphate poisoning, blocking muscarinic receptors to reduce secretions and bradycardia; pralidoxime is given concurrently but atropine takes priority.
Question 4: A patient is found unresponsive with miosis, respiratory rate of 6 breaths/min, and oxygen saturation of 78%. What is the most appropriate antidote?
- Flumazenil 0.2mg IV
- Naloxone 0.4–2mg IV (Correct answer)
- Physostigmine 1mg IV
- N-acetylcysteine IV infusion
Correct answer: Naloxone 0.4–2mg IV
The classic opioid toxidrome — miosis, respiratory depression, and decreased consciousness — is rapidly reversed by naloxone, a competitive opioid antagonist.
Question 5: A patient rescued from a house fire presents with headache, confusion, vomiting, and cherry-red skin. What is the most appropriate immediate treatment?
- Arrange urgent hyperbaric oxygen therapy
- Administer 100% oxygen via non-rebreather mask (Correct answer)
- Give the cyanide antidote kit
- Administer sodium thiosulfate 12.5g IV
Correct answer: Administer 100% oxygen via non-rebreather mask
High-flow 100% oxygen via non-rebreather mask is the immediate first-line treatment for carbon monoxide poisoning, accelerating the half-life reduction of carboxyhemoglobin from ~5 hours to ~60–90 minutes.
Question 6: A patient on digoxin develops nausea, yellow-green visual halos, and a ventricular rate of 38 bpm with complete heart block on ECG. What is the definitive treatment?
- Calcium gluconate 1g IV
- Magnesium sulfate 2g IV
- Digoxin-specific antibody fragments (DigiFab) (Correct answer)
- Transvenous temporary pacing alone
Correct answer: Digoxin-specific antibody fragments (DigiFab)
Digoxin-specific antibody fragments (DigiFab/Digibind) are the definitive antidote for life-threatening digoxin toxicity, binding and neutralizing free digoxin for renal elimination.
Question 7: A patient presents with tinnitus, diaphoresis, hyperventilation, and arterial blood gas showing pH 7.50, PaCO2 25 mmHg, and HCO3 18 mEq/L after aspirin ingestion. Which finding would most strongly indicate a need for hemodialysis?
- Serum salicylate level > 40 mg/dL
- Serum salicylate level > 100 mg/dL or end-organ dysfunction (Correct answer)
- Any respiratory alkalosis on blood gas
- Presence of tinnitus and hyperventilation alone
Correct answer: Serum salicylate level > 100 mg/dL or end-organ dysfunction
Hemodialysis is indicated for severe salicylate toxicity with levels >100 mg/dL, renal failure, pulmonary edema, altered mental status, or refractory acidosis.
FACEM Toxicology and Poisoning 1
A 25-year-old presents 4 hours after ingesting 15g of acetaminophen.
What is the most appropriate initial management step?