CFRN Environmental and Toxicological Emergencies 5 — Questions and Answers
Question 1: A patient is transported after ingesting methanol. Metabolic acidosis with a high anion gap and elevated osmol gap is present. What is the mechanism of methanol toxicity?
- Direct hepatocellular necrosis from methanol itself
- Conversion to formaldehyde and formic acid by alcohol dehydrogenase (Correct answer)
- Competitive inhibition of cytochrome P450 enzymes
- Direct renal tubular toxicity from the parent compound
Correct answer: Conversion to formaldehyde and formic acid by alcohol dehydrogenase
Alcohol dehydrogenase metabolizes methanol to formaldehyde and then formic acid, which causes optic nerve damage and severe metabolic acidosis.
Question 2: During transport of a hypothermic patient (core temp 30°C) with a stable cardiac rhythm, which intervention should be avoided?
- Passive external rewarming with blankets
- Active core rewarming with warmed humidified oxygen
- Rough handling or jostling of the patient (Correct answer)
- Monitoring continuous cardiac rhythm
Correct answer: Rough handling or jostling of the patient
Rough handling of a hypothermic patient can precipitate ventricular fibrillation due to myocardial irritability at low core temperatures.
Question 3: A patient presents with mydriasis, dry flushing skin, urinary retention, tachycardia, and delirium after ingesting an unknown substance. Which toxidrome is present?
- Cholinergic toxidrome
- Anticholinergic toxidrome (Correct answer)
- Sympathomimetic toxidrome
- Opioid toxidrome
Correct answer: Anticholinergic toxidrome
The classic anticholinergic toxidrome ('mad as a hatter, red as a beet, dry as a bone, blind as a bat, hot as Hades') includes mydriasis, hyperthermia, dry skin, urinary retention, and delirium.
Question 4: A scuba diver develops joint pain, mottled skin, and neurological symptoms during air transport after a rapid ascent. The flight nurse should:
- Maintain standard cabin altitude to minimize patient discomfort
- Fly at the lowest safe altitude and arrange immediate hyperbaric recompression (Correct answer)
- Administer diuretics to facilitate nitrogen excretion
- Perform needle decompression of the chest bilaterally
Correct answer: Fly at the lowest safe altitude and arrange immediate hyperbaric recompression
Decompression sickness requires flying as low as possible (maximizing atmospheric pressure) and urgent transfer to a hyperbaric facility for recompression therapy.
Question 5: A patient who ingested a large quantity of opioids is given naloxone with good effect, but 45 minutes later becomes unresponsive again. What is the most appropriate action?
- Administer a second single-dose bolus of naloxone and observe
- Initiate a continuous naloxone infusion and arrange for extended monitoring (Correct answer)
- Discontinue naloxone as its effects have worn off permanently
- Switch to flumazenil for ongoing sedation management
Correct answer: Initiate a continuous naloxone infusion and arrange for extended monitoring
Many opioids outlast the duration of naloxone (30–90 min); a continuous infusion prevents renarcotization while the opioid is being metabolized.
Question 6: A patient is being transported after a marine envenomation from a box jellyfish sting. In addition to pain management, which antidote is available for severe systemic toxicity?
- Antivenom specific to Chironex fleckeri (Correct answer)
- Calcium gluconate IV
- Neostigmine
- Protamine sulfate
Correct answer: Antivenom specific to Chironex fleckeri
Chironex fleckeri (box jellyfish) antivenom is available and indicated for severe systemic envenomation including cardiovascular collapse and respiratory failure.
Question 7: A 6-year-old child has ingested approximately 20 adult iron tablets. The child is currently asymptomatic 90 minutes after ingestion. Which statement best guides management?
- Asymptomatic presentation means significant iron toxicity has been ruled out
- Early asymptomatic phase can be followed by a severe systemic toxic phase 6–24 hours later (Correct answer)
- Activated charcoal is the treatment of choice for iron ingestion
- Syrup of ipecac should be administered to induce emesis
Correct answer: Early asymptomatic phase can be followed by a severe systemic toxic phase 6–24 hours later
Iron toxicity has a characteristic biphasic course; initial GI symptoms may improve before severe systemic toxicity (shock, metabolic acidosis) develops hours later.
CFRN Environmental and Toxicological Emergencies 5
A patient is transported after ingesting methanol.
Metabolic acidosis with a high anion gap and elevated osmol gap is present.
What is the mechanism of methanol toxicity?