Asphyxial deaths: treatment to shorten HbCO half-life: practice question

A Forensic Medicine question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Forensic Medicine · Asphyxial deaths: treatment to shorten HbCO half-life

Sample item

A woman rescued from a house filled with fumes from a charcoal stove has a markedly raised carboxyhaemoglobin level. Which treatment shortens the carboxyhaemoglobin half-life the most?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Hyperbaric oxygen

The half-life of carboxyhaemoglobin is several hours on room air, falls to about an hour on high-flow oxygen, and falls further under hyperbaric conditions. Hyperbaric oxygen is therefore the quickest way to remove carbon monoxide, and is considered in severe poisoning, loss of consciousness or pregnancy. Methylene blue treats methaemoglobinaemia, not carbon monoxide poisoning.

Option by option

  • A. Breathing room air

    Room air gives the slowest elimination, taking several hours.

  • B. Oxygen by non-rebreather mask

    High-flow oxygen helps greatly, but the half-life is longer than with hyperbaric oxygen.

  • C. Hyperbaric oxygen (correct)

    Correct. Oxygen at higher than atmospheric pressure displaces carbon monoxide fastest.

  • D. Methylene blue infusion

    Methylene blue reduces methaemoglobin and has no role in carbon monoxide poisoning.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

More Forensic Medicine questions

Questions about this Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is C, Hyperbaric oxygen. The half-life of carboxyhaemoglobin is several hours on room air, falls to about an hour on high-flow oxygen, and falls further under hyperbaric conditions.

Why is "Breathing room air" not the answer?

Room air gives the slowest elimination, taking several hours.

Why is "Oxygen by non-rebreather mask" not the answer?

High-flow oxygen helps greatly, but the half-life is longer than with hyperbaric oxygen.

Why is "Methylene blue infusion" not the answer?

Methylene blue reduces methaemoglobin and has no role in carbon monoxide poisoning.

What concept does this question test?

It tests Asphyxial deaths: treatment to shorten HbCO half-life in Forensic Medicine. Hyperbaric oxygen is therefore the quickest way to remove carbon monoxide, and is considered in severe poisoning, loss of consciousness or pregnancy. Methylene blue treats methaemoglobinaemia, not carbon monoxide poisoning.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Asphyxial deaths: treatment to shorten HbCO half-life?

Learn postmortem changes with their timelines, and toxicology as poison, sign, test and antidote. Then use the flashcards and the other Forensic Medicine questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.