Asphyxial deaths: classification of anoxia: 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: classification of anoxia

Sample item

A 60-year-old man dies suddenly of massive pulmonary embolism. In the classification of anoxia used in forensic medicine, which type best describes the tissue oxygen lack here?

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

The answer and the reasoning

C. Stagnant anoxia, because blood flow to the tissues has failed

Anoxia is classified as anoxic (low oxygen in inspired air or blocked airway), anaemic (reduced oxygen-carrying capacity), stagnant (circulatory failure) and histotoxic (cellular enzyme block). Failure of forward blood flow, as in embolism, shock or cardiac failure, produces stagnant anoxia.

Option by option

  • A. Anoxic anoxia, because the inspired oxygen tension is low

    Anoxic anoxia arises from low ambient oxygen, high altitude or airway obstruction, not from a circulatory block.

  • B. Histotoxic anoxia, because cells cannot use delivered oxygen

    Histotoxic anoxia arises from poisons such as cyanide that inhibit cellular respiration.

  • C. Stagnant anoxia, because blood flow to the tissues has failed (correct)

    Correct. Circulatory failure means oxygenated blood does not reach tissues.

  • D. Anaemic anoxia, because haemoglobin cannot carry oxygen

    Anaemic anoxia arises from anaemia or carbon monoxide, where the blood carries too little usable haemoglobin.

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.

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Questions about this Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is C, Stagnant anoxia, because blood flow to the tissues has failed. Anoxia is classified as anoxic (low oxygen in inspired air or blocked airway), anaemic (reduced oxygen-carrying capacity), stagnant (circulatory failure) and histotoxic (cellular enzyme block).

Why is "Anoxic anoxia, because the inspired oxygen tension is low" not the answer?

Anoxic anoxia arises from low ambient oxygen, high altitude or airway obstruction, not from a circulatory block.

Why is "Histotoxic anoxia, because cells cannot use delivered oxygen" not the answer?

Histotoxic anoxia arises from poisons such as cyanide that inhibit cellular respiration.

Why is "Anaemic anoxia, because haemoglobin cannot carry oxygen" not the answer?

Anaemic anoxia arises from anaemia or carbon monoxide, where the blood carries too little usable haemoglobin.

What concept does this question test?

It tests Asphyxial deaths: classification of anoxia in Forensic Medicine. Failure of forward blood flow, as in embolism, shock or cardiac failure, produces stagnant anoxia.

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: classification of anoxia?

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.