Asphyxial deaths: decompression sickness: 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: decompression sickness

Sample item

A commercial diver surfaces quickly from a deep dive. Thirty minutes later he has severe pain in the knees and shoulders and itching of the skin. What is the underlying cause?

ARupture of alveoli with air entering pulmonary veinsBCarbon dioxide retention in the tissuesCOxygen toxicity from breathing compressed airDNitrogen bubbles released as ambient pressure falls

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

The answer and the reasoning

D. Nitrogen bubbles released as ambient pressure falls

Under pressure, extra nitrogen dissolves in the tissues. When ascent is too rapid it comes out of solution as bubbles in joints, skin, spinal cord and blood. This causes the bends, skin itching and neurological features, and treatment is recompression in a hyperbaric chamber.

Option by option

A. Rupture of alveoli with air entering pulmonary veins
Alveolar rupture is pulmonary barotrauma, which is linked to breath-holding during ascent.
B. Carbon dioxide retention in the tissues
Carbon dioxide retention causes headache and confusion, not joint pain.
C. Oxygen toxicity from breathing compressed air
Oxygen toxicity causes seizures and lung injury and does not cause joint pain on surfacing.
D. Nitrogen bubbles released as ambient pressure falls (correct)
Correct. Rapid decompression allows dissolved nitrogen to form bubbles.

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.

Questions about this Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is D, Nitrogen bubbles released as ambient pressure falls. Under pressure, extra nitrogen dissolves in the tissues.

Why is "Rupture of alveoli with air entering pulmonary veins" not the answer?

Alveolar rupture is pulmonary barotrauma, which is linked to breath-holding during ascent.

Why is "Carbon dioxide retention in the tissues" not the answer?

Carbon dioxide retention causes headache and confusion, not joint pain.

Why is "Oxygen toxicity from breathing compressed air" not the answer?

Oxygen toxicity causes seizures and lung injury and does not cause joint pain on surfacing.

What concept does this question test?

It tests Asphyxial deaths: decompression sickness in Forensic Medicine. When ascent is too rapid it comes out of solution as bubbles in joints, skin, spinal cord and blood. This causes the bends, skin itching and neurological features, and treatment is recompression in a hyperbaric chamber.

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: decompression sickness?

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.