Respiratory system: Cheyne-Stokes breathing: practice question

A Physiology 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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Physiology · Respiratory system: Cheyne-Stokes breathing

Sample item

A 68-year-old man with severe left ventricular failure shows cycles of waxing and waning breathing separated by apnoeic periods. Which mechanism best explains this pattern?

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

The answer and the reasoning

C. Prolonged lung-to-brain circulation time delays chemoreceptor feedback, so the control loop oscillates

In heart failure the low cardiac output lengthens the circulation time between the lungs and the central chemoreceptors, and chemosensitivity is often increased. Chemoreceptors therefore sense blood gas changes late, causing overshoot and undershoot of ventilation and alternating hyperventilation and apnoea.

Option by option

  • A. Permanent destruction of the pre-Botzinger complex

    Destruction of the rhythm generator would cause irreversible apnoea, not cyclic breathing.

  • B. Increased lung compliance causing exaggerated Hering-Breuer reflexes

    Lung compliance in cardiac failure is reduced, and Hering-Breuer reflexes do not explain the cycles.

  • C. Prolonged lung-to-brain circulation time delays chemoreceptor feedback, so the control loop oscillates (correct)

    Correct. Delay in the feedback loop causes oscillation.

  • D. Loss of carotid body chemoreceptor function

    Carotid bodies are generally hypersensitive in this condition, not absent.

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 Physiology question

What is the answer to this Physiology question?

The best answer is C, Prolonged lung-to-brain circulation time delays chemoreceptor feedback, so the control loop oscillates. In heart failure the low cardiac output lengthens the circulation time between the lungs and the central chemoreceptors, and chemosensitivity is often increased.

Why is "Permanent destruction of the pre-Botzinger complex" not the answer?

Destruction of the rhythm generator would cause irreversible apnoea, not cyclic breathing.

Why is "Increased lung compliance causing exaggerated Hering-Breuer reflexes" not the answer?

Lung compliance in cardiac failure is reduced, and Hering-Breuer reflexes do not explain the cycles.

Why is "Loss of carotid body chemoreceptor function" not the answer?

Carotid bodies are generally hypersensitive in this condition, not absent.

What concept does this question test?

It tests Respiratory system: Cheyne-Stokes breathing in Physiology. Chemoreceptors therefore sense blood gas changes late, causing overshoot and undershoot of ventilation and alternating hyperventilation and apnoea.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Respiratory system: Cheyne-Stokes breathing?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology 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.