Respiratory physiology and ventilation: curriculum recognition: practice question

A Anaesthesia 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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Anaesthesia · Respiratory physiology and ventilation: curriculum recognition

Sample item

A paralysed patient on volume control with a fixed set breath size has a PaCO2 of 58 mmHg and pH 7.26, with adequate oxygenation. Which single ventilator change most directly corrects this?

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

The answer and the reasoning

B. Increase the number of breaths per minute

With the breath size fixed, minute ventilation is changed by altering the rate, and CO2 clearance rises with alveolar ventilation. PEEP and oxygen fraction mainly affect oxygenation. Check that the expiratory time is still enough to avoid air trapping.

Option by option

  • A. Reduce the inspired oxygen fraction

    Lowering the oxygen fraction does not alter CO2 elimination.

  • B. Increase the number of breaths per minute (correct)

    Correct. A higher rate increases minute and alveolar ventilation, lowering PaCO2.

  • C. Increase PEEP

    PEEP aids oxygenation and does not increase CO2 clearance.

  • D. Add an inspiratory hold time

    An inspiratory hold improves gas distribution only slightly and shortens expiratory time.

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 Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is B, Increase the number of breaths per minute. With the breath size fixed, minute ventilation is changed by altering the rate, and CO2 clearance rises with alveolar ventilation.

Why is "Reduce the inspired oxygen fraction" not the answer?

Lowering the oxygen fraction does not alter CO2 elimination.

Why is "Increase PEEP" not the answer?

PEEP aids oxygenation and does not increase CO2 clearance.

Why is "Add an inspiratory hold time" not the answer?

An inspiratory hold improves gas distribution only slightly and shortens expiratory time.

What concept does this question test?

It tests Respiratory physiology and ventilation: curriculum recognition in Anaesthesia. PEEP and oxygen fraction mainly affect oxygenation. Check that the expiratory time is still enough to avoid air trapping.

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 Respiratory physiology and ventilation: curriculum recognition?

Make a table of each agent, its key advantage and its main side effect. Then use the flashcards and the other Anaesthesia 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.