Respiratory medicine: asthma exacerbation: practice question

A General 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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General Medicine · Respiratory medicine: asthma exacerbation

Sample item

A patient with acute severe asthma has a respiratory rate of 34/min, cannot complete sentences, and becomes drowsy. Which blood-gas change is especially ominous after initial hyperventilation?

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

The answer and the reasoning

C. A normalizing or rising PaCO2

Early severe asthma often causes hypocapnia from hyperventilation. A normal or rising PaCO2 can indicate tiring respiratory muscles and impending ventilatory failure.

Option by option

  • A. A low PaCO2

    Low PaCO2 is common early in an attack and is less ominous by itself.

  • B. A mild respiratory alkalosis

    Respiratory alkalosis reflects hyperventilation rather than failure to ventilate.

  • C. A normalizing or rising PaCO2 (correct)

    Correct. Carbon dioxide retention in this setting is a red flag for exhaustion.

  • D. An increased oxygen saturation on supplemental oxygen

    Oxygen saturation alone may improve while ventilatory fatigue progresses.

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 General Medicine question

What is the answer to this General Medicine question?

The best answer is C, A normalizing or rising PaCO2. Early severe asthma often causes hypocapnia from hyperventilation.

Why is "A low PaCO2" not the answer?

Low PaCO2 is common early in an attack and is less ominous by itself.

Why is "A mild respiratory alkalosis" not the answer?

Respiratory alkalosis reflects hyperventilation rather than failure to ventilate.

Why is "An increased oxygen saturation on supplemental oxygen" not the answer?

Oxygen saturation alone may improve while ventilatory fatigue progresses.

What concept does this question test?

It tests Respiratory medicine: asthma exacerbation in General Medicine. A normal or rising PaCO2 can indicate tiring respiratory muscles and impending ventilatory failure.

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 medicine: asthma exacerbation?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General 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.