Intravenous and inhalational agents: ventilation and rise in alveolar concentration: 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 · Intravenous and inhalational agents: ventilation and rise in alveolar concentration

Sample item

During inhalational induction with a blood-soluble volatile agent, how does increasing alveolar ventilation affect the rate of rise of alveolar concentration?

AIt makes the rise slower, because pulmonary vessels dilateBIt has no effect, as only solubility mattersCIt makes the rise slower, because more agent is washed outDIt makes the rise faster

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

The answer and the reasoning

D. It makes the rise faster

Greater alveolar ventilation delivers the agent to the alveoli faster and replaces what blood has removed. The effect is most obvious for soluble agents, where uptake is large and ventilation limits the rise.

Option by option

A. It makes the rise slower, because pulmonary vessels dilate
Hyperventilation does not dilate pulmonary vessels in a way that slows the rise.
B. It has no effect, as only solubility matters
Solubility is important, but ventilation also determines the rise, particularly for soluble agents.
C. It makes the rise slower, because more agent is washed out
Ventilation delivers the agent; it does not wash out the inspired concentration during induction.
D. It makes the rise faster (correct)
Correct. Faster delivery of the agent to the alveoli speeds the rise, especially for soluble agents.

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 Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is D, It makes the rise faster. Greater alveolar ventilation delivers the agent to the alveoli faster and replaces what blood has removed.

Why is "It makes the rise slower, because pulmonary vessels dilate" not the answer?

Hyperventilation does not dilate pulmonary vessels in a way that slows the rise.

Why is "It has no effect, as only solubility matters" not the answer?

Solubility is important, but ventilation also determines the rise, particularly for soluble agents.

Why is "It makes the rise slower, because more agent is washed out" not the answer?

Ventilation delivers the agent; it does not wash out the inspired concentration during induction.

What concept does this question test?

It tests Intravenous and inhalational agents: ventilation and rise in alveolar concentration in Anaesthesia. The effect is most obvious for soluble agents, where uptake is large and ventilation limits the rise.

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 Intravenous and inhalational agents: ventilation and rise in alveolar concentration?

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.