Monitoring: capnography: 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 · Monitoring: capnography

Sample item

During controlled ventilation, the capnogram baseline fails to return to zero between breaths. What is the most likely physiological explanation?

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

The answer and the reasoning

D. Rebreathing of carbon dioxide

A raised inspired carbon dioxide baseline indicates rebreathing, which may result from exhausted carbon dioxide absorbent, faulty valves, or inadequate fresh-gas flow in relevant circuits. It should prompt a systematic circuit check.

Option by option

  • A. Severe hypothermia

    Hypothermia does not by itself create an elevated inspired CO2 baseline.

  • B. Complete circuit disconnection

    Disconnection typically causes a sudden loss of the waveform.

  • C. Esophageal extubation with no ventilation

    Esophageal intubation usually produces absent or rapidly disappearing persistent exhaled CO2.

  • D. Rebreathing of carbon dioxide (correct)

    Correct. Inspired CO2 should normally return close to zero; an elevated baseline signals rebreathing.

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 D, Rebreathing of carbon dioxide. A raised inspired carbon dioxide baseline indicates rebreathing, which may result from exhausted carbon dioxide absorbent, faulty valves, or inadequate fresh-gas flow in relevant circuits.

Why is "Severe hypothermia" not the answer?

Hypothermia does not by itself create an elevated inspired CO2 baseline.

Why is "Complete circuit disconnection" not the answer?

Disconnection typically causes a sudden loss of the waveform.

Why is "Esophageal extubation with no ventilation" not the answer?

Esophageal intubation usually produces absent or rapidly disappearing persistent exhaled CO2.

What concept does this question test?

It tests Monitoring: capnography in Anaesthesia. It should prompt a systematic circuit check.

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 Monitoring: capnography?

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.