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

A sudden sustained fall in end-tidal carbon dioxide during anaesthesia should raise concern for which event?

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

The answer and the reasoning

B. Pulmonary embolism or severe loss of cardiac output

End-tidal CO2 falls when pulmonary perfusion or cardiac output abruptly falls, as in massive embolism or cardiac arrest. Hypoventilation and rebreathing usually raise it.

Option by option

  • A. Malignant hyperthermia only

    Malignant hyperthermia typically raises CO2 production and end-tidal CO2.

  • B. Pulmonary embolism or severe loss of cardiac output (correct)

    Correct. Less perfusion delivers less CO2 to alveoli.

  • C. Rebreathing carbon dioxide

    Rebreathing increases inspired and end-tidal CO2.

  • D. Hypoventilation alone

    Hypoventilation retains CO2 and raises end-tidal values.

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.

More Anaesthesia questions

Questions about this Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is B, Pulmonary embolism or severe loss of cardiac output. End-tidal CO2 falls when pulmonary perfusion or cardiac output abruptly falls, as in massive embolism or cardiac arrest.

Why is "Malignant hyperthermia only" not the answer?

Malignant hyperthermia typically raises CO2 production and end-tidal CO2.

Why is "Rebreathing carbon dioxide" not the answer?

Rebreathing increases inspired and end-tidal CO2.

Why is "Hypoventilation alone" not the answer?

Hypoventilation retains CO2 and raises end-tidal values.

What concept does this question test?

It tests Monitoring: capnography in Anaesthesia. Hypoventilation and rebreathing usually raise it.

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.