Basic resuscitation: end-tidal CO2 during CPR: 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 · Basic resuscitation: end-tidal CO2 during CPR

Sample item

During CPR in an intubated patient, the end-tidal CO2 abruptly rises from 12 to 40 mmHg without any change in compression quality. What is the most likely interpretation?

AReturn of spontaneous circulationBOesophageal intubationCRight main bronchus intubationDA fall in cardiac output

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

The answer and the reasoning

A. Return of spontaneous circulation

End-tidal CO2 reflects pulmonary blood flow during CPR. An abrupt sustained rise suggests return of spontaneous circulation, so a pulse and rhythm check is performed. A persistently very low value despite good compressions indicates poor perfusion.

Option by option

A. Return of spontaneous circulation (correct)
Correct. Restored pulmonary blood flow raises CO2 delivery to the lungs.
B. Oesophageal intubation
Oesophageal placement gives a flat or absent trace.
C. Right main bronchus intubation
Endobronchial intubation does not produce a sudden fourfold rise.
D. A fall in cardiac output
A fall in cardiac output reduces end-tidal CO2.

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 A, Return of spontaneous circulation. End-tidal CO2 reflects pulmonary blood flow during CPR.

Why is "Oesophageal intubation" not the answer?

Oesophageal placement gives a flat or absent trace.

Why is "Right main bronchus intubation" not the answer?

Endobronchial intubation does not produce a sudden fourfold rise.

Why is "A fall in cardiac output" not the answer?

A fall in cardiac output reduces end-tidal CO2.

What concept does this question test?

It tests Basic resuscitation: end-tidal CO2 during CPR in Anaesthesia. An abrupt sustained rise suggests return of spontaneous circulation, so a pulse and rhythm check is performed. A persistently very low value despite good compressions indicates poor perfusion.

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 Basic resuscitation: end-tidal CO2 during CPR?

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.