Aspiration: Mendelson syndrome: 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 · Aspiration: Mendelson syndrome

Sample item

Which gastric content characteristics are classically associated with severe aspiration pneumonitis (Mendelson syndrome)?

AParticulate food only, regardless of pHBpH above 5 and volume of 5 mLCpH of 7 and volume above 100 mLDpH below 2.5 and volume above 25 mL (0.4 mL/kg)

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

The answer and the reasoning

D. pH below 2.5 and volume above 25 mL (0.4 mL/kg)

Chemical pneumonitis is most severe when aspirated fluid has a pH under 2.5 and a volume exceeding about 25 mL or 0.4 mL/kg. Acid injures the alveolar epithelium and causes bronchospasm and hypoxia.

Option by option

A. Particulate food only, regardless of pH
Particulate matter causes obstruction, but the classical syndrome describes acid injury.
B. pH above 5 and volume of 5 mL
A high pH with small volume causes little injury.
C. pH of 7 and volume above 100 mL
Neutral pH is not strongly injurious chemically.
D. pH below 2.5 and volume above 25 mL (0.4 mL/kg) (correct)
Correct. Low pH and large volume are the classical thresholds.

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, pH below 2.5 and volume above 25 mL (0.4 mL/kg). Chemical pneumonitis is most severe when aspirated fluid has a pH under 2.

Why is "Particulate food only, regardless of pH" not the answer?

Particulate matter causes obstruction, but the classical syndrome describes acid injury.

Why is "pH above 5 and volume of 5 mL" not the answer?

A high pH with small volume causes little injury.

Why is "pH of 7 and volume above 100 mL" not the answer?

Neutral pH is not strongly injurious chemically.

What concept does this question test?

It tests Aspiration: Mendelson syndrome in Anaesthesia. 5 and a volume exceeding about 25 mL or 0.4 mL/kg. Acid injures the alveolar epithelium and causes bronchospasm and hypoxia.

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 Aspiration: Mendelson syndrome?

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.