Pharynx and tonsils: obesity hypoventilation: practice question

A ENT 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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ENT · Pharynx and tonsils: obesity hypoventilation

Sample item

A man with BMI 42 and severe obstructive sleep apnoea has morning headaches. Which finding best suggests obesity hypoventilation syndrome in addition?

AAwake oxygen saturation of 98 percentBLow serum bicarbonate on venous bloodCAwake arterial carbon dioxide tension above 45 mmHgDRaised apnoea-hypopnoea index alone

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

The answer and the reasoning

C. Awake arterial carbon dioxide tension above 45 mmHg

Obesity hypoventilation syndrome combines obesity with awake daytime hypercapnia not explained by other causes. A raised serum bicarbonate on routine tests is a useful screen, and such patients often need positive airway pressure.

Option by option

A. Awake oxygen saturation of 98 percent
A normal saturation is expected in OSA and does not point to hypoventilation.
B. Low serum bicarbonate on venous blood
Chronic hypercapnia raises bicarbonate through renal compensation; a low value would argue against it.
C. Awake arterial carbon dioxide tension above 45 mmHg (correct)
Correct. Daytime hypercapnia is the defining feature that separates it from simple OSA.
D. Raised apnoea-hypopnoea index alone
A high apnoea-hypopnoea index defines severity of OSA and does not reveal awake hypoventilation.

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 ENT question

What is the answer to this ENT question?

The best answer is C, Awake arterial carbon dioxide tension above 45 mmHg. Obesity hypoventilation syndrome combines obesity with awake daytime hypercapnia not explained by other causes.

Why is "Awake oxygen saturation of 98 percent" not the answer?

A normal saturation is expected in OSA and does not point to hypoventilation.

Why is "Low serum bicarbonate on venous blood" not the answer?

Chronic hypercapnia raises bicarbonate through renal compensation; a low value would argue against it.

Why is "Raised apnoea-hypopnoea index alone" not the answer?

A high apnoea-hypopnoea index defines severity of OSA and does not reveal awake hypoventilation.

What concept does this question test?

It tests Pharynx and tonsils: obesity hypoventilation in ENT. A raised serum bicarbonate on routine tests is a useful screen, and such patients often need positive airway pressure.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Pharynx and tonsils: obesity hypoventilation?

Learn tuning fork results and audiogram patterns by sketching them. Then use the flashcards and the other ENT 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.