Paediatric airway: tube size: 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 · Paediatric airway: tube size

Sample item

What is the approximate internal diameter of a cuffed endotracheal tube for an 8-year-old child using the formula age/4 + 3.5?

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

The answer and the reasoning

D. 5.5 mm

For cuffed tubes the formula is age divided by 4 plus 3.5, so for 8 years it is 2 + 3.5 = 5.5 mm. For uncuffed tubes the formula is age/4 + 4, which gives 6 mm.

Option by option

  • A. 7.5 mm

    7.5 mm is an adult female size.

  • B. 4.5 mm

    4.5 mm would be too small for this age.

  • C. 6.5 mm

    6.5 mm would be too large for a cuffed tube at this age.

  • D. 5.5 mm (correct)

    Correct. 8/4 + 3.5 = 5.5 mm.

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 D, 5.5 mm. For cuffed tubes the formula is age divided by 4 plus 3.

Why is "7.5 mm" not the answer?

7.5 mm is an adult female size.

Why is "4.5 mm" not the answer?

4.5 mm would be too small for this age.

Why is "6.5 mm" not the answer?

6.5 mm would be too large for a cuffed tube at this age.

What concept does this question test?

It tests Paediatric airway: tube size in Anaesthesia. 5, so for 8 years it is 2 + 3.5 = 5.5 mm. For uncuffed tubes the formula is age/4 + 4, which gives 6 mm.

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 Paediatric airway: tube size?

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.