Local anaesthetics: tumescent anaesthesia: 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 · Local anaesthetics: tumescent anaesthesia

Sample item

In tumescent liposuction, lignocaine doses far above the usual 7 mg/kg maximum can be used. Why?

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

The answer and the reasoning

C. The dilute solution with adrenaline in subcutaneous fat is absorbed slowly, with delayed low peak levels

In tumescent technique, a large volume of very dilute lignocaine with adrenaline is infiltrated into subcutaneous fat. Vasoconstriction and the poor vascularity of fat slow absorption, so peak plasma levels occur late and remain lower than expected. Doses of 35 mg/kg or more have been used, but toxicity can still occur and monitoring continues for hours.

Option by option

  • A. Adrenaline makes lignocaine non-toxic

    Adrenaline slows absorption but does not remove toxicity.

  • B. Lignocaine is not absorbed from fat at all

    Some lignocaine is absorbed, and late toxicity is still possible.

  • C. The dilute solution with adrenaline in subcutaneous fat is absorbed slowly, with delayed low peak levels (correct)

    Correct. Slow absorption explains the tolerated dose.

  • D. The drug is rapidly metabolised in fat

    Metabolism occurs in the liver and is not accelerated in fat.

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.

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Questions about this Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is C, The dilute solution with adrenaline in subcutaneous fat is absorbed slowly, with delayed low peak levels. In tumescent technique, a large volume of very dilute lignocaine with adrenaline is infiltrated into subcutaneous fat.

Why is "Adrenaline makes lignocaine non-toxic" not the answer?

Adrenaline slows absorption but does not remove toxicity.

Why is "Lignocaine is not absorbed from fat at all" not the answer?

Some lignocaine is absorbed, and late toxicity is still possible.

Why is "The drug is rapidly metabolised in fat" not the answer?

Metabolism occurs in the liver and is not accelerated in fat.

What concept does this question test?

It tests Local anaesthetics: tumescent anaesthesia in Anaesthesia. Vasoconstriction and the poor vascularity of fat slow absorption, so peak plasma levels occur late and remain lower than expected. Doses of 35 mg/kg or more have been used, but toxicity can still occur and monitoring continues for hours.

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 Local anaesthetics: tumescent anaesthesia?

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.