Muscle relaxants: phase II block: 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 · Muscle relaxants: phase II block

Sample item

Which feature favours a phase II (dual) block after large doses of suxamethonium?

AAbsence of fadeBPotentiation by neostigmineCFasciculationsDFade on train-of-four and post-tetanic potentiation

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

The answer and the reasoning

D. Fade on train-of-four and post-tetanic potentiation

Phase II block resembles a non-depolarising block, with fade on train-of-four, tetanic fade and post-tetanic potentiation. Anticholinesterases may partly reverse it once fade is established.

Option by option

A. Absence of fade
Phase I, not phase II, shows no fade.
B. Potentiation by neostigmine
Neostigmine potentiates phase I block, not phase II.
C. Fasciculations
Fasciculations are seen when onset occurs in phase I.
D. Fade on train-of-four and post-tetanic potentiation (correct)
Correct. These are typical of phase II block.

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, Fade on train-of-four and post-tetanic potentiation. Phase II block resembles a non-depolarising block, with fade on train-of-four, tetanic fade and post-tetanic potentiation.

Why is "Absence of fade" not the answer?

Phase I, not phase II, shows no fade.

Why is "Potentiation by neostigmine" not the answer?

Neostigmine potentiates phase I block, not phase II.

Why is "Fasciculations" not the answer?

Fasciculations are seen when onset occurs in phase I.

What concept does this question test?

It tests Muscle relaxants: phase II block in Anaesthesia. Anticholinesterases may partly reverse it once fade is established.

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 Muscle relaxants: phase II block?

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.