Muscle relaxants: relaxant choice with hyperkalaemia: 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: relaxant choice with hyperkalaemia

Sample item

A patient in renal failure with potassium 6.2 mmol/L needs a rapid sequence induction for bowel obstruction and intubating conditions are needed within about a minute. Which relaxant is most suitable?

AMivacuriumBRocuroniumCVecuroniumDSuxamethonium

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

The answer and the reasoning

B. Rocuronium

At a high dose rocuronium produces intubating conditions in about a minute without raising potassium, and sugammadex is available for rescue. Suxamethonium raises potassium by a further 0.5 mmol/L or so, which is unwise at 6.2. Mivacurium and vecuronium are too slow for rapid sequence induction.

Option by option

A. Mivacurium
Mivacurium has a slow onset and is not suitable for rapid sequence intubation.
B. Rocuronium (correct)
Correct. Its fast onset suits rapid sequence induction and it does not raise potassium.
C. Vecuronium
Vecuronium takes several minutes to work and so cannot secure the airway quickly.
D. Suxamethonium
Suxamethonium releases potassium and is relatively contraindicated when the level is already high.

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 B, Rocuronium. At a high dose rocuronium produces intubating conditions in about a minute without raising potassium, and sugammadex is available for rescue.

Why is "Mivacurium" not the answer?

Mivacurium has a slow onset and is not suitable for rapid sequence intubation.

Why is "Vecuronium" not the answer?

Vecuronium takes several minutes to work and so cannot secure the airway quickly.

Why is "Suxamethonium" not the answer?

Suxamethonium releases potassium and is relatively contraindicated when the level is already high.

What concept does this question test?

It tests Muscle relaxants: relaxant choice with hyperkalaemia in Anaesthesia. Suxamethonium raises potassium by a further 0.5 mmol/L or so, which is unwise at 6.2. Mivacurium and vecuronium are too slow for rapid sequence induction.

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 Muscle relaxants: relaxant choice with hyperkalaemia?

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.