Malignant hyperthermia: 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 · Malignant hyperthermia

Sample item

During general anaesthesia with sevoflurane and succinylcholine, a patient develops unexplained tachycardia, jaw rigidity and a rapidly rising end-tidal CO2 despite increased ventilation. Which sign is the earliest and most sensitive indicator of malignant hyperthermia?

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

The answer and the reasoning

D. Unexplained rise in end-tidal carbon dioxide

Malignant hyperthermia is a hypermetabolic crisis from uncontrolled calcium release in skeletal muscle after volatile agents or succinylcholine. The earliest sign is a rising end-tidal CO2 resistant to increased ventilation with tachycardia, and fever is a later sign. Dantrolene is the specific treatment.

Option by option

  • A. Cardiac arrest from hyperkalaemia

    Cardiac arrest from hyperkalaemia is a late complication of an untreated crisis.

  • B. Core temperature above 40 C

    Marked fever is a late feature and can be absent early on.

  • C. Dark cola-coloured urine

    Myoglobinuria with dark urine occurs later from muscle breakdown.

  • D. Unexplained rise in end-tidal carbon dioxide (correct)

    Correct. Increased CO2 production is the first and most sensitive sign of the hypermetabolic state.

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, Unexplained rise in end-tidal carbon dioxide. Malignant hyperthermia is a hypermetabolic crisis from uncontrolled calcium release in skeletal muscle after volatile agents or succinylcholine.

Why is "Cardiac arrest from hyperkalaemia" not the answer?

Cardiac arrest from hyperkalaemia is a late complication of an untreated crisis.

Why is "Core temperature above 40 C" not the answer?

Marked fever is a late feature and can be absent early on.

Why is "Dark cola-coloured urine" not the answer?

Myoglobinuria with dark urine occurs later from muscle breakdown.

What concept does this question test?

It tests Malignant hyperthermia in Anaesthesia. The earliest sign is a rising end-tidal CO2 resistant to increased ventilation with tachycardia, and fever is a later sign. Dantrolene is the specific treatment.

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 Malignant hyperthermia?

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.