Intravenous and inhalational agents: halothane and catecholamines: 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 · Intravenous and inhalational agents: halothane and catecholamines

Sample item

During halothane anaesthesia, a surgeon infiltrates the wound with adrenaline and ventricular ectopics appear. What is the mechanism?

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

The answer and the reasoning

C. Sensitisation of the myocardium to catecholamines

Halothane sensitises the myocardium to the arrhythmogenic effect of circulating or infiltrated catecholamines, so adrenaline doses must be limited. Sevoflurane and isoflurane do this much less.

Option by option

  • A. Halothane-induced vagal stimulation

    Vagal stimulation causes bradycardia, not ventricular ectopics.

  • B. Release of potassium from the cells

    Potassium release is a feature of suxamethonium, not halothane.

  • C. Sensitisation of the myocardium to catecholamines (correct)

    Correct. Halothane lowers the arrhythmia threshold to catecholamines.

  • D. Coronary steal

    Coronary steal is described with isoflurane and does not cause ectopics from adrenaline.

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, Sensitisation of the myocardium to catecholamines. Halothane sensitises the myocardium to the arrhythmogenic effect of circulating or infiltrated catecholamines, so adrenaline doses must be limited.

Why is "Halothane-induced vagal stimulation" not the answer?

Vagal stimulation causes bradycardia, not ventricular ectopics.

Why is "Release of potassium from the cells" not the answer?

Potassium release is a feature of suxamethonium, not halothane.

Why is "Coronary steal" not the answer?

Coronary steal is described with isoflurane and does not cause ectopics from adrenaline.

What concept does this question test?

It tests Intravenous and inhalational agents: halothane and catecholamines in Anaesthesia. Sevoflurane and isoflurane do this much less.

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 Intravenous and inhalational agents: halothane and catecholamines?

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.