Intravenous and inhalational agents: ketamine in catecholamine depletion: 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: ketamine in catecholamine depletion

Sample item

A young man in prolonged haemorrhagic shock, whose catecholamine stores are exhausted, becomes more hypotensive after ketamine induction. What explains this?

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

The answer and the reasoning

A. Direct myocardial depression is unmasked when sympathetic stimulation is lost

Ketamine normally supports blood pressure through central sympathetic stimulation and catecholamine reuptake inhibition. In a patient with depleted catecholamines the drug's direct negative inotropic effect predominates, so a reduced dose is used in critically ill patients.

Option by option

  • A. Direct myocardial depression is unmasked when sympathetic stimulation is lost (correct)

    Correct. Without a sympathetic drive, the direct myocardial depressant effect shows.

  • B. Blockade of cardiac beta receptors producing bradycardia

    Ketamine does not block beta receptors.

  • C. Vagal stimulation causing heart block

    Ketamine does not act through vagal stimulation or heart block.

  • D. Histamine release causing widespread vasodilation

    Ketamine is not a significant histamine releaser.

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 A, Direct myocardial depression is unmasked when sympathetic stimulation is lost. Ketamine normally supports blood pressure through central sympathetic stimulation and catecholamine reuptake inhibition.

Why is "Blockade of cardiac beta receptors producing bradycardia" not the answer?

Ketamine does not block beta receptors.

Why is "Vagal stimulation causing heart block" not the answer?

Ketamine does not act through vagal stimulation or heart block.

Why is "Histamine release causing widespread vasodilation" not the answer?

Ketamine is not a significant histamine releaser.

What concept does this question test?

It tests Intravenous and inhalational agents: ketamine in catecholamine depletion in Anaesthesia. In a patient with depleted catecholamines the drug's direct negative inotropic effect predominates, so a reduced dose is used in critically ill patients.

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 Intravenous and inhalational agents: ketamine in catecholamine depletion?

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.