Intravenous and inhalational agents: factors lowering MAC: 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: factors lowering MAC

Sample item

Which of the following decreases the minimum alveolar concentration of volatile anaesthetics?

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

The answer and the reasoning

C. Hypothermia

MAC falls with hypothermia, pregnancy, old age, acute alcohol intoxication, hyponatraemia and central alpha-2 agonists or opioids. It rises with hyperthermia, hypernatraemia and chronic alcohol abuse. Thyroid state does not alter MAC.

Option by option

  • A. Chronic alcohol abuse

    Chronic alcohol use increases anaesthetic requirement, whereas acute intoxication decreases it.

  • B. Hyperthyroidism

    Thyroid disease does not change MAC.

  • C. Hypothermia (correct)

    Correct. MAC falls by roughly 2 to 5 percent for each degree Celsius of cooling.

  • D. Hypernatraemia

    Hypernatraemia increases MAC.

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, Hypothermia. MAC falls with hypothermia, pregnancy, old age, acute alcohol intoxication, hyponatraemia and central alpha-2 agonists or opioids.

Why is "Chronic alcohol abuse" not the answer?

Chronic alcohol use increases anaesthetic requirement, whereas acute intoxication decreases it.

Why is "Hyperthyroidism" not the answer?

Thyroid disease does not change MAC.

Why is "Hypernatraemia" not the answer?

Hypernatraemia increases MAC.

What concept does this question test?

It tests Intravenous and inhalational agents: factors lowering MAC in Anaesthesia. It rises with hyperthermia, hypernatraemia and chronic alcohol abuse. Thyroid state does not alter MAC.

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: factors lowering MAC?

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.