Complications and emergencies: hypertonic saline in head injury: 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 · Complications and emergencies: hypertonic saline in head injury

Sample item

A hypotensive polytrauma patient with a severe head injury and raised intracranial pressure needs osmotherapy. Why might hypertonic saline be preferred to mannitol?

AIt lowers the serum sodium to reduce cerebral oedemaBIt acts only by diuresis, reducing brain water through urine lossCIt lowers intracranial pressure and expands intravascular volume, unlike mannitol diuresisDIt has no effect on blood pressure or volume status

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

The answer and the reasoning

C. It lowers intracranial pressure and expands intravascular volume, unlike mannitol diuresis

Both agents raise plasma osmolality and draw water out of brain tissue. Mannitol causes an osmotic diuresis and can worsen hypovolaemia, whereas hypertonic saline expands plasma volume and supports blood pressure and cerebral perfusion.

Option by option

A. It lowers the serum sodium to reduce cerebral oedema
Hypertonic saline raises the serum sodium.
B. It acts only by diuresis, reducing brain water through urine loss
Diuresis is the mannitol mechanism, not that of hypertonic saline.
C. It lowers intracranial pressure and expands intravascular volume, unlike mannitol diuresis (correct)
Correct. It treats intracranial pressure and hypovolaemia together.
D. It has no effect on blood pressure or volume status
It tends to support blood pressure by volume expansion.

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 C, It lowers intracranial pressure and expands intravascular volume, unlike mannitol diuresis. Both agents raise plasma osmolality and draw water out of brain tissue.

Why is "It lowers the serum sodium to reduce cerebral oedema" not the answer?

Hypertonic saline raises the serum sodium.

Why is "It acts only by diuresis, reducing brain water through urine loss" not the answer?

Diuresis is the mannitol mechanism, not that of hypertonic saline.

Why is "It has no effect on blood pressure or volume status" not the answer?

It tends to support blood pressure by volume expansion.

What concept does this question test?

It tests Complications and emergencies: hypertonic saline in head injury in Anaesthesia. Mannitol causes an osmotic diuresis and can worsen hypovolaemia, whereas hypertonic saline expands plasma volume and supports blood pressure and cerebral perfusion.

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 Complications and emergencies: hypertonic saline in head injury?

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.