Critical care: heparin reversal with protamine: 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 · Critical care: heparin reversal with protamine

Sample item

How much protamine is generally given to neutralise heparin?

A1 mg per 1000 unitsBA fixed 500 mgC10 mg per 100 unitsDAbout 1 mg per 100 units of heparin

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

The answer and the reasoning

D. About 1 mg per 100 units of heparin

One milligram of protamine neutralises approximately 100 units of heparin, adjusted for the heparin given and the time elapsed. It is given slowly to avoid hypotension. It only partly reverses low molecular weight heparin.

Option by option

A. 1 mg per 1000 units
This dose would be inadequate.
B. A fixed 500 mg
A fixed dose does not account for the heparin given.
C. 10 mg per 100 units
This is ten times too much and would itself cause anticoagulation.
D. About 1 mg per 100 units of heparin (correct)
Correct. The ratio is about 1 mg per 100 units.

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 D, About 1 mg per 100 units of heparin. One milligram of protamine neutralises approximately 100 units of heparin, adjusted for the heparin given and the time elapsed.

Why is "1 mg per 1000 units" not the answer?

This dose would be inadequate.

Why is "A fixed 500 mg" not the answer?

A fixed dose does not account for the heparin given.

Why is "10 mg per 100 units" not the answer?

This is ten times too much and would itself cause anticoagulation.

What concept does this question test?

It tests Critical care: heparin reversal with protamine in Anaesthesia. It is given slowly to avoid hypotension. It only partly reverses low molecular weight heparin.

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 Critical care: heparin reversal with protamine?

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.