Compartment syndrome: delta pressure: practice question

A Orthopaedics 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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Orthopaedics · Compartment syndrome: delta pressure

Sample item

A patient with a tibial fracture has pain on passive stretch and a tense calf. His diastolic pressure is 70 mmHg and the measured anterior compartment pressure is 48 mmHg. How should this be interpreted?

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

The answer and the reasoning

B. The difference is under 30 mmHg, consistent with compartment syndrome needing fasciotomy

Perfusion of the compartment depends on the difference between diastolic blood pressure and compartment pressure, and a difference below 30 mmHg supports the diagnosis when clinical features are present. Here the difference is 22 mmHg. Treatment is urgent fasciotomy.

Option by option

  • A. The pressure difference is normal and observation is enough

    A difference of 22 mmHg is not normal.

  • B. The difference is under 30 mmHg, consistent with compartment syndrome needing fasciotomy (correct)

    Correct. A difference under 30 mmHg with symptoms warrants fasciotomy.

  • C. The compartment pressure is irrelevant to the diagnosis

    Pressure measurements support the diagnosis when it is uncertain.

  • D. Only an arterial injury explains the findings

    Arterial injury may coexist, but these findings indicate compartment ischaemia.

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 Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is B, The difference is under 30 mmHg, consistent with compartment syndrome needing fasciotomy. Perfusion of the compartment depends on the difference between diastolic blood pressure and compartment pressure, and a difference below 30 mmHg supports the diagnosis when clinical features are present.

Why is "The pressure difference is normal and observation is enough" not the answer?

A difference of 22 mmHg is not normal.

Why is "The compartment pressure is irrelevant to the diagnosis" not the answer?

Pressure measurements support the diagnosis when it is uncertain.

Why is "Only an arterial injury explains the findings" not the answer?

Arterial injury may coexist, but these findings indicate compartment ischaemia.

What concept does this question test?

It tests Compartment syndrome: delta pressure in Orthopaedics. Here the difference is 22 mmHg. Treatment is urgent fasciotomy.

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 Compartment syndrome: delta pressure?

Pair each fracture with its classic complication and nerve injured. Then use the flashcards and the other Orthopaedics 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.