A 25-year-old develops acute compartment syndrome of the forearm after a both-bone forearm fracture and closed reduction. The diagnosis of compartment syndrome relies on measuring compartment pressure. The critical threshold for fasciotomy based on the delta pressure (diastolic pressure minus compartment pressure) is:

• A Absolute compartment pressure > 20 mmHg
• B Delta pressure < 30 mmHg ✓
• C Compartment pressure > 50 mmHg regardless of BP
• D Delta pressure < 10 mmHg

Explanation

McQueen and Court-Brown demonstrated that the delta pressure (diastolic BP minus compartment pressure) is the most reliable threshold for fasciotomy. A delta pressure <30 mmHg indicates tissue perfusion is critically impaired and fasciotomy should be performed regardless of absolute compartment pressure. This threshold accounts for haemodynamically unstable patients in whom a compartment pressure of 30 mmHg in a hypotensive patient (diastolic 50 mmHg) represents a delta of only 20 mmHg — high risk. Using absolute compartment pressure >30 mmHg alone over-diagnoses in hypertensive patients.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.