Compartment syndrome of the forearm is most reliably diagnosed by measuring compartment pressure. The threshold for fasciotomy based on absolute compartment pressure (ΔP = diastolic BP − compartment pressure) is:

• A Absolute compartment pressure >30 mmHg alone
• B Absolute compartment pressure >40 mmHg alone
• C Compartment pressure exceeding mean arterial pressure
• D ΔP (diastolic BP − compartment pressure) ≤30 mmHg, regardless of absolute pressure ✓

Explanation

The Whitesides threshold (ΔP ≤30 mmHg) is the most clinically validated criterion for performing emergency fasciotomy. ΔP represents the perfusion pressure across the compartment: when diastolic blood pressure minus compartment pressure is ≤30 mmHg, microcirculatory perfusion is critically impaired even if the absolute compartment pressure is below 30 mmHg (relevant in hypotensive patients where a compartment pressure of 25 mmHg with a diastolic of 50 mmHg gives ΔP of 25 — indicating the need for fasciotomy). Relying solely on absolute pressure thresholds can miss compartment syndrome in hypotensive polytrauma patients.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.