Which findings define acute compartment syndrome?

• A. Hypotension and tachycardia
• B. Pain out of proportion to injury with compartment pressure >30-45 mm Hg
• C. Numbness only
• D. Normal exam

Answer: (A)

Acute compartment syndrome is a surgical emergency caused by rising pressure within a closed muscle compartment that impairs blood flow and tissue viability. The defining finding is pain that is out of proportion to the exam and worsens with passive stretching of the involved muscle, usually accompanied by elevated intracompartment pressure. Clinically, pressures above roughly 30 mm Hg are concerning, and some clinicians use the delta pressure concept (diastolic blood pressure minus the compartment pressure ≤ 30 mm Hg) to guide urgency for fasciotomy. Numbness or paresthesias can occur but are later signs, and a normal exam or systemic signs like low blood pressure do not define the condition. Thus, severe, disproportionate pain with elevated compartment pressure best identifies acute compartment syndrome.