Clinical meaning
Compartment syndrome occurs when pressure within a closed fascial compartment exceeds capillary perfusion pressure, causing tissue ischemia and necrosis. Normal compartment pressure is 0-8 mmHg; clinical concern begins at >30 mmHg or within 30 mmHg of diastolic blood pressure (delta pressure). Increased pressure results from internal expansion (hemorrhage, edema from fractures, crush injuries, reperfusion injury) or external compression (casts, tight bandages, circumferential burns). Ischemia triggers an inflammatory cascade increasing capillary permeability and further edema, creating a vicious cycle. Irreversible muscle necrosis begins at 4-6 hours of ischemia; nerves are damaged at 4 hours. The anterior compartment of the leg is most commonly affected. Untreated, it leads to Volkmann contracture (forearm) or permanent functional loss.
Diagnosis & workup
Diagnostics & workup: - Clinical diagnosis based on the 6 Ps (Pain out of proportion is the earliest and most reliable sign; pulselessness is a LATE and often absent finding) - Compartment pressure measurement (Stryker device): absolute pressure >30 mmHg or delta pressure <30 mmHg (diastolic BP minus compartment pressure <30) indicates compartment syndrome - Pain with PASSIVE stretch of muscles within the affected compartment (most specific clinical finding) - Tense, swollen compartment on palpation ('wood-like' firmness) - Serum CK (creatine kinase): markedly elevated if rhabdomyolysis develops - BMP: monitor for hyperkalemia, hyperphosphatemia, and acute kidney injury from myoglobin nephrotoxicity - Urine myoglobin and urinalysis: dark tea-colored urine suggests myoglobinuria