Clinical meaning
Compartment syndrome represents a surgical emergency driven by the interplay between intracompartmental pressure, tissue perfusion pressure, and the duration of ischemia. Normal compartment pressure is 0-8 mmHg. As pressure rises above 30 mmHg (or within 30 mmHg of diastolic blood pressure), capillary perfusion fails. The ischemia-reperfusion cascade causes further edema through endothelial injury and inflammatory mediator release, creating a self-perpetuating cycle. Irreversible myonecrosis begins at 4-6 hours, and complete necrosis occurs by 12 hours. Rhabdomyolysis from muscle death releases myoglobin, potassium, phosphate, and creatine kinase, potentially causing acute kidney injury, cardiac arrhythmias, and DIC. The clinician must make rapid clinical decisions, differentiate from other causes of limb pain, order compartment pressure monitoring, coordinate emergent fasciotomy, and manage the complex systemic sequelae.
Diagnosis & workup
Diagnostics & workup: - Perform serial clinical assessment: the 6 Ps are clinical but PAIN is the most sensitive early indicator - Order continuous or serial compartment pressure monitoring (Stryker intracompartmental pressure device) - Use delta pressure (ΔP = diastolic BP - compartment pressure) for surgical decision-making; ΔP <30 mmHg mandates fasciotomy - Order STAT CK levels (rhabdomyolysis: CK >5× normal or >1000 U/L) - Order CMP: potassium (hyperkalemia from muscle necrosis), calcium (hypocalcemia), phosphorus (hyperphosphatemia), creatinine (AKI) - Order serial urinalysis: myoglobinuria (positive blood on dipstick without RBCs on microscopy) - Order coagulation studies (PT/INR, fibrinogen, D-dimer) if DIC is suspected - Order 12-lead ECG and continuous cardiac monitoring for hyperkalemia management