A 32-year-old male presents to the emergency department 6 hours after a motor vehicle collision with a closed fracture of the right femur. On examination, the limb is swollen and tense. The skin over the fracture site is intact but shows early signs of blistering. Compartment pressures measured in the anterior compartment are 65 mmHg (diastolic BP 80 mmHg). What is the most appropriate next step in management?

Explanation

## Acute Compartment Syndrome (ACS) Recognition and Management ### Clinical Presentation This patient demonstrates classic signs of acute compartment syndrome (ACS): - Closed fracture with significant soft tissue trauma - Tense, swollen compartment - Early skin changes (blistering indicates severe tissue ischemia) - Compartment pressure measurement is diagnostic ### Compartment Pressure Interpretation **Key Point:** The critical threshold for ACS diagnosis is when compartment pressure approaches the diastolic blood pressure. In this case: - Compartment pressure: 65 mmHg - Diastolic BP: 80 mmHg - Pressure gradient: 80 − 65 = 15 mmHg (abnormal; normal is >30 mmHg) A pressure gradient <30 mmHg indicates loss of capillary perfusion and is an absolute indication for fasciotomy. ### Why Fasciotomy is Urgent **High-Yield:** Fasciotomy must be performed within 6–8 hours of symptom onset to prevent irreversible muscle necrosis, rhabdomyolysis, acute kidney injury, and permanent disability. This patient is already at 6 hours with clinical signs of severe ischemia (blistering). ### Pathophysiology of ACS ```mermaid flowchart TD A[Fracture + Soft tissue trauma]:::outcome --> B[Edema within fascial compartment] B --> C[Increased compartment pressure] C --> D{Pressure gradient<br/>BP - Comp Pressure}:::decision D -->|>30 mmHg| E[Adequate perfusion]:::outcome D -->|<30 mmHg| F[Capillary occlusion]:::urgent F --> G[Muscle ischemia]:::urgent G --> H[Necrosis + Rhabdo<br/>if untreated]:::urgent F --> I[Fasciotomy<br/>within 6-8 hrs]:::action I --> J[Salvage muscle<br/>& prevent complications]:::outcome ``` ### Clinical Pearl **The "5 P's" of compartment syndrome** (Pain out of proportion, Pressure, Paresthesia, Pallor, Pulselessness) are LATE findings. Do NOT wait for all 5 P's — compartment pressure measurement is the gold standard. Pain with passive stretch of muscles in the affected compartment is the earliest and most sensitive clinical sign. ### Why Other Options Fail | Option | Why Wrong | |--------|----------| | Antibiotics + observation | ACS is a surgical emergency; observation allows irreversible necrosis. Antibiotics have no role in preventing ischemic injury. | | Traction + elevation | Elevation may worsen perfusion by reducing hydrostatic pressure gradient. Traction does not address the underlying compartment pressure. | | MRI before intervention | Imaging delays life- and limb-saving fasciotomy. Compartment pressure measurement is diagnostic; imaging is contraindicated. | **Warning:** Delaying fasciotomy by even 2–4 hours significantly increases the risk of permanent contracture, loss of function, and systemic complications (hyperkalemia, myoglobinuria, acute renal failure).