A 28-year-old male presents to the emergency department 6 hours after a motor vehicle accident with a closed fracture of the right femur. On examination, the limb is swollen, tense, and painful with pain on passive stretching of the foot. Compartment pressure measurement shows 65 mmHg (diastolic BP 80 mmHg). What is the most appropriate next step in management?

Explanation

## Acute Compartment Syndrome (ACS) — Recognition and Management ### Clinical Diagnosis The patient presents with classic signs of acute compartment syndrome: - Severe pain out of proportion to clinical findings - Pain on passive stretch of muscles in the affected compartment (most sensitive early sign) - Compartment pressure 65 mmHg with diastolic BP 80 mmHg → perfusion pressure = 80 − 65 = 15 mmHg (critically low) **Key Point:** Compartment pressure ≥30 mmHg (or within 30 mmHg of diastolic BP) is diagnostic of ACS and requires urgent surgical decompression. Perfusion pressure <30 mmHg indicates tissue ischemia. ### Why Fasciotomy Is Urgent ACS is a surgical emergency. Delay of even 6–8 hours leads to irreversible muscle necrosis, rhabdomyolysis, acute kidney injury, and permanent disability (Volkmann's contracture in the lower limb). **High-Yield:** The **"pain out of proportion" + pain on passive stretch + elevated compartment pressure** triad mandates immediate fasciotomy. Do NOT wait for imaging or further observation. ### Management Algorithm ```mermaid flowchart TD A[Suspected ACS: severe pain, pain on passive stretch]:::outcome --> B{Compartment pressure measurement}:::decision B -->|≥30 mmHg or within 30 of DBP| C[Emergency fasciotomy]:::urgent B -->|<30 mmHg| D[Conservative management, serial exams]:::action C --> E[Prevent muscle necrosis, rhabdo, AKI]:::outcome D --> F[Monitor closely for progression]:::action ``` **Clinical Pearl:** In the operating room, fasciotomy must decompress all affected compartments (femur has 3 compartments: anterior, medial, posterior). Two-incision technique is standard. ### Why Other Options Fail - **Antibiotics + observation:** Delays definitive treatment; ACS progresses rapidly to irreversible damage within hours. - **Ice and elevation:** Reduces swelling temporarily but does not address the underlying pressure problem; tissue ischemia continues. - **CT angiography:** While vascular injury is a differential, the clinical picture (pain on passive stretch, elevated compartment pressure) is pathognomonic for ACS, not vascular occlusion. Imaging delays life-saving surgery. **Warning:** Do NOT confuse ACS with simple swelling. The **perfusion pressure** (diastolic BP − compartment pressure) is the critical parameter. A pressure of 65 mmHg in a patient with DBP 80 mmHg is a surgical emergency.