A 32-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 and tense. Compartment pressure measured at the anterior thigh compartment is 65 mmHg (diastolic BP = 80 mmHg). Urine dipstick shows 4+ myoglobin. Which of the following is the most appropriate immediate management?

Explanation

## Acute Compartment Syndrome (ACS) — Diagnosis and Management ### Clinical Recognition **Key Point:** Acute compartment syndrome is a surgical emergency. The combination of a tense, swollen compartment with elevated compartment pressure (>65 mmHg or within 30 mmHg of diastolic BP) and myoglobinuria indicates established muscle necrosis. ### Compartment Pressure Interpretation | Finding | Significance | |---------|-------------| | Pressure >30 mmHg above diastolic BP | Indicates loss of capillary perfusion | | Pressure 65 mmHg with diastolic BP 80 mmHg | Differential = 15 mmHg (critical) | | Myoglobinuria present | Evidence of muscle breakdown already occurring | **High-Yield:** The diagnostic threshold is compartment pressure ≥30 mmHg above diastolic BP, or absolute pressure >65 mmHg in high-risk patients. Once ACS is diagnosed, fasciotomy must not be delayed. ### Why Fasciotomy Is Urgent 1. Muscle necrosis begins within 4–6 hours of ischemia 2. Myoglobinuria indicates irreversible muscle damage is already underway 3. Fasciotomy within 6–8 hours can salvage viable muscle; beyond 12 hours, salvage is minimal 4. Delaying fasciotomy risks rhabdomyolysis → acute kidney injury → death **Clinical Pearl:** The "5 P's" (Pain, Pressure, Paresthesia, Pallor, Pulselessness) are late findings. Do NOT wait for all 5 P's — compartment syndrome is a clinical + pressure diagnosis. ### Management Algorithm ```mermaid flowchart TD A[Suspected ACS: tense compartment + pain out of proportion]:::outcome A --> B{Compartment pressure measured?}:::decision B -->|Not yet| C[Measure pressure immediately]:::action B -->|Yes| D{Pressure ≥30 mmHg above diastolic<br/>OR >65 mmHg absolute?}:::decision C --> D D -->|Yes| E[Urgent fasciotomy within 6-8 hrs]:::urgent D -->|No| F[Serial measurements + clinical observation]:::action E --> G[Prevent rhabdo complications:<br/>IV fluids, urine alkalinization]:::action F --> H{Pressure rising or<br/>symptoms worsening?}:::decision H -->|Yes| E H -->|No| I[Continue conservative care]:::action ``` **Mnemonic:** **FASCIOTOMY** — **F**ascial release is the **A**nswer when **S**urgical **C**ompartment pressure is **I**ncreased **O**ver threshold; **T**ime is **O**f the essence; **M**uscle necrosis **Y**ields to early intervention. ### Why Other Options Are Wrong - **Elevation + ice:** Reduces swelling temporarily but does NOT relieve compartment pressure; tissue ischemia continues. - **Skeletal traction + observation:** Delays definitive treatment; by the time pressure rises further, irreversible damage has occurred. Observation is acceptable only if pressure is borderline and trending down. - **IV fluids + bicarbonate alone:** Correct for rhabdo prevention (prevents myoglobin precipitation in renal tubules) but does NOT address the underlying compartment pressure; fasciotomy is the primary intervention. [cite:Rockwood & Green's Fractures in Adults 9e Ch 1]