A 32-year-old man presents to the emergency department 6 hours after a crush injury to his left leg from a fallen concrete slab. He complains of severe pain out of proportion to clinical findings and pain on passive stretching of the foot. His leg is tense and swollen. Compartment pressure measurement shows 65 mmHg (diastolic BP 80 mmHg). What is the most appropriate immediate next step in management?

Explanation

## Clinical Diagnosis and Pathophysiology **Key Point:** Compartment syndrome is a surgical emergency requiring urgent decompression. The clinical presentation — severe pain disproportionate to findings, pain on passive stretch, and tense swelling — combined with elevated compartment pressure (65 mmHg) meeting the threshold for intervention confirms the diagnosis. ## Compartment Pressure Interpretation | Parameter | Value | Significance | |-----------|-------|---------------| | Measured pressure | 65 mmHg | Elevated | | Diastolic BP | 80 mmHg | Reference | | Pressure differential (DBP − CP) | 15 mmHg | **Critical** | | Threshold for fasciotomy | <30 mmHg differential | Intervention indicated | **High-Yield:** The critical pressure differential is typically considered when compartment pressure exceeds (diastolic BP − 30 mmHg). In this case, 80 − 65 = 15 mmHg, which is **below the safe threshold**, mandating immediate surgical decompression. ## Management Algorithm ```mermaid flowchart TD A[Suspected compartment syndrome]:::outcome --> B{Clinical signs present?}:::decision B -->|Pain out of proportion + pain on passive stretch| C[Measure compartment pressure]:::action C --> D{Pressure differential < 30 mmHg?}:::decision D -->|Yes| E[Emergency fasciotomy]:::urgent D -->|No| F[Observe, repeat measurements]:::action E --> G[Tissue salvage and limb preservation]:::outcome ``` **Clinical Pearl:** The "5 P's" of compartment syndrome (Pain, Pressure, Paresthesia, Pallor, Pulselessness) are late findings. Early diagnosis relies on **high clinical suspicion** and compartment pressure measurement. Waiting for all 5 P's to develop results in irreversible tissue necrosis and amputation. **Warning:** Elevation and compression are **contraindicated** in compartment syndrome — they worsen the pressure gradient and accelerate tissue damage. Fasciotomy must not be delayed for imaging or conservative measures. ## Timing and Outcome **Key Point:** Irreversible muscle necrosis begins after 6–8 hours of elevated compartment pressure. This patient is already at the threshold of tissue viability. Every minute of delay increases the risk of permanent disability, rhabdomyolysis, acute kidney injury, and amputation. [cite:Rockwood & Green's Fractures in Adults Ch 1]