What are the signs of compartment syndrome?

Signs of Compartment Syndrome

Pain out of proportion to the injury and pain on passive stretching of the affected muscle compartment are the most reliable early signs of compartment syndrome, while pulselessness and pallor are late signs indicating irreversible damage has likely occurred. 1

Early Signs (Most Important for Timely Diagnosis)

• Pain:

  • Severe pain disproportionate to the injury
  • Pain that is unresponsive to appropriate analgesia
  • Pain on passive stretching of muscles in the affected compartment

• Paresthesia:

  • Numbness or tingling in the distribution of nerves passing through the compartment
  • Early sign of nerve compression

• Pressure/Tension:

  • Tense, swollen compartment on palpation
  • Firmness of the affected compartment

• Paresis:

  • Weakness in the affected muscle groups
  • Decreased active movement

Late Signs (Indicate Significant Damage)

• Pulselessness: Loss of distal pulses
• Pallor: Pale appearance of the affected limb
• Paralysis: Complete loss of motor function
• Poikilothermia: Cool skin temperature in the affected limb

Diagnostic Considerations

1. Clinical Assessment:

   • The "4 Ps" (early signs): Pain, Pain with passive stretch, Paresthesia, Paresis
   • The additional "2 Ps" (late signs): Pulselessness, Pallor 1

2. Compartment Pressure Measurement:

   • Indicated when clinical diagnosis is uncertain or in unconscious/sedated patients
   • Absolute pressure ≥30 mmHg is concerning
   • Differential pressure (diastolic BP - compartment pressure) <30 mmHg is diagnostic 1

Risk Factors for Compartment Syndrome

• Fractures (especially tibial shaft)
• Crush injuries
• Reperfusion after ischemia
• Hemorrhagic injuries
• Hypotension
• Burns
• Tight casts or dressings 1

Important Clinical Pearls

1. High Negative Predictive Value: The absence of clinical signs is more reliable in excluding compartment syndrome than their presence is in confirming it 1

2. Diagnostic Challenges:

   • Clinical signs have low sensitivity but high specificity
   • Diagnosis is particularly difficult in:
     • Sedated or unconscious patients
     • Children
     • Patients with altered mental status 1, 2

3. Monitoring Protocol:

   • In high-risk patients, assess for signs every 30 minutes to 1 hour during the first 24 hours 1
   • Use scoring charts (e.g., Royal College of Nursing chart) to maintain awareness 1

4. Diagnostic Value of Combined Signs:

   • Single signs have limited predictive value (severe pain alone: ~25% predictive)
   • Presence of both severe pain and pain on passive stretch: 68% predictive
   • Pain + pain on passive stretch + paralysis: 93% predictive (but paralysis indicates late-stage damage) 1

Early recognition and prompt surgical intervention with fasciotomy are essential to prevent permanent disability, limb loss, and potentially life-threatening complications such as rhabdomyolysis and acute kidney injury 3, 2, 4.