Compartment Syndrome: The 5 Ps, Delta Pressure & Fasciotomy Guide

Acute Compartment Syndrome

Compartment Syndrome is a surgical emergency where increased pressure within a closed fascial space reduces capillary perfusion, leading to tissue necrosis. "Time is Muscle."

1. Pathophysiology

• Mechanism: Trauma (Fracture), Crush injury, Tight casts, or Reperfusion injury.
• Cycle: Edema -> Increased Pressure -> Venous outflow obstruction -> More Edema -> Arterial inflow occlusion -> Necrosis.
• Sites: Most common in the Lower Leg (Anterior compartment) and Forearm (Volar compartment).

2. Clinical Diagnosis (The 5 Ps)

1. PAIN: Out of proportion to the injury. Pain on Passive Stretch is the earliest and most sensitive sign.
2. Paresthesia: Early sign of nerve ischemia.
3. Pallor: Late sign.
4. Paralysis: Very late sign (muscle death).
5. Pulselessness: Terminal sign (do not wait for this!).

3. Management

• Diagnosis: Clinical suspicion is key. Measure pressure if patient is unconscious (Stryker needle).
  • Delta Pressure: Diastolic BP - Compartment Pressure. If < 30 mmHg, it is diagnostic.
• Treatment: Remove all dressings/casts immediately. Keep limb at heart level (NOT elevated). Emergency Fasciotomy.

25 Practice MCQs

Q1. The earliest and most sensitive clinical sign of compartment syndrome is:

Answer: A). Pain that is disproportionate to the injury.

Q2. Which is a LATE sign indicating irreversible damage?

Answer: C). Arterial flow is the last to be compromised.

Q3. Volkmann's Ischemic Contracture is a sequela of compartment syndrome in the:

Answer: A). Typically following supracondylar humerus fracture.

Q4. The "Delta Pressure" threshold for fasciotomy is usually:

Answer: A). If perfusion pressure drops below 30, ischemia begins.

Q5. The most common fracture associated with compartment syndrome of the leg is:

Answer: A). Especially proximal third.

Q6. Initial management of suspected compartment syndrome includes:

Answer: A). Splitting the cast reduces pressure by ~30-50%.

Q7. Why should the limb NOT be elevated high?

Answer: A). Keep at heart level to balance inflow and outflow.

Q8. Fasciotomy involves:

Answer: A). Wounds are left open (Delayed primary closure).

Q9. Which nerve is affected in Anterior Compartment Syndrome of the leg?

Answer: A). Also weakness in toe extension.

Q10. Muscle necrosis begins after ischemia of:

Answer: A). Irreversible damage occurs by 8 hours.

Q11. Acute Compartment Syndrome can occur without a fracture. True/False?

Answer: A). Even burns or vigorous exercise can cause it.

Q12. Myoglobinuria (Dark urine) indicates:

Answer: A). Risk of renal failure.

Q13. Which compartment of the leg is most frequently involved?

Answer: A). Rigid boundaries.

Q14. What is the "Holden's Sign"?

Answer: B). Tense swelling.

Q15. The 5th P (Pulselessness) is unreliable because:

Answer: A). Pulses persist until pressure > 120mmHg+ (very late).

Q16. Chronic Exertional Compartment Syndrome is seen in:

Answer: A). Pain begins with exercise, resolves with rest.

Q17. Normal compartment pressure is:

Answer: A). >30 is the danger zone.

Q18. Foot drop in compartment syndrome is due to ischemia of:

Answer: A). And EHL/EDL (Anterior compartment).

Q19. Skin closure after fasciotomy is usually done:

Answer: A). Muscles swell too much to close primarily.

Q20. The most sensitive nerve to ischemia is:

Answer: B). Hence Paresthesia is an early sign.

Q21. In the forearm, the deep flexor compartment contains:

Answer: A). Most at risk in forearm fractures.

Q22. Which analgesia can mask compartment syndrome?

Answer: A). Requires careful monitoring.

Q23. Claw toe deformity is a late sequela of:

Answer: A). Ischemic contracture of toe flexors.

Q24. Gunshot wounds cause compartment syndrome due to:

Answer: A). High risk.

Q25. Pain on passive extension of the Big Toe specifically tests the:

Answer: B). Specific stretch for FHL.