What are the clinical manifestations and management of crush syndrome?

Crush Syndrome: Clinical Manifestations and Management

Crush syndrome is a life-threatening systemic manifestation of traumatic muscle injury that requires immediate aggressive fluid resuscitation, ideally even before extrication of the victim, to prevent acute kidney injury and reduce mortality. 1

Pathophysiology

Crush syndrome develops following prolonged compression of muscle tissue, commonly seen in:

• Earthquake victims trapped under collapsed buildings
• Motor vehicle accidents
• "Found down" scenarios (e.g., intoxicated patients)
• Limb compression during prolonged immobility 2, 3

The pathophysiological cascade involves:

1. Prolonged muscle compression leading to tissue ischemia
2. Increased intra-compartmental pressure causing decreased muscle perfusion
3. Muscle damage resulting in tissue edema and intravascular hypovolemia
4. Upon reperfusion (after extrication), release of myoglobin and potassium into circulation
5. Systemic manifestations including hyperkalemia, metabolic acidosis, and acute kidney injury 1, 4

Clinical Manifestations

Immediate Presentation

• Swollen, tense limb(s) with decreased pulses
• Pain disproportionate to visible injury
• Hypotension and tachycardia due to hypovolemia
• Signs of compartment syndrome (pain, pallor, paresthesia, pulselessness, paralysis) 1, 2

Laboratory Abnormalities

• Elevated creatine kinase (marker of muscle damage)
• Hyperkalemia (potentially life-threatening)
• Metabolic acidosis
• Elevated blood urea nitrogen and creatinine
• Myoglobinuria (dark, tea-colored urine) 1

Late Complications

• Acute kidney injury (myoglobinuric)
• Hyperkalemia-induced cardiac arrhythmias
• Acute respiratory distress syndrome
• Disseminated intravascular coagulation
• Sepsis from necrotic muscle tissue 4, 5

Management

Pre-Extrication Phase

• Begin IV fluid resuscitation immediately - even before extrication
• Insert IV cannula or intraosseous needle if vein access difficult
• Infuse 0.9% saline at 1L/hour 1

During Extrication

• Continue saline infusion at 1L/hour
• If extrication takes >2 hours, reduce rate to ≥0.5L/hour 1

Post-Extrication Phase

1. Fluid Management:

   • Continue aggressive fluid resuscitation (3-6L/day depending on monitoring capability)
   • Avoid potassium-containing fluids (Lactated Ringer's, Hartmann's solution)
   • Avoid starch-based fluids (increase risk of AKI)
   • Monitor for signs of fluid overload, especially in anuria 1

2. Laboratory Monitoring:

   • Electrolytes (especially potassium)
   • Acid-base status
   • Creatine kinase
   • Blood urea nitrogen and creatinine
   • Use point-of-care testing if laboratory infrastructure unavailable 1

3. Surgical Management:

   • Prompt fasciotomy for compartment syndrome
   • Debridement of necrotic muscle tissue 2, 5

4. Renal Replacement Therapy:

   • Earlier initiation may improve survival in trauma-associated AKI
   • Indications: severe hyperkalemia, acidosis, fluid overload 1

Special Considerations

Fluid Resuscitation Individualization

Adjust fluid administration based on:

• Scale of disaster (3-6L/day if close monitoring impossible)
• Environmental conditions (less fluid in low temperatures)
• Time spent under rubble (more fluid for delayed rescue, conservative approach if days)
• Patient demographics (elderly, children, low body mass need less fluid)
• Volume status and urine output 1

Controversies in Management

• Bicarbonate: Theoretical benefit for preventing myoglobin cast formation, but evidence doesn't show benefit over fluid resuscitation alone
• Mannitol: Has diuretic and antioxidant properties but limited evidence of benefit beyond crystalloid resuscitation 1

Importance of Early Intervention

Even delayed fluid therapy can be beneficial. A study of Marmara earthquake victims showed that aggressive fluid treatment under close monitoring prevented established acute renal failure in many patients, even when started an average of 46.5 hours after injury 6.

Pitfalls to Avoid

• Failure to recognize crush syndrome: Consider in any patient with history of prolonged limb compression
• Delayed fluid resuscitation: Begin fluids immediately, ideally before extrication
• Using potassium-containing fluids: Can worsen hyperkalemia
• Missing compartment syndrome: Perform fasciotomies promptly when indicated
• Inadequate monitoring: Watch for hyperkalemia, which can develop rapidly after extrication 1, 2