Rhabdomyolysis and Crush injury

Section: Trauma Curriculum: Curriculum, page 76

Rhabdomyolysis

Definition

• Skeletal muscle injury and leakage of intracellular contents into plasma

Causes

• Trauma - Crush, electrocution, fall with long lies
• Other - Drugs, infection

Pathophysiology

• Myoglobin release into plasma which overwhelms Haptoglobin pick up rate
• Collects in Renal Glomeruli
• Renal tubular dysfunction
• Nephrotoxicity
• Intrarenal vasoconstriction
• AKI
• Occurs due to reduced EC volume = renal vasoconstriction

Presentation

• Triad
  • Myalgia
  • Generalised weakness
  • Darkened urine
• CK – 5 x upper limit of normal
• Other bloods to check
  • FBC, U+E, Urea, Nitrogen, BSL, Ca, K, LFT
  • LDH

Treatment

• Aggressive fluid resus → UO aim 200ml/hr
• May need dialysis
• May need fasciotomies

Crush Injury

• Leads to rhabdomyolysis
• Key features include release of myoglobin by injured muscle into circulation
• Accumulation in glomeruli leading to acute kidney injury, renal vasoconstriction and requirement for dialysis
• Considerations
  • Limb
    • Compartment syndrome due to increased compartment pressure from oedema of muscle injury in contained myofascial space
    • Need for fasciotomies
    • Orthopaedic injury to limb
  • End organ dysfunction
    • Aggressive fluid resus - > 200ml/hr UO
    • Dialysis for renal impairment
• Assessment
  • CK, renal function and electrolytes
  • Urine myoglobin
  • ECG due to renal electrolyte abnormalities causing arrhythmia