Surgical Critical Care: Rhabdomyolysis

Basics

• Definition: Muscle Necrosis Causing Release of Intracellular Contents
• Final Common Pathway: Release of Intracellular Calcium
  • From ATP Depletion or Direct Injury
  • Cell Death from Protease Activation, Mitochondria Dysfunction & Reactive Oxygen Species
• Cell Death Causes Release of CK, Electrolytes, Myoglobin and Other Enzymes

Causes

• Trauma
• Crush Injury
• Exertional
• Infection
• Electrolyte Disturbances
• Drugs/Toxins

Presentation

• Classic Triad:
  • Muscle Pain/Myalgia
  • Muscle Weakness
  • Dark Red-Brown Urine
• Lethargy
• Tachycardia
• Nausea/Vomiting
• Abdominal Pain
• Altered Mental Status
• Complications:
  • AKI – From Hypovolemia & Nephrotoxic Myoglobin
  • Compartment Syndrome
  • DIC

Diagnosis

• Labs:
  • Elevated CK
  • Myoglobinuria
  • Hyperkalemia
  • Hyperphosphatemia
  • Hypocalcemia (Enters into Damaged Myocytes)
    • May See Rebound Hypercalcemia with Recovery
  • Anion Gap Metabolic Acidosis
  • High Uric Acid
• Diagnosis: Acute CK Elevation with Either an Acute Neuromuscular Illness or Dark Urine
  • CK > 5,000 U/L (In General but No Absolute Cutoff)

Treatment

• Primary Goal of Tx: Prevention of AKI
  • Aggressive IV Fluids
  • Bicarbonate
    • Alkalinize the Urine to Prevent Cast Formation
    • Contraindications: Hypocalcemia, pH ≥ 7.5 or HCO3 < 30
• May Require Dialysis for Volume Overload, Acidemia, Hyperkalemia or Uremia
• Generally Avoid Mannitol or Diuretics