What fluids and rate should be ordered for rhabdomyolysis (Rhabdo) management?

Fluid Management for Rhabdomyolysis

For patients with rhabdomyolysis, administer isotonic saline (0.9% NaCl) at 15-20 mL/kg/hour for the first hour (approximately 1-1.5 liters in an average adult), followed by continued aggressive fluid resuscitation at 4-14 mL/kg/hour, with a target of at least 6L daily for severe cases. 1, 2

Initial Fluid Resuscitation

• Begin with isotonic saline (0.9% NaCl) at 15-20 mL/kg/hour for the first hour 1, 2
• For an average adult, this equals approximately 1-1.5 liters in the first hour 1
• Early and aggressive fluid resuscitation is crucial to prevent acute kidney injury (AKI) 3, 4

Subsequent Fluid Management

• After initial resuscitation, adjust fluid type and rate based on:

  • Serum electrolyte levels
  • Hydration status
  • Urine output

• For patients with normal or elevated corrected serum sodium:

  • Switch to 0.45% NaCl at 4-14 mL/kg/hour 1, 2

• For patients with low corrected serum sodium:

  • Continue 0.9% NaCl at 4-14 mL/kg/hour 1, 2

• Total volume requirements:

  • For severe rhabdomyolysis (CPK >15,000 IU/L): At least 6L daily 1
  • For moderate rhabdomyolysis: 3-6L daily 1
  • Target fluid replacement to correct estimated deficits within 24 hours 1, 2

Electrolyte Management

• Once renal function is assured, add potassium to IV fluids:
  • 20-30 mEq/L (2/3 KCl and 1/3 KPO4) 1, 2
  • Monitor serum electrolytes regularly 2

Monitoring Parameters

• Hemodynamic response (blood pressure improvement)
• Urine output (target >300 mL/hour) 5
• Serial creatinine and CPK measurements
• Clinical signs of improved hydration
• Signs of fluid overload (pulmonary edema, peripheral edema)
• Ensure change in serum osmolality does not exceed 3 mOsm/kg/hour 1, 2

Special Considerations

• Patients with cardiac or renal compromise:

  • More careful monitoring of serum osmolality
  • Frequent assessment of cardiac, renal, and mental status 1
  • More cautious fluid administration 2

• Elderly patients:

  • Higher risk of fluid overload
  • Require more cautious fluid administration 2

• Continue IV fluid therapy until CPK levels decrease to <1,000 U/L 5

Important Caveats

• Retrospective studies show that patients who developed AKI had longer time to initiate fluid resuscitation compared to those who did not 1
• While bicarbonate and mannitol are sometimes used, evidence does not strongly support their routine use 3, 6
• Monitor for compartment syndrome, which may require fasciotomy 1, 5
• Careful monitoring for hyperkalemia and other electrolyte abnormalities is essential 5, 6

The evidence strongly supports early, aggressive fluid resuscitation as the cornerstone of rhabdomyolysis management to prevent AKI, with isotonic saline being the preferred initial fluid choice 1, 3, 4.