What is the role of bicarbonate (sodium bicarbonate) in the management of rhabdomyolysis?

Bicarbonate Use in Rhabdomyolysis Management

Current evidence does not support the routine use of sodium bicarbonate in rhabdomyolysis, as aggressive fluid resuscitation with normal saline alone is the cornerstone of therapy for preventing acute kidney injury. 1

Pathophysiology and Rationale

Historically, bicarbonate has been advocated in rhabdomyolysis based on theoretical grounds:

• Alkalinization of urine may prevent precipitation of myoglobin casts in renal tubules 2
• Increasing urine pH above 6.5 might reduce myoglobin toxicity in the kidneys

However, this theoretical benefit has not been consistently demonstrated in clinical studies.

Evidence Against Routine Bicarbonate Use

• The Eastern Association for the Surgery of Trauma conditionally recommends against treatment with bicarbonate in patients with rhabdomyolysis based on their systematic review and meta-analysis 1
• Recent propensity score-matched cohort study (2022) found that bicarbonate therapy was associated with:
  • Higher incidence of acute kidney injury
  • Higher rates of dialysis dependency
  • Higher 30-day mortality
  • Longer hospital stays compared to non-bicarbonate therapy 3
• Bicarbonate administration may lead to complications:
  • Volume overload (significantly higher in bicarbonate groups) 3
  • Decreased free calcium, potentially worsening hypocalcemia associated with crush injury 2

Current Best Practice

1. Primary intervention: Early and aggressive fluid resuscitation with isotonic crystalloids (normal saline) to restore renal perfusion and increase urine flow 1, 4

   • Target fluid administration: 1000 mL/h initially, to be tapered by at least 50% after 2 hours 2
   • Individualize based on patient's clinical status, avoiding volume overload

2. Avoid potassium-containing fluids (Lactated Ringer's, Hartmann's, Plasmalyte A) as potassium levels may increase markedly following reperfusion 2

3. Avoid starch-based fluids as they are associated with increased rates of AKI and bleeding 2

4. Monitor closely:

   • Electrolytes (especially potassium, calcium, sodium)
   • Acid-base status
   • Creatine kinase
   • Renal function (BUN, creatinine)
   • Volume status and urine output

Special Considerations

While routine use is not recommended, bicarbonate might still be considered in specific scenarios:

• Patients with severe metabolic acidosis (pH < 7.1) 2
• Cases with established acute kidney injury with significant acidosis

Common Pitfalls to Avoid

1. Overreliance on bicarbonate: Assuming bicarbonate is necessary for all rhabdomyolysis cases
2. Volume overload: Excessive fluid administration, particularly with bicarbonate, can lead to pulmonary edema and heart failure
3. Neglecting the primary therapy: Focusing on bicarbonate while delaying or inadequately providing fluid resuscitation
4. Ignoring electrolyte imbalances: Failing to monitor and correct calcium, potassium, and phosphate abnormalities

Conclusion

The cornerstone of rhabdomyolysis management remains early and aggressive fluid resuscitation with isotonic crystalloids. Despite traditional practice, current evidence does not support routine bicarbonate administration for preventing acute kidney injury in rhabdomyolysis. Clinicians should focus on adequate fluid resuscitation while monitoring for and treating complications such as electrolyte abnormalities and volume overload.