What is the treatment for metabolic acidosis?

Treatment of Metabolic Acidosis

The treatment of metabolic acidosis should focus on addressing the underlying cause while administering sodium bicarbonate for severe cases with pH <7.3 or serum bicarbonate <15 mEq/L to prevent adverse clinical outcomes. 1

Diagnosis and Assessment

Before initiating treatment, proper assessment is essential:

• Determine the type of metabolic acidosis:

  • Calculate anion gap = [Na+] - ([HCO3-] + [Cl-])
  • High anion gap: diabetic ketoacidosis, lactic acidosis, toxic ingestions
  • Normal anion gap: renal tubular acidosis, diarrhea, urinary diversion

• Obtain arterial blood gases to assess:

  • pH
  • Bicarbonate level
  • PaCO2 (to evaluate respiratory compensation)
  • Anion gap

Treatment Algorithm

1. Treat the Underlying Cause

• Diabetic Ketoacidosis:

  • Insulin therapy with fluid resuscitation
  • For patients with ketosis/ketoacidosis, treatment with subcutaneous or intravenous insulin should be initiated to rapidly correct hyperglycemia and metabolic derangement 2
  • Once acidosis resolves, metformin can be initiated while continuing insulin therapy

• Lactic Acidosis:

  • Improve tissue perfusion and oxygenation
  • Treat underlying infection if present
  • Discontinue medications that may contribute (metformin)

• Renal Failure:

  • Consider dialysis for severe acidosis with renal failure
  • Maintain serum total CO2 >22 mEq/L in chronic kidney disease 2

• Diarrhea-induced Acidosis:

  • Fluid resuscitation with bicarbonate-containing solutions

2. Sodium Bicarbonate Administration

According to FDA guidelines for sodium bicarbonate 1:

• Severe Acidosis (pH <7.2 or bicarbonate <15 mEq/L):

  • Initial dose: 1-2 mEq/kg IV over 1-2 hours
  • Subsequent dosing based on arterial blood gas monitoring
  • In cardiac arrest: 50 mL (44.6-50 mEq) may be given initially and continued at a rate of 50 mL every 5-10 minutes if necessary

• Less Urgent Metabolic Acidosis:

  • 2-5 mEq/kg body weight over 4-8 hours
  • Target partial correction rather than complete normalization in first 24 hours
  • Aim for bicarbonate of approximately 20 mEq/L at the end of first day

3. Special Considerations

• Chronic Kidney Disease:

  • Maintain serum total CO2 >22 mmol/L to improve bone histology and reduce protein catabolism 2
  • Avoid citrate-containing alkali salts in CKD patients exposed to aluminum

• Pediatric Patients:

  • For metabolic acidosis in children, sodium bicarbonate may be used at 1-2 mEq/kg given slowly 2
  • For sodium channel blocker overdose, titrate bicarbonate to maintain serum pH of 7.45-7.55

Monitoring and Adjustments

• Monitor arterial or venous blood gases every 2-4 hours during acute treatment
• Check serum electrolytes, particularly potassium and calcium
• Adjust therapy based on clinical response and laboratory values
• Avoid overcorrection which can lead to metabolic alkalosis

Pitfalls and Caveats

1. Avoid rapid bicarbonate administration which may cause:

   • Paradoxical intracellular acidosis
   • Hypernatremia
   • Volume overload
   • Hypocalcemia (decreased ionized calcium)
   • Hypokalemia

2. Do not attempt full correction of bicarbonate deficit in first 24 hours as this may lead to unrecognized alkalosis due to delayed respiratory adjustment 1

3. In diabetic ketoacidosis, insulin and fluid therapy are primary treatments; bicarbonate is generally reserved for severe acidosis (pH <7.0) or when hemodynamic instability is present

4. In lactic acidosis, focus on treating the underlying cause rather than just correcting the acidosis with bicarbonate

By following this structured approach to metabolic acidosis treatment, clinicians can effectively manage this condition while minimizing potential complications.