What is the treatment for metabolic acidosis?

Treatment of Metabolic Acidosis

Sodium bicarbonate is the primary treatment for metabolic acidosis, with dosage and administration determined by the severity and underlying cause of the acidosis. 1

Diagnosis and Classification

Before initiating treatment, it's essential to identify the type and cause of metabolic acidosis:

1. Laboratory evaluation:

   • Arterial blood gases (pH, PaCO2, HCO3-)
   • Serum electrolytes with calculated anion gap
   • Serum ketones
   • Blood glucose
   • Renal function tests

2. Classification:

   • High anion gap metabolic acidosis: Diabetic ketoacidosis, lactic acidosis, toxic ingestions
   • Normal anion gap metabolic acidosis: Renal tubular acidosis, diarrhea, ureterosigmoidostomy

Treatment Algorithm

1. Severe Metabolic Acidosis (pH < 7.1 or bicarbonate < 10 mEq/L)

• Administer IV sodium bicarbonate:

  • Initial dose: 1-2 mEq/kg IV 1
  • For cardiac arrest: 50 mL (44.6-50 mEq) IV, repeated every 5-10 minutes as needed 1
  • For less urgent forms: 2-5 mEq/kg over 4-8 hours 1

• Important cautions:

  • Avoid rapid correction to prevent alkalosis
  • Target initial correction to bicarbonate of ~20 mEq/L within first 24 hours 1
  • Monitor arterial blood gases and electrolytes during treatment

2. Specific Causes of Metabolic Acidosis

Diabetic Ketoacidosis (DKA)

• First priority: Fluid resuscitation with isotonic saline (0.9% NaCl) at 15-20 mL/kg/hr during first hour 2
• Insulin therapy: After initial fluid resuscitation 2
• Bicarbonate therapy: Only for severe acidosis (pH < 7.0) or when accompanied by shock or coma 2

Lactic Acidosis

• Primary treatment: Address underlying cause (shock, sepsis, tissue hypoxia)
• Fluid resuscitation: To improve tissue perfusion
• Bicarbonate: Consider for severe acidosis (pH < 7.1) 1

Chronic Kidney Disease-Associated Acidosis

• Target: Maintain serum total CO2 > 22 mEq/L 2
• Oral bicarbonate supplementation: For chronic management
• Avoid citrate-containing alkali salts in patients exposed to aluminum 2

3. Special Populations

Pediatric Patients

• Metabolic acidosis in children:
  • For severe acidosis: IV sodium bicarbonate 1-2 mEq/kg 2
  • For diabetic ketoacidosis: Initial treatment with subcutaneous or IV insulin to correct hyperglycemia and metabolic derangement 2

Monitoring and Adjustment

• Frequent monitoring:

  • Arterial blood gases
  • Serum electrolytes
  • Clinical response

• Avoid complications:

  • Hypernatremia from excessive bicarbonate administration
  • Paradoxical CSF acidosis
  • Hypocalcemia
  • Volume overload

Pitfalls to Avoid

1. Overcorrection: Attempting full correction of low bicarbonate in first 24 hours can cause alkalosis 1

2. Ignoring the underlying cause: Treatment should address the primary disorder causing acidosis 1

3. Relying solely on bicarbonate therapy: In conditions like DKA, fluid resuscitation and insulin are more important than bicarbonate 2

4. Failure to monitor: Treatment requires stepwise approach with frequent reassessment 1

5. Using citrate-containing alkali in chronic kidney disease patients exposed to aluminum (increases aluminum absorption) 2

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