What is the treatment for metabolic acidosis?

Treatment of Metabolic Acidosis

Treatment of metabolic acidosis must be directed at the underlying cause first, with bicarbonate therapy reserved for specific indications based on etiology, severity, and patient population. 1, 2

Initial Assessment and Stabilization

Before initiating treatment, identify the specific cause through:

• Arterial blood gas analysis to determine pH, PaCO2, and bicarbonate levels 3
• Serum anion gap calculation ([Na+] - [HCO3-] + [Cl-]) to distinguish between normal anion gap (hyperchloremic) and elevated anion gap acidosis 4
• Electrolyte monitoring, particularly potassium, as acidosis causes transcellular potassium shifts leading to hyperkalemia 1, 2

Etiology-Specific Treatment Approaches

Diabetic Ketoacidosis (DKA)

For DKA, focus on insulin therapy, fluid resuscitation, and electrolyte replacement rather than bicarbonate administration. 1, 2

• Continuous intravenous insulin is the standard of care for critically ill and mentally obtunded patients 1
• Restoration of circulatory volume and tissue perfusion is the primary goal 1
• Bicarbonate administration has NOT been shown to improve resolution of acidosis or time to discharge in DKA 1, 2
• Once acidosis resolves, initiate metformin while continuing subcutaneous insulin 5

Chronic Kidney Disease-Associated Acidosis

Treat CKD-associated acidosis when serum bicarbonate is consistently <18 mmol/L to prevent bone and muscle metabolism abnormalities. 1, 2

• Oral sodium bicarbonate 2-4 g/day (25-50 mEq/day) effectively increases serum bicarbonate in CKD patients 1
• Target serum bicarbonate ≥22 mmol/L in maintenance dialysis patients 1
• Avoid citrate alkali salts in CKD patients exposed to aluminum as they increase aluminum absorption 1
• Monitor serum bicarbonate monthly in dialysis patients 1

Acute Severe Metabolic Acidosis

For life-threatening acute metabolic acidosis (cardiac arrest, severe shock, circulatory insufficiency), sodium bicarbonate is indicated despite controversy. 6

Cardiac Arrest Dosing:

• Initial rapid IV dose: 1-2 vials (44.6-100 mEq) 6
• Continue 50 mL (44.6-50 mEq) every 5-10 minutes as indicated by arterial pH and blood gas monitoring 6
• In cardiac arrest, risks from acidosis exceed those of hypernatremia 6

Non-Emergent Metabolic Acidosis Dosing:

• 2-5 mEq/kg body weight over 4-8 hours depending on severity 6
• Target total CO2 content of approximately 20 mEq/L at end of first day rather than complete correction 6
• Therapy should be stepwise and monitored with blood gases, plasma osmolarity, arterial lactate, and hemodynamics 6

Critical Caveats and Pitfalls

Bicarbonate Administration Risks

Bicarbonate therapy can worsen intracellular acidosis, reduce ionized calcium, and produce hyperosmolality. 1, 2, 3

• Do NOT attempt full correction of low total CO2 in first 24 hours due to delayed ventilatory readjustment 6
• Achieving normal or above-normal CO2 values within the first day is likely associated with grossly alkaline blood pH 6
• Bicarbonate solutions are hypertonic and may produce undesirable rises in plasma sodium 6

Lactic Acidosis and Tissue Hypoperfusion

For metabolic acidosis from tissue hypoperfusion, use sodium bicarbonate cautiously as it has not reduced morbidity or mortality in clinical studies 2, 3

• Focus on treating the underlying cause of hypoperfusion first 6
• Bicarbonate may exacerbate intracellular acidosis in these conditions 2, 3

Special Population Considerations

In children with renal tubular acidosis, normalize serum bicarbonate for normal growth parameters. 1

In youth with ketosis/ketoacidosis and diabetes, initiate subcutaneous or IV insulin to rapidly correct hyperglycemia and metabolic derangement, then add metformin once acidosis resolves. 5

Monitoring During Treatment

• Measure electrolytes frequently, especially potassium which shifts with pH changes 1, 2
• Monitor arterial blood gases to guide stepwise bicarbonate dosing 6
• Assess plasma osmolarity to detect hyperosmolality from bicarbonate 6
• Track hemodynamics and cardiac rhythm in shock-associated acidosis 6