Treatment of Metabolic Acidosis
Treatment of metabolic acidosis must be directed at the underlying cause first, with bicarbonate therapy reserved for specific severe situations, particularly diabetic ketoacidosis requiring insulin and fluid resuscitation, and chronic kidney disease when serum bicarbonate falls below 18 mmol/L. 1, 2
Immediate Assessment and Etiology-Specific Treatment
The cornerstone of management is identifying and treating the root cause rather than simply correcting the pH 3, 4. The approach differs dramatically based on etiology:
Diabetic Ketoacidosis (DKA)
- Focus on insulin therapy, fluid resuscitation, and electrolyte replacement as primary treatment 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 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 concentrations 1
- Target serum bicarbonate ≥ 22 mmol/L in maintenance dialysis patients 1
- Correction improves serum albumin, decreases protein degradation, and increases branched chain amino acids 1
- Avoid citrate alkali salts in CKD patients exposed to aluminum salts due to increased aluminum absorption risk 1
Bicarbonate Therapy: When and How
Indications for IV Sodium Bicarbonate
Sodium bicarbonate is indicated for 3:
- Severe renal disease with metabolic acidosis
- Uncontrolled diabetes (though see DKA caveat above)
- Circulatory insufficiency due to shock or severe dehydration
- Cardiac arrest
- Severe primary lactic acidosis
- Certain drug intoxications (barbiturates, salicylates, methyl alcohol)
- Severe diarrhea with significant bicarbonate loss
Dosing Protocols
In cardiac arrest: 3
- Initial rapid IV dose: 44.6-100 mEq (one to two 50 mL vials)
- Continue 44.6-50 mEq every 5-10 minutes as needed based on arterial pH and blood gas monitoring
- The risks from acidosis exceed those of hypernatremia in this emergency setting 3
In less urgent metabolic acidosis: 3
- Adults and older children: 2-5 mEq/kg body weight over 4-8 hours
- Dose depends on severity judged by total CO₂ content, blood pH, and clinical condition
- Do NOT attempt full correction in first 24 hours—target total CO₂ of ~20 mEq/L to avoid rebound alkalosis 3
- Therapy should be stepwise since response is not precisely predictable 3
Critical Monitoring Parameters
Monitor the following closely during treatment 1, 2:
- Potassium levels: Acidosis causes transcellular shift of potassium leading to hyperkalemia; correction may unmask hypokalemia 1, 2
- Arterial blood gases and pH 3
- Plasma osmolarity 3
- Arterial blood lactate 3
- Hemodynamics and cardiac rhythm 3
- Serum bicarbonate monthly in dialysis patients 1
Important Caveats and Pitfalls
Bicarbonate therapy has significant limitations and risks: 2, 6
- May worsen intracellular acidosis despite improving blood pH 2, 6
- Can reduce ionized calcium 2, 6
- Produces hyperosmolality 2, 6
- Bicarbonate solutions are hypertonic and may cause undesirable rise in plasma sodium 3
Avoid bicarbonate in tissue hypoperfusion-related acidosis without careful consideration 2, as it may paradoxically worsen intracellular acidosis 6.
In severe symptoms requiring rapid correction (cardiac arrest, severe shock, severe diabetic acidosis), vigorous bicarbonate therapy is justified despite risks, as the dangers of severe acidosis outweigh the complications of treatment 3.