Treatment of Metabolic Acidosis
The treatment of metabolic acidosis should primarily focus on identifying and addressing the underlying cause, while providing bicarbonate therapy when serum bicarbonate is consistently below 18 mmol/L, particularly in chronic kidney disease patients. 1, 2
Etiology-Based Treatment Approach
- For diabetic ketoacidosis (DKA), focus on insulin therapy, fluid resuscitation, and electrolyte replacement rather than bicarbonate administration, as bicarbonate has not been shown to improve resolution of acidosis or time to discharge 1, 2
- In chronic kidney disease (CKD)-associated acidosis, treat when serum bicarbonate is consistently < 18 mmol/L to prevent bone and muscle metabolism abnormalities 1, 2
- For severe metabolic acidosis associated with shock, circulatory insufficiency, cardiac arrest, or severe primary lactic acidosis, vigorous bicarbonate therapy is indicated 3
- In cases of drug intoxications (barbiturates, salicylates, methyl alcohol) and hemolytic reactions, sodium bicarbonate is indicated to promote alkalinization 3
- For severe diarrhea with significant bicarbonate loss, sodium bicarbonate replacement is recommended 3
Bicarbonate Therapy Guidelines
- For chronic kidney disease patients, oral sodium bicarbonate (2-4 g/day or 25-50 mEq/day) can effectively increase serum bicarbonate concentrations 1
- In cardiac arrest, rapid intravenous administration of 44.6 to 100 mEq (1-2 vials of 50 mL) may be given initially and continued at 44.6-50 mEq every 5-10 minutes if necessary, guided by arterial pH and blood gas monitoring 3
- For less urgent forms of metabolic acidosis, approximately 2-5 mEq/kg body weight of sodium bicarbonate over 4-8 hours is recommended, depending on the severity of acidosis 3
- In maintenance dialysis patients, aim to maintain serum bicarbonate at or above 22 mmol/L 1
Monitoring and Precautions
- Monitor serum bicarbonate levels monthly in maintenance dialysis patients 1
- Closely monitor electrolytes, particularly potassium levels, as acidosis can cause hyperkalemia due to transcellular shift of potassium 1, 2
- Avoid full correction of low total CO2 content during the first 24 hours of therapy, as this may lead to unrecognized alkalosis due to delayed ventilatory adjustment 3
- Target a total CO2 content of about 20 mEq/liter at the end of the first day of therapy, which is usually associated with normal blood pH 3
- Use bicarbonate with caution as it may worsen intracellular acidosis, reduce ionized calcium, and produce hyperosmolality 1, 2
- For patients with chronic metabolic acidosis, correction of acidosis can improve bone histology and reduce excess protein catabolism 1, 4
Special Considerations
- Avoid citrate alkali salts in CKD patients exposed to aluminum salts as they may increase aluminum absorption 1
- In children with renal tubular acidosis, normalization of serum bicarbonate is important for normal growth parameters 1
- Measurement of the anion gap [(Na+ + K+) - (Cl- + HCO3-)] helps diagnose the cause of metabolic acidosis and guide appropriate treatment 5, 6
- Bicarbonate therapy should always be planned in a stepwise fashion since the degree of response from a given dose is not precisely predictable 3
- Treatment of severe metabolic acidosis requires close monitoring of blood pH and gases to avoid "overshoot" alkalosis 5