What is the treatment for metabolic acidosis?

Treatment of Metabolic Acidosis

Treatment of metabolic acidosis must be directed at the underlying cause rather than routine bicarbonate administration, as sodium bicarbonate has not demonstrated mortality benefit in most acute organic acidoses and may worsen intracellular acidosis. 1

Etiology-Based Treatment Approach

Diabetic Ketoacidosis (DKA)

• Continuous intravenous insulin is the standard of care for critically ill and mentally obtunded patients with DKA. 2, 1
• Restoration of circulatory volume and tissue perfusion is the primary goal, along with resolution of ketoacidosis and correction of electrolyte imbalances. 2, 1
• Successful transition from intravenous to subcutaneous insulin requires administration of basal insulin 2-4 hours before stopping the intravenous insulin to prevent recurrence of ketoacidosis and rebound hyperglycemia. 2
• Bicarbonate administration has not been shown to improve resolution of acidosis or time to discharge in DKA and is generally not recommended. 2, 1

Chronic Kidney Disease-Associated Acidosis

• Treat when serum bicarbonate is consistently < 18 mmol/L to prevent bone and muscle metabolism abnormalities. 1
• Oral sodium bicarbonate (2-4 g/day or 25-50 mEq/day) can effectively increase serum bicarbonate concentrations. 1
• Maintain serum bicarbonate at or above 22 mmol/L in maintenance dialysis patients. 1
• Correction of acidemia has been associated with increased serum albumin, decreased protein degradation rates, and increased plasma concentrations of branched chain amino acids. 1
• In children with renal tubular acidosis, normalization of serum bicarbonate is important for normal growth parameters. 1

Acute Organic Acidosis (Lactic Acidosis, Shock)

• The only effective treatment for organic acidosis is cessation of acid production via improvement of tissue oxygenation. 3
• In cardiac arrest, rapid intravenous dose of one to two 50 mL vials (44.6 to 100 mEq) of sodium bicarbonate may be given initially and continued at a rate of 50 mL every 5 to 10 minutes if necessary. 4
• In cardiac arrest, the risks from acidosis exceed those of hypernatremia, despite bicarbonate solutions being hypertonic. 4
• For less urgent forms of metabolic acidosis, the amount of bicarbonate to be given over 4-8 hours is approximately 2 to 5 mEq/kg of body weight, depending on severity. 4

Continuous Renal Replacement Therapy (CRRT) Patients

• Either lactate or bicarbonate can be used as buffer in most CRRT patients. 2
• Bicarbonate is preferred in patients with lactic acidosis and/or liver failure. 2
• Worsening of acidosis has been noted when lactate was used in patients with lactic acidosis or liver failure. 2

Critical Monitoring Requirements

• Monitor electrolytes, particularly potassium levels, as acidosis causes hyperkalemia due to transcellular shift of potassium. 1, 5
• In metabolic acidosis associated with shock, therapy should be monitored by measuring blood gases, plasma osmolarity, arterial blood lactate, hemodynamics, and cardiac rhythm. 4
• Monitor serum bicarbonate levels monthly in maintenance dialysis patients. 1
• Bicarbonate therapy should always be planned in a stepwise fashion since the degree of response from a given dose is not precisely predictable. 4

Common Pitfalls to Avoid

• It is unwise to attempt full correction of a low total CO2 content during the first 24 hours of therapy, as this may be accompanied by unrecognized alkalosis due to delayed readjustment of ventilation. 4
• Achievement of total CO2 content of about 20 mEq/liter at the end of the first day of therapy will usually be associated with normal blood pH. 4
• Values for total CO2 brought to normal or above normal within the first day are very likely to be associated with grossly alkaline blood pH values with ensuing undesired side effects. 4
• Administration of bicarbonate solutions may worsen intracellular acidosis, reduce ionized calcium, and produce hyperosmolality. 1
• Avoid using furosemide unless hypervolemia, hyperkalemia, and/or renal acidosis are present. 1
• Avoid using hypotonic fluids (e.g., glucose solutions) for fluid resuscitation. 1
• Citrate alkali salts should be avoided in CKD patients exposed to aluminum salts as they may increase aluminum absorption. 1

Specific Clinical Scenarios

Severe Metabolic Acidosis (pH < 7.2)

• Specific treatment with sodium bicarbonate may be required when pH is less than 7.2. 5
• Blood pH and gases should be monitored closely to avoid an "overshoot" alkalosis. 5

Drug Intoxications

• Sodium bicarbonate is indicated in certain drug intoxications, including barbiturates (where dissociation of the barbiturate-protein complex is desired), poisoning by salicylates or methyl alcohol, and hemolytic reactions requiring alkalinization of the urine. 4

Severe Diarrhea

• Sodium bicarbonate is indicated in severe diarrhea which is often accompanied by significant loss of bicarbonate. 4