What is the treatment for metabolic acidosis?

Treatment of Metabolic Acidosis

The treatment of metabolic acidosis should focus on addressing the underlying cause while providing supportive care, with sodium bicarbonate administration indicated for severe cases with pH < 7.3, especially in cardiac arrest, circulatory insufficiency, and severe primary lactic acidosis. 1

Diagnostic Approach

• Evaluate acid-base parameters including pH, partial pressure of CO2, and HCO3- concentration in arterial blood for stable patients, and in central venous blood for patients with impaired tissue perfusion 2
• Calculate the serum anion gap to differentiate between normal (hyperchloremic) anion gap and elevated anion gap metabolic acidosis 2
• Monitor serum bicarbonate levels monthly in maintenance dialysis patients 3

Treatment Based on Etiology

Diabetic Ketoacidosis (DKA)

• Focus on insulin therapy, fluid resuscitation, and electrolyte replacement 3
• Restoration of circulatory volume and tissue perfusion is a primary goal 3
• Continuous intravenous insulin is standard of care for critically ill and mentally obtunded patients 3
• Bicarbonate administration has not been shown to improve resolution of acidosis or time to discharge in DKA 3

Chronic Kidney Disease-Associated Acidosis

• Treat when serum bicarbonate is consistently < 18 mmol/L to prevent bone and muscle metabolism abnormalities 4
• Oral sodium bicarbonate (2-4 g/day or 25-50 mEq/day) can effectively increase serum bicarbonate concentrations 3
• Maintain serum bicarbonate at or above 22 mmol/L in maintenance dialysis patients 3
• Correction of acidemia has been associated with increased serum albumin, decreased protein degradation rates, and increased plasma concentrations of branched chain amino acids 3

Severe Acute Metabolic Acidosis

• Sodium bicarbonate is indicated for severe metabolic acidosis, especially in cardiac arrest, circulatory insufficiency due to shock or severe dehydration, and severe primary lactic acidosis 1
• In cardiac arrest, administer 44.6 to 100 mEq (1-2 vials of 50 mL) rapidly intravenously, followed by 44.6 to 50 mEq every 5-10 minutes if necessary 1
• For less urgent forms of metabolic acidosis, administer approximately 2-5 mEq/kg body weight over 4-8 hours 1
• Recent evidence suggests bicarbonate administration is associated with a small but significant reduction in mortality for ICU patients with metabolic acidosis (pH < 7.3) 5

Special Considerations

Dosing Caution

• Avoid attempting full correction of low total CO2 content during the first 24 hours to prevent unrecognized alkalosis 1
• Target achievement of total CO2 content of about 20 mEq/liter at the end of the first day 1
• Monitor treatment by measuring blood gases, plasma osmolarity, arterial blood lactate, hemodynamics, and cardiac rhythm in metabolic acidosis associated with shock 1

Potential Adverse Effects

• Bicarbonate solutions are hypertonic and may produce an undesirable rise in plasma sodium concentration 1
• Administration may worsen intracellular acidosis, reduce ionized calcium, and produce hyperosmolality 4, 2
• In cardiac arrest, the risks from acidosis exceed those of hypernatremia 1

Alternative Treatments

• Tris(hydroxymethyl)aminomethane (THAM) improves acidosis without producing intracellular acidosis and may be worth further investigation 2
• Selective sodium-hydrogen exchanger 1 (NHE1) inhibitors have shown promise in animal studies of acute lactic acidosis 2

Monitoring During Treatment

• Monitor electrolytes, particularly potassium levels, as acidosis can cause hyperkalemia due to transcellular shift of potassium 4
• Plan therapy in a stepwise fashion since the degree of response from a given dose is not precisely predictable 1
• Adjust subsequent treatment based on clinical response and laboratory parameters 1

By addressing both the underlying cause and the acid-base disturbance itself, treatment of metabolic acidosis can help prevent complications and improve outcomes in affected patients.