Treatment of Metabolic Acidosis

Introduction to Metabolic Acidosis Management

• Metabolic acidosis management involves various interventions, including ventilation and bicarbonate administration, with the goal of improving patient outcomes, as recommended by the American Heart Association and other guideline societies 1, 2, 3, 4

Recommendations for Sodium Bicarbonate Use

• The American College of Critical Care Medicine recommends against using sodium bicarbonate to treat metabolic acidosis arising from tissue hypoperfusion (lactic acidosis) unless pH falls below 7.15 5
• The American College of Critical Care Medicine and the Society of Critical Care Medicine recommend against sodium bicarbonate therapy for shock patients with hypoperfusion-induced lactic acidemia unless pH falls below 7.15, and even then should be used cautiously with close monitoring of hemodynamics and electrolytes 6, 7
• For patients with pH ≥ 7.15, strong evidence recommends against bicarbonate therapy for hypoperfusion-induced lactic acidemia 6
• For patients with pH < 7.15, bicarbonate therapy may be considered based on clinical context 6, 7

Initial Dosing and Administration

• The recommended initial IV dose for metabolic acidosis is 1-2 mEq/kg, which should be titrated to effect based on pH and clinical response, with a high level of evidence based on clinical trials, as recommended by the American Heart Association 8, 2
• A stepwise approach to sodium bicarbonate therapy is recommended, starting with 2-5 mEq/kg over 4-8 hours, and adjusting based on clinical response, with a target total CO2 content of about 20 mEq/L at the end of the first day, as recommended by the Surviving Sepsis Campaign guidelines 9
• The initial IV bolus dose of sodium bicarbonate is 1-2 mEq/kg, and in cardiac arrest, 44.6-100 mEq initially, then 44.6-50 mEq every 5-10 minutes as needed, as recommended by the American Heart Association and the Surviving Sepsis Campaign guidelines 9

Special Considerations and Alternative Therapies

• THAM (tromethamine) may be considered as an alternative to sodium bicarbonate, as it does not increase serum sodium and may even decrease it, particularly in patients with hypernatremia or mixed acidosis with high PaCO2 levels, as recommended by the American Heart Association 2, 4
• Increasing fruit and vegetable intake can increase serum bicarbonate levels while providing additional benefits such as decreased systolic blood pressure and weight reduction, as recommended by the American Journal of Kidney Diseases 1
• The American Journal of Kidney Diseases recommends an oral dose of 2-4 g/day (25-50 mEq/day) of sodium bicarbonate to effectively increase serum bicarbonate concentrations in patients with chronic kidney disease 10

Monitoring and Adverse Effects

• Regular monitoring of arterial blood gases, serum electrolytes (especially potassium, calcium, and sodium), ECG, blood pressure, and mental status is essential during bicarbonate administration, as recommended by the American Heart Association and the American Academy of Pediatrics 2, 11, 10, 12, 13, 14, 15
• Sodium bicarbonate therapy can cause hypernatremia, a potential adverse effect, as cautioned by the American Heart Association, and experts recommend avoiding extreme hypernatremia (serum sodium not to exceed 150-155 mEq/L) 4

Guideline Recommendations

Fluid Management

• The Kidney International guideline recommends using isotonic saline (0.9% NaCl) at 15-20 ml/kg/h initially to restore intravascular volume in shock patients 16
• The Kidney International guideline advises avoiding volume overload, especially in patients with acute lung injury 16
• For patients with lactic acidosis and acute kidney injury, bicarbonate is preferred as a buffer in continuous renal replacement therapy (CRRT) 16
• The Kidney International guideline recommends avoiding lactate-containing dialysate/replacement fluids as they may worsen acidosis in patients with lactic acidosis or liver failure 16