Sodium Bicarbonate Dosing for Severe Metabolic Acidosis
For severe metabolic acidosis (pH < 7.1), the recommended initial dose of sodium bicarbonate is 1-2 mEq/kg (1-2 mL/kg of 8.4% solution) administered intravenously, repeated as needed to achieve clinical stability while avoiding extreme hypernatremia or alkalemia. 1, 2
Initial Dosing Guidelines
- For adults with severe metabolic acidosis, administer 1-2 mEq/kg IV of sodium bicarbonate (8.4%, 1 mEq/mL) as an initial dose 2, 3
- In cardiac arrest, a rapid intravenous dose of 44.6 to 100 mEq (one to two 50 mL vials) may be given initially and continued at a rate of 44.6 to 50 mEq every 5-10 minutes if necessary, as indicated by arterial pH and blood gas monitoring 3
- For less urgent forms of metabolic acidosis, administer approximately 2-5 mEq/kg of body weight over a 4-8 hour period, depending on the severity of acidosis 3
- In pediatric patients with severe acidosis, consider 1-2 mEq/kg sodium bicarbonate over 1 hour 2, 4
Clinical Indications
- Sodium bicarbonate is indicated for severe metabolic acidosis (pH < 7.1 and bicarbonate < 10 mEq/L) 2, 4
- It is particularly beneficial in specific conditions including:
Administration Considerations
- Administer sodium bicarbonate slowly to avoid rapid alkalinization and its associated complications 3
- For sodium channel blocker toxicity (e.g., tricyclic antidepressants), after initial bolus, continue with an infusion of 150 mEq NaHCO3/L solution at 1-3 mL/kg/h to maintain alkalosis 2
- Bicarbonate therapy should always be planned in a stepwise fashion since the degree of response from a given dose is not precisely predictable 3
- In general, avoid attempting full correction of a low total CO2 content during the first 24 hours of therapy, as this may lead to unrecognized alkalosis 3
Monitoring Parameters
- Monitor arterial blood gases, serum electrolytes, and clinical response during administration 3
- Avoid extreme hypernatremia (serum sodium not to exceed 150-155 mEq/L) 2
- Avoid extreme alkalemia (serum pH not to exceed 7.50-7.55) 2
- Monitor for hypokalemia during alkalemia therapy 2
- Monitor for signs of fluid overload, especially in patients with cardiac or renal dysfunction 4
Special Considerations
- For patients with acute kidney injury (AKIN score of 2-3), sodium bicarbonate may be particularly beneficial, as it has been associated with improved survival 6
- Do not mix sodium bicarbonate with vasoactive amines or calcium 2
- In diabetic ketoacidosis, sodium bicarbonate should only be considered if pH remains < 7.0 after initial hour of hydration therapy 5, 4
- For maintenance dialysis patients, serum bicarbonate should be maintained at or above 22 mmol/L 2
Potential Adverse Effects
- Sodium bicarbonate administration can cause extracellular alkalosis, shifting the oxyhemoglobin curve and inhibiting oxygen release 2
- It can cause hypernatremia and hyperosmolarity 2
- Excess CO2 production may lead to paradoxical intracellular acidosis 2
- Sodium bicarbonate can inactivate simultaneously administered catecholamines 2
- Overly rapid correction of acidosis can lead to paradoxical central nervous system acidosis, cerebral edema, and hypocalcemia 4
Clinical Decision Algorithm
- Confirm severe metabolic acidosis (pH < 7.1, bicarbonate < 10 mEq/L) 2, 4
- Determine if special conditions exist (hyperkalemia, sodium channel blocker toxicity, acute kidney injury) 2, 5
- Calculate initial dose: 1-2 mEq/kg (1-2 mL/kg of 8.4% solution) 2, 3
- Administer dose slowly while monitoring clinical response 3
- Reassess with arterial blood gases and adjust subsequent dosing based on clinical response and laboratory values 3
- Continue treatment until pH > 7.2, while avoiding extreme hypernatremia or alkalemia 2, 3