Sodium Bicarbonate Dosing for Metabolic Acidosis
For adults with metabolic acidosis, the recommended initial dose of sodium bicarbonate is 1-2 mEq/kg IV administered slowly, while for children the dose is 1-3 mEq/kg. 1, 2, 3, 4
Adult Dosing
- Initial bolus: 1-2 mEq/kg IV given slowly over 10-20 minutes 3, 4
- For cardiac arrest: 50-150 mEq (50-150 mL of 8.4% solution) may be given rapidly, followed by 50 mEq every 5-10 minutes if necessary based on arterial pH and blood gas monitoring 4
- For sodium channel blocker toxicity (e.g., tricyclic antidepressants): 50-150 mEq bolus, followed by an infusion of 150 mEq/L solution at 1-3 mL/kg/h 1, 2
- For less urgent metabolic acidosis: 2-5 mEq/kg administered over 4-8 hours 4
- Maximum recommended cumulative dose: 6 mEq/kg to avoid hypernatremia, fluid overload, and metabolic alkalosis 5
Pediatric Dosing
- Initial bolus: 1-3 mEq/kg IV 1, 2
- For newborns and infants: Use only 0.5 mEq/mL concentration (diluted solution) 2
- Maintenance: Similar to adults, prepare 150 mEq/L solution and infuse at 1-3 mL/kg/h for sodium channel blocker toxicity 1
pH-Based Dosing Recommendations
- pH < 6.9: Bicarbonate therapy may be beneficial, administer 1-2 mEq/kg IV 3
- pH 6.9-7.0: Administer 1-2 mEq/kg over 1 hour 3
- pH > 7.0: Bicarbonate therapy generally not necessary 3
Monitoring and Duration of Therapy
- Monitor serum bicarbonate every 2-4 hours during active infusion 3, 6
- Follow venous pH and anion gap to monitor resolution of acidosis 3
- Continue sodium bicarbonate infusion until serum bicarbonate reaches ≥22 mmol/L or pH rises above 7.0 3, 6
- Ensure effective ventilation is established before administering bicarbonate, as ventilation is needed to eliminate excess CO2 produced 2, 3
Example Dosing Calculation
For a 70 kg adult with severe metabolic acidosis (pH 6.8):
- Initial dose: 1-2 mEq/kg = 70-140 mEq
- Administration: Give slowly over 10-20 minutes
- Subsequent therapy: Based on clinical response and repeat blood gas analysis
Cautions and Potential Adverse Effects
- Avoid extremes of hypernatremia (serum sodium not to exceed 150-155 mEq/L) 2
- Avoid extremes of alkalemia (serum pH not to exceed 7.50-7.55) 2
- Monitor for and treat hypokalemia during alkalemia therapy 2
- Bicarbonate can cause extracellular alkalosis, shifting the oxyhemoglobin curve and inhibiting oxygen release 2, 3
- Can lead to hypernatremia, hyperosmolarity, and excess CO2 production causing paradoxical intracellular acidosis 2, 3
- Can inactivate simultaneously administered catecholamines 2
- Do not mix with vasoactive amines or calcium 2
Special Considerations
- Routine use is not supported for sepsis-related acidosis, particularly when arterial pH is >7.15 2, 7
- In sodium channel blocker poisoning (e.g., tricyclic antidepressants), combine with hyperventilation (PCO2 ~30-35 mmHg) for optimal serum alkalinization 5
- For patients with DKA, evidence suggests bicarbonate therapy does not decrease time to resolution of acidosis even with pH <7.0 8
- Bicarbonate administration can cause dose-dependent increases in cerebral blood flow, which may be problematic in certain vulnerable populations 9
Remember that the best method of reversing acidosis is to treat the underlying cause and restore adequate circulation, with bicarbonate therapy serving as an adjunctive measure for severe cases 2.