Bicarbonate Correction Formula for Metabolic Acidosis
The standard formula for bicarbonate correction is: Bicarbonate deficit (mEq) = 0.3 × body weight (kg) × base deficit, though this may overestimate requirements during shock or cardiac arrest, where reduced distribution volumes necessitate more conservative dosing. 1, 2
Standard Dosing Formulas
Initial Bolus Dosing
- Adults and older children: 1-2 mEq/kg IV administered slowly 3, 1
- Pediatric patients: 1-3 mEq/kg IV given slowly 3
- Newborn infants: 1-2 mEq/kg IV using only 0.5 mEq/mL (4.2%) concentration 3
Maintenance Dosing for Severe Acidosis
- For pH <7.1: Administer approximately 2-5 mEq/kg body weight over 4-8 hours, depending on severity 1
- Target correction: Aim to bring pH up to 7.2, not full correction to normal in first 24 hours 1, 4
Specific Clinical Scenarios
Diabetic Ketoacidosis (DKA)
- pH <6.9: Infuse 100 mmol sodium bicarbonate in 400 mL sterile water at 200 mL/h 3
- pH 6.9-7.0: Infuse 50 mmol sodium bicarbonate in 200 mL sterile water at 200 mL/h 3
- pH ≥7.0: Bicarbonate therapy not indicated 3
Cardiac Arrest
- Initial dose: 50 mL (44.6-50 mEq) given rapidly, may repeat every 5-10 minutes based on arterial blood gas monitoring 1
- Conservative approach: Do not exceed 50 mmol per dose with intervals of at least 10 minutes due to reduced cardiac output (approximately 25% of normal) during CPR 2
Sodium Channel Blocker/Tricyclic Antidepressant Toxicity
- Bolus: 50-150 mEq, followed by infusion of 150 mEq/L solution at 1-3 mL/kg/h 3
- Target: Maintain serum sodium 150-155 mEq/L and pH 7.50-7.55 3
Critical Preparation Guidelines
Concentration Requirements
- Newborns and children <2 years: Must dilute 8.4% solution 1:1 with normal saline to achieve 4.2% concentration 3
- Children ≥2 years and adults: May use 8.4% solution, though dilution often performed for safety 3
- Never mix: Sodium bicarbonate with calcium-containing solutions or vasoactive amines 3
Important Caveats
When NOT to Use Full Formula
- During CPR/shock: Functional distribution space may be reduced by 70-80%, requiring only 20-30% of calculated dose 2
- Sepsis with pH ≥7.15: Routine bicarbonate not recommended for hypoperfusion-induced lactic acidemia 3
- Tissue hypoperfusion: Best treatment is addressing underlying cause and restoring circulation, not bicarbonate 3
Monitoring Parameters
- Avoid overcorrection: Target total CO2 of approximately 20 mEq/L at end of first day, not complete normalization 1
- Recheck frequently: Arterial blood gases, plasma osmolarity, serum sodium, and potassium (treat hypokalemia during alkalinization) 3, 1
- Watch for complications: Hypernatremia, hyperosmolarity, paradoxical intracellular acidosis from excess CO2 production, and decreased oxygen release from leftward shift of oxyhemoglobin curve 3