What is the recommended dosage of sodium bicarbonate (NaHCO3) in metabolic acidosis?

Sodium Bicarbonate Dosing in Metabolic Acidosis

For adults with severe metabolic acidosis (pH < 7.1), administer sodium bicarbonate 1-2 mEq/kg IV as a slow bolus, which can be repeated based on arterial blood gas monitoring, while for children the dose is 1-2 mEq/kg IV given slowly. 1, 2

Initial Dosing Strategy

Adult Dosing

• Administer 1-2 mEq/kg (equivalent to 1-2 mL/kg of 8.4% solution) as a slow intravenous bolus for severe metabolic acidosis with pH < 7.1 1, 2
• In cardiac arrest, give one to two 50 mL vials (44.6 to 100 mEq) initially, continuing at 50 mL every 5-10 minutes as indicated by arterial pH and blood gas monitoring 2
• For less urgent metabolic acidosis, infuse 2-5 mEq/kg over 4-8 hours depending on severity 2

Pediatric Dosing

• Standard dose: 1-2 mEq/kg IV administered slowly 1, 3
• For newborn infants, use only 0.5 mEq/mL (4.2%) concentration—dilute 8.4% solution 1:1 with normal saline or sterile water 1, 3
• Children ≥2 years may receive 8.4% solution, though dilution to 4.2% is often performed for safety 1

Specific Clinical Scenarios

Diabetic Ketoacidosis (DKA)

• Bicarbonate is indicated ONLY if pH < 6.9 in adult DKA patients 4, 1
• For pH < 6.9: infuse 100 mmol sodium bicarbonate in 400 mL sterile water at 200 mL/hour 1
• For pH 6.9-7.0: infuse 50 mmol sodium bicarbonate in 200 mL sterile water at 200 mL/hour 1
• Do NOT use bicarbonate if pH ≥ 7.0 4, 1

Sodium Channel Blocker/Tricyclic Antidepressant Toxicity

• Administer 50-150 mEq bolus (using hypertonic 8.4% solution) followed by continuous infusion of 150 mEq/L solution at 1-3 mL/kg/hour 1, 3
• Target arterial pH 7.45-7.55 and resolution of QRS prolongation 1
• This is a Class I (strong) recommendation for life-threatening cardiotoxicity 1

Sepsis-Related Lactic Acidosis

• The Surviving Sepsis Campaign explicitly recommends AGAINST sodium bicarbonate therapy when pH ≥ 7.15 1
• Two randomized controlled trials showed no difference in hemodynamic variables or vasopressor requirements compared to equimolar saline 1
• Consider bicarbonate only if pH < 7.15 after optimizing ventilation and hemodynamics, though evidence for benefit is lacking even at this threshold 1

Critical Administration Guidelines

Concentration and Preparation

• For pediatric patients under 2 years, dilute 8.4% solution 1:1 with normal saline to achieve 4.2% concentration 1
• The 8.4% solution is extremely hypertonic (2 mOsmol/mL) and can cause hyperosmolar complications 1
• Never mix sodium bicarbonate with calcium-containing solutions or vasoactive amines 1, 3

Rate of Administration

• Administer as a SLOW intravenous push, not rapid bolus 1, 2
• Flush IV cannula with normal saline before and after administration to prevent catecholamine inactivation 1
• In cardiac arrest, rapid infusion may be necessary despite risks, as acidosis risks exceed hypernatremia risks 2

Monitoring Requirements

Essential Parameters

• Monitor arterial blood gases every 2-4 hours during active therapy to assess pH, PaCO2, and bicarbonate response 1, 3
• Monitor serum electrolytes every 2-4 hours, particularly sodium, potassium, and ionized calcium 1
• Check serum bicarbonate levels every 2-4 hours during infusion 3

Treatment Targets

• Target pH 7.2-7.3, NOT complete normalization 1
• Avoid serum sodium > 150-155 mEq/L 1
• Avoid pH > 7.50-7.55 1
• Monitor and treat hypokalemia, as bicarbonate shifts potassium intracellularly 1

Important Contraindications and Cautions

When NOT to Use Bicarbonate

• Do not use routinely in cardiac arrest 1
• Avoid in hypoperfusion-induced lactic acidemia with pH ≥ 7.15 1
• Not indicated in DKA with pH ≥ 7.0 4, 1
• No evidence supports use in severe malaria 1

Common Pitfalls

• Bicarbonate must be given ONLY after effective ventilation is established, as it produces excess CO2 that requires adequate ventilation for elimination 1
• Sodium and fluid overload can occur, particularly with hypertonic solutions 1
• Can cause paradoxical intracellular acidosis if ventilation is inadequate 1
• Decreases ionized calcium, potentially affecting cardiac contractility 1
• May increase lactate production paradoxically 1
• Causes extracellular alkalosis, shifting the oxyhemoglobin curve and inhibiting oxygen release 1

Repeat Dosing Strategy

• Repeat dosing should be guided by arterial blood gas analysis, not given empirically 1, 2
• Continue infusion until serum bicarbonate reaches ≥22 mmol/L in chronic kidney disease patients 3
• In DKA, target bicarbonate ≥18 mEq/L and venous pH > 7.3 1
• It is unwise to attempt full correction of acidosis within the first 24 hours, as this may cause unrecognized alkalosis due to delayed ventilatory readjustment 2
• Achieving total CO2 content of approximately 20 mEq/L at the end of the first day is usually associated with normal blood pH 2

Special Populations

Hyperkalemia

• Use bicarbonate as adjunct therapy to shift potassium intracellularly while definitive treatments are initiated 1
• Note that bicarbonate decreases serum potassium, which may be beneficial in hyperkalemia but requires monitoring 1

Chronic Kidney Disease

• Maintain serum bicarbonate at or above 22 mmol/L in maintenance dialysis patients 1
• Oral sodium bicarbonate 2-4 g/day (25-50 mEq/day) effectively increases serum bicarbonate in CKD patients 1