What is the recommended dose of sodium bicarbonate (NaHCO3) infusion for an adult patient with severe metabolic acidosis?

Sodium Bicarbonate Infusion Dosing for Adults

For severe metabolic acidosis in adults, administer 1-2 mEq/kg IV (typically 50-100 mL of 8.4% solution) given slowly over several minutes as the initial dose. 1, 2, 3

Initial Bolus Dosing

• The standard initial dose is 1-2 mEq/kg administered intravenously, which translates to approximately 50-100 mEq or 50-100 mL of 8.4% sodium bicarbonate solution for most adults 1, 2, 3
• This dose should be given slowly over several minutes, not as a rapid push, to minimize complications 1, 3
• In cardiac arrest specifically, one to two 50 mL vials (44.6 to 100 mEq) may be given initially and continued at 50 mL every 5-10 minutes if necessary, guided by arterial pH and blood gas monitoring 3

pH-Based Treatment Thresholds

• Bicarbonate is indicated when pH < 7.1 with base excess < -10 mEq/L 1, 2, 4
• For pH 6.9-7.0, administer 50 mmol sodium bicarbonate in 200 mL sterile water infused at 200 mL/hour 1
• For pH < 6.9, administer 100 mmol sodium bicarbonate in 400 mL sterile water infused at 200 mL/hour 1
• Do not give bicarbonate if pH ≥ 7.15 in sepsis-related or hypoperfusion-induced lactic acidemia, as multiple trials show no benefit and potential harm 1, 5

Continuous Infusion Protocol

• After initial bolus, if ongoing alkalinization is needed, prepare a 150 mEq/L solution and infuse at 1-3 mL/kg/hour 1
• For less urgent metabolic acidosis, administer 2-5 mEq/kg over 4-8 hours, depending on severity 3
• Target pH of 7.2-7.3, not complete normalization, as overshooting can cause rebound alkalosis 1, 3, 4

Critical Pre-Administration Requirements

• Ensure adequate ventilation is established before giving bicarbonate, as it produces CO2 that must be eliminated to prevent paradoxical intracellular acidosis 1, 2
• In mechanically ventilated patients, maintain minute ventilation to achieve PaCO2 of 30-35 mmHg 1
• Never mix bicarbonate with calcium-containing solutions or vasoactive amines (epinephrine, norepinephrine, dopamine), as precipitation or inactivation will occur 1, 2

Concentration Selection

• Adults typically receive 8.4% solution (1 mEq/mL) without dilution 1
• Consider diluting to 4.2% concentration in sodium-sensitive states such as heart failure or renal impairment to minimize sodium load 1
• Isotonic bicarbonate (4.2%) is preferred over hypertonic formulations to prevent hyperosmolarity complications 1

Mandatory Monitoring Parameters

• Monitor arterial blood gases every 2-4 hours during active therapy to assess pH, PaCO2, and bicarbonate response 1, 2
• Monitor serum electrolytes every 2-4 hours, specifically sodium (target <150-155 mEq/L), potassium, and ionized calcium 1, 2
• Stop bicarbonate if serum sodium exceeds 150-155 mEq/L or pH exceeds 7.50-7.55 1
• Monitor for hypokalemia and replace potassium as needed, since bicarbonate shifts potassium intracellularly 1

Special Clinical Scenarios

Sodium Channel Blocker/TCA Toxicity

• Give initial bolus of 50-150 mEq using hypertonic solution (1000 mEq/L), titrated to resolution of QRS prolongation and hypotension 1
• Follow with continuous infusion of 150 mEq/L solution at 1-3 mL/kg/hour to maintain alkalosis 1

Hyperkalemia

• Use bicarbonate as adjunct therapy to shift potassium intracellularly while definitive treatments are initiated 1
• Combine with glucose/insulin for synergistic effect 1

Diabetic Ketoacidosis

• Only give bicarbonate if pH < 6.9 in adult DKA patients 1, 2
• Bicarbonate is not necessary if pH ≥ 7.0 1

Common Pitfalls to Avoid

• Do not give bicarbonate routinely in cardiac arrest - it does not improve outcomes and is only considered after first epinephrine dose fails or in specific situations (severe acidosis pH <7.1, hyperkalemia, TCA overdose) 1
• Avoid rapid or excessive administration - can cause hypernatremia, hyperosmolarity, hypokalemia, hypocalcemia, and paradoxical intracellular acidosis 1, 2
• Do not attempt full correction in first 24 hours - this may cause unrecognized alkalosis due to delayed ventilatory readjustment 3
• Never give bicarbonate without adequate ventilation - CO2 production will worsen intracellular acidosis if not eliminated 1, 2
• Flush IV line with normal saline before and after bicarbonate to prevent catecholamine inactivation 1

Maximum Dosing Limits

• Do not exceed 6 mEq/kg total dose, as this commonly causes hypernatremia, fluid overload, metabolic alkalosis, and cerebral edema 1
• Limit rate to no more than 8 mEq/kg/day in high-risk patients 1

Treatment Endpoint

• Continue bicarbonate until pH reaches 7.2-7.3 or serum bicarbonate reaches ≥22 mmol/L 2, 4
• Discontinue when target pH achieved, hemodynamic stability restored, or complications develop (hypernatremia, excessive alkalemia) 1