When is sodium bicarbonate (NaHCO3) prescribed?

When to Prescribe Sodium Bicarbonate

Sodium bicarbonate should be prescribed for severe metabolic acidosis with pH <7.0-7.1, life-threatening sodium channel blocker/tricyclic antidepressant toxicity with QRS widening, hyperkalemia as adjunctive therapy, and chronic kidney disease patients with serum bicarbonate <22 mmol/L, but NOT for routine use in cardiac arrest, sepsis-related lactic acidosis with pH ≥7.15, or diabetic ketoacidosis with pH ≥7.0. 1, 2

Primary Indications

Severe Metabolic Acidosis

• Administer sodium bicarbonate when arterial pH falls below 7.0-7.1 with base deficit <-10, but only after establishing effective ventilation to eliminate the CO2 produced by bicarbonate metabolism 1, 2
• The FDA label specifically indicates use in severe renal disease, uncontrolled diabetes, circulatory insufficiency due to shock or severe dehydration, cardiac arrest, and severe primary lactic acidosis 2
• Target pH should be 7.2-7.3, not complete normalization, as overshooting can cause harmful alkalosis 1

Toxicological Emergencies

• For tricyclic antidepressant overdose with QRS widening >120 ms: Give 50-150 mEq IV bolus of hypertonic solution (1000 mEq/L), targeting arterial pH 7.45-7.55 1, 3
• For other sodium channel blocker toxicity: Administer 50-150 mEq bolus followed by continuous infusion of 150 mEq/L solution at 1-3 mL/kg/hour 1, 3
• The FDA label supports use in barbiturate, salicylate, and methyl alcohol poisoning where alkalinization aids drug elimination 2

Hyperkalemia

• Use as adjunctive temporizing measure to shift potassium intracellularly while definitive treatments (dialysis, insulin/glucose) are initiated 1
• Combine with glucose/insulin for synergistic effect, but never use as monotherapy 1
• Monitor potassium every 2-4 hours as bicarbonate-induced alkalosis can cause significant intracellular shift 1

Chronic Kidney Disease

• Prescribe oral sodium bicarbonate 2-4 g/day (25-50 mEq/day) when serum bicarbonate falls below 22 mmol/L 1
• This improves protein metabolism, increases serum albumin, and reduces hospitalizations 1

Specific Clinical Scenarios

Diabetic Ketoacidosis

• Only administer if pH <6.9 - no benefit shown for pH ≥7.0 and may cause harm in pediatric patients 1, 4
• For pH 6.9-7.0: Give 50 mmol in 200 mL sterile water at 200 mL/hour 1
• For pH <6.9: Give 100 mmol in 400 mL sterile water at 200 mL/hour 1

Cardiac Arrest

• Do NOT use routinely - the American College of Cardiology recommends against routine administration 1
• Consider only after first epinephrine dose fails in asystolic arrest, or in arrests due to hyperkalemia or sodium channel blocker toxicity 1
• If used: Give 1-2 mEq/kg IV slowly, flush line with normal saline before and after to prevent catecholamine inactivation 1

Sepsis and Lactic Acidosis

• The Surviving Sepsis Campaign explicitly recommends AGAINST sodium bicarbonate for hypoperfusion-induced lactic acidemia when pH ≥7.15 1
• Two randomized trials showed no difference in hemodynamic variables or vasopressor requirements compared to equimolar saline 1
• Exception: Recent evidence suggests possible benefit in patients with pH <7.2 AND acute kidney injury, though this remains investigational 5

Dosing Guidelines

Adults

• Initial dose: 1-2 mEq/kg IV (50-100 mL of 8.4% solution) given slowly over several minutes 1, 2
• For cardiac arrest: May repeat 50 mL (44.6-50 mEq) every 5-10 minutes guided by arterial pH 2
• For less urgent situations: 2-5 mEq/kg over 4-8 hours 2

Pediatrics

• Standard dose: 1-2 mEq/kg IV given slowly 1, 3
• For infants <2 years: MUST dilute 8.4% solution 1:1 with normal saline to achieve 4.2% concentration 1, 3
• For newborns: Use only 0.5 mEq/mL (4.2%) concentration 1, 3

Critical Safety Considerations

Contraindications and Precautions

• Never mix with calcium-containing solutions or vasoactive amines - causes precipitation and catecholamine inactivation 1, 3
• Ensure adequate ventilation before administration - bicarbonate produces CO2 that must be eliminated to prevent paradoxical intracellular acidosis 1
• Avoid in patients who cannot increase minute ventilation to clear excess CO2 1

Monitoring Requirements

• Check arterial blood gases every 2-4 hours to assess pH, PaCO2, and bicarbonate response 1, 3
• Monitor serum electrolytes every 2-4 hours: sodium (keep <150-155 mEq/L), potassium (replace as needed), ionized calcium 1
• Stop therapy when pH reaches 7.2-7.3, serum sodium exceeds 150-155 mEq/L, or pH exceeds 7.50-7.55 1

Adverse Effects to Anticipate

• Sodium and fluid overload - particularly problematic in heart failure and renal dysfunction 1
• Decreased ionized calcium - can worsen cardiac contractility, especially with doses >50-100 mEq 1
• Paradoxical intracellular acidosis if ventilation inadequate 1
• Hypokalemia from intracellular potassium shift - requires aggressive replacement 1
• Increased lactate production - a paradoxical effect that can worsen lactic acidosis 1

Common Pitfalls to Avoid

• Do not attempt full correction in first 24 hours - lag in ventilatory adjustment can cause unrecognized alkalosis 2
• Do not use empirically without arterial blood gas confirmation of severe acidosis 1
• Do not ignore the underlying cause - bicarbonate buys time but does not treat the disease 1
• Do not administer rapidly in non-arrest situations - hypertonic solutions can cause dangerous sodium shifts 2
• Do not use for rhabdomyolysis - urinary alkalinization does not improve patient-centered outcomes 4