When should sodium bicarbonate be administered to a patient with acidosis?

When to Give Sodium Bicarbonate

Sodium bicarbonate should be administered for severe metabolic acidosis with pH <7.1 and base deficit <-10, life-threatening sodium channel blocker/tricyclic antidepressant toxicity with QRS widening, and acute kidney injury with severe acidemia (pH ≤7.20), but should NOT be given routinely for hypoperfusion-induced lactic acidosis when pH ≥7.15. 1

Primary Indications for Sodium Bicarbonate

Severe Metabolic Acidosis

• Administer when pH <7.1 AND base deficit <-10 after ensuring effective ventilation is established 1
• Initial dose: 1-2 mEq/kg IV (50-100 mL of 8.4% solution) given slowly over several minutes 1, 2
• Target pH of 7.2-7.3, NOT complete normalization 1
• The FDA label specifies 44.6-100 mEq initially in cardiac arrest, repeated every 5-10 minutes as guided by arterial blood gas monitoring 2

Life-Threatening Toxicologic Emergencies

• Tricyclic antidepressant overdose with QRS >120 ms: Give 50-150 mEq bolus of hypertonic solution (1000 mEq/L), targeting arterial pH 7.45-7.55 1
• 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
• This is a Class I (strong) recommendation from the American Heart Association 1

Acute Kidney Injury with Severe Acidemia

• The most recent high-quality evidence shows benefit in patients with AKIN score 2-3 and pH ≤7.20 3
• The BICARICU-1 trial (2018) demonstrated improved 28-day survival in the prespecified acute kidney injury stratum (54% vs 37%, p=0.0283) 3
• A 2025 target trial emulation across 12 Australian ICUs confirmed a 1.9% absolute mortality reduction (risk ratio 0.86,95% CI 0.80-0.91) 4

Specific Clinical Scenarios

• Hyperkalemia: Use as temporizing measure while definitive therapy is initiated, combined with glucose/insulin for synergistic effect 1
• Diabetic ketoacidosis: Only if pH <6.9; give 100 mmol in 400 mL sterile water at 200 mL/hour 1
• Chronic kidney disease: Oral sodium bicarbonate 2-4 g/day to maintain serum bicarbonate ≥22 mmol/L 1

Absolute Contraindications and When NOT to Give

Do NOT Give Bicarbonate When:

• pH ≥7.15 in sepsis-related or hypoperfusion-induced lactic acidosis - this is an explicit recommendation from the Surviving Sepsis Campaign 1
• Two randomized controlled trials showed no difference in hemodynamics or vasopressor requirements compared to saline 1
• Anuric patients without renal replacement therapy - will cause inevitable hypernatremia, fluid overload, and worsened cardiac failure 5
• In one study, bicarbonate was independently associated with 6.27-fold higher mortality in lactic acidosis patients 5
• Respiratory acidosis - treat with ventilation, not bicarbonate 1
• Routine cardiac arrest - the American College of Cardiology recommends against routine use 1

Critical Prerequisite: Adequate Ventilation

• Never give bicarbonate without ensuring adequate ventilation first 1
• Bicarbonate produces CO2 that must be eliminated; giving it without adequate ventilation causes paradoxical intracellular acidosis 1
• The American Academy of Pediatrics emphasizes this is mandatory before any bicarbonate administration 1

Dosing Algorithm

Adults

1. Initial bolus: 1-2 mEq/kg (50-100 mL of 8.4% solution) IV slowly over several minutes 1, 2
2. For toxicity: 50-150 mEq bolus, then infusion of 150 mEq/L at 1-3 mL/kg/hour 1
3. Stepwise approach: The FDA recommends 2-5 mEq/kg over 4-8 hours, not attempting full correction in first 24 hours 2

Pediatrics

• Children: 1-2 mEq/kg IV given slowly 1
• Infants <2 years: Use only 0.5 mEq/mL (4.2%) concentration - dilute 8.4% solution 1:1 with normal saline 1
• Never exceed 8 mEq/kg/day in neonates 1

Monitoring Requirements

Essential Parameters Every 2-4 Hours:

• Arterial blood gases: Monitor pH, PaCO2, bicarbonate 1
• Serum sodium: Stop if >150-155 mEq/L 1
• Serum potassium: Bicarbonate shifts potassium intracellularly, causing hypokalemia requiring replacement 1
• Ionized calcium: Large doses decrease ionized calcium, worsening cardiac contractility 1

Target Goals:

• pH 7.2-7.3 (not complete normalization) 1
• Avoid pH >7.50-7.55 1
• Serum sodium <150-155 mEq/L 1

Critical Safety Considerations

Common Pitfalls to Avoid:

• Never mix with calcium-containing solutions or vasoactive amines (causes precipitation/inactivation) 1
• Flush IV line with normal saline before and after bicarbonate administration 1
• Do not give in anuric patients without concurrent renal replacement therapy 5
• Avoid in respiratory acidosis - will worsen CO2 retention 1

Adverse Effects:

• Hypernatremia and hyperosmolarity 1, 3
• Metabolic alkalosis 3
• Hypocalcemia 1, 3
• Hypokalemia 1
• Paradoxical intracellular acidosis if ventilation inadequate 1
• Sodium and fluid overload 1

Alternative Management in Anuric Patients

For anuric patients with severe acidosis, the correct approach is NOT bicarbonate but rather: 5

• Initiate urgent renal replacement therapy (CRRT or hemodialysis with bicarbonate-based dialysate) 5
• Optimize ventilation to ensure adequate CO2 clearance 5
• Treat underlying shock and restore circulation 5
• Bicarbonate-buffered dialysate provides controlled alkali delivery without the sodium/volume load 1