What are the indications for intravenous (IV) bicarbonate (bicarb)?

Indications for Intravenous Bicarbonate

Intravenous bicarbonate is indicated for severe metabolic acidosis (pH <7.0-7.1) from specific causes including cardiac arrest, drug intoxications (tricyclic antidepressants, sodium channel blockers), hyperkalemia, and certain metabolic conditions, but is NOT recommended for routine use in sepsis-related lactic acidosis or cardiac arrest. 1, 2

Established Indications

Severe Metabolic Acidosis with Specific Etiologies

• Cardiac arrest: Initial dose of 1-2 mEq/kg (44.6-100 mEq) IV push, repeated every 5-10 minutes as needed based on arterial blood gas monitoring 1
• Drug intoxications requiring alkalinization:
  • Tricyclic/tetracyclic antidepressant overdose with life-threatening cardiotoxicity (QRS >120 ms): 50-150 mEq bolus of hypertonic solution (1000 mEq/L), followed by infusion of 150 mEq/L at 1-3 mL/kg/h 2
  • Sodium channel blocker toxicity: Same dosing as tricyclic overdose 2
  • Barbiturate, salicylate, or methanol poisoning 1
• Hyperkalemia: Bicarbonate shifts potassium intracellularly 2
• Hemolytic reactions: Alkalinization of urine diminishes nephrotoxicity of hemoglobin breakdown products 1

Metabolic Conditions

• Severe diabetic ketoacidosis (DKA): Only when pH <6.9 (100 mmol in 400 mL sterile water at 200 mL/h for pH <6.9; 50 mmol in 200 mL at 200 mL/h for pH 6.9-7.0) 2
  • Critical caveat: Not indicated if pH ≥7.0, as studies show no benefit in time to acidosis resolution and increased insulin/fluid requirements 3, 2
• Severe renal disease with documented metabolic acidosis 1
• Circulatory insufficiency due to shock or severe dehydration 1
• Severe primary lactic acidosis (non-sepsis related) 1
• Severe diarrhea with significant bicarbonate loss 1

Chronic Kidney Disease

• Maintenance dialysis patients: Maintain serum bicarbonate ≥22 mmol/L using oral sodium bicarbonate 2-4 g/day (25-50 mEq/day) 2

Contraindications and Situations Where NOT Indicated

Sepsis-Related Lactic Acidosis

• Do NOT use bicarbonate for hypoperfusion-induced lactic acidemia when pH ≥7.15 4
• Two blinded RCTs showed no difference in hemodynamics or vasopressor requirements compared to equimolar saline 4
• The 2016 Surviving Sepsis Campaign guidelines explicitly recommend against routine use 4

Cardiac Arrest (Routine Use)

• Routine bicarbonate administration is NOT recommended in cardiac arrest (Class III recommendation) 4
• Restoration of circulation with high-quality CPR and appropriate ventilation are the mainstays of correcting acidosis 4
• Exception: Use only in special resuscitation situations (hyperkalemia, tricyclic overdose, preexisting metabolic acidosis) 4

Severe Malaria

• No evidence supports bicarbonate use; acidosis typically resolves with correction of hypovolemia and treatment of anemia 2

Dosing Guidelines

Adults

• Initial dose: 1-2 mEq/kg IV (50-100 mL of 8.4% solution) administered slowly 2, 1
• Maintenance: 2-5 mEq/kg over 4-8 hours depending on severity 1
• Target: Bring pH to approximately 7.2, NOT full correction to normal in first 24 hours 1

Pediatrics

• Children: 1-2 mEq/kg IV given slowly 2
• Children <2 years: Must dilute 8.4% solution 1:1 with normal saline to achieve 4.2% concentration 2
• Newborns: Use only 0.5 mEq/mL (4.2%) concentration 2

Critical Safety Considerations

Adverse Effects to Monitor

• Sodium and fluid overload: Bicarbonate solutions are hypertonic 4
• Paradoxical intracellular acidosis: Excess CO₂ production diffuses into cells 4
• Extracellular alkalosis: Shifts oxyhemoglobin curve, inhibiting oxygen release 4
• Hypernatremia and hyperosmolarity: Monitor serum sodium, keep <150-155 mEq/L 2
• Hypokalemia during alkalemia: Monitor and treat as needed 2
• Increased lactate and PaCO₂ 4
• Decreased serum ionized calcium 4
• Inactivation of simultaneously administered catecholamines 4, 2

Administration Precautions

• Never mix with calcium-containing solutions or vasoactive amines 2
• Ensure adequate ventilation before administration: Ventilation is required to eliminate excess CO₂ produced 2
• Monitor arterial pH, blood gases, plasma osmolarity, and electrolytes during therapy 1
• Avoid extremes of alkalemia: Keep pH <7.50-7.55 2

Practical Algorithm for Decision-Making

1. Check arterial pH and identify cause of acidosis
2. If pH ≥7.15 AND sepsis-related lactic acidosis: Do NOT give bicarbonate 4
3. If pH <7.0-7.1: Consider bicarbonate ONLY if:
   • Cardiac arrest with ongoing CPR 1
   • Drug intoxication (tricyclic, sodium channel blocker) 2
   • Hyperkalemia requiring urgent treatment 2
   • DKA with pH <6.9 2
   • Severe renal disease or primary lactic acidosis 1
4. Establish effective ventilation FIRST before bicarbonate administration 2
5. Give initial dose of 1-2 mEq/kg IV slowly 1
6. Recheck arterial blood gas and adjust: Target pH 7.2, not full correction 1
7. Monitor for complications: Hypernatremia, hypokalemia, fluid overload 2

The key principle is that treating the underlying cause and restoring adequate circulation is always superior to bicarbonate therapy alone 2, and bicarbonate should be reserved for specific severe situations where pH is critically low or specific toxidromes are present.