What are the uses and dosages of sodium bicarbonate in treating conditions associated with excess acid?

Sodium Bicarbonate Uses and Dosages for Treating Acidosis

Sodium bicarbonate is primarily indicated for treating severe metabolic acidosis (pH < 7.1), hyperkalemia, and tricyclic antidepressant overdose, with specific dosing of 1-2 mEq/kg IV administered slowly for adults. 1, 2

Primary Indications for Sodium Bicarbonate

• FDA-approved for treating metabolic acidosis in severe renal disease, uncontrolled diabetes, circulatory insufficiency due to shock, severe dehydration, extracorporeal circulation of blood, cardiac arrest, and severe primary lactic acidosis 1
• Strongly recommended (Class 1, Level B-NR) for treating life-threatening cardiotoxicity from tricyclic and tetracyclic antidepressant poisoning 3
• Reasonable (Class 2a, Level C-LD) for treating life-threatening cardiotoxicity caused by other sodium channel blockers 3
• Indicated for drug intoxications including barbiturates, salicylates, and methyl alcohol poisoning 1
• Used in hemolytic reactions requiring alkalinization of urine to reduce nephrotoxicity 1
• Indicated in severe diarrhea with significant bicarbonate loss 1

Dosing Guidelines

For Metabolic Acidosis:

• Standard initial dose: 1-2 mEq/kg IV administered slowly 2, 4
• For severe acidosis (pH < 7.1 and base excess < -10): 50 mmol (50 ml of 8.4% solution) 3
• Further administration depends on clinical situation and repeat arterial blood gas analysis 3

For Sodium Channel Blocker Toxicity:

• Adults: Hypertonic solution (1000 mEq/L) given as IV bolus 3
• Children: Hypertonic solution (500 mEq/L) given as IV bolus 3
• Titrate to resolution of hypotension and QRS prolongation 3
• May continue with infusion of 150 mEq NaHCO₃/L solution to maintain alkalosis after initial bolus 2

pH-Based Recommendations:

• pH < 6.9: Bicarbonate therapy may be beneficial 4
• pH 6.9-7.0: 1-2 mEq/kg over 1 hour 4
• pH > 7.0: Generally not necessary 4

Monitoring and Administration Guidelines

• Ensure effective ventilation is established before administering bicarbonate (ventilation needed to eliminate excess CO₂ produced) 2, 4
• Monitor serum bicarbonate every 2-4 hours during active infusion therapy 4
• Follow venous pH and anion gap to monitor resolution of acidosis 4
• Continue infusion until serum bicarbonate reaches ≥22 mmol/L or pH rises above 7.0 4
• Avoid extremes of hypernatremia (serum sodium not to exceed 150-155 mEq/L) 3
• Avoid extremes of alkalemia (serum pH not to exceed 7.50-7.55) 3
• Monitor and treat hypokalemia during alkalemia therapy 3
• Do not mix sodium bicarbonate with vasoactive amines or calcium 2

Cautions and Contraindications

• Not recommended for routine use in cardiac arrest 2
• Not recommended for hypoperfusion-induced lactic acidemia with pH ≥ 7.15 in sepsis 2, 5, 6
• Not supported for routine use in diabetic ketoacidosis, may cause harm in pediatric patients 5
• Potential adverse effects include:
  • Extracellular alkalosis (shifting oxyhemoglobin curve and inhibiting oxygen release) 2
  • Hypernatremia and hyperosmolarity 2
  • Excess CO₂ production causing paradoxical intracellular acidosis 2, 7
  • Inactivation of simultaneously administered catecholamines 2
  • Hypokalemia and hypocalcemia 8, 7
  • Sodium and fluid overload 5

Alternative Alkalizing Agents

• THAM (tromethamine) may be preferred in patients with:
  • Hypernatremia (THAM decreases serum sodium while bicarbonate increases it) 8
  • Mixed acidosis with high PaCO₂ levels (bicarbonate increases PaCO₂ while THAM may decrease it) 8
• However, sodium bicarbonate has a longer-lasting alkalizing effect than THAM 8
• THAM is not recommended for patients with hyperkalemia (bicarbonate decreases serum potassium, THAM does not) 8

Practical Considerations

• For preparation stability: 100 mL of 8.4% sodium bicarbonate diluted in 150 mL normal saline in a 250 mL polyolefin bag maintains stable bicarbonate concentration for up to 48 hours 9
• For newborn infants, use only 0.5 mEq/mL concentration, with dilution of available stock solutions as necessary 2