When is bicarbonate (bicarb) therapy indicated in shock?

Bicarbonate Therapy in Shock

Bicarbonate therapy is not recommended for shock patients with hypoperfusion-induced lactic acidemia unless the pH falls below 7.15, and even then should be used cautiously with close monitoring of hemodynamics and electrolytes. 1

pH Thresholds for Bicarbonate Administration

The decision to administer bicarbonate in shock depends primarily on the severity of acidosis:

• pH ≥ 7.15: Strong evidence recommends against bicarbonate therapy for hypoperfusion-induced lactic acidemia 1
• pH 7.0-7.15: Consider bicarbonate therapy based on clinical context 1
• pH < 7.0: Bicarbonate therapy may be indicated, especially in severe metabolic acidosis 1, 2

Specific Indications for Bicarbonate in Shock

Bicarbonate is indicated in the following shock-related conditions:

• Circulatory insufficiency due to shock with severe acidosis (pH < 7.0) 2
• Severe primary lactic acidosis 2
• Cardiac arrest 1, 2
• Specific drug intoxications (barbiturates, salicylates, methyl alcohol) 2

Dosing and Administration Protocol

When bicarbonate therapy is indicated:

1. Initial dosing:

   • 1-2 mEq/kg IV as initial dose 1, 2
   • In cardiac arrest: 44.6-100 mEq initially, then 44.6-50 mEq every 5-10 minutes as needed 1, 2

2. Maintenance therapy:

   • For less urgent metabolic acidosis: 2-5 mEq/kg over 4-8 hours 2
   • Target total CO2 content of about 20 mEq/L at the end of the first day 2

3. Administration method:

   • Slow infusion is preferred over rapid bolus to minimize adverse effects 3
   • Can be added to other intravenous fluids 2

Monitoring During Bicarbonate Therapy

Close monitoring is essential during bicarbonate administration:

• Arterial blood gases
• Serum electrolytes (especially potassium, calcium, and sodium)
• ECG
• Blood pressure
• Mental status
• Hemodynamic parameters 1

Potential Complications and Precautions

Bicarbonate therapy carries several risks that require careful consideration:

• Hypernatremia (avoid serum sodium exceeding 150-155 mEq/L) 1
• Paradoxical intracellular acidosis 4
• Decreased cardiac output and blood pressure 4
• Decreased ionized calcium (approximately 10% drop) 3
• Decreased vascular responsiveness to catecholamines 3
• Excessive CO2 production requiring adequate ventilation 3

Alternative Approaches

When bicarbonate is contraindicated or ineffective:

• THAM (tromethamine) may be considered as an alternative, particularly in patients with hypernatremia or mixed acidosis with high PaCO2 levels 1
• Bicarbonated Ringer's solution has shown promise in recent research for hemorrhagic shock resuscitation, with potential benefits including better acid-base balance maintenance and tissue protection 5, 6
• The most effective therapy for lactic acidosis due to shock remains treating the underlying cause of shock 3

Clinical Pearls

• Avoid attempting full correction of low total CO2 content during the first 24 hours to prevent rebound alkalosis 2
• In septic shock with arterial hyperlactatemia, some evidence suggests bicarbonate infusion may facilitate weaning from mechanical ventilation and reduce ICU stay length, though mortality benefits are unproven 7
• When continuous renal replacement therapy is used during severe acidosis, bicarbonate-based replacement fluid is preferred over citrate 3