When to order sodium bicarbonate with arterial blood gas (ABG) pH analysis in cases of acidosis?

From the Guidelines

Sodium bicarbonate should be ordered when arterial pH falls below 7.15, particularly in cases of severe metabolic acidosis, as suggested by the most recent guidelines 1. The typical dosage is 50-100 mEq IV, which can be repeated based on subsequent pH measurements and clinical response. Treatment is most appropriate for patients with severe acidemia causing hemodynamic instability, decreased cardiac contractility, or arrhythmias. Some key points to consider when deciding to order sodium bicarbonate include:

• The patient's arterial pH level, with a threshold of 7.15 or lower indicating potential need for bicarbonate therapy 1
• The presence of severe metabolic acidosis, which may require bicarbonate administration to help normalize pH
• The patient's clinical status, including signs of hemodynamic instability, decreased cardiac contractility, or arrhythmias, which may be improved with bicarbonate therapy
• The potential risks and side effects of bicarbonate administration, such as paradoxical CNS acidosis, volume overload, hypernatremia, and hyperosmolality Sodium bicarbonate administration is specifically indicated in certain conditions like severe diabetic ketoacidosis unresponsive to initial therapy, certain drug overdoses, and renal tubular acidosis. However, it should be used cautiously and with careful monitoring of arterial blood gases, electrolytes, and clinical status to guide dosing adjustments and prevent complications. The underlying cause of acidosis should always be addressed simultaneously. Sodium bicarbonate works by increasing serum bicarbonate levels, which helps buffer excess hydrogen ions and normalize pH. Regular monitoring and careful consideration of the patient's individual needs and response to treatment are essential to ensure effective and safe use of sodium bicarbonate.

From the FDA Drug Label

In cardiac arrest, a rapid intravenous dose of one to two 50 mL vials (44.6 to 100 mEq) may be given initially and continued at a rate of 50 mL (44. 6 to 50 mEq) every 5 to 10 minutes if necessary (as indicated by arterial pH and blood gas monitoring) to reverse the acidosis. In metabolic acidosis associated with shock, therapy should be monitored by measuring blood gases, plasma osmolarity, arterial blood lactate, hemodynamics and cardiac rhythm.

• Monitoring: Sodium bicarbonate should be ordered with pH monitoring, specifically arterial pH and blood gas monitoring, to assess the need for and response to therapy.
• Indications: This monitoring is particularly important in situations such as cardiac arrest and metabolic acidosis associated with shock.
• Therapy adjustment: The results of pH monitoring should be used to adjust the dose and frequency of sodium bicarbonate administration 2.

From the Research

Ordering Sodium Bicarbonate with pH

• The decision to order sodium bicarbonate with pH depends on the severity of metabolic acidosis and the underlying clinical situation 3, 4, 5.
• In general, bicarbonate should be given at an arterial blood pH of ≤7.0, and the amount given should be calculated to bring the pH up to 7.2 3.
• However, the current literature suggests limited benefit from bicarbonate therapy for patients with severe metabolic acidosis (pH < 7.1 and bicarbonate < 6 mEq/L) 4.
• Bicarbonate therapy may yield improvement in survival for patients with accompanying acute kidney injury 4.
• For patients with lactic acidosis, eliminating the triggering conditions remains the most effective therapy, and administration of sodium bicarbonate does not improve cardiovascular function or reduce mortality 6, 5.
• The use of sodium bicarbonate to correct severe acidemia may be tempting to clinicians, but previous studies have failed to show improved patient outcomes following bicarbonate administration 5, 7.
• If administered, bicarbonate is best given as a slow IV infusion in the setting of adequate ventilation and calcium replacement to mitigate its untoward effects 5.