Stability of bicarbonate in normal saline: a technical report

Area of Science:

• Critical Care Medicine
• Clinical Pharmacy
• Biochemistry

Background:

• The efficacy of intravenous sodium bicarbonate for severe metabolic acidosis is debated, partly due to a lack of double-blind studies.
• Achieving double-blinding necessitates evaluating the stability of sodium bicarbonate solutions in common medical packaging, such as polyolefin bags.

Purpose of the Study:

• To assess the stability of 8.4% sodium bicarbonate diluted in normal saline within polyolefin bags over a 48-hour period.
• To determine the impact of storage on pH, Pco2, and bicarbonate concentration.

Main Methods:

• Seven samples of 100 mL 8.4% sodium bicarbonate diluted in 150 mL normal saline were prepared in 250 mL polyolefin bags.
• Measurements of pH, Pco2, and bicarbonate concentration were taken at baseline (0 hours), 24 hours, and 48 hours.

Main Results:

• A statistically significant decrease in pH and Pco2 was observed over 48 hours.
• The hourly rate of change for pH was -0.001 (P=0.043) and for Pco2 was -0.098 (P<0.001).
• Bicarbonate concentration remained stable, with a non-significant hourly rate of change of -0.009 (P=0.42).

Conclusions:

• Sodium bicarbonate diluted in normal saline within polyolefin bags exhibits minimal changes in pH and Pco2 over 48 hours.
• Bicarbonate concentration remains stable under these conditions, supporting its use in blinded clinical trials for metabolic acidosis.