Adding lactate to the prime solution during hypothermic cardiopulmonary bypass: a quantitative acid-base analysis

Area of Science:

• Cardiovascular Surgery
• Acid-Base Balance
• Biochemistry

Background:

• Cardiopulmonary bypass (CPB) can induce metabolic acidosis.
• Stewart's quantitative acid-base approach models pH using PCO(2), weak acids, and strong ion difference.
• Hypoalbuminemia during CPB can lead to oncotic and weak acid deficits.

Purpose of the Study:

• To investigate the effect of lactate in CPB prime on acid-base balance.
• To analyze CPB-induced acid-base changes using Stewart's quantitative model.
• To evaluate the role of synthetic colloids in managing CPB-related deficits.

Main Methods:

• Prospective study of 20 coronary surgery patients undergoing CPB.
• Comparison between CPB prime with and without lactate.
• Measurement of various blood parameters including pH, PCO(2), lactate, albumin, and electrolytes before and after CPB.

Main Results:

• Lactated prime resolved metabolic acidosis by the end of CPB.
• The strong ion gap increased in both groups, but its composition differed.
• Stewart analysis identified polyanionic gelatin as a weak acid contributing to the anion gap.

Conclusions:

• Exogenous lactate effectively attenuates CPB-related acidosis.
• Polyanionic synthetic colloids may temporarily compensate for deficits during CPB.
• Stewart's method provides a detailed understanding of acid-base disturbances during CPB.