Etiology of Intraoperative Metabolic Acidosis upon Cardiopulmonary Bypass

Abstract

Objective: Upon usage of cardiopulmonary bypass (CPB), intraoperative metabolic acidosis is frequently found. Its etiology has not been yet fully understood. In accordance with the traditional concept of dilution, the fast administration of large volumes with minor bicarbonate concentration into the patients' systemic circulation causes dilutional acidosis. During initiation of CPB, the priming volume is rapidly administered. Using crystalloid cardioplegia, additional volume is introduced within the first minutes of CPB. Usually, both the priming as well as the cardioplegic solution contain less than physiological bicarbonate concentration. Therefore, CPB constitutes an excellent model for studying dilutional metabolic acidosis. Although the lactic acidosis' severity is known to correlate with CPB duration, little is known about the contribution of dilutional acidosis. Aim of the study was to prove the general existence of dilutional acidosis and evaluate its impact on intraoperative metabolic acidosis upon CPB.