Comparative quantitative acid-base analysis in coronary artery bypass, severe sepsis, and diabetic ketoacidosis

The main objective of this study was to assess the relationship of standard base excess (SBE) to delta strong ion difference effective (DeltaSIDe) in critical illness. Critical illness is characterized by variable plasma nonvolatile weak acid components (DeltaA(-)), and SBE becomes discordant with DeltaSIDe. The author hypothesized that both acid-base models are equivalent when SBE and DeltaSIDe are corrected for DeltaA(-). A retrospective chart review was performed to assess this hypothesis by looking at changes in SBE, DeltaSIDe, and DeltaA(-) in 30 coronary artery bypass graft surgery patients, 30 severe sepsis patients, and 15 diabetic ketoacidosis patients. SBE equals the sum of the DeltaSIDe and DeltaA(-). The SBE quantifies the magnitude of the metabolic acid-base derangement, the DeltaSIDe quantifies the plasma strong cation/anion imbalance, and the DeltaA(-) quantifies the magnitude of the hypoalbuminemic alkalosis. The partitioning of SBE into physicochemical components can facilitate analyses of complex acid-base disorders in critical illness.