title: Reexamination of Stewart's quantitative analysis of acid-base status.
abstract: To provide experimental verification to Stewart's quantitative approach to acid-base analysis, the effects of acute maximal treadmill exercise (VO2max test) on venous acid base status were studied in 17 male subjects aged 18-23 yr. Venous CO2 tension (PCO2) total plasma proteins ([PTOT]), [H+], and concentrations of strong ions [( Na+], [K+], [Cl-] and lactate ion concentration ([La-]) were measured before and within 1 min post-exercise. Mean post-exercise PCO2, [PTOT], [K+], and [La-] were significantly higher than the corresponding pre-exercise values (P less than 0.05), there was a strong tendency for a significant change in [Na+] (P less than 0.056), and no changes were found in [Cl-]. Changes in venous acid-base status were analyzed quantitatively by applying relevant physicochemical theory. Altered values measured in the independent variables ([PTOT], PCO2, and net strong ion difference, [SID]) were used to calculate the corresponding changes in the dependent quantities. Comparison of individual measured and calculated values for the only one of these that is normally measured, ([H+]), yielded the theoretically expected agreement. PCO2 and [SID] changes accounted for most [H+] changes. These results demonstrate the usefulness of the quantitative approach (i.e., [H+]-PCO2 diagram) in the analysis and in understanding of plasma acid base changes with exercise and in clinical situations.
authors.affiliation: Department of Research and Sport Medicine, Zinman College, Wingate Institute, Israel.
authors.forename: Y
authors.initials: Y
authors.lastname: Weinstein
authors.forename: A
authors.initials: A
authors.lastname: Magazanik
authors.forename: A
authors.initials: A
authors.lastname: Grodjinovsky
authors.forename: O
authors.initials: O
authors.lastname: Inbar
authors.forename: R A
authors.initials: RA
authors.lastname: Dlin
authors.forename: P A
authors.initials: PA
authors.lastname: Stewart
mesh_terms: D000136:Acid-Base Equilibrium / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D001784:Blood Gas Analysis; D005080:Exercise Test; D006339:Heart Rate; D006801:Humans; D007773:Lactates / Q000032:analysis; D008297:Male; D010101:Oxygen Consumption; D005082:Physical Exertion; D011659:Pulmonary Gas Exchange; D012044:Regression Analysis
chemical_list: D007773:Lactates