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The Scientific World Journal
Volume 2014, Article ID 907521, 6 pages
http://dx.doi.org/10.1155/2014/907521
Clinical Study

Effect of the Independent Acid Base Variables on Anion Gap Variation in Cardiac Surgical Patients: A Stewart-Figge Approach

12nd Department of Intensive Care Medicine, “G. Papanikolaou” General Hospital of Thessaloniki, G. Papanikolaou Avenue, Exohi, 57010 Thessaloniki, Greece
2Department of Cardiothoracic Surgery, “G. Papanikolaou” General Hospital of Thessaloniki, G. Papanikolaou Avenue, Exohi, 57010 Thessaloniki, Greece

Received 26 August 2013; Accepted 24 December 2013; Published 3 February 2014

Academic Editors: L. M. Gillman, D. Karakitsos, and A. E. Papalois

Copyright © 2014 Michalis Agrafiotis et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose. To determine the effect of each of independent acid base variables on the anion gap (AG) value in cardiac surgical patients. Methods. This retrospective study involved 128 cardiac surgical patients admitted for postoperative care. The variation of AG () between the day of admission and the first postoperative day was correlated via a multiple linear regression model with the respective variations of the independent acid base variables, that is, apparent strong ion difference (), strong ion gap (SIG), carbon dioxide (PCO2), and albumin and phosphate concentrations. Results. The variations of all the above variables contributed significantly to the prediction of (adjusted , , and ). According to the standardized coefficients (β),   (β = 0.948, ), (β = 0.260, ), and (β = 0.191, ) were the major determinants of with lesser contributions from (β = 0.071, ) and (β = −0.067, ). Conclusions. All the independent acid base variables contribute to the prediction of the AG value. However, albumin and phosphate and SIG variations seem to be the most important predictors, while AG appears to be rather stable with changes in PCO2 and .