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International Journal of Nephrology
Volume 2011, Article ID 413760, 5 pages
http://dx.doi.org/10.4061/2011/413760
Research Article

Volume Assessment in Mechanically Ventilated Critical Care Patients Using Bioimpedance Vectorial Analysis, Brain Natriuretic Peptide, and Central Venous Pressure

1Division of Nephrology, London Health Sciences Center, London, Canada N6A 5A5
2Helsinki University Central Hospital, Division of Nephrology, 00029 Helsinki, Finland
3St Bortolo Hospital, Department of Nephrology, 36100 Vicenza, Italy
4Division of Nephrology, Department of Medical and Surgical Sciences, University of Padua, 35128 Padua, Italy
5St Bortolo Hospital, Department of Anesthesia and Intensive Care, 36100 Vicenza, Italy

Received 6 July 2010; Accepted 28 September 2010

Academic Editor: Mitchell H. Rosner

Copyright © 2011 Andrew A. House 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. Strategies for volume assessment of critically ill patients are limited, yet early goal-directed therapy improves outcomes. Central venous pressure (CVP), Bioimpedance Vectorial Analysis (BIVA), and brain natriuretic peptide (BNP) are potentially useful tools. We studied the utility of these measures, alone and in combination, to predict changing oxygenation. Methods. Thirty-four mechanically ventilated patients, 26 of whom had data beyond the first study day, were studied. Relationships were assessed between CVP, BIVA, BNP, and oxygenation index (O2I) in a cross-sectional (baseline) and longitudinal fashion using both univariate and multivariable modeling. Results. At baseline, CVP and O2I were positively correlated ( ; ), while CVP and BIVA were weakly correlated ( ; ). The association between slopes of variables over time was negligible, with the exception of BNP, whose slope was correlated with O2I ( ; ). Comparing tertiles of CVP, BIVA, and BNP slopes with the slope of O2I revealed only modest agreement between BNP and O2I ( ; ). In a regression model, only BNP was significantly associated with O2I; however, this was strengthened by including CVP in the model. Conclusions. BNP seems to be a valuable noninvasive measure of volume status in critical care and should be assessed in a prospective manner.