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Critical Care Research and Practice
Volume 2013, Article ID 583598, 7 pages
Research Article

Central Venous-to-Arterial Gap Is a Useful Parameter in Monitoring Hypovolemia-Caused Altered Oxygen Balance: Animal Study

1Department of Anaesthesiology and Intensive Therapy, University of Szeged, Semmelweis Utca 6., Szeged 6725, Hungary
2Department of Anaesthesiology and Intensive Therapy, MH Honved Hospital, Róbert Károly Körút 44., Budapest 1134, Hungary
3Institute of Surgical Research, University of Szeged, Pécsi Utca 6., Szeged 6720, Hungary

Received 9 February 2013; Revised 10 July 2013; Accepted 19 July 2013

Academic Editor: Samuel A. Tisherman

Copyright © 2013 Szilvia Kocsi 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.


Monitoring hypovolemia is an everyday challenge in critical care, with no consensus on the best indicator or what is the clinically relevant level of hypovolemia. The aim of this experiment was to determine how central venous oxygen saturation (ScvO2) and central venous-to-arterial carbon dioxide difference (CO2 gap) reflect hypovolemia-caused changes in the balance of oxygen delivery and consumption. Anesthetized, ventilated Vietnamese minipigs ( ) were given a bolus followed by a continuous infusion of furosemide. At baseline and then in five stages hemodynamic, microcirculatory measurements and blood gas analysis were performed. Oxygen extraction increased significantly, which was accompanied by a significant drop in ScvO2 and a significant increase in CO2 gap. There was a significant negative correlation between oxygen extraction and ScvO2 and significant positive correlation between oxygen extraction and CO2 gap. Taking % and CO2 gap >6 mmHg values together to predict an oxygen extraction >30%, the positive predictive value is 100%; negative predicted value is 72%. Microcirculatory parameters, capillary perfusion rate and red blood cell velocity, decreased significantly over time. Similar changes were not observed in the sham group. Our data suggest that % and CO2 gap >6 mmHg can be complementary tools in detecting hypovolemia-caused imbalance of oxygen extraction.