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Critical Care Research and Practice
Volume 2012 (2012), Article ID 703196, 8 pages
http://dx.doi.org/10.1155/2012/703196
Clinical Study

Echocardiographic Measures of Diastolic Function Are Preload Dependent during Triggered Positive Pressure Ventilation: A Controlled Crossover Study in Healthy Subjects

1Department of Anaesthesiology and Intensive Care, Aarhus University Hospital, Skejby, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark
2Institute of Clinical Medicine, Aarhus University, 8000 Aarhus C, Denmark

Received 25 June 2012; Revised 23 August 2012; Accepted 27 August 2012

Academic Editor: Edward A. Abraham

Copyright © 2012 Peter Juhl-Olsen 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

Background. The use of echocardiography in intensive care settings impacts decision making. A prerequisite for the use of echocardiography is relative resistance to changes in volume status and levels of positive pressure ventilation (PPV). Studies on indices of diastolic function report conflicting results with regard to dependence on volume status. Evidence is scarce on PPV. Methods. Ten healthy subjects were exposed to 6 levels of positive end-expiratory pressure (PEEP) and pressure support (PS) following a baseline reading. All ventilator settings were performed at three positions: horizontal, reverse-Trendelenburg, and Trendelenburg. Echocardiography was performed throughout. Results. During spontaneous breathing, early diastolic transmitral velocity ( ) changed with positioning ( ), whereas early diastolic velocity of the mitral annulus ( ) was independent ( ). With PPV, and proved preload dependent ( ). Increases in PEEP, PS, or a combination influenced and in reverse-Trendelenburg- and horizontal positions, but not in the Trendelenburg position. Discussion. The change towards preload dependency of with PPV suggests that PPV increases myocardial preload sensitivity. The susceptibility of and to preload changes during PPV discourages their use in settings of volume shifts or during changes in ventilator settings. Conclusion. Positioning and PPV affect and .