Endotoxemia increases relative perfusion to dorsal-caudal lung regions.
Gerbino, Anthony J., William A. Altemeier, Carmel Schimmel, and Robb W. Glenny.
Departments of 1Medicine and 2Physiology and Biophysics, University of Washington, Seattle, Washington 98195
APStracts 8:0021A, 2001.
Changes in the spatial distribution of perfusion during acute lung injury and their impact on gas exchange are poorly understood. We tested whether endotoxemia caused topographical differences in perfusion and whether these differences caused meaningful changes in regional ventilation-to-perfusion ratios and gas exchange. Regional ventilation and perfusion were measured in anesthetized, mechanically ventilated pigs in the prone position before and during endotoxemia with the use of aerosolized and intravenous fluorescent microspheres. On average, relative perfusion halved in ventral and cranial lung regions, doubled in caudal lung regions, and increased 1.5-fold in dorsal lung regions during endotoxemia. In contrast, there were no topographical differences in perfusion before endotoxemia and no topographical differences in ventilation at any time point. Consequently, endotoxemia increased regional ventilation-to-perfusion ratio in the caudal-to-cranial and dorsal-to-ventral directions, resulting in end-capillary "po2" values that were significantly lower in dorsal-caudal than ventral-cranial regions. We conclude that there are topographical differences in the pulmonary vascular response to endotoxin that may have important consequences for gas exchange in acute lung injury.
Received 15 September 2000; accepted in final form 8 November 2000
APS Manuscript Number A932-0.
Article publication pending J Appl Physiol
ISSN 1080-4757 Copyright 2001 The American Physiological Society.
Published in APStracts on 29 January 2001