The Effects of Dexamethasone and Oxygen in Ventilated Adult Sheep with Early Phase Acute Respiratory Distress Syndrome Monique EngelRelana M. E. NowackiPim BodenLucy K. Reiss • Stefan UhligNiki L. ReynaertPoornima GopalEmiel F. M. Wouters • Coen H. M. P. WillemsNico KloosterboerTim G. A. M. Wolfs • Luc J. I. ZimmermannGijs D. VosBoris W. Kramer

Background Acute respiratory distress syndrome (ARDS) is a life-threating condition with high morbidity and mortality. Inflammation is the main factor in the pathogenesis of ARDS. Therefore systemic corticosteroids are a rational therapeutic approach, but the effect of corticosteroids is still unclear. In this study, we looked at the effects of corticosteroids in ventilated sheep with ARDS, induced by lung lavage. Methods We performed a prospective, randomised study in 64 ventilated sheep with ARDS, to evaluate the effect of corticosteroids and oxygen concentration on gas exchange and lung injury. Oxygenation index (OI) and ventilation efficacy index (VEI) were calculated to evaluate gas exchange. Lung injury was assessed by inflammatory response in broncho-alveolar lavage fluid (BALF) and plasma and histology of the lung. Results OI, VEI, lung inflammation, surfactant production, or lung histology was not influenced by corticosteroids. In the 100 % oxygen groups, OI was higher and total number of cells and disaturated phospholipids were lower in BALF. Conclusion Our study showed that corticosteroids did not influence inflammation in early phase ARDS and that hyperoxia aggravated lung injury which could not be modulated by dexamethasone in early phase ARDS.