Effects of SEvoflurane on Gas Exchange and Inflammation in Patients With ARDS (SEGA Study)

BACKGROUND: Acute respiratory distress syndrome (ARDS) is characterized by hypoxemic respiratory failure that can be lethal in 30 to 60% of patients. Its pathophysiological landmark, diffuse alveolar damage, is associated with alveolar inflammation, epithelial injury and alveolar fluid clairance impairment. Several preclinical studies have shown that early sevoflurane inhalation improves gas exchange, reduces alveolar edema and attenuates pulmonary and systemic inflammation in experimental models of ARDS. To date, no clinical trial has assessed the effects of early sevoflurane inhalation in ARDS patients. DESIGN NARRATIVE: The purpose of this prospective, randomized, controlled study is to evaluate the effects of a 48-hour sevoflurane inhalation strategy on gas exchange and both systemic and pulmonary inflammation in the early phase of ARDS. After inclusion, ICU patients with moderate to severe ARDS (according to the Berlin definition of ARDS criteria; JAMA 2010) will be randomized into two groups : * a "conventional group", in which intravenous sedation with midazolam will be administered * a "sevoflurane group", in which patients will inhale sevoflurane during a 48 hour-period, through dedicated devices Arterial blood gases will be analyze before randomization and at 24, 48, 72, 96, and 120 hours. Bronchoalveolar lavages (BAL) and blood samples will be assessed before randomization and at 48 hours, in order to measure tumor necrosis factor-alpha (TNFα), interleukin (IL)-1β, IL-6, IL-8 and sRAGE levels. Duplicate assays will be performed with Multiplex (TNFα/interleukins) or ELISA (sRAGE). During the 48-hour treatment period, bispectral index (BIS®) values ranging from 40 to 50 will be targeted and neuromuscular blocking agents (cisatracurium) will be administered in both groups. Protective ventilation strategies will be applied, as well as other guidelines or recommendations on the management of ICU patients with ARDS.