Acute Respiratory Distress Syndrom is associated to lung and systemic inflammation, which could be worsened by mechanical ventilation.This included a proteasis - antiproteasis imbalance which could participate to a fibrosis process.

Low tidal-volume ventilation (6 mL/kg) with low plateau pressure (< 30 cm H2O) has been proved to decrease mortality when compared with more conventionnal high-volume (12 mL/kg) ventilation.Moreover, this lung-protective approach decrease lung annd systemic inflammation.

Using recruitment maneuvers (i.e. the application during a short time of high pressures with the intention to re-open the lung, followed by an increase of PEEP-level to keep the lung open, in an attempt to decrease the alveolar shear-stress) has been proposed to improve oxygen and to reduce bio-trauma.

However, the effect of such maneuvers on the inflammatory response and on the evolution of ARDS remains unknown.

Therefore we have planned a randomized, monocentric, controlled trial consisting of the comparison of two approaches of mechanical ventilation in Acute Lung Injury. This trial will include 30 hemodynamically stable patients fulfilling the ALI or ARDS criteria defined by the US and European Consensus Conference.

They will be randomized in two groups: standard low-volume ventilation vs. recruitment maneuvers.

The main objective of our study is to compare both ventilatory strategies in termes of lung and systemic inflammation.

The primary outcome measures will be the proteasis activity as measured in broncho alveolar fluid (BAL) and pro- and antiinflammatory cytokines activity as measured in the BAL and in the blood. Two samples (BAL and blood) will be obtained at a 48-72 hours interval. In the recruitment maneuver group, the first BAL will be obtained two hours before the maneuver.

Secondary outcome measures will be gaz exchange, respiratory mechanics, systemic hemodynamics and visceral dysfunction scores.