Intubated patients with the acute respiratory distress syndrome (ARDS) are usually treated with protective ventilation limiting plateau pressure below 30 centimeter of water (cmH2O) and, if possible, a driving pressure under 15 cmH2O. However, these airway pressures might not reflect the actual pressure applied to the lung. Transpulmonary pressure is the difference between airway pressure and pleural pressure, the latter is estimated by the esophageal pressure, and so it better reflects the ventilatory induced lung injury (VILI). One of the consequences of the VILI is a increase of pulmonary edema and it could be estimated by the extravascular lung water, obtained by trans-pulmonary thermodilution. So it could exist a link between the driving trans-pulmonary pressure and the extravascular lung water.