Positive end-expiratory pressure and tidal volume in the acute respiratory distress syndrome - A continuous controversy

Acute lung injury/acute respiratory distress syndrome is a common condition encountered in the intensive care units. Mechanical ventilator is a life-saving tool for these patients, but it also can induce further unwished lung injury. The setting of the positive end-expiratory pressure(PEEP) and tidal volume is like a two-face sword. It can improve the oxygenation status, but on the other hand, it may also induce barotrauma, volutrauma and biotrauma. It was well-known that the lower tidal volume and higher PEEP may be helpful for patients with ARDS. But the same setting for different patients will induce opposite results. That means the safe area for each patient is not the same. To achieve the best setting for each patient is a challenge for the physicians. The concept of the "baby lung" help us to set the ventilator more safely and adequately.