Alveolar recruitment in acute respiratory distress syndrome: should we open the lung (no matter what) or may accept (part of) the lung closed?

The conceptual model of acute respiratory distress syndrome (ARDS) includes: (a) lung inflammation; (b) severe hypoxemia; (c) edema, hyaline membranes, and alveolar hemorrhage.Common denominator is the loss of aerated lung tissue due to alveolar collapse.To open collapsed alveoli has been, therefore, proposed to restore gas exchange [1] with interventions such as positive endexpiratory pressure (PEEP), recruitment maneuvers, and prone position [2].Moreover, loss of lung volume may contribute to ventilator-induced lung injury (VILI) [2].We will review the physiology of alveolar recruitment and address the implications of the "full recruitment" vs "partial recruitment" approaches (Fig. 1).