Determinants and Prevention of Ventilator-Induced Lung Injury.

Ventilator-induced lung injury develops from interactions between the lung parenchyma and applied mechanical power. In acute respiratory distress syndrome, the lung is smaller size with an inhomogeneous structure. The same mechanical force applied on a reduced parenchyma would produce volutrauma; the concentration of mechanical forces at inhomogeneous interfaces produces atelectrauma. Higher positive end-expiratory pressures favor volutrauma and reduce atelectrauma; lower values do the opposite. Volutrauma and atelectrauma harms and benefits, however, seem to be equivalent at 5 to 15 cm HO. At values greater than 15 cm HO, the risk of damage outweighs the benefits of major atelectrauma prevention.