Expiratory flow-limitation in mechanically ventilated patients: A risk for ventilator-induced lung injury?

Core Tip

Core tip: Expiratory flow limitation (EFL), the inability of expiratory flow to increase despite increasing driving pressure, is a common unrecognized occurrence during mechanical ventilation in a variety of intensive care unit conditions. It implies cyclic compression/decompression of the airways, is associated with intrinsic positive end-expiratory pressure (PEEPi) and inhomogeneous filling, and is often concomitant with cyclic recruitment/derecruitment. In acute respiratory distress syndrome, the development of abnormally high stresses is potentially injurious for the lung. External PEEP abolishes EFL and decreases ventilation and intrinsic PEEP heterogeneity, improving gas exchange. Moreover, external PEEP prevents cyclic airway collapse/reopening, possibly protecting the parenchyma from low lung volume ventilator-induced lung injury.