How to recruit the injured lung.

Alveolar recruitment represents a challenging issue in ALI/ARDS patients. Multiple techniques have been compared: intermittent sighs, sustained application of high pressure in single or multiple episodes, use of progressive higher PEEP and lower tidal volumes (VT), with a fixed upper limit, and increase of PEEP, without modifying VT. Encouraging results emerge also from the use of prone position, that allows a better distribution of transalveolar forces, thus reducing ventilator induced lung injury. Moreover the use of spontaneous breathing, such as Bi-PAP mode, enhances re-expansion of dorsal lung regions and intriguing, but still uncertain results derive from biological variability of ventilatory pattern. Finally, a pressure-volume (P-V) curve of respiratory system can be employed to set appropriate PEEP level, to prevent collapse of new recruited alveoli. To monitor alveolar recruitment we can use P-V curves, continuous intra-arterial gas analysis, electrical impedence tomography. It is worth noting that different recruiting techniques are characterised by different efficacy and adverse hemodynamic effects. In conclusion, The "Open lung" approach should not be applied to every patient; it should be reserved to restore lung volume if deterioration occurs, by means of adequate PEEP level and lowest acceptable FiO(2).