Influence of lung mechanical properties and alveolar architecture on the pathogenesis of ischemia-reperfusion injury.

We tested the hypothesis that lung preservation techniques disarrange lung architecture, increase pulmonary impedance and lead to ischemia-reperfusion injury, which can be prevented by re-establishment of optimal lung geometry. In the first phase, fresh, cold ischemic, preserved lungs insufflated to total lung capacity (TLC) and preserved lungs ventilated with tidal volume prior to reperfusion were submitted to a 60-min ex-vivo reperfusion to evaluate the gas exchange, pulmonary hemodynamic and lung mechanics' properties. In the second phase, we evaluated the mechanical properties of lungs submitted to the same conditions of the first phase. Cold ischemic lungs developed fulminant edema during the first 15 min of ex-vivo reperfusion, whereas gas exchange, hemodynamic and mechanic properties of lungs insufflated to TLC and ventilated during 10 min prior to reperfusion were similar to fresh lungs. After the pulmonary vascular flush pulmonary impedance and alveolar collapsed area increased significantly. The insufflation to TLC and 10 min of tidal ventilation reduced the lung impedance and the percentage of alveolar collapsed area. Lung preservation techniques disarrange alveolar architecture, which lead to ischemia-reperfusion injury; recruitment maneuvers decrease the pulmonary inhomogeneities and protect the lungs against the ischemia-reperfusion injury.