ALI and acute respiratory distress syndrome (ARDS) are characterized by an increased permeability of the alveolar-capillary barrier resulting in lung edema with protein-rich fluid, thus resulting in impairment of arterial oxygenation. ALI/ARDS is defined as a lung disease with acute onset, noncardiac, diffuse bilateral pulmonary infiltrates and a paO2/FiO2 ≤ 300 for ALI or a paO2/FiO2 ≤ 200 for ARDS. The ageadjusted incidence of ALI/ARDS is estimated with 86.2 per 100,000 person-years. Despite all innovations in intensive care medicine, the mortality of ARDS remains up to 40%.