Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 1 1 2015 10 03 27 33 EN Ata Mahmoodpoor Fellowship of Critical Care Medicine, Cardiovascular Research Center, Tabriz University of Medical Sciences, Tabriz, Iran Atabak Najafi Anesthesiology and Critical Care Department, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Reza Afhami Anesthesiology Department, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran. Mohammad Taghi Mortazavi Anesthesiology Department, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran. Sarvin Sanaie Lung and Tuberculosis Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. Afshin Iranpour Department of Anesthesiology and Intensive Care, UAE. Vahid Fattahi Anesthesiology Department, Faculty of Medicine, Tabriz, Iran. 2015 10 03 2015 10 03 Acute respiratory distress syndrome (ARDS) is a complex disorder of heterogeneous etiologies characterized by a consistent, recognizable pattern of lung injury and a potentially devastating form of acute inflammatory lung injury with a high short-term mortality rate and significant long-term consequences among survivors. Recently, the new definition of ARDS has been published, and this definition suggested severity-oriented respiratory treatment by introducing three levels of severity according to PaO2/FiO2 and positive end-expiratory pressure. Supportive care, principally with mechanical ventilation, remains the cornerstone of therapy from maintaining normal physiological parameters to avoiding ventilator-induced lung injury while providing adequate gas exchange. Basic elements of this strategy consist of avoiding lung overdistension by limiting tidal volumes and airway pressures, use of PEEP with or without lung recruitment maneuvers in patients with severe ARDS. This review focuses on changes in ARDS definition, epidemiology, clinical and basic research, and current and future directions in treatment. https://aacc.tums.ac.ir/index.php/aacc/article/view/24 https://aacc.tums.ac.ir/index.php/aacc/article/download/24/193