Diagnosis and management of acute lung injury

Severe acute lung injury, also known as the adult respiratory distress syndrome (ARDS), is a dynamic and explosive clinical syndrome which exacts a mortality of approximately 50%. The criteria for the diagnosis of severe acute lung injury include five principal elements: hypoxemia despite high concentrations of supplemental oxygen, diffuse pulmonary infiltrates on chest radiographs, decreased lung compliance, appropriate antecedent history, and the absence of congestive heart failure. Identifying an appropriate antecedent history requires consideration of a diverse group of etiologies which may injure alveolar structures via either the air-lung or blood-lung interface. The management of patients with acute lung injury should be approached with four principal goals: (1) cardiopulmonary resuscitation and stabilization; (2) rapid identification and elimination of the cause of lung injury; (3) achieving adequate tissue oxygen delivery and support of other end-organs; and (4) prevention, recognition, and aggressive treatment of any complications that develop during the course of therapy. Recent observations have suggested that conventional methods of positive-pressure ventilation may indirectly injure alveolar tissue, thereby perpetuating lung injury. Furthermore, the optimal use of fluid and hemodynamic support remains controversial. Thus, controlled clinical trials are necessary to develop oxygenation, ventilatory, and hemodynamic support strategies which optimize recovery and minimize further injury and to define the role of newer pharmacologic agents in the prevention and treatment of acute lung injury.