ABSTRACT
Definitions Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) constitute the major reason for acute respiratory failure in the surgical population, including trauma. The AmericanEuropean Consensus Committee on ARDS in 1994 defined ALI as a syndrome of pulmonary inflammation and increased capillary permeability that is associated with a constellation of clinical, radiological, and physiological abnormalities that cannot be explained by, but may coexist with, left atrial failure or pulmonary capillary hypertension.(1) The clinical criteria for ALI are acute respiratory failure with a PaO2/FiO2 ratio < 300 mmHg, bilateral lung infiltrates visible on CXR, and a pulmonary artery occlusion pressure (PAOP) < 18 mmHg or no clinical evidence of increased left atrial pressure. ARDS is a more severe form of ALI representing the advanced manifestation of the loss of functional and structural integrity of the lungs. It shares the same clinical criteria with ALI except that the ratio of PaO2/FiO2 is < 200 mmHg, regardless of the positive end-expiratory pressure (PEEP) level used on the mechanical ventilator.
