Acute Lung Injury (ALI) is a syndrome consisting of acute hypoxemic respiratory failure with bilateral pulmonary infiltrates that is associated with both pulmonary and nonpulmonary risk factors (eg. sepsis, trauma) and that is not due primarily to left atrial hypertension. Although a distinction between ALI and a more severe subtype (termed acute respiratory distress syndrome (ARDS) has been made, the pathogenesis, risk factors, and outcomes appear to be similar and for the purposes of this protocol, the term acute lung injury [ALI] will be used to encompass both entities. Accepted consensus definitions of ALI have been introduced and are now widely used for laboratory and clinical investigations of ALI. Acute Lung Injury (ALI) is defined as: