The pathogenesis of ARDS appears to be from damage to the alveolar-capillary barrier, which is composed of the microvascular endothelium and the alveolar epithelium. This damage may occur from direct or indirect lung injury. The mechanism of injury to the alveolar capillary barrier appears to be through neutrophil-mediated injury, pro-inflammatory cytokines, ventilator-induced lung injury with alveolar over distention and abnormalities of the coagulation system. This results in blood clot formation in the microcirculation of the lung. Thrombolytics can dissolve blood clots and result in increased blood flow to the organs. This treatment may benefit ARDS patients, thus the purpose of this study.