Activated Protein C to Treat Acute Lung Injuries

BACKGROUND: The hypothesis that procoagulant and inflammatory mechanisms may have a dual role in tissue injury was tested in the phase III clinical trial of recombinant Xigris for severe sepsis (Bernard, 2001). There was a significant reduction in mortality from 30% to 24% in patients treated with Xigris. However, there is no information on the effect of Xigris on patients with sepsis and co-existing ALI. Because Xigris is known to have both anti-coagulant and anti-inflammatory properties, it is plausible that it may be effective at treating patients with ALI from pulmonary and non-pulmonary infectious causes. There is also a good rationale for the hypothesis that Xigris may be effective at treating ALI from non-infectious causes. In experimental lung injury, from a non-infectious cause, such as hyperoxia or a like acid-lung injury, pro-coagulant mechanisms play a role in the pathogenesis of the ALI (Eitzman, 1996; Barazzone, 1996). Furthermore, research has shown that plasma-protein C deficiency occurs in almost all patients with ALI, and reduced Protein C levels are associated with a higher mortality and more non-pulmonary organ system dysfunction, even in patients with non-septic causes of ALI (Ware, 2003). Elevated levels of thrombomodulin, a product of endothelial injury, were measured in the plasma of all patients with ALI regardless of the clinical disorder associated with lung injury. The elevations of thrombomodulin were much higher in edema fluid than in plasma, suggesting that local activation and release of thrombomodulin had occurred, probably from both epithelial and endothelial sources from the lung, again supporting the hypothesis that a common pathway to lung injury may occur in both septic and non-septic causes of ALI. In addition, there is considerable evidence that the normal fibrinolytic mechanisms are impaired in the alveolar compartment in patients with ALI. Elevated levels of plasminogen-activator-inhbitor-1 (PAI-1) in the plasma of pulmonary edema fluid have a predictive value for identifying patients with ALI who are more likely to die than survive, regardless of the clinical risk factors that predisposes the development of ALI (Prabhakaran, 2003). Thus, this supports the rationale for testing Xigris as a treatment for patients with ALI, regardless of the clinical disorder associated with the cause of the lung injury. Since Xigris has both anti-coagulant and anti-inflammatory properties (Esmon, 2000; Grey, 1994), this treatment could reverse both the intravascular and the extravascular lung injuries and allow the lung epithelial and endothelial barriers to recover from a functional breakdown of both barriers. This study will evaluate the effects of the treatment of biochemical markers on alveolar epithelial injury. DESIGN NARRATIVE: Participants will be randomly assigned to receive either Xigris or saline placebo, to be administered continuously for 96 hours. Participants will be followed for 28 days, regardless of whether the drug is stopped for an adverse event, if the participant or physician decides to stop the drug, if the participant is discharged from the hospital with unassisted breathing, or until death.