Bronchoalveolar coagulation and fibrinolysis in endotoxemia and pneumonia

Objectives: To review the involvement of coagulation and fibrinolysis in the pathogenesis of acute lung injury during severe infection. To review the cross-talk between coagulation and inflammation that may affect this response. Data Sources: Published articles on experimental and clinical studies of coagulation and fibrinolysis during infection, inflammation, acute lung injury, and evolving acute respiratory distress syndrome. Conclusions: Fibrin deposition is an important feature of pulmonary infection or severe inflammation. The mechanisms that contribute to this fibrin deposition are bronchoalveolar tissue factor-mediated thrombin generation and localized depression of urokinase plasminogen activator-mediated fibrinolysis, caused by the increase of plasminogen activator inhibitors. These effects on pulmonary coagulation and fibrinolysis are regulated by various proinflammatory cytokines. Rather than being a unidirectional relationship, the interaction between inflammation and coagulation involves significant cross-talk. Coagulation and fibrinolytic proteins may have an additional role beyond fibrin turnover and inflammation, e.g., in mechanisms mediating cell recruitment and migration.