The Role of Bronchoalveolar Hemostasis in the Pathogenesis of Acute Lung Injury

ABSTRACT

Disturbed alveolar fibrin turnover is intrinsic to acute lung injury/acute respiratory distress syndrome (ALI/ARDS) and pneumonia and is important to its pathogenesis. Recent studies also suggest disturbed alveolar fibrin turnover to be a feature of ventilator-induced lung injury (VILI). The mechanisms that contribute to alveolar coagulopathy are localized tissue factor–mediated thrombin generation, impaired activity of natural coagulation inhibitors, and depression of bronchoalveolar urokinase plasminogen activator–mediated fibrinolysis, caused by the increase of plasminogen activator inhibitors. Administration of anticoagulant agents (including activated protein C, antithrombin, tissue factor–factor VIIa pathway inhibitors, and heparin) and profibrinolytic agents (including plasminogen activators) attenuate pulmonary coagulopathy. Several preclinical studies show additional anti-inflammatory effects of these therapies in ALI/ARDS and pneumonia. In this article, we review the involvement of coagulation and fibrinolysis in the pathogenesis of ALI/ARDS pneumonia and VILI and the potential of anticoagulant and profibrinolytic strategies to reverse pulmonary coagulopathy and pulmonary inflammatory responses.

KEYWORDS

Acute lung injury - acute respiratory distress syndrome - coagulation - fibrinolysis

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