Pulmonary coagulopathy as a new target in lung injury--a review of available pre-clinical models.

Despite recent advances in supportive care, acute lung injury (ALI) and its more severe form acute respiratory distress syndrome (ARDS) are clinical entities with high morbidity and high mortality. In systemic inflammation, like sepsis, uncontrolled host defense can lead to systemic activation of coagulation on the one hand, and attenuation of fibrinolysis on the other. In ALI/ARDS similar but local disturbances in fibrin turnover occur, leading to excessive alveolar fibrin deposition compromising pulmonary integrity and function. Therapies in patients with sepsis have specifically focused on coagulation disturbances. Evidence from preclinical and clinical investigations suggests pharmacologically targeting pulmonary "coagulopathy" could be of benefit to patients with ALI/ARDS as well. Recent animal studies have demonstrated that administration of heparins, activated protein C (APC), Antithrombin (AT), Tissue factor-Factor VIIa (TF-FVIIa) pathway inhibitors, plasminogen activators (PA) and thrombomodulin (TM) can attenuate pulmonary coagulopathy and reduce lung injury and/or improve oxygenation. Some of these studies have also shown anti-inflammatory effects of treatment targeting at coagulation. To date there are no published studies that have specifically studied the effects of anticoagulants on ALI/ARDS however there are on-going clinical trials. A solid base has to be provided by preclinical studies to justify clinical studies on new pharmacologic therapies for ALI/ARDS. In this systematic literature review we give an overview of the models for ALI/ARDS that have been used so far on the topic of pulmonary coagulopathy and focus on the pharmacological interventions that have been evaluated with these models. Finally, the applicability of the different approaches for future research on this subject will be discussed.