Treprostinil Sodium Inhalation for Patients At High Risk for ARDS

ARDS is defined by acute hypoxemia, respiratory failure and the presence of bilateral lung infiltrates. ARDS is a syndrome of inflammation and increased permeability that may coexist with left atrial or pulmonary capillary hypertension. Several recent trials in ARDS / ALI (Acute Lung Injury) have generated interest in the use of Prostacyclin (PGI2) and prostacyclin analogs in improving oxygenation in ARDS / ALI. PGI2 is an arachidonic acid metabolite naturally produced in the lung by endothelial cells, dendritic cells, smooth muscle cells and fibroblasts. PGI2 is a potent selective pulmonary vasodilator and inhibitor of platelet aggregation. The cellular effects include smooth muscle relaxation, inhibition of cell migration, decreased dextran permeability in epithelial cell cultures in vitro, decreased high tidal volume mechanical ventilation injury in mice and inhibition of fibroblast adhesion and differentiation. PGI2 has broad anti-inflammatory activity, inhibiting the production of Tumor necrosis factor alpha (TNFα), interleukin 1 beta (IL-1β), interleukin 6 (IL-6) and granulocyte macrophage colony-stimulating factor (GMCSF) in human alveolar macrophages. The study objectives are: 1. To assess the feasibility of a randomized trial of treprostinil inhalation in patients with acute hypoxemic respiratory failure not requiring positive pressure ventilation. 2. To evaluate the tolerability of inhaled treprostinil for patients with acute hypoxemic respiratory failure 3. To assess the effect of treprostinil inhalation on oxygenation in patients with acute hypoxic respiratory failure with, or at risk for, development of ARDS 4. To assess the effect of treprostinil inhalation on various biomarkers thought to be related to the pathogenesis and/or clinical course of ARDS. The hypothesis is: Treprostinil solution for inhalation (TYVASO) is safe and will improve oxygenation and other secondary outcomes related to acute hypoxemic respiratory failure and positive pressure ventilation initiation and duration, as well as exhibit effects on ARDS-related pro-inflammatory and pro-fibrotic biomarkers.