The primary endpoint in this study is the difference in the change in AaDO2 over the treatment course, between treatment and placebo groups. The secondary endpoints include partial pressure of arterial oxygen (paO2), exhaled NO, diffusion lung capacity for carbon monoxide (DLCO), cardiac output (CO), total peripheral resistance (TPR), pulmonary artery systolic pressure (PAP) (on echocardiogram), endotoxin levels, endothelin-1 (ET-1) levels, MELD score (model for end-stage liver disease) (based on creatinine, bilirubin and INR), baseline dyspnea index (BDI), transitional dyspnea index (TDI), and Chronic Respiratory Disease Questionnaire (CRQ).