Role of Heme-oxygenase (HO) and Nitric Oxide (NO) Pathway in Patients With Obstructive Sleep Apnea (OSA) and Pulmonary Hypertension (PH)

Research design: This is a controled prospective study. Methodology: Patients with newly diagnosed and untreated OSA with total apnea-hypopnea index (AHI) \>5/h, and control (AHI\ 35 mmHg or mean PA pressure\>25 mmHg. The investigators will recruit subjects with and without PH and OSA in three separate groups: 1. group one : OSA+ PH, 2. group two: normal individual with no OSA and no PH, 3. group three: OSA with no PH Pulmonary function test will be done to exclude patients with underlying lung disease. The inclusion criteria is: Age \>20, AHI \>5, AHI \ 35 mmHg OR Mean PA pressure\>25 mmHg, RVSP \< 35 mmHg OR Mean PA pressure \< 25 mmHg (as control). Subjects will be excluded if they had known peripheral vascular disease, liver disease, hemolytic anemia, inflammatory disease, active infection, or if they were pregnant, on therapy for OSA, on chronic steroid treatment, or younger than 20 years of age, patients with left heart failure (systolic or diastolic), patients are on PH medications including sildenafil, active smokers, COPD and asthma, active infection or inflammatory disease and collagen vascular disease. Nocturnal polysomnography will be performed and scored according to the American Academy of Sleep Medicine. Exhaled Carbon monoxide (CO) will be measured with a calibrated fuel cell type electrochemical device with sensor sensitivity of 1 ppm. The mean of three reproducible measurements will be recorded and corrected for ambient CO. Exhaled Nitric Oxide (NO) will be measured. At each testing session, at least three flow-regulated FENO measurements will be performed. The investigators will repeat 2D E