High Altitude (HA) Residents With High Altitude Pulmonary Hypertension (HAPH), Pulmonary Artery Pressure (PAP) Assessed at HA (3200 m) vs LA (760 m)

Exclusion Criteria

• •Highlanders who cannot follow the study investigations,
• •Patients with moderate to severe concomitant lung disease (FEV1\<70% or forced vital capacity \<70%), severe parenchymal lung disease, heavy smoking \>20 cigarettes/day or \>20 pack-years.
• •Coexistent unstable systemic hypertension or coronary artery disease that required adjustment of medication within the last 2 months
• •Regular use of medication that affects control of breathing (benzodiazepines, opioids, acetazolamide)