Altitude Related Illness In Patients With Respiratory Disease

Inclusion Criteria: * Chronic obstructive pulmonary disease (COPD), GOLD grade 1-2 * Living at low altitude (\<800m) Exclusion Criteria: * COPD exacerbation * severe COPD, GOLD grade 3 or 4 * arterial oxygen saturation \<92% at low altitude (\<800 m) * Diabetes, uncontrolled cardiovascular disease such as systemic arterial hypertension, coronary artery disease; previous stroke; pneumothorax in the last 2 months, untreated or symptomatic peptic ulcer disease, glaucoma, obstructive sleep apnea. * Internal, neurologic or psychiatric disease that interfere with protocol compliance including current heavy smoking (\>20 cigarettes per day). * pregnant or nursing patients