This study evaluates whether structured self-monitoring (SSM) by a symptom checklist in combination with a pulse oximeter worn at the wrist allows lowlanders with COPD to accurately identify whether or not they will experience an altitude-related illness during altitude travel.

This study evaluates whether structured self-monitoring (SSM) by a symptom checklist in combination with a pulse oximeter worn at the wrist allows lowlanders with COPD to accurately identify whether or not they will experience an altitude-related illness during altitude travel. After baseline evaluation at 760 m, patients will travel by bus within 3-5 h to the Tuja Ashu high altitude clinic at 3'100 m and stay there for 2 days. During this period, participants will perform SSM. They are instructed to report to study personnel if they fulfill predefined criteria for impeding altitude-related illness.

A planned interim analysis will be performed after the first year of the study or after completion of study by 80 participants, whichever comes first to allow any necessary adaptations of the sample size or terminate the study early for futility or high accuracy of the index test.

Inclusion criteria

• Male and female patients, age 18-75 yrs.
• COPD diagnosed according to GOLD, FEV1 40-80% predicted, SpO2 ≥92%, PaCO2 <6 kPa at 760 m.
• Born, raised and currently living at low altitude (<800 m).
• Written informed consent.

Exclusion criteria

• COPD exacerbation, very severe COPD with hypoxemia at low altitude (FEV1 <40% predicted; oxygen saturation on room air <92% or hypercapnia at 760 m).
• Other lung disease or disorder of control of breathing
• Comorbidities such as uncontrolled cardiovascular disease, i.e., unstable systemic arterial hypertension, coronary artery disease; previous stroke, internal, neurologic, rheumatologic or psychiatric disease that interfere with protocol compliance including current heavy smoking (>20 cigarettes per day)

Patients with COPD, FEV1 40-80% predicted living at low altitude.