Exercise Performance on Ambient Air vs. Low-Flow Liquid Oxygen Therapy in Chronic Lung Diseases

The investigators aim to study the effect of liquid oxygen therapy (4l/min, nasal) )in Swiss residents with pulmonary vascular diseases (PVD) defined as pulmonary arterial hypertension (PAH) or chronic thromboembolic pulmonary hypertension (CTEPH).

Inclusion Criteria: * Minimum 18 years of age * Written informed consent * Patients with diagnosed pulmonary arterial hypertension (PAH), distal chronic thromboembolic pulmonary hypertension (CTEPH), chronic obstructive pulmonary disease (COPD) with emphysema, COPD without emphysema, or interstitial lung disease * Former desaturation under exercise defined as SpO2-decrease \>3% * Treated with a stable drug therapy (with no changes for at least 14 days prior to screening) Exclusion Criteria: * Severe hypoxemia needing supplemental oxygen therapy defined as PaO2 \< 6.9 kPa * Inability or contraindications to undergo the investigated intervention * Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, walk disability etc.