Exercise Performance on Ambient Air vs. Low-Flow Liquid Oxygen Therapy in Pulmonary Vascular Disease (PVD)

Participants with PVD diagnosed with precapillary PH with right heart catheterization and classified to groups 1 and 4 (PAH or CTEPH) who live in Switzerland will have 6-minute walk distance (6MWD) test with and without nasal liquid oxygen therapy (LOX) approximately 4l/min via nasal cannula according to a randomized cross-over design.

The trial aims to test that the 6MWD with LOX is inferior to a 6MWD in the same participant under ambient air.

• 6-minute walk distance (6MWD) test on ambient conditions (Other): 6-minute walk distance (6MWD) test will be performed on ambient air according to clinical standards
• 6-minute walk distance (6MWD) test with supplemental oxygen (LOX) (Other): 6-minute walk test(6MWT) test will be performed according to clinical standards with supplemental liquid oxygen therapy (LOX, approximately 4l/min, nasal)

Primary outcomes

• 6-minute walk distance (6MWD) with supplemental oxygen therapy (SOT) vs. ambient air [Distance will be measured at the end of 6 minutes from the 6MWT]: Change in 6MWD in meter between supplemental liquid oxygen therapy (LOX) via nasal cannula vs. ambient air

Secondary outcomes

• SpO2 at rest and peak 6MWD with supplemental liquid oxygen therapy (LOX) vs. ambient air [6 minutes]: Change of the arterial oxygen saturation by pulse oximeter (SpO2) at rest and at peak 6MWD with LOX approximately 4l /min vs. ambient air
• Heart rate at rest and peak 6MWD with supplemental liquid oxygen therapy (LOX) vs. ambient air [6 minutes]: Change of heart rate (bpm) at rest and at peak 6MWD with LOX vs. ambient air
• Borg dyspnea at rest and peak 6MWT with supplemental liquid oxygen therapy (LOX) s. ambient air [6 minutes]: Change of Borg dyspnea scale (CR10, 0-10 where 10 is the worst dyspnea) at rest and at peak 6MWD with LOX vs. ambient air
• Borg leg fatigue scale at rest and peak 6MWD with supplemental liquid oxygen therapy (LOX) vs. ambient air [6 minutes]: Change of Borg leg fatigue scale (CR10, 0-10 where 10 is the strongest led fatugue) at rest and at peak 6MWT with LOX vs. ambient air
• Blood pressure at rest and peak 6MWD with supplemental liquid oxygen therapy (LOX) vs. ambient air [6 minutes]: Change of blood pressure (mmHg) at rest and at peak 6MWD with LOX vs. ambient air

Sex: All, ages: 18 Years to any

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.

• Silvia Ulrich, Prof. Dr. med., Principal investigator, University Hospital Zurich, Department of Pulmonology