In this project, the investigators aim to assess changes of physiological parameters obtained non-invasively through PPG and accelerometry signals between before and during LTOT (long-term oxygen therapy) and investigate if those changes are different in patients with worsening frailty and/or improving quality of life.

For this, they will record optical (PPG) and accelerometry data via a datalogger on 40 patients undergoing LTOT and assess the PPG-derived physiological signals.

Inclusion Criteria:

• Age ≥ 18-year-old, and
• Chronic respiratory disease including a) chronic obstructive pulmonary disease, b) interstitial lung disease, c) pulmonary hypertension, d) bronchiectasis, and
• Prescribed new LTOT due to a chronic respiratory disease with resting and/or exertional hypoxemia, and
• Able to speak/read/understand German or French, and
• Willing and able to understand and provide signed informed consent

Exclusion Criteria:

• Pregnant or lactating women, or
• Inability to follow the procedures/instructions of the study (e.g. due to language, psychological disorders, dementia, etc.), or
• Patients having a subordination link to the investigators, or
• Patients with isolated nocturnal oxygen therapy or LTOT prescription for a heart disease, sleep associated breathing disorder, neuromuscular disease or lung cancer, or
• Known participation in another human research project (ClinO/HRO) that may affect the objectives of this study.

Patients with a respiratory disease and newly prescribed LTOT