Aim of this study is to investigate the effects of an Oxymizer pendant nasal cannula in hypoxemic patients with idiopathic pulmonary fibrosis during walking.

Patients will be recruited during an inpatient pulmonary rehabilitation program. They will perform three shuttle walk tests on three consecutive days (see below). While performing those tests, the patient's prescribed oxygen flow rate is applicated either through the conventional nasal cannula (CNC) or the Oxymizer.On the first day, patients perform an incremental shuttle walk test to determine maximum walking speed using a conventional nasal cannula.

On two consecutive days, patients will perform two endurance shuttle walk tests at 85% of the maximum incremental shuttle walk test speed. Supplemental oxygen will be provided via nasal cannula at the prescribed oxygen flow rate. Patients will be randomly assigned to perform one test with the Oxymizer and the other one with a conventional nasal cannula.

Inclusion Criteria:

• firmed diagnosis of idiopathic pulmonary fibrosis
• indication for supplemental oxygen therapy during exercise
• referred to an inpatient rehabilitation program at the Schön Klinik Berchtesgadener Land

Exclusion Criteria:

• cardiovascular diseases that influence the patient's physical performance
• orthopedic comorbidities that prevent the patient from performing an incremental or endurance shuttle walk test
• carbon dioxide pressure above 45 mmHg at rest and ambient air