Oxygen therapy is a cornerstone in treating patients with severe chronic obstructive pulmonary disease. Usually, oxygen supplementation is delivered using constant-flow rates. Varying oxygenation levels may occur throughout patients´ changing activity. There is some evidence available that an auto-regulating oxygen flow system (FreeO2), which adjusts the oxygen flow automatically to prevent desoxygenation could be beneficial in comparison to a constant oxygen dose of 2 liter/min during walking. However, these possible benefits are unknown if the FreeO2 is compared to a constant oxygen dose according to the individual prescription. Therefore, the primary aim of this study is to investigate the effects of auto-regulated oxygen flow rates compared to constant oxygen flow rates as prescribed according to international guidelines on walking capacity in patients with COPD.

Rationale:

Hypoxemia is frequently observed in COPD and thus can negatively impact exercise tolerance. Supplemental oxygen or long-term oxygen therapy is recommended to ensure that the patient is still able to manage his daily life. Usually, oxygen supplementation is delivered using constant flow rates during day- and nighttime or as needed. However, studies have shown, that auto-regulated oxygen flow systems (FreeO2) may enhance the patients endurance, lower the time in severe hypoxemia and increase the time spent within the SpO2 target range.

Aim of this study is to investigate the effects off an auto-regulated oxygen flow system in hypoxemic COPD patients on the patient´s endurance, the oxygen saturation, the pCO2 blood level as well as on heart rate and breathing frequency compared to the effects off the prescribed constant flow (according to the British Thoracic Society Guidelines for Home Oxygen Use in Adults) during an endurance shuttle walk test (ESWT). Additionally, patients experience, e.g. comfort and Preference of the Oxygen-delivery System will be documented.

Design:

This study is a randomized, controlled cross-over trial. Following an initial incremental shuttle walk test (ISWT) in order to determine the participants individual maximal walking capacity, the participant will perform 2 endurance shuttle walk tests (ESWT) at 85% of the maximal walking rate. In randomized order, the participants will perform one ESWT with constant flow as prescribed and one ESWT with the auto-regulated oxygen flow system.

Inclusion Criteria:

• GOLD III/ IV
• Hypoxemia (PaO2<55 mmHg) under roomair conditions (rest or during exercise) or SpO2 <88% during exercise
• established Long-term oxygen therapy or given indication for a Long-term oxygen therapy
• Age: 40 to 80 years
• Participation in an inpatient pulmonary rehabilitation program (Schoen Klinik BGL, Germany)
• Written informed consent

Exclusion Criteria:

• Acute Exacerbation of COPD
• Clinical signs of any acute cardiac comorbidity
• Not able to walk

The Partcipant and Investigator is blinded to the type of oxygen supply (constant flow or auto-regulated flow).