Effects of Supplemental Oxygen Delivery Via Demand Versus Continuous Flow in Hypoxemic COPD Patients

Oxygen supplementation has been proven to be effective in hypoxemic COPD patients by increasing oxygenation and reducing dyspnea. In clinical practice there are three common oxygen delivery systems used: continuous oxygen flow (CF), demand oxygen delivery with liquid oxygen (DDL) and demand oxgen delivery with portable oxygen concentrator (DDC). The CF involves considerable wastage of oxygen because oxygen is supplied during in- and exhalation. Demand oxygen delivery saves oxygen and results in a comparable oxygen saturation at rest in COPD patients. However, it is unknown, if oxygen supplementation via demand oxygen delivery is also sufficient during exercise in hypoxemic COPD patients. In addition, it has to be considered that the lower weight of demand oxygen delivery system might enable patients for higher physical activity level and mobility in daily life. The effects of These three oxygen delivery systems shall be investigated by a randomized, controlled cross-over Trial. Every patient has to perform an Incremental Shuttle Walk Test and three Endurance Shuttle Walk Tests with three different oxygen supplementation (via CF, DDL or DDK) in randomized order.

The Principal Investigator will inform each patient about procedure, content and measurements of the study. It is obligatory that each patient participating in the study gives a written informed consent. Following an initial incremental shuttle walk test (ISWT) in order to determine the individual maximum capacity, patients will perform three endurance shuttle walk tests (ESWT) at 85% of the maximal pace. In randomized order, patients will complete one ESWT on CF, one on DDL (liquid oxygen) and one on DDC (portable oxygen concentrator). The time between the three ESWTs will be 24 hours in order to give enough time for regeneration. All patients will use the same oxygen devices (CF: Companion 1000 (CE 0050), Chart Industries, Inc. Garfield Heights, Ohio, USA; DD \[liquid oxygen\]: Caire Spirit 300 (CE 0029), Chart Industries, Inc. Garfield Heights, Ohio, USA), DD \[portable concentrator\]: Inogen G2, California, USA) and will carry the oxygen device in a backpack. Continuous oxygen flow in liter per minute will be compared to the level of demand delivery (e.g.: 2 l/min CF will be compared to DD level 2).