Background: Portable oxygen concentrators (POCs) featuring the latest integrated oxygen conserving devices (OCDs) provide greater patient accessibility and mobility during ambulation and travel. Recent POCs are compact, lightweight, battery-operated, and require no refill-time, thus meeting patients' clinical and lifestyle needs. There is, however, a lack of research on the clinical performance of the latest POCs that could help to determine their ability to maintain patients' oxygen saturations ≥ 90 % during exercise.

Aim: The purpose of this study is to compare the ability of three POCs, with maximum oxygen production capabilities of 950 to 3000 ml per minute, to maintain oxygen saturations ≥ 90 % in patients with chronic lung disease during exercise.

Method: Six minute walk tests (6-MWTs) will be administered in order to measure oxygen saturations by pulse oximetry (SpO2) in up to 20 patients with a diagnosis of either Chronic Obstructive Pulmonary Disease (COPD), or Pulmonary Fibrosis (PF) with documented exertional oxygen desaturations of ≤ 85% on room air. All participants will participate in 4 different 6-minute walk tests: the first will be a control walk performed with the participants' current oxygen system set at their prescribed exertional flow rate. Then, the participants will perform a walk test with each of the three POCs set at the units' maximum pulse dose setting. The order in which the participants use the POCs will be randomly assigned using a sequence generator.

Hypothesis: It is hypothesized that all three POCs will provide oxygen saturations ≥ 90 % during exercise in patients with chronic lung disease with moderate to severe exertional oxygen desaturation.

Participants will attend two study sessions. During the session 1 participants will perform a 6-minute walk test on room air oxygen to assess their suitability for the study. Only those participants with documented exertional oxygen desaturations of ≤ 85% as measured by pulse oximetry during this walk will be asked to return for the second session. During session 2 participants will perform a further four 6-minute walk tests spread over a morning and afternoon testing session. All all data for primary and secondary outcomes will be measured at session 2.

Inclusion Criteria:

• Existing diagnosis of chronic obstructive lung disease or pulmonary fibrosis
• completed the pulmonary rehabilitation program at The Ottawa Hospital Rehabilitation Centre between January 30th 2008 and March 31st 2011
• medically stable
• medical prescription for long term oxygen therapy
• 18 years or older

Exclusion Criteria:

• non-ambulatory
• not independent for activities of daily living
• not active in the community
• show limited improvement with any level of continuous oxygen flow rate
• require more than 6 litres per minute of oxygen on continuous flow during exertion
• experienced an exacerbation of their respiratory medical condition over the last 6 weeks, or have not fully recovered from a recent exacerbation
• have moderate to severe orthopaedic or neurological conditions limiting their ability to walk
• have any other impairments that could affect the consistency of the 6-minute walk test
• have severe co-morbid conditions
• are limited by their cardiac condition or have been diagnosed with a cardiac condition since completion of their pulmonary rehabilitation
• severe cognitive or memory deficit
• speak neither French nor English