In the literature, the effects of acute oxygen administration on exercise tolerance and related symptoms have often appeared to be contradictory. Some investigations have reported benefits from acute oxygen supply during exertion, including increased exercise performance, reduced dyspnea, and better cardiorespiratory adaptations, whereas other studies have reported no improvement. Recently, we advanced then the hypothesis that some patients would be non-responders and even worsen under oxygen treatment. The preliminary results confirmed our hypothesis since we demonstrated that while 56% of the patients were improved with supplemental oxygen, 16% were non-responders and 28% were negative-responders (decreased performance and increased dyspnea during endurance exercise with supplemental oxygen). However, this was a pilot study offering preliminary insights and tentative conclusions that must be confirmed in a larger case series.

The aims of this retrospective study was :

1. To confirm on cohorte and with clinical test (the 6-minute walking test - 6WT) the deleterious responses to acute oxygen supplementation in LTOT (long terme oxygenotherapy treatment) and non-LTOT patients who exhibit exercise desaturation.
2. To identify the predictive factors among the clinical data (i.e., anthropometric, spirometric and gazometric data) and/or functional data recorded during rehabilitation program

During this study, a retrospective data collection will be carried out using the informations contained in the medical folders of patients admitted in our centers for pulmonary rehabiliation program.

We will select patients who meet the following criteria:

A) patients having two 6WT early in their program B) who desaturate (SpO2 <90% for 3 consecutive min) during the first 6WT and who will have been properly corrected with a supply of oxygen during the second walk test.

The analyzed parameters will be distance and dyspnea during the tests

Inclusion Criteria:

• Obstructive airflow limitation defined by FEV1/CVF < 70% and FEV1 < 80 %
• Patients with or without long terme oxygenotherapy
• Patients exhibited during the first test, an exercise-induced desaturation, defined by SaO2 < 90% for 3 consecutive minutes during the 6-minute walking test in the air condition for non-LTOT or with the flow normally recommended during exercise for LTOT patients (i.e., flow rate of rest + 1L/min)
• Patients with no desaturation during the test with oxygen supply

Exclusion Criteria:

Patients with chronic obstructive pulmonary disease and exhibiting an exercise-induced desaturation during six minute walkink test.