inclusion criteria: one or both the following points: need for 24-hour oxygen therapy to have a resting spo2 of at least 94% or exercise-induced desaturation, defined as a reduction of at least 3% of spo2 mean measured during the 6-minute test (6mwt) compared to spo2 measured at rest reduced tolerance to effort highlighted by the 6mwt with a value of the meters travelled less than 70 percent of the predicted one

inclusion criteria: one or both the following points: need for 24-hour oxygen therapy to have a resting spo2 of at least 94% or exercise-induced desaturation, defined as a reduction of at least 3% of spo2 mean measured during the 6-minute test (6mwt) compared to spo2 measured at rest reduced tolerance to effort highlighted by the 6mwt with a value of the meters travelled less than 70 percent of the predicted one

inclusion criteria: - one or both the following points: 1. need for 24-hour oxygen therapy to have a resting spo2 of at least 94% or exercise-induced desaturation, defined as a reduction of at least 3% of spo2 mean measured during the 6-minute test (6mwt) compared to spo2 measured at rest 2. reduced tolerance to effort highlighted by the 6mwt with a value of the meters travelled less than 70 percent of the predicted one

inclusion criteria: - one or both the following points: 1. need for 24-hour oxygen therapy to have a resting spo2 of at least 94% or exercise-induced desaturation, defined as a reduction of at least 3% of spo2 mean measured during the 6-minute test (6mwt) compared to spo2 measured at rest 2. reduced tolerance to effort highlighted by the 6mwt with a value of the meters travelled less than 70 percent of the predicted one