This study should also allow to specify the best parameters in respiratory functional explorations useful for the follow-up in COPD and to specify the relevance of functional indications other than the forced expiration volume at 1 second (FEV1) or the functional residual capacity (FRC) to estimate in a more relevant way the clinical improve with the increase of the therapeutic load (increase of posology, association of two bronchodilatators, addition of an anti-inflammatory drug, thus etc…) at already handled patients suffering from a persistent dyspnoea insufficiently relieved.