Evaluation of high intensity NIMV in terms of physiological parameters has been performed in short-term studies in COPD patients. However, the support pressure levels used in exacerbated patients seem contradictory and the muscular unloading levels are uncertain. The objective of study is to determine the discharge level of the inspiratory musculature reached at the same pressure support (PS) values in a group of hospital and domiciliary ventilators. Patients with COPD in at least 6 months of treatment with home NIMV and in stable phase of their disease will be included. Eight commercial ventilators will be used, each patient will use 2 different ventilators. A 5 minute record will be taken at baseline (without NIMV). Subsequently, 5 minutes in NIMV in 3 levels of PS (15/10/20) for each ventilator (15/10/20) and patient with expiratory positive airway pressure (EPAP) of 5 centimeters of water (cmH2O) will be recorded. The results will be compared between the different ventilators and PS values using a general linear model for repeated variables to determine the differences between ventilators and PS levels of respiratory muscular unloading in COPD patients

Inclusion Criteria:

• Patients with COPD diagnoses based on a spirometry performed the previous year during stability.
• COPD patients with home NIV treatment of at least 6 months with acceptable compliance and adaptation.
• Stable patients or just before hospital discharge due to an exacerbation with gasometric stability.

Exclusion Criteria:

• Respiratory acidosis in blood gas analysis, just in case of recent exacerbation
• Patients with restrictive pathology and /or obesity (IMC>35)
• Poor quality of EMG signals.