High-Flow in Hypercapnic Stable COPD Patients

Inclusion Criteria: * Diagnosed with COPD (FEV1/FVC \< 70%) and long term indication for home NIV for initiated at least 3 months prior the inclusion. * Compliance with NIV (less than 5 hours and more than 1 hour) per night on average during the last 3 months prior to inclusion. * Naïve to Nasal High Flow (NHF) therapy, i.e. having not used NHF in the last 6 months prior to inclusion. * Able to understand, follow objectives and methods of protocol in French language. * Patient affiliated to social security insurance or beneficiary of social health insurance. * Willing and able to give written Informed Consent and to comply with the requirements of the study protocol. Exclusion Criteria: * Significant uncontrolled cardiac disease (investigator judgment), and/or Left Ventricular Ejection Fraction (LVEF) \< 45%. * Known co-existing obstructive sleep apnea requiring expiratory pressure above 6 cmH20. * Severe nasal obstruction, previous upper airway surgery preventing the usage of NHF, or, at the discretion of investigator, any other contraindication for using the NHF. * Patients who are unable or unwilling to give informed consent. * Participating in another research study. * Patient protected by the Law, under guardianship or curators. * Pregnancy and nursing mothers * Patient not covered by a health insurance.