Nasal High Flow Versus Non-invasive Ventilation for Early Treatment of Acute Exacerbation of Chronic Obstructive Pulmonary Disease With Hypercapnic Acidosis

Adult Patient admitted to the ED for acute exacerbation of COPD (AE-COPD)and respiratory acidosis (PaCO2 \> 45 mmHg and pH \<7.35), for whom ventilatory assistance by NIV is indicated (SPLF 2017, GOLD2023 recommendations) Inclusion Criteria: * Patients with ability to understand and give an informed consent * Patients affiliated with or who benefit from a social security * Patients admitted to the emergency department for a clinical suspicion of AE-COPD based on clinical history, physical examination and chest X-ray (SPLF 2017) * Patients with acute respiratory failure defined by: Respiratory rate ≥ 25 bpm AND/OR Signs of respiratory failure (use of accessory respiratory muscles, paradoxical abdominal movement) * Patients with respiratory acidosis defined by PaCO2 \> 45 mmHg AND pH \< 7.35 (measured on arterial blood gas) Exclusion Criteria: * Patients who have already received NIV treatment before inclusion (including in-hospital or prehospital, with the exception of NIV at home) * Contraindication to non-invasive ventilation (SPLF 2017 and GOLD 2023 recommendations) * Patient uncooperative, agitated, opponent of the technique