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

The purpose of this study is to determine whether nasal high flow is non inferior to non invasive ventilation (NIV) in the early treatment of patients with acute exacerbation of chronic obstructive pulmonary disease (AE-COPD) and hypercapnic acidosis in the emergency department (ED). After obtaining informed consent, participants will be randomly assigned to receive either nasal high flow or non invasive ventilation (NIV, reference treatment) as respiratory support. Researchers will compare both respiratory support groups to see if their blood gas analysis and respiration return to normal ranges.

Prospective multicenter comparative therapeutic study, with a randomized controlled parallel and open design. Nasal high flow will be compared to NIV (reference treatment) for early treatment of AE-COPD associated with hypercapnic acidosis.

Adult patients admitted to the ED for AE-COPD with hypercapnic acidosis will be randomized to receive either nasal high flow or NIV as ventilatory support. Ventilatory support will be applied in 2h sessions and resumed as needed according to international guidelines for NIV treatment. Close monitoring of clinical and gas parameters will be conducted with repeat assessment and serial blood gas testing at 2h and after each 2h session of respiratory support in the ED (2h, 4h, 6h) and at 24h.

Standard oxygen therapy will be administered as required between ventilatory support sessions to maintain a target peripheral oxygen saturation (SpO2 : 88-92%).

Patient's dyspnea and comfort will be assessed before treatment and at 2h, and after each respiratory support session in the ED Patients will receive standard medical treatment for AE-COPD (bronchodilator, corticosteroids and antibiotics) according to current practice and 2023 global initiative guidelines for the management of COPD (GOLD).

Patients will be followed up at day 28 by means of medical records review and telephone interview

Eligibility Criteria:
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