Weaning From Noninvasive Ventilation

Inclusion Criteria: Patients will be screened by the physician 24 hours (±6 hours) after initiation of NIV treatment if: * Age ≥18 years old * Hypercapnic ARF ( baseline pH\<7.35, paCO2\>45 mmHg, BORG\>4) * Breathing frequency\< 25 bpm under NIV * pH \>7.35 under NIV * 10% or more decrease from baseline PaCO2 under NIV * Kelly ≤ 2 under NIV (Alert. Follows simple/3 step complex commands) * PaO2 between 60 and 70 mmHg under NIV * No need for sedation * Systolic blood pressure 90-180 mmHg without vasopressors * Body temperature 36-38°C * Heart rate 50-120 bpm The patient will be enrolled to the study and will be randomized to one of the NIV weaning protocols, if passes daily weaning criteria listed below after 1 hour of spontaneous breathing (with supplementary oxygen), * Respiratory rate 8-30 bpm * Systolic blood pressure 90-180 mmHg without vasopressors * Body temperature 36-38°C * Heart rate 50-120 bpm * Neurologic score of Kelly ≤2 (Alert. Follows simple/ 3-step complex commands), * SaO2 ≥88-92% with a FiO2≤40%. * pH≥7.35 * Absence of severe dyspnea (BORG\>4). Exclusion Criteria: * Age \<18 years old * NIV use at home for chronic respiratory failure * CPAP use for acute respiratory failure * NIV use as palliative treatment * Severe heart failure with cardiac index ≤ 2 L/min/m2 * Severe hepatic failure with bilirubin ≥ 34.2µmol/L * Severe renal failure with creatinine ≥ 220 µmol/L