Influence of Automatic Oxygen Titration Device (FreeO2) on Percentage of Time Within Oxygen Saturation Target and Induced Hypercapnia During Noninvasive Ventilation for Patients Hospitalized for an Acute Exacerbation of COPD or a Bariatric Surgery
The main objective is to evaluate the FreeO2 device combined with noninvasive respiratory support technique for COPD patients and postoperative bariatric surgery patients. The main hypothesis is that FreeO2 device for oxygen therapy associated with NIV or nasal high flow oxygen therapy (NHFOT) allows to reach better oxygenation and avoid hypoxemia and hyperoxia.
• Respiratory acidosis (pH \<= 7.35 and PaCO2 \> 45 mmHg), with or without NIV (last blood gas available during hospitalization)
• Oxygen therapy and/or SpO2 \<90% room air (FiO2 \<= 50% or nasal cannula \<= 7 L/min to maintain SpO2 90%)
• High flow nasal cannula with flow \<= 30 L/min
• Patients using CPAP before the surgery (obstructive sleep apnea documented).
• Patients with obesity hypoventilation syndrome in addition to obstructive sleep apnea can be included.