Effect of Boussignac CPAP Ventilation on PaO2 and PaO2/FiO2 Ratio in Morbidly Obese Patients Undergoing Bariatric Surgery

Inclusion Criteria: * Patients age between 18 and 65 years of age * Morbidly obese with a body mass index \> 35 kg/m2 * Laparoscopic gastric bypass Exclusion Criteria: * Patient refusal * American Society of Anesthesiologists' (ASA) class IV * Lung parenchyma disease * Chronic Obstructive Pulmonary Disease * Moderate to severe asthma * Pre-existing cardiac failure (above class II in the New York Heart Association (NYHA) classification) * Estimated pulmonary artery pressure ≥35mmHg * Hemoglobin concentration (\[Hgb\]) less than 7 g / dL * Need for invasive ventilation during preoperative immediate post-extubation defined in the preoperative period * Patients with obstructive sleep apnea previously treated with CPAP * Severe psychiatric disorder * Language barrier