Effect of High Versus Low Fraction of Inspired Oxygen During Alveolar Recruitment

to compare the effect of high oxygen fraction (FiO2 1.0) vs. low oxygen fraction (FiO2 0.4) on clinical outcome on intraoperative and postoperative atelectasis and PPC. We will asses the impact of FiO2, especially during RM, on atelectasis development, using modified LUSS in obese patients with atelectasis undergoing laparoscopic bariatric surgery.