General anesthesia and mechanical ventilation decrease pulmonar volume; attenuate small airway closure, atelectasis, and increase the rate of hypoxia and postoperative pulmonary complications. Lung volume in obese patients decreases inversely with the increase in body mass index. Obesity is associated with increased atelectasis, hypoxia and postoperative pulmonary complication rates during anesthesia . Alveolar recruitment maneuver is a technique where high positive end-expiratory pressure (PEEP) is applied for for short periods, follwed by a continuous PEEP appşication throughout surgery. This has become a standard practice during anesthesia in recent years. Oxygen reserve index (ORi) is an index measured with a non-invasive finger-tip sensor and shows the oxygen content of the venous blood. It is effective at high oxygen levels and may indicate the presence of hyperoxia. Our aim is to examine the effect of alveolar recruitment maneuver on oxygenation parameters under anesthesia and the correlation with ORi in morbidly obese patients.

Patients with body mass index> 40 m2, scheduled for bariatric surgery under general anesthesia will be monitorised with the ORi sensor and monitored at regular intervals. Preoperative and postoperative lung aeration will be evaluated with lung ultrasaund. İntraoperative standart anesthesia will be administered by an anesthesiolıgist not aware of the ultrasound. Alveolar recruitment will be applied by the same anesthesiologist if necessary. Blood gas samples obtained throughout surgery will be evaluated. ORİ values and intraoperative vital, respiratory, neuromuscular monitoring parameters will be obtained. Postoperative pulmonary complicationsa will be evaluated at postoperative day 5.

Finding will be compared between patients who received recruitment and who did not.

Inclusion Criteria:

Bariatric surgery general anesthesia and mechanical ventilation via orotracheal entubation Age between 18-65 ASA I-III BMI > 40 m-2

Exclusion Criteria:

Previous history of thorasic surgery, pneumothorax Chemo or Radiotherapy to the chest within 2 months History of Respiratory disease (COPD, emphysema, pneumonia, lung malignancy, Lung Bulla ) Emergency surgery Cardiovascular, renal, hepatic, neuromuscular disease İntracrabial pathology or trauma High intraoptic pressure Pulmonary Hypertension Pregnancy Criticall illness, or history of mechanical ventilation within 1 month

obese patients with BMI> 40 scheduşed for bariatric surgery

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