Effect of Two Different Surgical Positions on Pulmonary Functions in Laparoscopic Gastrectomies

Inclusion Criteria: * Patients who can tolerate general anesthesia and pneumoperitoneum. * Patients who can give informed consent for surgery. * Patients over 18 years of age * patients with body mass index (BMI) \> 30 kg/m2 * Patients with American Society of Anesthesiologists (ASA) physical status I and II Exclusion Criteria: * Patients with serious underlying cardiovascular disease (e.g. congestive heart failure, conduction disorders and ischemic heart disease). * Patients with chronic kidney disease stage 3 or greater (creatinine clearance less than 60 mL/min). * patients with a history of cerebrovascular disease such as intracranial hypertension, cerebral infarction, cerebral hemorrhage, carotid artery stenosis or cerebral ischemia; * Patients with a history of chronic lung diseases such as chronic obstructive pulmonary disease, asthma, pulmonary bullae or respiratory failure; * Patients who have had previous abdominal surgery, including resection of the esophagus, stomach, liver and pancreas. * Surgeries lasting longer than 90 minutes * Patients with ASA class IV * patients with psychiatric disorders * pregnant or breastfeeding patients * patients with a history of seizures