The aim of this study is to evaluate the effect of the Reverse Trendelenburg position on oxygenation (SpO₂/FiO₂ ratio) in the early postoperative period in patients undergoing laparoscopic surgery. In our study, obesity is considered as a comparative subgroup in terms of variability of this effect; additionally, the STOP-BANG score, which measures the risk of obstructive sleep apnea syndrome, is examined as an auxiliary indicator.

Inclusion Criteria:

• Patients over 18 years old
• Patients who give consent to participate in the study
• Patients who underwent elective laparoscopic cholecystectomy in Reverse Trendelenburg (30 degrees) position
• ASA I-III patients
• Patients with operation time < 3 hours

Exclusion Criteria:

• Patients under 18 years old
• Patients who did not give consent
• Patients with asthma, COPD, or known respiratory disease
• Patients whose procedure could not be completed or who had missing data
• Patients with general anesthesia duration < 90 minutes will not be included

Adults over 18, ASA I-III patients, patients who give consent to participate, patients undergoing elective laparoscopic surgery (obesity surgery, cholecystectomy, umbilical hernia, etc.)