Effects of Standard and Modified Z-Trendelenburg Positions on Cerebral Oxygenation and Optic Nerve Sheath Diameter

The purpose of this study is to compare the effects of the standard Trendelenburg position and the modified Z-Trendelenburg position on cerebral oxygenation and optic nerve sheath diameter (ONSD) in patients undergoing laparoscopic surgery. The prolonged use of the standard Trendelenburg position combined with pneumoperitoneum can increase intracranial pressure and affect cerebral blood flow. In this study, researchers will use non-invasive methods, including Near-Infrared Spectroscopy (NIRS) to monitor regional cerebral oxygenation, and ocular ultrasonography to measure ONSD as an indicator of intracranial pressure changes. The main goal is to determine whether the modified Z-Trendelenburg position serves as a safer physiological alternative by reducing these potential adverse effects compared to the standard position.

Inclusion Criteria: Patients aged between 18 and 70 years American Society of Anesthesiologists (ASA) physical status I or II Scheduled for elective laparoscopic surgery requiring Trendelenburg position Provided written informed consent Exclusion Criteria: Patient refusal to participate History of severe cerebrovascular disease Known increased intracranial pressure Pre-existing ocular pathology that could affect optic nerve sheath diameter (ONSD) measurements (e.g., glaucoma, optic neuritis, ocular trauma) Severe cardiovascular or pulmonary disease Body Mass Index (BMI) greater than 35 kg/m\^2 Pregnancy