Objective: This study investigates the impact of carbon dioxide (CO2) pneumoperitoneum on optic nerve sheath diameter (ONSD) and intracranial pressure (ICP) in patients undergoing total laparoscopic hysterectomy. Previous research suggests that pneumoperitoneum can lead to elevated ICP, with the standard intracranial monitoring technique being invasive intraventricular catheter placement. In contrast, bedside ultrasound assessment of ONSD offers a noninvasive alternative for detecting increased ICP.

Methods: The Hypothesize will be standard gas insufflation pressure significantly increases ONSD, while low-pressure insufflation will maintain ONSD levels. The primary aim is to compare ONSD variations pre- and post-CO2 insufflation in patients subjected to both low-pressure and standard-pressure laparoscopic surgery. Secondary aims include evaluating end-tidal CO2 measurements between the two groups.

It has been shown in many studies that pneumoperitoneum containing carbon dioxide (CO2) during laparoscopy increases intracranial pressure (ICP). (1) Evaluation of the Effect of Intraabdominal Pressure on Optic Nerve Sheath Diameter in Patients Undergoing Total Laparoscopic Hysterectomy. The standard technique for monitoring ICP is the placement of an intraventricular catheter connected to an external pressure transducer. (2) Bedside evaluation of optic nerve sheath diameter (ONSD) with ultrasound technique is a more practical and noninvasive method used to determine high ICP (>20 mmHg). The anatomical continuity of the dura with the optic nerve sheath (ONSD) allows the use of this technology, and thus an increase in ICP can be transmitted from the subarachnoid space to the ONSD. (3)

Low-pressure pneumoperitoneum reduces analgesic consumption after laparoscopic cholecystectomy in studies, but the effect of standard and low intraabdominal pressures on ICP has not yet been clarified. (4)

In our thesis, assuming that standard gas insufflation pressure will increase ONSD, but low gas insufflation pressure will not cause a change, the primary aim was to compare ONSD between two groups of low-pressure and standard-pressure laparoscopic surgery before and after CO2 insufflation preoperatively. Second, the end-tidal CO2 measurements between the two groups will be evaluated.

Inclusion Criteria:

• The study will be conducted in patients under 18 years of age with American Society of Anesthesiologists (ASA) I-II.

Exclusion Criteria:

• Patients with a history of neurological disease, glaucoma, surgery exceeding 2 hours, known chronic obstructive pulmonary disease (COPD), heart disease, and previous lung surgery will be excluded from the study. Patients with intraoperative hemodynamic problems; ETCO2 greater than 45 mmHg, plateau pressure over 30 cmH2, and peak inspiratory pressure over 35 cmH2 will be excluded from the study.