A Comparative Study of Ventilation Strategies in Different Surgical Positions on Intracranial Pressure and Cerebral Blood Flow During Laparoscopic Surgery

The purpose of this clinical trial is to investigate the effects of laparoscopic surgery in the Trendelenburg and Reverse Trendelenburg positions, and variable tidal volume ventilation (V-VCV), pressure-regulated volume-controlled ventilation (PRVC), conventional volume-controlled ventilation (C-VCV), and pressure-controlled ventilation (PCV) on esophageal pressure, airway pressure, tidal volume, intracranial pressure, and cerebral blood flow. The study aims to address the following primary questions:Does laparoscopic surgery in the Trendelenburg or Reverse Trendelenburg position increase esophageal pressure, airway pressure, and intracranial pressure, and decrease tidal volume and cerebral blood flow? Do variable tidal volume ventilation (V-VCV), pressure-regulated volume-controlled ventilation (PRVC), conventional volume-controlled ventilation (C-VCV), or pressure-controlled ventilation (PCV) increase esophageal pressure, airway pressure, and intracranial pressure, and decrease tidal volume and cerebral blood flow? The investigators will compare variable tidal volume ventilation (V-VCV), pressure-regulated volume-controlled ventilation (PRVC), conventional volume-controlled ventilation (C-VCV), and pressure-controlled ventilation (PCV) to determine which ventilation mode results in the least physiological disturbance for patients. Participant Procedures: Participants will: Be positioned according to the surgical requirements.Be randomly assigned to mechanical ventilation with either variable tidal volume ventilation (V-VCV), pressure-regulated volume-controlled ventilation (PRVC), conventional volume-controlled ventilation (C-VCV), or pressure-controlled ventilation (PCV). Undergo assessments at the following time points: immediately after endotracheal intubation, immediately after pneumoperitoneum, immediately after position change (Trendelenburg or Reverse Trendelenburg), 30 minutes after position change, and 1 hour after position change. Have their esophag