Low Pneumoperitoneum Pressure for Delirium Prevention in Elderly Laparoscopy

Postoperative delirium (POD) is a common and serious complication in elderly patients undergoing laparoscopic pelvic surgery, and it may be linked to the rise in intracranial pressure caused by carbon dioxide pneumoperitoneum and the Trendelenburg position. Optic nerve sheath diameter (ONSD), measured non-invasively by ultrasound, serves as a surrogate marker for intracranial pressure. This prospective, randomized, double-blind, parallel-group trial will enroll 110 patients aged 60 years or older scheduled for elective laparoscopic pelvic surgery lasting more than 2 hours. Patients will be randomly assigned (1:1) to undergo surgery with either low intraabdominal pressure (8-10 mmHg) or standard intraabdominal pressure (14 mmHg). All patients will receive standardized general anesthesia with deep neuromuscular blockade (post-tetanic count 1-2), BIS-guided depth of anesthesia, standardized ventilation, and multimodal analgesia. The primary objective is to determine whether low intraabdominal pressure reduces the incidence of POD, assessed with the 4AT on postoperative Days 1 and 2. The secondary objective is to compare changes in ONSD across four intraoperative time points and to explore the relationship between ONSD changes and POD occurrence. The trial is designed to clarify whether reducing pneumoperitoneum pressure mitigates intracranial pressure elevation and lowers delirium risk in this vulnerable population.