Comparison of ONSD between the two groups.

ObjectivePositive end-expiratory pressure (PEEP) is widely used during surgery, but its effects on lung and brain protection remain debated. This study aimed to evaluate the impact of individualized PEEP on lung ultrasound score (LUS) and optic nerve sheath diameter (ONSD) in elderly patients undergoing laparoscopic rectal cancer surgery.MethodsForty-six patients aged 60–79 years undergoing laparoscopic rectal tumour resection between June 2022 and December 2022 were randomized into two groups: Group E (individualized PEEP guided by driving pressure) and Group C (control group, PEEP = 5 cm H2O). LUS was assessed 30 minutes postoperatively. ONSD was measured at 5 minutes before anesthesia induction (T0), 5 minutes after tracheal tube insertion (T1), 5 and 60 minutes after Trendelenburg positioning (T2, T3), and 30 minutes postoperatively (T4). Arterial oxygen index (OI) and arterial partial pressure of carbon dioxide (PaCO2) were recorded post-intubation and pre-extubation. Postoperative pulmonary and neurological complications were followed up.ResultsPostoperative LUS was significantly lower in Group E than in Group C (P P P ConclusionsDuring laparoscopic radical resection for rectal cancer, individualized PEEP reduces LUS scores, improves oxygenation, and does not increase ONSD values compared to fixed PEEP.Trial registrationChinese Clinical Trial Registry: ChiCTR2200060434.