Effects of individualized PEEP on pulmonary function, cerebral blood flow and postoperative cognitive function in patients undergoing laparoscopic radical resection of rectal cancer.

Objective: To evaluate the effects of individualized PEEP on pulmonary function, cerebral blood flow, and postoperative cognitive function in patients undergoing laparoscopic radical resection of rectal cancer.

Methods: 100 patients who underwent laparoscopic radical rectal cancer surgery at our hospital between August 2021 and May 2023 were randomized into two groups: the DP group (optimal PEEP group oriented to driving pressure) and the Cdyn group (optimal PEEP group oriented to pulmonary compliance). Anesthesia was induced in both groups with 0.3 mg/kg of remizolam + 0.15 mg/kg of CIS atracurium + 0.5 ug/kg of sufentanil. Lung ultrasound score (LUS), peak and plateau airway pressures (PEAK, PLAT), oxygenation index (OI), driving pressure (DP), and pulmonary dynamic compliance (Cdyn) were measured at different time points. Cerebral blood flow and cognitive function were also assessed. T₀: before induction of anesthesia; T₁: before postoperative extubation of the tracheal tube; T₂: 1 h after extubation; T₃: on the third postoperative day; T₄: 5 min after determining the optimal PEEP; T₅: 1 h after the establishment of pneumoperitoneum; T₆: 2 h after the establishment of the pneumoperitoneum; T₇: 20 min at the end of pneumoperitoneum.

Results: There were no significant differences in general information between the two groups, P > 0.05. Compared with the DP group, the Cdyn group had lower LUS at T₃, higher PEAK at T₅, T₆, and T₇, lower PLAT and OI at T₆ and T₇, lower DP at T₄, T₆, and T₇, and lower Cdyn at T₆ and T₇, P < 0.05. The Cdyn group had lower cerebral blood flow at T₄ and T₆, P < 0.05. The Cdyn group had higher cognitive function at stage T₃ as assessed by MMSE, P < 0.05.

Conclusion: PEEP guided by lung compliance improves pulmonary function, cerebral blood flow, and cognitive function, offering clinical benefits.