Objective:To evaluate the effect of driving pressure-guided individualized positive end-expiratory pressure (PEEP) titration on atelectasis in elderly patients undergoing robot-assisted radical prostatectomy.Methods:Fifty elderly patients, aged 65-80 yr, of American Society of Anesthesiologists physical status Ⅱ or Ⅲ, with body mass index of 19-28 kg/m 2, undergoing elective robot-assisted radical prostatectomy under general anesthesia, were divided into 2 groups ( n=25 each) according to the random number table method: traditional lung-protective ventilation group (group C) and driving pressure-guided individualized PEEP group (group D). The method for setting PEEP was as follows: PEEP 5 cmH 2O was used throughout operation in group C. In group D, the optimal PEEP was titrated after intubation and mechanical ventilation and Trendelenburg position-pneumoperitoneum construction, the initial value was the lowest PEEP allowed by the anesthesia machine, the PEEP was increased by 1 cmH 2O (PEEP≤12 cmH 2O) every 4 min, the plateau pressure and PEEP were simultaneously recorded to calculate the driving pressure, and the corresponding PEEP was considered as the optimal PEEP for the individual when the driving pressure reached the minimum.Ultrasound examination was performed after catheterization of radial artery (T 0), after anesthesia induction (T 1), 4 min after developing optimal PEEP ventilation (T 2, 4 min after developing ventilation in group C), after restoration of body position (T 3), before extubation (T 4), and at 2 h after admission to postanesthesia care unit (T 5). Atelectatic aeration loss scores were recorded at T 0, T 1, T 4 and T 5.Bilateral optic nerve sheath diameter was measured at T 0-4.Arterial blood gas analysis was performed at T 0, T 2, T 3 and T 5, PaO 2 and PaCO 2 were recorded, and oxygenation index was calculated.The postoperative pulmonary complications within 3 days after operation were recorded. Results:Compared with group C, atelectasis aeration loss scores at T 4, 5 and PaCO 2 at T 2, 3 were significantly decreased, and PaO 2 and oxygenation index were increased at T 2, 3, 5 in group D ( P<0.05). There were no significant differences in the bilateral optic nerve sheath diameter and incidence of postoperative pulmonary complications between the two groups ( P>0.05). Conclusion:Driving pressure-guided individualized PEEP can increase intraoperative oxygenation and decrease the development of atelectasis in elderly patients undergoing robot-assisted radical prostatectomy.