There is an increasing trend in the use of robotic-assisted radical prostatectomy or cystectomy (RARPC). Preventing lung atelectasis without inducing overdistention of the lung is challenging. Many studies tried to optimize PEEP titration by using methods such as dead space fraction guided and static pulmonary compliance directed techniques, or by using electrical impedance tomography. However, the use of these methods is limited by inaccuracy and the need for sophisticated devices. Bedside Lung ultrasound is fast, easy and economic technique that is gaining interest in the operating room. Ultrasound-guided PEEP titration has been used in bariatric surgeries (different position and usually shorter procedure time) and proved effective in improving oxygenation, compliance and reducing the incidence of postoperative pulmonary atelectasis and hypoxia without causing hemodynamic instability. The aim of this study is to evaluate the effectiveness of intraoperative individualized lung ultrasound-guided stepwise PEEP optimization in patients undergoing RARPC on oxygenation, intraoperative and early postoperative pulmonary complications.