Extreme steep Trendelenburg position of 25-40 degrees could contribute to Atelectasis formation, particularly in dependent regions and elevate mechanical stress in pulmonary parenchyma, triggering significant perioperative pulmonary dysfunction. Administration of General Anesthesia further decreases the End -Expiratory lung volume (EELV) forming Atelectasis and leads to a deterioration in respiratory mechanics and gas exchange. Ventilation strategy employing high tidal volumes could over distend normal lungs, thereby activating a local inflammatory reaction. Furthermore , zero- positive end-expiratory pressure or low levels of positive end-expiratory pressure (PEEP) could induce repetitive collapse and reopening of Alveoli, which ultimately result in an inflammatory injury. In recent years , intraoperative lung-protective mechanical ventilation (LPV) has been reportedly able to attenuate ventilator- induced lung injuries  (VILI) by employing a low tidal volume (Vt), an appropriate level of PEEP and recruitment maneuvers (RMs). In recent years, intraoperative lung-protective mechanical ventilation (LPV) has been reportedly able to attenuate ventilator-induced lung injuries (VILI) by employing a low tidal volume (Vt), an appropriate level of PEEP , and recruitment maneuvers (RMs) .The goals of these interventions are to minimize alveolar over distention, to prevent repeated collapse and reopening of alveoli and to reduce atelectasis.