Ultrasound Evaluation of Preventive Measures for Postoperative Lung Atelectasis After Surgery

Patients will be ventilated with PEEP of 8 cm H2O and fluid management: 500 ml of Ringer's lactate in the recovery room before surgery and Ringer's lactate at a rate of 4 mL/kg/hour from the beginning to the end of the surgery.

Patients will be ventilated with PEEP of 8 cm H2O, and then RM (30 cm H2O for 30 s) will be applied immediately after the second LUS examination and repeated every 30 minutes till emergence and fluid management: 500 ml of Ringer's lactate in recovery room before surgery and Ringer's lactate at a rate of 4 mL/kg/hour from the beginning to the end of the surgery

Patients will be ventilated with PEEP of 8 cm H2O, and then RM (30 cm H2O for 30 s) will be applied immediately after the second LUS examination and repeated every 30 minutes till emergence and restrictive fluid management (RF). Ringer's lactate at a rate of 3 mL/kg/hour from the beginning to the end of the surgery