Driving Pressure-guided Positive End-expiratory Pressure to Prevent Postoperative Atelectasis in Obese Children: a Prospective, Randomized Controlled Clinical Trial

Inclusion Criteria: * Age 3-18 years old; * According to the People's Republic of China health industry standard "Overweight and Obesity Screening threshold for school-age children and adolescents WS\_T586-2018" defined as obesity; * American Society of Anesthesiologists (ASA) grades I - II; * Children with healthy lungs and hearts; * Patients with general anesthesia under tracheal intubation; * Clear mind and able to cooperate with the anesthesiologist to receive treatment; * Patients who plan to have elective surgery under general anesthesia and the estimated operation duration is ≥2 hours. Exclusion Criteria: * PEEP contraindications: (a) bronchopleural fistula; (b) hypovolemic shock; (c) right ventricular failure; * American Society of Anesthesiologists (ASA) grade greater than II; * Pulmonary dysfunction, congenital heart disease children; * Refusal to participate in the study and/or use personal data, preoperative intubation or ventilation of children; * Children with upper respiratory tract infection within 2 weeks.