Objective:To compare the effects of different lung recruitment maneuvers in infants undergoing laparoscopic surgery.Methods:A total of 70 pediatric patients of either sex, aged 1-6 yr, weighing 10-24 kg, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, scheduled for elective laparoscopic surgery from September 2020 to June 2021 with expected operation time≤2 h, were divided into 2 groups ( n=35 each) by a random number table method: recruitment maneuver using incremental positive end-expiratory pressure (PEEP) group (PV group) and recruitment maneuver using controlled lung expansion group (RM group). The children underwent pressure-controlled ventilation after tracheal intubation, and lung recruitment was performed at 20 min after pneumoperitoneum, immediately after pneumoperitoneum, and at the end of operation and before tracheal extubation.In PV group, PEEP was gradually increased, the upper limit of airway pressure was 35 mmHg, PEEP was increased by 5 cmH 2O, ventilation was performed for 30 s, then PEEP was increased to 15 cmH 2O, ventilation was continued for 30 s, then the parameters were adjusted to the original ones, and ventilation was continued until the next lung recruitment.In RM group, manual ventilation mode was used, the pressure valve was adjusted to 30 cmH 2O, the pressure was increased to the maximum by rapid oxygenation, the breathing cuff was manually squeezed until the airway pressure achieved 30-35 mmHg, and 30 s later ventilation was performed with the original ventilation parameters, lasting for 30 s until the next lung recruitment.Peak airway pressure and mean airway pressure were recorded at 5 min after tracheal intubation (T 1), 20 min after pneumoperitoneum (T 2), immediately after pneumoperitoneum (T 3) and before extubation after surgery (T 4), and dynamic lung compliance was calculated.Blood gas analysis was performed at T 2 and T 4, and arterial partial pressure of oxygen and arterial partial pressure of carbon dioxide were recorded, oxygenation index, alveolar-arterial oxygen partial pressure difference and respiratory index were calculated.Lung ultrasonography scores were assessed before tracheal extubation (T 0) and at T 4 and 20 min after entering the postanesthesia care unit (T 5). The time of tracheal extubation and length of postoperative hospital stay were recorded.Hypoxemia in postanesthesia care unit and occurrence of pulmonary complications within 3 days after operation were recorded. Results:Compared with RM group, peak airway pressure and mean airway pressure were significantly decreased at T 2, 3, dynamic lung compliance was increased at T 2-4, arterial partial pressure of oxygen and oxygenation index were decreased , arterial partial pressure of carbon dioxide, alveolar-arterial oxygen partial pressure difference and respiratory index were increased at T 2 and T 4, lung ultrasonography scores were decreased at T 4 and T 5, and the incidence of postoperative hypoxemia was increased, and tracheal extubation time was prolonged in RM group ( P<0.05). Conclusions:Lung recruitment maneuver using incremental PEEP provides better efficacy than that using controlled lung expansion in infants undergoing laparoscopic surgery.