Effects of Different Inhaled Oxygen Concentrations on Lung Function in Older Patients After Laparoscopic Gastrointestinal Surgery Under General Anesthesia

This was a multicenter, prospective, parallel-grouping, randomized controlled clinical study comparing low FiO2 (40%) and high FiO2 (80%) levels in older patients undergoing laparoscopic gastrointestinal surgery. the investigators planned to enroll 1098 subjects aged \> 65 years for laparoscopic gastrointestinal surgery at 19 clinical trial centers in China, randomized in a 1:1 ratio, to use two inhaled oxygen concentrations during surgery. All patients will be performed via the lung-protective ventilation strategy. The respiratory parameters are VT: 6-8ml/kg, PEEP: 6-8 cmh2O, RR: 1:2, and respiratory rate will be adjusted by maintaining a partial pressure of carbon dioxide at 35-45 mmHg. Manual lung recruitment maneuvers will be performed after tracheal intubation and before tracheal extubation. The main outcome measure was the oxygenation index on the postoperative 48h. The secondary outcome measures were the 7-day postoperative pulmonary complications and 30-day mortality rates et al.