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.
Age not less than 65 years
American Society of Anesthesiologists grades I-III
No history of drug allergies or abnormal anesthesia.
The duration of mechanical ventilation was expected to be more than 2 hours.
History of acute lung injury or acute respiratory distress syndrome (ARDS) within 3 months.
Cardiac function Class IV (New York Heart Association classification)
Chronic renal failure (renal cell filtration rate <30 ml min-11.73/m2), severe liver disease
Patients with blurred consciousness and cognitive dysfunction