To determine whether high perioperative inspired oxygen fraction (FiO2) compared with low FiO2 has more deleterious postoperative clinical outcomes in patients undergoing non-thoracic surgery under general anesthesia.

Meta-analysis of randomized controlled trials.

Operating room, postoperative recovery room and surgical ward.

Surgical patients under general anesthesia.

High perioperative FiO2 (≥0.8) vs. low FiO2 (≤0.5).