The Effects of Intraoperative Inspired Oxygen Fraction on Postoperative Pulmonary Parameters in Patients with General Anesthesia: A Systemic Review and Meta-Analysis

High intraoperative inspired oxygen concentration is applied to prevent desaturation during induction and recovery of anesthesia. However, high oxygen concentration may lead to postoperative pulmonary complications. The purpose of this study is to compare the postoperative pulmonary parameters according to intraoperative inspired oxygen fraction in patients undergoing general anesthesia. We identified all randomized controlled trials investigating postoperative differences in arterial gas exchange according to intraoperative fraction of inspired oxygen (FiO(2)). A total of 10 randomized controlled trials were included, and 787 patients were analyzed. Postoperative PaO2 was lower in the high FiO(2) group compared with the low FiO(2) group (mean difference (MD) -4.97 mmHg, 95% CI -8.21 to -1.72, p = 0.003). Postoperative alveolar-arterial oxygen gradient (AaDO(2)) was higher (MD 3.42 mmHg, 95% CI 0.95 to 5.89, p = 0.007) and the extent of atelectasis was more severe (MD 2.04%, 95% CI 0.14 to 3.94, p = 0.04) in high intraoperative FiO(2) group compared with low FiO(2) group. However, postoperative SpO(2) was comparable between the two groups. The results of this meta-analysis suggest that high inspired oxygen fraction during anesthesia may impair postoperative pulmonary parameters. Cautious approach in intraoperative inspired oxygen fraction is required for patients susceptible to postoperative pulmonary complications.