Effect of low vs high intraoperative fraction of inspired oxygen on postoperative organ complications: a systematic review and meta-analysis of randomized controlled trials

Purpose

Intraoperative supplemental oxygen may induce postoperative organ complications by aggravating oxidative stress and vasoconstriction. This meta-analysis was to determine whether the higher fraction of inspired oxygen (FiO₂) would increase the risk of organ complications among patients under general anesthesia.

Methods

We performed a systematic literature review for randomized controlled studies among surgical patients receiving ≥ 60% FiO₂ compared with ≤ 40% FiO₂ and meta-analysis of risk ratios (RR) comparing higher FiO₂ against lower for pulmonary, cardiac, neurological, and kidney complications. We systematically explored MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials to December 2024.

Results

We included 20 qualifying randomized controlled trials with a total of 5,793 patients. Low FiO₂ was associated with less atelectasis (RR, 0.78; 95% CI, 0.63–0.97), lower percentage of atelectasis (mean difference, –1.80; 95% CI, –3.30 to –0.57), and more acute kidney injury (RR, 1.64; 95% CI, 1.15–2.34). No evidence of association with low FiO₂ was found for other complications in this meta-analysis: cardiac complications (RR, 1.15; 95% CI, 0.96–1.53) and delirium (RR, 1.13; 95% CI, 0.87–1.46).

Conclusions

The current study indicated that lower intraoperative oxygen reduced postoperative incidence and severity of atelectasis but result in more acute kidney injury. More high-quality trials are warranted regarding the optimal fraction of intraoperative inspired oxygen.

Registration

Prospectively registered at the International Prospective Registry of Systemic Reviews (CRD42023479131).