Fraction of inspired oxygen during general anesthesia for non‐cardiac surgery: Systematic review and meta‐analysis

Abstract

Background: Controversy exists regarding the effects of a high versus a low intraoperative fraction of inspired oxygen (FiO 2 ) in adults undergoing general anesthesia. This systematic review and meta-analysis investigated the effect of a high versus a low FiO 2 on postoperative outcomes.Methods: PubMed and Embase were searched on March 22, 2022 for randomized clinical trials investigating the effect of different FiO 2 levels in adults undergoing general anesthesia for non-cardiac surgery. Two investigators independently reviewed studies for relevance, extracted data, and assessed risk of bias. Meta-analyses were performed for relevant outcomes, and potential effect measure modification was assessed in subgroup analyses and meta-regression. The evidence certainty was evaluated using GRADE.Results: This review included 25 original trials investigating the effect of a high (mostly 80%) versus a low (mostly 30%) FiO 2 . Risk of bias was intermediate for all trials. A high FiO 2 did not result in a significant reduction in surgical site infections (OR: 0.91, 95% CI 0.81-1.02 [p = .10]). No effect was found for all other included outcomes, including mortality (OR = 1.27, 95% CI: 0.90-1.79 [p = .18]) and hospital length of stay (mean difference = 0.03 days, 95% CI À0.25 to 0.30 [p = .84). Results from subgroup analyses and meta-regression did not identify any clear effect modifiers across outcomes. The certainty of evidence (GRADE) was rated as low for most outcomes.Maria Høybye and Peter C. Lind contributed equally.

Intraoperative respiratory and hemodynamic strategies for reducing nausea, vomiting, and pain after surgery: Systematic review and meta‐analysis

“…Given this, additional trials are needed before a definitive effect can be concluded. Moreover, it is important to consider these results in the context of other outcomes, such as mortality, length of stay, and postoperative complications as reported previously 4,6 …”

“…Overall, the search identified 23,454 unique records of which 535 full-text articles were assessed for eligibility. Of 209 manuscripts included in previous reviews, [4][5][6][7] 63 manuscripts including relevant outcomes for the current manuscript were identified. Review of references and previous reviews resulted in identification of two additional manuscripts, yielding a total of 65 manuscripts (Figure S1).…”

“…This paper is part of a larger systematic review project including clinical trials assessing various respiratory and hemodynamic interventions and targets for patients undergoing non‐cardiac surgery under general anesthesia. Previous manuscripts from this review project have focused on the outcomes mortality, length of stay, and postoperative complications 4–7 . In this manuscript, we focus on the outcomes of postoperative pain, nausea, and vomiting.…”

“…Previous manuscripts from this review project have focused on the outcomes mortality, length of stay, and postoperative complications. [4][5][6][7] In this manuscript, we focus on the outcomes of postoperative pain, nausea, and vomiting.…”

“…Pre‐, intra‐, and postoperatively, various medical interventions are used to minimize pain, nausea, and vomiting in the postoperative setting and avoid severe complications 3 . Recent reviews have shown limited effects of specific intra‐operative respiratory and hemodynamic interventions on “hard” endpoints such as hospital length of stay and mortality 4–7 . However, identification of intraoperative respiratory and hemodynamic interventions and specific targets that can influence the development and intensity of postoperative pain, nausea, and vomiting would be valuable additions in a multimodal approach.…”