Ventilation Strategies During General Anesthesia for Noncardiac Surgery: A Systematic Review and Meta-Analysis

Abstract

BACKGROUND: The optimal ventilation strategy during general anesthesia is unclear. This systematic review investigated the relationship between ventilation targets or strategies (eg, positive end-expiratory pressure [PEEP], tidal volume, and recruitment maneuvers) and postoperative outcomes. METHODS: PubMed and Embase were searched on March 8, 2021, for randomized trials investigating the effect of different respiratory targets or strategies on adults undergoing noncardiac surgery. Two investigators reviewed trials for relevance, extracted data, and assessed risk of bias. Meta-analyses were performed for relevant outcomes, and several subgroup analyses were conducted. The certainty of evidence was evaluated using Grading of Recommendations Assessment, Development and Evaluation (GRADE). RESULTS: This review included 63 trials with 65 comparisons. Risk of bias was intermediate for all trials. In the meta-analyses, lung-protective ventilation (ie, low tidal volume with PEEP) reduced the risk of combined pulmonary complications (odds ratio [OR], 0.37; 95% confidence interval [CI], 0.28–0.49; 9 trials; 1106 patients), atelectasis (OR, 0.39; 95% CI, 0.25–0.60; 8 trials; 895 patients), and need for postoperative mechanical ventilation (OR, 0.36; 95% CI, 0.13–1.00; 5 trials; 636 patients). Recruitment maneuvers reduced the risk of atelectasis (OR, 0.44; 95% CI, 0.21–0.92; 5 trials; 328 patients). We found no clear effect of tidal volume, higher versus lower PEEP, or recruitment maneuvers on postoperative pulmonary complications when evaluated individually. For all comparisons across targets, no effect was found on mortality or hospital length of stay. No effect measure modifiers were found in subgroup analyses. The certainty of evidence was rated as very low, low, or moderate depending on the intervention and outcome. CONCLUSIONS: Although lung-protective ventilation results in a decrease in pulmonary complications, randomized clinical trials provide only limited evidence to guide specific ventilation strategies during general anesthesia for adults undergoing noncardiac surgery.

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

“…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).…”

“…Although the minimally clinical important difference in pain varies substantially depending on the setting, most studies consider a change of 1 near or below the minimally clinical important difference 81 . However, given the safety of recruitment maneuvers, this intervention can be considered 5 …”

“…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.…”