Perioperative Supplemental Oxygen and Postoperative Nausea and Vomiting: Subanalysis of a Trial, Systematic Review, and Meta-analysis.

BACKGROUND: Intraoperative supplemental oxygen may reduce postoperative nausea and vomiting by mitigating hypoxic stress on the gastrointestinal tract. The authors therefore tested the hypothesis that supplemental oxygen reduces nausea and vomiting in adults recovering from colorectal surgery at the Cleveland Clinic between January 28, 2013, and March 11, 2016. METHODS: Initially, the authors conducted an unplanned subanalysis of a previous trial that evaluated the effect of 80% versus 30% intraoperative inspired oxygen on surgical site infection. Specifically, they assessed the effect of 80% versus 30% oxygen concentration on the incidence of postoperative nausea and/or vomiting. Thereafter, the authors conducted a systematic review and meta-analysis of the effect of supplemental oxygen on postoperative nausea and vomiting. RESULTS: The authors' underlying analysis included 5,057 colorectal surgeries on 4,001 patients. For 2,554 surgeries, assignment was to 80% oxygen, and in 2,503 surgeries, to 30%. Postoperative nausea and vomiting was 852 of 2,554 (33%) in 80% oxygen and 814 of 2,503 (33%) in 30% oxygen. The estimated relative risk (95% CI) of 80% versus 30% oxygen on postoperative nausea and vomiting was 1.04 (0.96 to 1.12) in a generalized estimating equation model adjusting for within-patient correlation for patients with multiple surgeries, P = 0.355. Furthermore, supplemental oxygen did not reduce antiemetic use (P = 0.911) or the severity of nausea and vomiting (P = 0.924). The authors' meta-analysis included 10 qualifying trials (6,749 patients) and did not find a difference in postoperative nausea and vomiting: relative risk, 0.97 [95% CI, 0.86 to 1.08], P = 0.55, I2 = 52%. CONCLUSIONS: The incidence of postoperative nausea and vomiting did not differ in patients assigned to 80% or 30% inspired oxygen. A meta-analysis of available trials similarly indicated that supplemental intraoperative oxygen does not reduce postoperative nausea and vomiting. Therefore, supplemental oxygen should not be given in the expectation that it will reduce nausea and vomiting.