Xenon Anesthesia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND: Xenon anesthesia has been studied for decades. However, no meta-analysis of randomized controlled trials (RCTs) on xenon anesthesia has been conducted. The aim of this study was to systematically review all available evidence from RCTs comparing xenon and other inhaled and IV anesthetics on anesthetic outcomes. Our meta-analysis attempted to quantify the effects of xenon anesthesia on clinical outcomes in relation to other anesthetics. METHODS: We found 43 RCTs from PubMed, MEDLINE, CENTRAL, EMBASE, and CINAHL (until January 2015). A total of 31 studies comparing xenon (841 patients) with other inhaled agents (836 patients) and 12 studies comparing xenon (373 patients) with propofol (360 patients) were found. We evaluated clinical outcomes, such as intraoperative hemodynamics, emergence, and postoperative nausea and vomiting (PONV). RESULTS: Patients undergoing xenon anesthesia had a lower heart rate and higher mean arterial pressure (MAP) intraoperatively than those receiving volatile anesthesia (mean difference = -6 min(-1) [99% confidence interval {99% CI} -10.0 to -2.3]; mean difference = 9 mm Hg [99% CI 3.1-14.4]) and propofol anesthesia (mean difference = -10 min(-1) [99% CI -12.4 to -6.6]; mean difference = 7 mm Hg [99% CI 0.85-13.2]). Compared with baseline, intraoperative MAP remained relatively stable (change < 5.5%, 99% CI within +/- 20% of the baseline) under xenon anesthesia, but MAP decreased by >= 15% under volatile (mean difference = -17 mm Hg [99% CI -29.5 to - 4.9], percentage change = -17.5%) and propofol (mean difference = -14 mm Hg [99% CI -26.1 to -2.5], percentage change = -15.0%) anesthesia. Patients had faster emergence from xenon than from volatile anesthesia: eyes opening (versus all volatile agents: mean 4 vs 7 minutes, percentage change = -49.8% [99% CI -55.1% to -44.0%]), tracheal extubation (versus all volatile agents: mean 4 vs 8 minutes percentage change = -44.6% [99% CI -57.3% to -28.1%]), orientation (versus sevoflurane: mean 5 vs 10 minutes, percentage change = -45.1% [99% CI -58.5% to -28.1%]), countdown (versus sevoflurane: mean 6 vs 10 minutes, percentage change = -41.7% [99% CI -50.3% to -31.6%]; versus isoflurane: mean 6 vs 14 minutes, percentage change = -57.7% [99% CI -65.7% to -48.3%]), and reaction on demand (versus sevoflurane: mean 4 vs 8 minutes, percentage change = -53.2% [99% CI -65.7% to -35.6%]). However, xenon anesthesia increased the risks of PONV (incidence 34.4% vs 19.9%; risk ratio = 1.72 [99% CI 1.10-2.69], risk difference = 0.19 [99% CI 0.04-0.33]). CONCLUSIONS: Xenon anesthesia provides relatively more stable intraoperative blood pressure, lower heart rate, and faster emergence from anesthesia than volatile and propofol anesthesia. However, xenon is associated with a higher incidence of PONV.