Background: Intraoperative high inspired oxygen fraction (FIo 2 ) is thought to reduce the incidence of surgical site infection (SSI) and postoperative nausea and vomiting, and to promote postoperative atelectasis. Methods: The authors searched for randomized trials (till September 2012) comparing intraoperative high with normal FIo 2 in adults undergoing surgery with general anesthesia and reporting on SSI, nausea or vomiting, or pulmonary outcomes. Results: The authors included 22 trials (7,001 patients) published in 26 reports. High FIo 2 ranged from 80 to 100% (median, 80%); normal FIo 2 ranged from 30 to 40% (median, 30%). In nine trials (5,103 patients, most received prophylactic antibiotics), the incidence of SSI decreased from 14.1% with normal FIo 2 to 11.4% with high FIo 2 ; risk ratio, 0.77 (95% CI, 0.59-1.00). After colorectal surgery, the incidence of SSI decreased from 19.3 to 15.2%; risk ratio, 0.78 (95% CI, 0.60-1.02). In 11 trials (2,293 patients), the incidence of nausea decreased from 24.8% with normal FIo 2 to 19.5% with high FIo 2 ; risk ratio, 0.79 (95% CI, 0.66-0.93). In patients receiving inhalational anesthetics without prophylactic antiemetics, high FIo 2 provided a significant protective effect against both nausea and vomiting. Nine trials (3,698 patients) reported on pulmonary outcomes. The risk of atelectasis was not increased with high FIo 2 . Conclusions: Intraoperative high FIo 2 further decreases the risk of SSI in surgical patients receiving prophylactic antibiotics, has a weak beneficial effect on nausea, and does not increase the risk of postoperative atelectasis. IT has been claimed that patients undergoing surgery with general anesthesia were benefiting from a higher than normal inspired oxygen fraction (FIo 2 ).1,2 Some authors have suggested that a high FIo 2 was a simple, inexpensive, and lowrisk intervention, and that the broader use of this technique should be encouraged in patients undergoing major abdominal procedures.3 Randomized trials have reported on a reduced risk of surgical site infection (SSI) in patients who were ventilated with 80% FIo 2 during surgery. 4,5 It was also shown that patients who were ventilated with high FIo 2 intraoperatively had a reduced incidence of postoperative nausea and vomiting (PoNV). 6,7 other authors were more cautious. 8,9 Skepticism has been partly related to the fact that high FIo 2 may have deleterious What This Article Tells Us That Is New• Intraoperative high inspired oxygen fraction decreases the risk of surgical site infection in surgical patients receiving prophylactic antibiotics, has a weak beneficial effect on nausea, and does not increase the risk of postoperative atelectasis

The effect of ketamine on postoperative delirium remains unclear but its administration may offer some protection towards POCD. Large, well-designed randomised trials are urgently needed to further clarify the efficacy of ketamine on neurocognitive outcomes.

BACKGROUND Blood transfusions are associated with morbidity and mortality. However, restrictive thresholds could harm patients less able to tolerate anemia. Using a context-specific approach (according to patient characteristics and clinical settings), the authors conducted a systematic review to quantify the effects of transfusion strategies. METHODS The authors searched MEDLINE, EMBASE, CENTRAL, and grey literature sources to November 2015 for randomized controlled trials comparing restrictive versus liberal transfusion strategies applied more than 24 h in adult surgical or critically ill patients. Data were independently extracted. Risk ratios were calculated for 30-day complications, defined as inadequate oxygen supply (myocardial, cerebral, renal, mesenteric, and peripheral ischemic injury; arrhythmia; and unstable angina), mortality, composite of both, and infections. Statistical combination followed a context-specific approach. Additional analyses explored transfusion protocol heterogeneity and cointerventions effects. RESULTS Thirty-one trials were regrouped into five context-specific risk strata. In patients undergoing cardiac/vascular procedures, restrictive strategies seemed to increase the risk of events reflecting inadequate oxygen supply (risk ratio [RR], 1.09; 95% CI, 0.97 to 1.22), mortality (RR, 1.39; 95% CI, 0.95 to 2.04), and composite events (RR, 1.12; 95% CI, 1.01 to 1.24-3322, 3245, and 3322 patients, respectively). Similar results were found in elderly orthopedic patients (inadequate oxygen supply: RR, 1.41; 95% CI, 1.03 to 1.92; mortality: RR, 1.09; 95% CI, 0.80 to 1.49; composite outcome: RR, 1.24; 95% CI, 1.00 to 1.54-3465, 3546, and 3749 patients, respectively), but not in critically ill patients. No difference was found for infections, although a protective effect may exist. Risk estimates varied with successful/unsuccessful transfusion protocol implementation. CONCLUSIONS Restrictive transfusion strategies should be applied with caution in high-risk patients undergoing major surgery.