***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Tissue oxygenation is a strong predictor of surgical site infection . Improving tissue oxygenation should thus reduce wound infection risk . Supplemental inspired oxygen can improve tissue oxygenation , but whether it reduces infection risk remains controversial . Low-dose dexamethasone is often given to reduce the risk of postoperative nausea and vomiting , but steroid-induced immunosuppression can increase infection risk . We therefore tested the hypotheses that supplemental perioperative oxygen reduces infection risk and that dexamethasone increases it . METHODS Using a factorial design , patients having colorectal resections expected to last ≥2 h were r and omly assigned to 30 % ( n=270 ) or 80 % ( n=285 ) inspired oxygen during and for 1 h after surgery , and to 4 mg intraoperative dexamethasone ( n=283 ) or placebo ( n=272 ) . Physicians blinded to group assignments evaluated wounds postoperatively , using US Centers for Disease Control criteria . RESULTS Subject and surgical characteristics were similar among study groups . Surgical site infection incidence was similar among groups : 30 % oxygen 15.6 % , 80 % oxygen 15.8 % ( P=1.00 ) ; dexamethasone 15.9 % , placebo 15.4 % , ( P=0.91 ) . CONCLUSIONS Supplemental oxygen did not reduce surgical site infection risk . The preponderance of clinical evidence suggests that administration of 80 % supplemental inspired oxygen does not reduce infection risk . We did not observe an increased risk of surgical site infection with the use of a single low dose of dexamethasone , indicating that it can be used for nausea and vomiting prophylaxis without promoting wound infections . CLINICAL TRIAL REGISTRATION Clinical Trials.gov number : NCT00273377 Background — Oxygen is commonly administered to patients with ST-elevation – myocardial infa rct ion despite previous studies suggesting a possible increase in myocardial injury as a result of coronary vasoconstriction and heightened oxidative stress . Methods and Results — We conducted a multicenter , prospect i ve , r and omized , controlled trial comparing oxygen ( 8 L/min ) with no supplemental oxygen in patients with ST-elevation – myocardial infa rct ion diagnosed on paramedic 12-lead ECG . Of 638 patients r and omized , 441 patients had confirmed ST-elevation – myocardial infa rct ion and underwent primary end-point analysis . The primary end point was myocardial infa rct size as assessed by cardiac enzymes , troponin I , and creatine kinase . Secondary end points included recurrent myocardial infa rct ion , cardiac arrhythmia , and myocardial infa rct size assessed by cardiac magnetic resonance imaging at 6 months . Mean peak troponin was similar in the oxygen and no oxygen groups ( 57.4 versus 48.0 & mgr;g/L ; ratio , 1.20 ; 95 % confidence interval , 0.92–1.56 ; P=0.18 ) . There was a significant increase in mean peak creatine kinase in the oxygen group compared with the no oxygen group ( 1948 versus 1543 U/L ; means ratio , 1.27 ; 95 % confidence interval , 1.04–1.52 ; P=0.01 ) . There was an increase in the rate of recurrent myocardial infa rct ion in the oxygen group compared with the no oxygen group ( 5.5 % versus 0.9 % ; P=0.006 ) and an increase in frequency of cardiac arrhythmia ( 40.4 % versus 31.4 % ; P=0.05 ) . At 6 months , the oxygen group had an increase in myocardial infa rct size on cardiac magnetic resonance ( n=139 ; 20.3 versus 13.1 g ; P=0.04 ) . Conclusion — Supplemental oxygen therapy in patients with ST-elevation – myocardial infa rct ion but without hypoxia may increase early myocardial injury and was associated with larger myocardial infa rct size assessed at 6 months . Clinical Trial Registration — URL : http://www . clinical trials.gov . Unique identifier : NCT01272713 BACKGROUND Administration of supplemental oxygen in the perioperative period is controversial , as it may increase long-term mortality . Our aim was to assess the association between 80 % oxygen and occurrence of subsequent cancer in patients undergoing abdominal surgery in a post hoc analysis of the PROXI trial . METHODS The 1386 patients in the PROXI trial underwent elective or emergency laparotomy between 2006 and 2008 with r and omization to either 80 % or 30 % oxygen during and for 2 h after surgery . We retrieved follow-up status regarding vital status , new cancer diagnoses , and new histological cancer specimens . Data were analysed using the Cox proportional hazards model . RESULTS Follow-up was complete in 1377 patients ( 99 % ) after a median of 3.9 yr . The primary outcome of new cancer diagnosis or new malignant histological specimen occurred in 140 of 678 patients ( 21 % ) in the 80 % oxygen group vs 150 of 699 patients ( 21 % ) assigned to 30 % oxygen ; hazards ratio 1.06 [ 95 % confidence interval ( CI ) 0.84 , 1.34 ] , P=0.62 . Cancer-free survival was significantly shorter in the 80 % oxygen group ; hazards ratio 1.19 ( 95 % CI 1.01 , 1.42 ) , P=0.04 , as was the time between surgery and new cancer , median 335 vs. 434 days in the 30 % oxygen group . In patients with localized disease , non-significant differences in cancer and cancer-free survival were found with hazard ratios of 1.31 and 1.29 , respectively . CONCLUSIONS Although new cancers occurred at similar rate , the cancer-free survival was significantly shorter in the 80 % oxygen group , but this did not appear to explain the excess mortality in the 80 % oxygen group . CLINICAL TRIAL REGISTRATION Clinical Trials.gov ( NCT01723280 ) Background The role of supplemental oxygen therapy in the healing of colorectal anastomosis is still very much at an experimental stage . The aim of the present study , prospect i ve r and omized , was to assess the effect of administration of perioperative supplemental oxygen therapy on infraperitoneal anastomosis , where the risk of leakage is higher STUDY OBJECTIVE To assess the efficacy of intraoperative inspired oxygen fractions ( FIO(2 ) ) of 0.8 and 0.5 when compared with st and ard FIO(2 ) of 0.3 in the prevention of postoperative nausea and vomiting ( PONV ) . DESIGN Prospect i ve , r and omized , double-blinded , controlled study . SETTING General hospital , postanesthesia care unit ( PACU ) , and gynecology floor room . PATIENTS 120 ASA physical status I and II women , aged 21 to 76 years , undergoing elective gynecologic laparoscopic surgery . INTERVENTIONS Patients were r and omized to receive a gas mixture of 30 % oxygen in air ( FIO(2 ) = 0.3 , Group G30 ) , 50 % oxygen in air ( FIO(2 ) = 0.5 , Group G50 ) , or 80 % oxygen in air ( FIO(2 ) = 0.8 , Group G80 ) ; there were 36 patients in each group . A st and ardized sevoflurane general anesthesia , postoperative pain management , and antiemetic regimen were used . MEASUREMENTS Frequency of nausea , vomiting , and both was assessed for early ( 0 to two hrs ) and late PONV ( two to 24 hrs ) , along with use of rescue antiemetic , degree of nausea , and severity of pain . MAIN RESULTS There was no overall difference in the frequency of PONV at the early and late assessment periods among the three groups . G80 patients had significantly less vomiting than Group G30 at two hours , 3 % ( 1/36 ) vs. 22 % ( 8/36 ) , respectively , P = 0.028 . Nausea scores , rescue antiemetic use , pain scores , and opioid consumption did not differ among the groups . CONCLUSION High intraoperative FIO(2 ) of 0.8 and FIO(2 ) of 0.5 do not prevent PONV in patients without antiemetic prophylaxis . An intraoperative FIO(2 ) of 0.8 has a beneficial effect on early vomiting only BACKGROUND Perioperative supplemental oxygen has been proposed to decrease the incidence of surgical site infection ( SSI ) in colorectal surgery with controversial results . We have assessed the influence of hyperoxygenation on SSI by using the most homogeneous study population . METHODS We studied , in a prospect i ve r and omized study , 81 patients , who underwent elective open infraperitoneal anastomosis for rectal cancer . Patients were assigned r and omly to an oxygen/air mixture with a fraction of inspired oxygen ( FiO2 ) of 30 % ( n = 41 ) or 80 % ( n = 40 ) . Administration was commenced after induction of anesthesia and maintained for 6 hours after surgery . RESULTS The overall wound infection rate was 21 % : 11 patients ( 26.8 % ) had wound infections in the 30 % FiO2 group and 6 ( 15 % ) in the 80 % FiO2 group ( P < .05 ) . The risk of SSI was 41 % lower in the 80 % FiO2 group . CONCLUSION Supplemental 80 % FiO2 reduced postoperative SSI with few risks to the patient and little associated cost OBJECTIVE The purpose of this study was to investigate whether supplemental oxygen during and for 2 hours after cesarean delivery reduces the incidence of postcesarean infectious morbidity . STUDY DESIGN We conducted a r and omized , controlled trial from 2008 - 2010 . Women who underwent cesarean delivery were r and omly assigned to receive either 2 L of oxygen by nasal cannula during cesarean delivery only ( st and ard care ) or 10 L of oxygen by nonrebreather mask ( intervention group ) during and for 2 hours after cesarean delivery .  Women who underwent scheduled or intrapartum cesarean delivery were eligible and were observed for 1 month after the procedure . The primary composite outcome was maternal infectious morbidity , which included endometritis and wound infection . RESULTS Five hundred eighty-five women were included in the final analysis .  Infectious morbidity occurred in 8.8 % of patients in the st and ard care group and in 12.2 % of patients in the supplemental oxygen group . There was no significant difference in the rate of infectious morbidity between the st and ard care and intervention groups ( relative risk , 1.4 ; 95 % confidence interval , 0.9 - 2.3 ) . CONCLUSION Supplemental oxygen does not reduce the rate of postcesarean delivery infectious morbidity , including endometritis and wound infection BACKGROUND : There is a plausible pathophysiologic rationale for increased long-term cardiovascular morbidity and mortality in patients receiving significant exposure to nitrous oxide .  However , this relationship has not been established clinical ly . The ENIGMA trial r and omized 2050 patients having noncardiac surgery lasting more than 2 hours to nitrous oxide – based or nitrous oxide – free anesthesia .  We conducted a follow-up study of the ENIGMA patients to evaluate the risk of cardiovascular events in the longer term . METHODS : The trial case report forms and medical records of all study patients were review ed . The date and cause of death and occurrence of myocardial infa rct ion or stroke were recorded . A telephone interview was then conducted with all surviving patients . The primary endpoint of the study was survival . RESULTS : The median follow-up time was 3.5 ( range : 0 to 5.7 ) years . Three hundred eighty patients ( 19 % ) had died since the index surgery , 91 ( 4.5 % ) were recorded as having myocardial infa rct ion , and 44 ( 2.2 % ) had a stroke during the entire follow-up period . Nitrous oxide did not significantly increase the risk of death [ hazard ratio = 0.98 ( 95 % confidence interval , CI : 0.80 to 1.20 ; P = 0.82 ) ] . The adjusted odds ratio for myocardial infa rct ion in patients administered nitrous oxide was 1.59 ( 95 % CI : 1.01 to 2.51 ; P = 0.04 ) and for stroke was 1.01 ( 95 % CI : 0.55 to 1.87 ; P = 0.97 ) . CONCLUSIONS : The administration of nitrous oxide was associated with increased long-term risk of myocardial infa rct ion , but not of death or stroke in patients enrolled in the ENIGMA trial . The 
    Output:
    
As the risk of adverse events , including mortality , may be increased by a fraction of inspired oxygen of 60 % or higher , and as robust evidence is lacking for a beneficial effect of a fraction of inspired oxygen of 60 % or higher on surgical site infection , our overall results suggest that evidence is insufficient to support the routine use of a high fraction of inspired oxygen during anaesthesia and surgery .