***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 
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    Input: 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 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 This explicit and strong recommendation has caused considerable concern in the anaesthesia community because it directly contradicts the results of many trials ( and a meta- analysis of those trials ) which showednobenefitof supplemental oxygen . The use of an increased inspired oxygen fraction ( FiO2 ) has a long history in anaesthesia , intensive care , and emergency medicine . Planned induction and extubation of anaesthesia are conducted with 100 % oxygen to enhance safety in the case of airwaydifficulty . Extra oxygen is alsogivenduringgeneral anaesthesia as 21 % is rarely sufficient , with concentrations ranging from 30 % to nearly 100 % depending on case factors and anaesthesiologist preference . There is considerable reason to expect that supplemental oxygen might reduce the risk of surgical site infection [ 21 ] . All surgical wounds become contaminated , and the primary defence against bacterial contamination isoxidativekillingbyneutrophils , a process that requires molecular oxygen and depends on the partial pressureofoxygenintissueovertheentire physiological range . Consistent with this theory , Hopf et al. [ 11 ] showed that surgical wound infection risk was inversely related to tissue oxygenation . Based on these observational data , the Outcomes Research Consortium r and omized 500 patients having colorectal resection to either 80%or30 % inspiredoxygen [ 9 ] . The incidence of SSI was halved from 11.2 AIM An association has been proposed between perioperative administration of 80 % oxygen and a lower incidence of wound infection after colorectal surgery . The present study was conducted to assess this hypothesis . METHODS Thirty-eight patients ( ASA classification 1 and 2 ) undergoing elective colorectal cancer surgery were allocated at r and om to 2 groups . Group 1 consisted of 19 patients who received an admixture of 80 % oxygen and 20 % nitrogen during anesthesia through an orotracheal tube and during the 2 first hours in the recovery room through a tight facemask with reservoir . Group 2 consisted of 19 patients who received an admixture of 70 % nitrous oxide and 30 % oxygen during anesthesia , followed by administration of 30 % oxygen delivered by a blender through a tight facemask with reservoir in the same manner than group 1 , during the first 2 hours in the recovery room . Wound infection was evaluated daily during hospital stay and after 7 days , 2 weeks , and 1 month . RESULTS The incidence of wound infection was 12.5 % in group 1 and 17.6 % in group 2 ( p=0.53 ) . CONCLUSIONS The results of this study showed no reduction in the incidence of wound infection following elective colorectal surgery in patients receiving 80 % oxygen during the perioperative period Background : Benefits and limitations of supplementation with 80 % fraction of inspired oxygen for preventing surgical site infections have not yet been clearly defined . Some studies have reported benefits in colorectal surgery , whereas trials in abdominal and gynecologic surgery have reported either no effect or a deleterious effect . Methods : Controlled , r and omized , assessor-blind multicenter trial , the ISO2 study , comparing the effects of hyperoxygenation ( fraction of inspired oxygen , 80 % ) with those of 30 % oxygen on the frequency of surgical site infections in routine abdominal , gynecologic , and breast surgery on 434 patients . Patients not seen in consultation after discharge were contacted . Results : In total , 208 patients received 30 % perioperative oxygen and 226 received 80 % .  There was no difference between the two groups for baseline , intraoperative , and postoperative characteristics , except for oxygen saturation at closure , higher in the 80 % group ( P = 0.01 ) . The frequency of 30-day surgical site infections was 7.2 % ( 15/208 ) in the 30 % group and 6.6 % ( 15/226 ) in the 80 % group ( relative risk , 0.92 ; 95 % CI [ 0.46–1.84 ] , P = 0.81 ) . Frequency of adverse events ( nausea and vomiting , sternal pain , cough , hypotension ) was similar in the two groups . Desaturation and bradycardia were more frequent in the 30 % group . In an up date d meta- analysis including the result of this trial and those of eight published r and omized trials , the overall relative risk was 0.97 ; 95 % CI ( 0.68–1.40 ) , I2 ( inconsistency degree ) = 73 % , ( P = 0.88 ) . Conclusions : The routine use of hyperoxygenation throughout abdominal , gynecologic , and breast surgery had no effect on the frequency of 30-day surgical site infections and was not accompanied by more frequent adverse effects Background A high perioperative inspiratory oxygen fraction ( FiO2 ) may reduce the frequency of surgical site infection . Perioperative atelectasis is caused by absorption , compression and reduced function of surfactant . It is well accepted , that ventilation with 100 % oxygen for only a few minutes is associated with significant formation of atelectasis . However , it is still not clear if a longer period of 80 % oxygen results in more atelectasis compared to a low FiO2.Our aim was to assess if a high FiO2 is associated with impaired oxygenation and decreased pulmonary functional residual capacity ( FRC ) . Methods Thirty-five patients scheduled for laparotomy for ovarian cancer were r and omized to receive either 30 % oxygen ( n = 15 ) or 80 % oxygen ( n = 20 ) during and for 2 h after surgery . The  oxygenation index ( PaO2/FiO2 )  was measured every 30 min during anesthesia and 90 min after extubation . FRC was measured the day before surgery and 2 h after extubation by a rebreathing method using the inert gas SF6 . Results Five min after intubation , the median PaO2/FiO2 was 69 kPa [ 53 - 71 ] in the 30%-group vs. 60 kPa [ 47 - 69 ] in the 80%-group ( P = 0.25 ) . At the end of anesthesia , the PaO2/FiO2 was 58 kPa [ 40 - 70 ] vs. 57 kPa [ 46 - 67 ] in the 30%- and 80%-group , respectively ( P = 0.10 ) . The median FRC was 1993 mL [ 1610 - 2240 ] vs. 1875 mL [ 1545 - 2048 ] at baseline and 1615 mL [ 1375 - 2318 ] vs. 1633 mL [ 1343 - 1948 ] postoperatively in the 30%- and 80%-group , respectively ( P = 0.70 ) . Conclusion We found no significant difference in oxygenation index or functional residual capacity between patients given 80 % and 30 % oxygen for a period of approximately 5 hours . Trial registration Clinical Trials.gov Identifier : NCT00637936 CONTEXT Use of 80 % oxygen during surgery has been suggested to reduce the risk of surgical wound infections , but this effect has not been consistently identified . The effect of 80 % oxygen on pulmonary complications has not been well defined . OBJECTIVE To assess whether use of 80 % oxygen reduces the frequency of surgical site infection without increasing the frequency of pulmonary complications in patients undergoing abdominal surgery . DESIGN , SETTING , AND PATIENTS The PROXI trial , a patient- and observer-blinded r and omized clinical trial conducted in 14 Danish hospitals between October 2006 and October 2008 among 1400 patients undergoing acute or elective laparotomy . INTERVENTIONS Patients were r and omly assigned to receive either 80 % or 30 % oxygen during and for 2 hours after surgery . MAIN OUTCOME MEASURES Surgical site infection within 14 days , defined according to the Centers for Disease Control and Prevention . Secondary outcomes included atelectasis , pneumonia , respiratory failure , and mortality . RESULTS Surgical site infection occurred in 131 of 685 patients ( 19.1 % ) assigned to receive 80 % oxygen vs 141 of 
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Conclusions The WHO up date d analyses did not show definite beneficial effect of the use of high perioperative FiO2 , overall , but there was evidence of effect of reducing the SSI risk in surgical patients under general anaesthesia with tracheal intubation .