Intra-operative high inspired oxygen fraction does not increase the risk of postoperative respiratory complications Alternating intervention clinical trial

BACKGROUND The WHO recommends routine intra-operative and early postoperative use of high inspired oxygen concentrations (hyperoxia). However, a high intra-operative inspired oxygen fraction (FiO(2)) might result in an increased risk of postoperative respiratory complications. AIM To test the hypothesis that intra-operative FiO(2) of 80% compared with 30% inspired oxygen decreases the postoperative ratio of arterial saturation to fraction of inspired oxygen (SpO(2)/FiO(2)). Secondarily, to evaluate whether an intra-operative inspired FiO(2) of 80% increases the incidence of pulmonary complications. DESIGN Posthoc subanalysis of a large alternating cohort trial. SETTING Cleveland Clinic, Cleveland, United States, from 2013 to 2016. PATIENTS Adults having colorectal surgery. Cases lasting less than 2 h, re-operations on the same hospitalisation, and cases with missing intra-operative or postoperative data were excluded. INTERVENTION Maintaining intra-operative FiO(2) at 30 or 80% and alternating this management every 2 weeks for a study period of 39 months. MAIN OUTCOME Minimal SpO(2)/FiO(2) ratio value in the postanaesthesia care unit. Secondary outcome was a composite of postoperative pulmonary complications throughout hospitalisation. RESULTS A total of 5056 patients were included. Groups were well balanced on all demographic, baseline and procedural variables. Median time-weighted averages of intraoperative FiO(2) in the 30 and 80% groups were 43% (IQR 38 to 54%, N = 2486) and 81% (IQR 78 to 82%, N = 2570), respectively. No difference was found in the lowest SpO(2)/ FiO(2) ratio (estimated median difference 0 [95% confidence interval: 0, 0], P = 0.91). The incidence of postoperative pulmonary complications was 16.3 and 17.6% in the 30 and 80% FiO(2) groups, respectively (relative risk 1.07 [ 95% confidence interval: 0.95, 1.21], P - 0.25). CONCLUSION Intra-operative hyperoxia did not change the postoperative SpO(2)/FiO(2) ratio or the risk for pulmonary complications. Clinicians should not refrain from using hyperoxia for fear of provoking respiratory complications.