Intra-operative oxygen concentration could affect postoperative morbidity-results of a randomised controlled...

The World Health Organisation recommends that all anaesthetised patients receive F_IO₂ 0.8 during surgery to reduce the risk of surgical site infections but did not consider the effect this might have on other clinical outcomes. A Cochrane systematic review concluded that insufficient evidence exists for routinely administering high oxygen concentrations intra-operatively to reduce surgical site infections, and that doing so might increase mortality. A feasibility trial was conducted looking at the feasibility of controlling intra-operative F_IO₂ and measuring systemic redox state. Here we explore further clinical outcomes from this study regarding postoperative complications and cognitive recovery. Twenty-eight adult patients undergoing major abdominal surgery for cancer resection were randomly allocated to receive either conservative (F_IO₂ = 0.3, n = 8), typical (F_IO₂ = 0.55, n = 10) or recommended (F_IO₂ = 0.8, n = 10) oxygen throughout anaesthesia. Rates of radiologically reported atelectasis, cognitive recovery and infective postoperative morbidity were all collected up to 7 days after surgery. Total intensive care unit length of stay was also recorded. Higher F_IO₂ levels were associated with lower rates of atelectasis - 6 (75%) versus 8 (80%) versus 3 (30%) for F_IO₂ = 0.30 versus 0.55 versus 0.80, respectively; p = 0.045. Postoperative cognitive recovery scores (0.7 (3.1) versus -0.1 (2.5) versus -1.8 (3.3), p = 0.277), Postoperative Morbidity Survey infection scores (5 (71%) versus 5 (56%) versus 3 (33%), p = 0.307) and intensive care unit length of stay (3 (2-4) versus 2.5 (2.00-3.75) versus 3 (2.00-5.25) days, p = 0.870) did not differ between groups. Changing the administered intra-operative oxygen concentration may alter postoperative clinical outcomes, and adequately powered clinical studies are urgently needed to investigate the impact of this.