The Effects of Intraoperative Oxygen used at Different Concentrations on Oxidative Stress Markers: A Randomized Prospective Study

Aim: In the case of hypoxia, despite the definite benefit of oxygen (O 2 ) administration, there is controversial evidence regarding the risk/benefit balance of high concentration O 2 inhalation during surgery as a precaution in those not previously hypoxic.The purpose of this study was to determine the effect of inspiratory O 2 (FiO 2 ) administered at different concentrations on oxidative stress during general anesthesia.Methods: This randomized prospective study was conducted from February to May 2021.According to intraoperative FiO 2 , the patients were divided into two groups: 50% FiO 2 (group 1) and 30% FiO 2 (group 2).Blood samples taken before preoxygenation and at the end of surgery were used to assess arterial partial O 2 pressure (PaO 2 ), total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI). Results:The study was completed with 40 patients.Intragroup plasma TOS, OSI, and PaO 2 levels increased significantly at the end of surgery (group 1 p=0.003,0.003, <0.001, and group 2 p=0.002, 0.044, 0.002) and TAS levels decreased (p<0.001 in both groups) were found.Because of intergroup surgery, TAS, TOS, and PaO 2 levels were higher in group 1 than in group 2 (respectively p=0.002, 0.002, <0.001). Conclusion:Since the use of high concentrations of O 2 (50%) causes a significant increase in oxidative stress, we think that it is important to use lower concentrations of O 2 in the intraoperative period in suitable patients.More research is urgently needed on perioperative O 2 therapy.