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 (PaO2), total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI). Results: The study was completed with 40 patients. Intragroup plasma TOS, 051, and PaO2 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 PaO2 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.