Effect of continuous administration of low-medium flow oxygen for non-ventilated lung during one lung ventilation surgery on blood gas analysis and oxidative stress response in lung tissue of tumor patient：A randomized controlled trial

Background: One-lung ventilation (OLV) induces hypoxia during the operation and oxidative stress to the non-ventilated lung (NVL) which may cause acute lung injury (ALI). Aims: We sought to find out whether continuous administration of low-medium flow oxygen for NVL during OLV can mitigate the oxidative stress in lung tissue of patient. Methods: After local Ethics Committee approval and informed consent, we randomly allocated fifty-seven patients scheduled for elective pulmonary tumor resection. The F14 tube was placed at 2-3cm beyond the carina of trachea in the NVL at the time of the beginning of the OLV in group O, administrating continuously with oxygen. Blood samples were taken from radial artery and internal jugular vein simultaneously for blood gas analysis, immediately after induction of anesthesia (T 1 ), 30min (T 2 ), 1h (T 3 ) and 2h (T 4 ) after OLV. Lung tissue was taken 5cm distant from the tumor for determination of superoxide dismutase(SOD) and malondialdehyde(MDA), and expression of heme oxygenase-1(HO-1) . Result: Compared with group C, the PaO 2 was significantly increased at T 2-4 and the PaCO 2 was significantly decreased at T 2,3 , the PvO 2 was significantly increased at T 2,3 and the PvCO 2 was significantly decreased at T 2-4 , the lung concentration of MDA was significantly lower and the local expression level of HO-1 in lung was significantly elevated in group O （ P <0.05）. Conclusion: The administration of continuous low-medium flow oxygen for NVL during OLV has shown the effect of pulmonary protection. The possible mechanism is related with the inhibition of the oxidative stress response in lung tissue.