Effect Of Different Fraction Of Inspired Oxygen On Ventilator-induced Lung Injury In Patients During Prolonged General Anesthesia

Objective:To study the effects of different FiO2(fraction of inspired oxygen)on ventilator-induced lung injury(VILI)in patients during prolonged general anesthesia.Methods:From April 2018 to April 2019,90 patients undergoing lower abdominal surgery during general anesthesia in the First Affiliated Hospital of Suzhou University were assessed,with general anesthesia rated as Ⅰ to Ⅱ by ASA and mechanical ventilation taken from 3 to 5 hours.According to the random number table method,they were divided into three groups,being group A with FiO2 at 30%,group B with FiO2 at 50%,and group C with FiO2 at 80%.SpO2 was recorded respectively 10 minutes before anesthesia(T0),1 hour after mechanical ventilation(T1),3 hours after mechanical ventilation(T2),and 30 minutes after extubation(T3).Radial arterial blood was drawn from patients to measure PaO2(arterial partial pressure of oxygen),in order to calculate OI(oxygenation index,PaO2/FiO2).ELISA(enzyme-linked immunosorbent assay)was used to detect the expression levels of SP-A(surfactant-associated protein A)and CC16(Clara cell protein 16)in plasma at T0,T1,and T2.The incidence of atelectasis was observed by ultrasonography at T0 and T3,then the LUS(lung ultrasound)scores were analyzed.Results:(1)Comparison of oxygenation function:Compared with T0,SpO2 decreased significantly at T3 in three groups and the difference was statistically significant(P<0.05).The OI showed a downward trend with time increasing and the difference was statistically significant(P<0.05).At T2 and T3,OI of group A was significantly higher than that of group B and group C,and the difference was statistically significant(P<0.05).However,there was no significant difference between group B and group C(P>0.05).(2)Comparison of the expression levels of SP-A and CC16 in plasma:Compared with T0,the concentration of SP-A in three groups increased significantly at T2 with statistical significance(P<0.05).The expression level of CC16 in plasma increased significantly at T1 and T2 in all three groups(P<0.05).CC16 concentration in group A at T2 was significantly lower than that in group B and group C,and the difference was statistically significant(P<0.05).However,there was no significant difference between group B and group C(P>0.05).(3)Comparison of lung ultrasonography:Compared with T0,the incidence of atelectasis and LUS scores increased significantly at T3 in three groups and the difference was statistically significant(P<0.05).The incidence of atelectasis in group A(53.3%)was significantly lower than that in group B(80.0%)and group C(86.7%)at T3,the difference was statistically significant(P<0.05).But the difference between group B and group C was not statistically significant(P>0.05).LUS scores was significantly lower in group A(2.27±2.65)than that in group B(5.10±3.43)and group C(6.40±3.36).The difference was statistically significant(P<0.05),however the difference between group B and C was not statistically significant(P>0.05).Conclusion:Compared with 50%FiO2 and 80%FiO2,patients during prolonged mechanical ventilation for 3 to 5 hours with 30%FiO2 can improve oxygenation,reduce lung injury,reduce the incidence of atelectasis,and make less severe.