Effects Of Different Oxygen Concentrations During General Anesthesia On Lung Function In Patients Undergoing Gastric Surgery

ObjectiveTo observe the preoperative and postoperative changes of lung function test,blood gas analysis,inflammatory factors and other indicators in patients undergoing gastric surgery after inhaling different oxygen concentrations during general anesthesia,and to evaluate the effects of different oxygen concentrations during general anesthesia on lung function of patients undergoing gastric surgery.MethodsNinety patients undergoing elective gastric surgery under general anesthesia in Chifeng Clinical Medical College,Inner Mongolia Medical University from May 2020 to June 2021were selected.They were divided into three groups according to random number table method and given different inhaled oxygen concentration（Fi O₂）respectively:There were 30 patients in group A（40%Fi O₂）,group B（60%Fi O₂）and group C（80%Fi O₂）.Lung function examination was performed on the day before operation and 24 hours after operation for patients in the three groups,and forced vital capacity（FVC）,forced expiratory volume in the first second（FEV₁）and rate in one second（FEV₁/FVC）were recorded.At the beginning and end of surgery,2ml of arterial blood was extracted for blood gas analysis,and oxygenation index（PO₂/Fi O₂）and alveolar-arterial oxygen partial pressure difference（PA-a DO₂）were recorded.At the beginning and end of surgery,4ml of arterial blood was extracted to detect inflammatory factor IL-6.Mean arterial pressure and pulmonary compliance were recorded at the beginning and end of surgery.The preoperative and postoperative changes of all indicators of the patients were compared and statistically analyzed.Results1.Pulmonary function indicators FVC,FEV₁,FEV₁/FVCIntra-group comparison:FVC and FEV₁were compared within the group respectively,and the postoperative and preoperative comparisons of group A,B and C were all decreased,with statistically significant differences（P<0.05）,which meant that no matter what oxygen concentration was set,the two indexes of FVC and FEV₁were both decreased after surgery compared with that before surgery.Comparison between groups:absolute values of preoperative and postoperative differences were taken for comparison between groups,in whichδFEV₁was significantly different between groups（P<0.05）,and the higher the oxygen concentration,the greater theδFEV₁（δFEV₁（group A）<δFEV₁（group B）<δFEV₁（group C））,which means that the higher the oxygen concentration,the more obvious the postoperative decline of FEV₁.2.Blood gas analysis indicators PO₂/Fi O₂,PA-a DO₂Intra-group comparison:Compared with the PO₂/Fi O₂group,PO₂/Fi O₂in groups A,B and C decreased after surgery and before surgery,with statistically significant differences（P<0.05）,which means that no matter what oxygen concentration was set,PO₂/Fi O₂decreased after surgery.Within the PA-a DO₂group,the postoperative and preoperative comparisons of groups A,B and C were all higher,and the differences were statistically significant（P<0.05）,which meant that no matter what oxygen concentration was set,PA-a DO₂was higher after surgery.Comparison between groups:The absolute value of the difference between the preoperative and postoperative PA-a DO₂was taken for comparison between groups.The difference between groups A,B and C was statistically significant（P<0.05）,and theδPA-a DO₂of groups A,B and C showed an increasing trend（δPA-a DO₂（group A）<δPA-a DO₂（group B）<δPA-a DO₂（group C））.This means that the higher the oxygen concentration,the greater the postoperative elevation of PA-a DO₂.3.Inflammatory cytokine IL-6Intra-group comparison:Intra-group comparison of group A,B and C showed A statistically significant increase in postoperative and preoperative comparison（P<0.05）,which meant that IL-6,an inflammatory factor,increased after surgery regardless of the oxygen concentration.Comparison between groups:The absolute value of the difference between preoperative and postoperative groups was taken for comparison between the two groups,δIL-6（group C）andδIL-6（group A）andδIL-6（group B）were significantly increased,and the difference was statistically significant（P<0.05）,but there was no significant difference betweenδIL-6（group A）andδIL-6（group B）（P>0.05）.This means that IL-6 increases most significantly at 80%of oxygen concentrations,and there is no significant difference between 40%and 60%of oxygen concentrations.Conclusion40%oxygen concentration had the least effect on lung function and postoperative inflammation in patients undergoing gastric surgery under general anesthesia.