The experimental study on secondary lung injury by aspiration in severe brain injury rats

Objective:To investigate gastric aspiration induced lung injury in severe brain injury.Methods:50 male SD rats were randomly divided into control group(n=10) and experimental group(n=40).The severe brain injury in experimental group was made by an improved method of Marmarou model,and then the aspiration models were made by intratracheal instillation of gastric juice.Each ten rats were killed to collect samples at 2 h,6 h,24 h and 48 h separately after the models were made.Plasma neutrophil elastase(Neutrophil Elastase,NE) content,the NE content and interleukin-8(IL-8) content in bronchoalveolar lavage fluid(BALF) were detected by using enzyme-linked immunosorbent assay(ELISA);immune turbidimetric determination was used for the albumin concentration in BALF;and optical microscope for pathological changes in lung tissue.Results:BALF and plasma NE levels began to increase at 2 h,which was significant compared with the control group(P0.05).NE in BALF increased at a significantly higher rate than in plasma;IL-8 level in BALF began to increase at 2h,and meanwhile,BALF albumin concentration was significantly increased(P0.05);NE,IL-8 in BALF and albumin concentration had positive correlation(P0.01).Conclusion:Aspiration after severe brain injury can cause inflammation in lung tissue,and NE and IL-8 take part in pulmonary inflammatory response,resulting in lung injury.