The Study Of NE Dynamic Changes In Lung Tissues And Blood Of The Severe Brain Injury Rats And Its Significance

Objective:To investigate effects of neutrophil elastase(NE) on acute lung injury(ALI) after the severe brain injury in order to provide the valuable experimental evidence for implementating lung protection of the SBI patients in early time.Methods:â‘ The rat models of severe brain injury were made using an improved Feeney model.â‘¡Sixty male SD rats were randomly divided into five groups:control group(group C,n=8) and experimental group(T₁～T₄,13 for each group).T₁～T₄ groups were sacrificed at 6,24, 48 and 72 hours after SBI,respectively.Group C was fed as usual without any treatment.â‘¢The water content of the brain was calculated by measuring the wet and dry weight of brain tissue.The levels of NE were measured in plasma and BALF by ELISA and the albumin concentration was detected by the immune turbidimetry.The pathological changes of lung tissues were observed by optical microscope and electron microscope.â‘£Statistical analysis was performed using SPSS13.0 statistics software.Results:â‘ The rats in experimental groups became apneic immediately after injury and the breath restored initiatively in a few seconds to a few minutes,then followed by shortness of breath, full-body convulsions,hemiplegia and coma.In the experimental groups,18 percent of rats dyspnea occurred,accompanied by cyanosis at orallips and limbs.Meanwhile,there were some haematodes secretions in their mouth and nasal cavity.The histological changes of the brain tissues showed the signs of the cerebral contusion and laceration,cerebral hemorrhage and edema.The water content of the brain increased significantly,it was statistically significant compared with the group C(P＜0.01).â‘¡Histomorphology,21% lung tissues of rats showed various degrees of hyperemia,edema and focal hemorrhage in experimental groups;45%lung tissues of the rats showed normal structure in the group T₁, 45%mild injury,10%severe injury;in group the T₂～T₄,42～50%lung tissues of of rats showed mild injury,22～29%severe injury in optical microscope.The rats of T₁～T4 showed different levels of pulmonary capillary endothelial cell swelling,telangiectasia, capillary hyperemia,mitochondria swelling,villi disappearing,lamellar body emptying in electron microscope.â‘¢In the group T₁～T₄,the levels of NE in BALF and plasma increased significantly more than the group C(P＜0.01),and The levels of NE in T₂ were highest in all the groups,the group T₃～T4 maintained at a higher level.There was a positive correlation between the NE levels in plasma and BALF(P＜0.01).â‘£The albumin concentration in BALF of T₁ group increased slightly,but it wasn't statistically significant compared with the group C(P＞0.05).The albumin concentration in groups T₂～T₄ increased significantly,it was statistically significant compared with the group C(P＜0.05). There was a positive correlation between the content of NE in BALF,plasma and the albumin concentration of BALF(P＜0.01).There was a positive correlation between the NE levels in plasma,BALF and the water in the brain tissue(P＜0.05,P＜0.01).Conclusion:â‘ Improved Feeney is an ideal way for making severe brain injury.â‘¡There are different levels of lung injury after severe brain injury,the most serious period is 24～72 hours post-injury.â‘¢NE is one of the important reasons of the severe brain damage secondary lung injury,and the relationship is more close between the increasing of NE in lung and lung injury.