氦氧机械通气对兔急性肺损伤模型的肺组织炎性反应和细胞凋亡的影响

目的：观察氦氧机械通气对盐酸所致兔急性肺损伤（acute lung injury,ALI）模型的肺组织炎性反应和肺泡上皮细胞凋亡的影响.方法：按照随机数字表法将20只健康新西兰家兔随机分为4组,空白对照组（N组）、模型组（M组）、空氧组（空气氧气混合组,O组,N2∶O2=1∶1）、氦氧组（H组,He∶O2=1∶1）,每组5只.N组仅行气管切开、机械通气,其余3组采用气管内灌注稀盐酸的方法建立ALI模型,N、M组给予空气通气,O、H组给予相应气体通气.通气治疗4h后处死家兔.分别于初始（气管插管）、模型建立、通气治疗4h3个时间点记录各组家兔气道峰压、胸肺总顺应性、动脉血气变化.在光学显微镜下观察肺组织的病理学改变,采用TUNEL法检测肺组织细胞凋亡率.结果：初始各组气道峰压、胸肺总顺应性、PaO2、PaCO2差异无统计学意义;模型建立后,与N组比较,M、O和H组的气道峰压升高,胸肺总顺应性、PaO2下降（P＜0.05）,PaCO2差异无统计学意义（P＞0.05）;通气4h后,H组气道峰压较M组和O组下降、胸肺总顺应性上升（P＜0.05）,但PaO2、PaCO2差异无统计学意义（P＞0.05）;与N组比较,M、O和H组的肺组织细胞凋亡指数升高（P＜0.05）,但M、O和H组细胞凋亡指数差异无统计学意义（P＞0.05）;病理结果提示,H组肺组织血管和（或）肺泡腔内的炎性渗出明显轻于O组.结论：氦氧机械通气能降低兔ALI模型的气道峰压,改善胸肺总顺应性,减轻肺组织的炎性渗出,但对PaO2、PaCO2及肺泡上皮细胞凋亡的改善不明显.

Effects of Helium-Oxygen Mechanical Ventilation on Inflammation and Lung Cell Apoptosis in Rabbits with Acute Lung Injury

Objective：To investigate the effects of helium-oxygen（heliox） mechanical ventilation on inflammation and lung cell apoptosis in rabbits with acute lung injury（ALI） induced by hydrochloric acid.Methods：A total of 20 healthy New Zealand rabbits were randomly divided into four groups according to random number table with 5 rabbits in each group.Rabbits in control group（Group N） underwent tracheotomy and ventilation.ALI was induced in rabbits of the other 3 groups by intra-tracheal instillation of diluted hydrochloric acid solution.Then rabbits in Group N and Group M were ventilated with air,while those in Group O were given air-oxygen （N2 ∶ O2 =1 ∶ 1） and those in Group H were given heliox （He ∶ O2 =1 ∶ 1）.All groups were volume-controlled ventilated.The rabbits were sacrificed after ventilation treatment for 4 h.The changes of airway peak pressure,lung-thorax compliance and arterial blood gases in all groups were recorded at three time points（the start of the experiment,the establishment of model and ventilation 4 h）.All lungs of the rabbits were excised for both histopathological examination and TUNEL test.Results：There were no statistically prominent differences in airway peak pressure,lung-thorax compliance,PaO2 and PaCO2 among four groups at the start of the experiment.After the establishment of the model,the airway peak pressure increased but lung-thorax compliance and PaO2 decreased in Group M,O and H,compared with group N,and the differences were statistically significant （P＜0.05）.However,There were no obvious differences in PaCO2 among the four groups（P＞0.05）.The airway peak pressure decreased and lung-thorax compliance increased prominently in Group H compared with those in Group M and Group O after ventilation 4 h,and the differences were statistically significant（P＜0.05）,but there were no significant differences in PaO2 and PaCO2 among them（P＞0.05）.Gompared with Group N,lung cell apoptosis index increased in Group M,O and H,and the differences were significant（P＜0.05）,while the differences among Group M,O and H were not statistically significant（P＞0.05）.Histopathological examination suggested that the inflammatory exudation in the perivascular and/or intra-alveolar areas in Group H was less than that in Group O.Conclusions：Treatment with heliox mechanical ventilation can decrease the airway peak pressure and inflammatory exudation of lung tissues,and increase lung-thorax compliance in rabbits ALI model,but it can not effectively improve lung cell apoptosis,PaO2 and PaCO2.