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目的探讨不同潮气量机械通气在大鼠急性肺损伤发生中的作用。方法32只Wistar大鼠随机分为对照组、小潮气量组、常规潮气量组和大潮气量组。分别在肉眼、光镜和电镜下观察各组大鼠肺组织病理学改变,测定动脉血气和BALF中性粒细胞计数(PMN)、蛋白含量和髓过氧化物酶(MPO)活性。结果小潮气量组肺组织在肉眼、光镜和电镜下观察与对照组比较差异无显著性；常规潮气量和大潮气量组肺组织在光镜和电镜下可观察到具有不同程度损伤改变,其BALF中PMN、MPO活性和蛋白含量均明显高于对照组和小潮气量组,而动脉血氧分压(PaO_2)明显低于对照组和小潮气量组(P＜0．01,P＜0．05)；大潮气量组BALF中MPO活性和蛋白含量与常规潮气量组比较差异也有显著性(P＜0．01)；小潮气量组各项指标与对照组比较差异均无统计学意义(P＞0．05)。结论小潮气量通气对正常肺组织无明显影响,但没有任何肺保护措施的常规潮气量通气对正常肺组织具有一定损伤作用,其损伤作用与中性粒细胞在肺内募集和活化有密切关系。
Objective To investigate the effect of different tidal volume mechanical ventilation on acute lung injury in rats. Methods Thirty-two Wistar rats were randomly divided into control group, small tidal volume group, conventional tidal volume group and large tidal volume group. The pathological changes of the lungs of the rats in each group were observed under naked eyes, light microscope and electron microscope respectively. The blood gas and BALF neutrophil count (PMN), protein content and myeloperoxidase (MPO) activity were measured. Results Compared with the control group, the lung tissue in the low tidal volume group showed no significant difference under the naked eye, light microscope and electron microscope. The lung tissue of the normal tidal volume and the large tidal volume group were observed to have varying degrees of damage under light and electron microscopy. The BALF PMO, MPO activity and protein content were significantly higher than the control group and the small tidal volume, while PaO_2 was significantly lower than the control group and the small tidal volume (P <0.01, P <0.05) There were also significant differences in MPO activity and protein content in BALF between the high tidal volume group and the normal tidal volume group (P <0.01). There was no significant difference between the low tidal volume group and the control group (P> 0.05). 05). Conclusion Small tidal volume ventilation has no obvious effect on normal lung tissue. However, conventional tidal volume ventilation without any protective measures of lung has a certain damage effect on normal lung tissue. The injury is closely related to recruitment and activation of neutrophils in the lung.