急性肺损伤新生猪不同机械通气治疗对肺泡Ⅱ型上皮细胞的影响

Impact of different mechanical ventilation therapy on alveolar type Ⅱ epithelial cells in neonatal pigs with acute lung injury

目的研究急性肺损伤(ALI)新生猪机械通气治疗对肺泡Ⅱ型上皮细胞(AECⅡ)病理结构的影响。方法选择24只出生3 d左右的新生健康猪,麻醉后均实施相同参数、相同模式的机械通气模式(控制性压力通气),并支气管灌洗9 g/L NaCl进行造模。造模后随机分为4组:对照组,HFOV组、CMV组和PLV组,每组6只。对照组ALI新生猪不实施机械通气,其余3组ALI新生猪分别实施高频振荡通气(HFOV)、常频机械通气(CMV)、部分液体通气(PLV)24 h以观察不同通气模式对ALI新生猪AECⅡ病理结构的影响。所有ALI新生猪机械通气24 h后在过度麻醉下注入60 g/L KCl使其自然死亡,取完整肺脏,制备电镜样本,免疫荧光法观察AECⅡ结构。比较各组相应时间段的血气分析指标:氧合指数(OI)值及PaO_2/FiO_2(P/F)值。结果 HFOV组、CMV组和PLV组机械通气治疗后P/F值、OI值与对照组比较差异无统计学意义(P均>0.05)。免疫荧光图像显示,对照组的AECⅡ呈椭球状,出现局部空泡化,且基质排布较疏松;CMV组AECⅡ形状排布不规整,体积呈变小趋势;HFOV组AECⅡ结构比较规整,没有出现较大空泡化;PLV组AECⅡ排布十分规整,无较大空泡化。HFOV组、CMV组和PLV组的AECⅡ面积、数量和荧光密度与对照组比较差异均有统计学意义(P均<0.05)。PLV组AECⅡ数据明显多于CMV组和HFOV组,且荧光密度也明显高于CMV组(P均<0.05)。结论不同通气方式对AECⅡ影响不同,CMV对AECⅡ损伤最重,PLV对AECⅡ损伤最轻,证明通过适当调整通气方法,可以有效减轻对AECⅡ细胞造成的损伤。

Objective To study the influences of different mechanical ventilation mode on the pathological structure of alveolar epithelial cell type Ⅱ （ AEC Ⅱ） in neonatal pigs with acute lung injury （ALI）. Methods Twenty-four healthy neonatal pigs born about 3 days were selected. In all neonatal pigs, mechanical ventilation of same parameter value and same mode （controlled pressure ventilation） after anesthesia and lavaging 9 g/L NaC1 via bronchi were performed to estab- lish ALI models. After modeling,the ALI neonatal pigs were randomly divided into four groups （n =6 each） ：control group, HFOV group, CMV group and PLV group. In control group, mechanical ventilation was not performed. In HFOV group, CMV group and PLV group, high frequency oscillatory ventilation （ HFOV）, constant frequency mechanical ventilation （ CMV ） and partial liquid ventilation （PLV） for 24 hours were respectively performed to observe the influence of different mechanical ventilation mode on pathological structure of AEC Ⅱ. Under excessive anesthesia,injection of 60 g/L KC1 was given after mechanical ventilation for 24 hours to cause natural death in all ALI neonatal pigs, then whole lung was taken, and electron microscope sample was prepared to observe the changes of AEC H structure with immunofluorescence method. The gas analysis indexes such as oxygenation index （OI） value and arterial oxygen partial pressure/fraction of inspire 02 （ PaO2/ FiO2 ,P/F） value were compared in corresponding time points among four groups. Results The P/F values and OI values after mechanical ventilation therapy in HFOV group, CMV group and PLV group were all similar with control group（ all P 〉 0.05）. After mechanical ventilation treatment, immunofluorescence image displayed that in control group, AEC Ⅱ appeared ellipsoid shape, local cavitation and the matrix of loose arrangement ; in CMV group, AEC Ⅱ appeared irregular shape and ar-rangement and a minifying trend of volume ;in HFOV group, AEC Ⅱ appeared relatively regular structure without larger vac- uolization ;in PLV group, AEC Ⅱ appeared very neat arrangement without larger vacuolization. There were significant differ- ences in AEC Ⅱ area, AEC Ⅱ number and AEC Ⅱ fluorescent density for the comparison of control group with HFOV group, CMV group and PLV group （ all P 〈 0.05 ）. The AEC Ⅱcount in PLV group was significantly higher than that in CMV group and HFOV group, and the fluorescence density was significantly higher than that in CMV group（ all P 〈 0. 05 ）. Conclusion Different ventilation methods have different influences on AEC Ⅱ. The injury of CMV to AEC Ⅱ is the most serious,while the injury of PLV to AEC Ⅱ is the lightest, therefore proper adjustment of ventilation method can effectively reduce the damage to AEC Ⅱ cells.