深低温停循环前肺缺血预处理对肺组织的保护作用

Protective effects of lung ischemic preconditioning prior to deep hypothermic circulatory arrest on lung tissues

目的探讨肺缺血预处理在深低温停循环(DHCA)中对肺组织的保护作用。方法 18只幼猪随机根据DHCA前预处理方式分为缺血预处理组(n=6)、联合预处理组(缺血缺氧预处理,n=6)和对照组(不予预处理,n=6)。检测三组体外循环前和体外循环结束即刻(体外循环后)肺静态顺应性、肺血管阻力指数、肺湿干质量比以及左心房与肺动脉肿瘤坏死因子α(TNF-α)、白介素(IL)8、10(IL-8、IL-10)浓度比值(TNF-α、IL-8、IL-10相对含量);取左下肺叶组织,HE染色光学显微镜观察肺组织水肿和炎症细胞浸润情况。结果体外循环前三组间各项指标比较差异无统计学意义;体外循环后,联合预处理组肺静态顺应性高于其他两组(P<0.05);缺血预处理组、联合预处理组肺血管阻力指数和IL-8、IL-10相对含量以及联合预处理组的肺湿干质量比均显著小于对照组(P<0.05)。与体外循环前比较,体外循环后三组肺静态顺应性降低,肺湿干质量比显著增大,TNF-α、IL-8、IL-10相对含量增加(均P<0.05);对照组和缺血预处理组肺血管阻力指数增加(P<0.05),而联合预处理组体外循环前后肺血管阻力指数比较差异无统计学意义(P>0.05)。组织学观察显示,与对照组和缺血预处理组相比,联合预处理组肺组织水肿和白细胞浸润程度较轻。结论肺缺血预处理可减轻DHCA缺血再灌注对肺组织的损伤。与单纯肺缺血预处理相比,肺缺血联合缺氧预处理对肺组织保护作用更佳。

Objective To investigate the protective effects of lung ischemic preconditioning in deep hypothermic circulatory arrest （DHCA） on lung tissues. Methods Eighteen piglets were randomly divided into ischemic preconditioning group （n=6）, joint preconditioning group （ischemic and anoxemic preconditioning, n=6） and control group （no preconditioning, n=6）. Values of lung static compliance, pulmonary vascular resistance index, lung wet weight to dry weight ratio and left atrium to pulmonary artery ratios of plasma tumor necrosis factor-α （TNF-α）, interleukin （IL）-8 and IL-10 levels （relative contents of TNF-α, IL-8 and IL-10） before and after cardiopulmonary bypass were measured in each group, and lung tissues were harvested for observations of pulmonary edema and inflammatory cell infiltration under light microscopy with HE staining. Results There was no significant difference in each parameter among groups before cardiopulmonary bypass. After cardiopulmonary bypass, lung static compliance of joint preconditioning group was higher than that of the other two groups （P〈0.05）, pulmonary vascular resistance index and relative contents of IL-8 and IL-10 in ischemic preconditioning group and joint preconditioning group, and lung wet weight to dry weight ratio in joint preconditioning group were significantly lower than those of control group （P〈0.05）. Compared with those before cardiopulmonary bypass, lung static compliance decreased, lung wet weight to dry weight ratio increased, and relative contents of TNF-α, IL-8 and IL-10 increased in three groups after cardiopulmonary bypass （P〈0.05 for all）, and pulmonary vascular resistance index increased in control group and ischemic preconditioning group （P〈0.05）, while there was no significant difference in pulmonary vascular resistance index before and after cardiopulmonary bypass in joint preconditioning group （P〉0.05）. Histological observations indicated that the pulmonary edema and inflammatory cell infiltration in joint preconditioning group were less severe than those in the other two groups. Conclusion Lung ischemic preconditioning may reduce ischemic reperfusion injury during DHCA, and lung ischemic and anoxemic preconditioning may yield better protective effects than single ischemic preconditioning.