目的 研究短时间机械通气对不同程度脓毒症大鼠膈肌功能的影响。方法 实验分组： SHAM 组、CLP50%组、CLP50%+MV6h 组、CLP75%组、CLP75%+MV6h 组；生物信号采集系统检测膈肌收缩 力和复合肌肉动作电位（compound muscle action potential，CMAP）；HE 染色观察肌纤维横截面积（cross⁃sec⁃ tion area，CSA）；TUNEL 法检测细胞凋亡；ELISA 检测血清炎症因子水平；Western blot 法检测肌肉萎缩相关蛋白表达。结果 CLP50%+MV6h 组与 CLP50%组比较，膈肌收缩力下降，血清 IL⁃6 水平及萎缩相关蛋白 水平增高。CLP75%+MV6h 组与 CLP75%组比较，CMAP 幅值降低，时长延长；收缩力降低，CSA 减少，炎症 因子水平增加，萎缩相关蛋白水平增高。与 CLP50%+MV6h 组相比，CLP75%+MV6h 组 CMAP 幅值降低，时 长增加；收缩力降低，CSA 减小，炎症因子水平及萎缩相关蛋白表达升高，凋亡指数增加。结论 短时间 机械通气可引起脓毒症大鼠膈肌功能障碍，并随着脓毒症程度增加，膈肌功能障碍越明显。

Objective To study the effect of short⁃duration mechanical ventilation on the function of the dia⁃ phragm in rats with different degrees of sepsis. Methods Experimental groups included SHAM group，CLP50% group，CLP50%+MV6h group，CLP75% group and CLP75%+MV6h group. Biological signal acquisition system was used to detect diaphragm contraction force and compound muscle action potential（CMAP）；HE staining was used to observe muscle fiber cross⁃sectional area（CSA）；TUNEL method was adopted to detect apoptosis；ELISA was used to detect serum inflammatory factors；the expression of muscle atrophy⁃related proteins was detected by Western blot. Results In the CLP50%+MV6h group，compared with the CLP50% group，diaphragm contractility was decreased， and serum IL ⁃6 levels and atrophy ⁃ related protein levels were increased. In the CLP75%+MV6h group，compared with the CLP75% group，CMAP amplitude was decreased and duration was prolonged；contractility was decreased， CSA was reduced，inflammatory factor levels were increased，and atrophy⁃related protein levels were increased. Com⁃ pared with the CLP50%+MV6h group，the CLP75%+MV6h group showed decreased CMAP amplitude and increased duration，decreased contractility，decreased CSA，increased inflammatory factor levels and atrophy ⁃ related protein expression，and increased apoptotic index. Conclusion In septic rats，a short⁃term of mechanical ventilation could exacerbate diaphragmatic dysfunction，which became more pronounced as the degree of sepsis increased.