老年大鼠皮肤持续受压致隐匿性压疮的机制研究

Research on mechanism of occult pressure ulcer caused by continuous pressure in aged rats

目的探讨老年大鼠皮肤受压致隐匿性压疮的发生机制,为临床上老年压疮早期干预和预防提供理论基础。方法将12只老年SD大鼠,随机分成对照组和模型组各6只。对照组不受压、模型组承受22.47kPa压力2h后两组大鼠一起实施安乐死。实验终点,肉眼观察受压部位皮肤颜色和形态的变化;光镜观察皮肤肌肉组织病理学变化;检测肌组织中肌酸磷酸激酶(CPK)、超氧化物歧化酶(SOD)和髓过氧化物酶(MPO);检测皮肤和肌组织中细胞凋亡指数(AI)。结果对照组肉眼观及镜下观均皮肤完整,颜色、结构正常;模型组肉眼观皮肤完整,受压局部出现持续非苍白性发红现象;光镜下复层鳞状上皮变薄,结构层次欠清晰,表皮与真皮部分分离,肌纤维有断裂迹象,轻度水肿,间隙增宽。真皮和肌肉组织中均可见明显炎性细胞浸润。两组SOD、CPK、MPO、AI比较,差异有统计学意义(均P<0.01)。结论老年大鼠皮肤持续受压2h以上可导致肌组织无菌炎性反应,引发氧化应激反应和细胞凋亡,使老年大鼠在皮肤完整情况下发生组织和细胞结构改变。

Objective To explore pathogenesis of occult pressure ulcer caused by continuous pressure in aged rats,and to provide theoretical information for early intervention and prevention of pressure ulcers in elderly population. Methods Twelve aged Sprague-Dawley rats were randomized into a control group and a model group of 6.The control group didn′t sustain any pressure,while the model group were pressurized with 22.47 kPa load for 2 hours.All rats were sacrificed mercifully at the end of experiment.Color and morphology of the pressurized skin were observed grossly by naked eyes;pathological changes of skin and muscle tissue were observed under optical microscopy;creatine phosphokinase（CPK）,superoxide dismutase（SOD）,myeloperoxidase（MPO）,and apoptosis index（AI） were tested. Results Pressurized skin of the model group presented persistent redness by naked eyes.Under optical microscopy,the pressurized skin showed these changes： the stratified squamous epithelium turned thin,and its structure became unclear;epithelium partially separated from derma;muscle fiber had slight rupture and edema.Derma and muscle tissue developed inflammation.Significant differences were found in the values of SOD,CPK,MPO,and AI between the two groups（P〈0.01 for all）. Conclusion The muscle tissue of SD rats will sustain sterile inflammatory reaction under continuous pressure for 2 hours and cause oxidative stress response and apoptosis,resulting in histological and cytological changes of skin.