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目的探讨尸体软组织生物力学性状时序性变化规律及其推断死亡时间的可行性。方法将实验大鼠用颈椎脱臼法处死,放置25℃恒温培养箱内即刻、6、12、18、24、30、36、42、48、60、72、96、120、144、168、192h,定时、定位、定向、定形切取大鼠胸部正中皮肤、腹壁肌肉、胸主动脉、结肠和小肠的生物力学试件,用电子万能材料试验机检测各试件的极限载荷、应变、应力生物力学参数。结果除主动脉外,尸体皮肤、肌肉、小肠、结肠的各项软组织生物力学参数均呈明显的死后时序性下降趋势。各参数下降趋势具有显著性差异的“窗口期”分别为:极限载荷:死后18h内皮肤、小肠呈下降趋势;24h内肌肉、结肠呈下降趋势;96～168h肌肉呈下降趋势;72～192h结肠呈下降趋势。应变:各组织在24h内均呈下降趋势,其结肠72～192h缓慢下降趋势。应力:皮肤18h内呈下降趋势,肌肉、小肠24h内呈下降趋势,结肠36h内呈下降趋势。结论大鼠尸体软组织各生物力学性状在不同的“窗口期”存在时序性变化规律,综合各指标可用于推断相应“窗口期”内的死亡时间。
Objective To explore the regularity of biomechanical properties of cadaver soft tissues and the feasibility of inferring the time of death. Methods The rats were sacrificed by cervical dislocation and placed in incubator at 25 ℃ for 6,12,18,24,30,36,42,48,60,72,96,120,144,168,192h, The biomechanical specimens of the middle of the thorax of the chest, the abdominal muscles, the thoracic aorta, the colon and the small intestine were cut out regularly, positioned, orientated and fixed. The ultimate load, strain, stress biomechanical parameters of each specimen were tested by electronic universal material testing machine . Results In addition to the aorta, the biomechanical parameters of soft tissue in the skin, muscle, small intestine and colon of the cadaver showed a declining trend after the death. The “window period” of the decreasing trend of each parameter were respectively: ultimate load: the skin and small intestine showed a decreasing trend within 18h after death; the muscle and colon decreased gradually during 24h and the muscle decreased gradually during 96 ~ 168h; 72 ~ 192h colon showed a downward trend. Strain: Each tissue showed a downward trend within 24h, the slow decline in the colon 72 ~ 192h. Stress: skin 18H showed a downward trend, muscle, small intestine showed a downward trend within 24h, colon 36h showed a downward trend. Conclusions The biomechanical properties of the cadaver soft tissue in rats vary regularly at different “window periods”, and all indexes can be used to infer the death time in the corresponding “window period”.