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目的观察分析家猪尸体胸主动脉生物力学性状指标的变化规律,探讨其在死亡时间(PMI)推断中的应用价值。方法采集180根家猪的主动脉,在恒定温度、湿度下,于2～230h之间每间隔12h设置1个取检材时间点组;各组主动脉检材用电子万能材料试验机拉伸检测极限载荷、极限载荷变形、平均力、应力、应变,宽度和厚度等生物力学参数指标;应用多元逐步回归方法进行统计学分析。结果家猪死后230h内,随PMI延长,胸主动脉大体观呈自溶腐败性变色、瘫软、液化趋势。生物力学参数指标中,极限载荷、平均力和应力呈随PMI延长呈明显下降趋势,PMI间隔24h组间比较差异性均有统计学意义(P<0.05),校正决定系数分别为0.923、0.806、0.867,估计标准误差分别为±18.39h、±29.88h、±24.58h,PMI间隔24h组间比较差异性均有统计学意义(P<0.05),其它指标与PMI之间相关性不显著均P>0.05。结论死后230h内家猪胸主动脉的极限载荷、平均力和应力的死后时序性变化,与PMI呈明显的负相关性,可用于PMI推断,其中极限载荷效果最佳。
Objective To observe the changes of the biomechanical parameters of the thoracic aorta in pigs and to explore its value in the inference of death time (PMI). Methods The aorta of 180 domestic pigs were collected and set at the time of 12h at intervals of 2 ~ 230h at a constant temperature and humidity. Each aorta was examined with an electronic universal testing machine The biomechanical parameters such as ultimate load, ultimate load deformation, average force, stress, strain, width and thickness were measured. Multiple stepwise regression was used for statistical analysis. Results Within 230h after death, with the prolongation of PMI, the thoracic aorta showed autolysis decay, discoloring and liquefaction tendency. The biomechanical parameters index, the ultimate load, average force and stress showed a significant downward trend with the PMI prolongation, PMI interval 24h group differences were statistically significant (P <0.05), the correction coefficients were 0.923,0.806, 0.867, respectively. The estimated standard errors were ± 18.39h, ± 29.88h, ± 24.58h respectively. There was significant difference in 24h between PMI intervals (P <0.05), while the correlation between other indexes and PMI was not significant P > 0.05. Conclusion The ultimate load, average force and post-mortem time series changes of domestic pig thoracic aorta within 230h after death are significantly negatively correlated with PMI and can be used for PMI inference. The ultimate load is the best.