利用尸体软组织生物力学性状时序性变化推断死亡时间

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。

Study on the postmortem interval estimation by timedependent changes of biomechanical properties of the soft tissues in rats

Objective To observe the timedependent changes of biomechanical properties of soft tissues in rats at early postmortem interval.Methods After the rats were executed by cervical vertebra dislocation,the rats were kept in an artificial climate incubator(25℃).The skin of chest,abdominal wall muscle,aorta pectoral,colon and small intestine were taken at 0,6,12,18,24,30,36,42,48,60,72,96,120,144,168and 192h in set position,direction and shape for determination of their biomechanical properties of max load,tensile stress and strain with the electronic universal testing machine.Results Except for aorta pectoral,biomechanical properties of the soft tissues including max load,max tensile stress and strain were grealy reduced with the extension of postmortem interval.The decline tendency for each biomechanical property showed a "window period" with significant difference.For max load,the skin and small intestine showed decline tendency within 18h,the muscle and colon within 24h.Further decline was noted for the muscle from 96h to 168h and for the colon from 72h to 192h postmortem.For max strain,all soft tissues presented decline tendency within 24h.Furthermore,the colon presented decline tendency from 72h to 192h postmortem.For max tensile stress,the skin revealed decline tendency within 18h,the muscle and small intestine within 24h,and the colon within 36h postmortem.Conclusion The timedependent changes of biomechanical properties of the murine soft tissues possess different "window period",which may be used for estimation of postmortem interval at the "window period" by the multiple parameters.