Yamada Hiroshi, Inoue Yoshiaki, Shimokawa Yuki, Sakata Keisuke
Department of Biological Functions Engineering, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu, 808-0196, Japan.
Med Biol Eng Comput. 2017 Jan;55(1):79-88. doi: 10.1007/s11517-016-1500-2. Epub 2016 Apr 22.
Pressure ulcers occur following sustained occlusion of microvessels at bony prominences under skin surface pressure (SSP). However, the mechanical conditions of the surrounding soft tissue leading to microvascular occlusion are not fully understood. This study determined the stiffness of homogenized skin with microvasculature at the sacrum that occludes microvessels at an SSP of 10 kPa (consistent with a standard mattress) and recovers from occlusion at 5 kPa (consistent with a pressure-redistribution mattress). We conducted two-dimensional finite element analyses under plane stress and plane strain conditions to determine the stiffness of the skin. The results for plane stress conditions show that the microvessel was occluded with a Young's modulus of 23 kPa in response to an SSP of 10 kPa at the center of the sacrum and that the circulation recovered following a reduction in the SSP to 5 kPa. The resulting Young's modulus is consistent with reported data. Our study indicates that the critical value of the SSP for microvascular occlusion is determined not only by the stiffness of homogenized skin with microvasculature but also by the intraluminal pressure, microvascular wall stiffness, and body support conditions.
在皮肤表面压力（SSP）作用下，骨隆突处微血管持续闭塞会导致压疮。然而，导致微血管闭塞的周围软组织的力学条件尚未完全明确。本研究测定了骶部带有微血管的均质化皮肤的刚度，该皮肤在10 kPa的SSP（与标准床垫一致）下会使微血管闭塞，而在5 kPa的SSP（与减压床垫一致）下会从闭塞状态恢复。我们在平面应力和平面应变条件下进行了二维有限元分析，以确定皮肤的刚度。平面应力条件下的结果表明，在骶骨中心处，当SSP为10 kPa时，微血管在23 kPa的杨氏模量作用下被闭塞，而当SSP降至5 kPa时循环恢复。所得的杨氏模量与已报道的数据一致。我们的研究表明，微血管闭塞的SSP临界值不仅取决于带有微血管的均质化皮肤的刚度，还取决于管腔内压力、微血管壁刚度和身体支撑条件。
