University of Minnesota Mechanical Engineering, Minneapolis, Minnesota, United States of America.
University of Minnesota Biomedical Engineering, Minneapolis, Minnesota, United States of America.
PLoS One. 2023 May 10;18(5):e0268608. doi: 10.1371/journal.pone.0268608. eCollection 2023.
Healthcare simulators have been demonstrated to be a valuable resource for training several technical and nontechnical skills. A gap in the fidelity of tissues has been acknowledged as a barrier to application for current simulators; especially for interventional procedures. Inaccurate or unrealistic mechanical response of a simulated tissue to a given surgical tool motion may result in negative training transfer and/or prevents the "suspension of disbelief" necessary for a trainee to engage in the activity. Thus, where it is relevant to training outcomes, there should be an effort to create healthcare simulators with simulated tissue mechanical responses that match or represent those of biological tissues. Historically, this data is most often gathered from preserved (post mortem) tissue; however, there is a concern that the mechanical properties of preserved tissue, that lacks blood flow, may lack adequate accuracy to provide the necessary training efficacy of simulators.
This work explores the effect of the "state" of the tissue testing status on liver and peritoneal tissue by using a customized handheld grasper to measure the mechanical responses of representative porcine (Sus domesticus) tissues in n = 5 animals across five test conditions: in vivo, post mortem (in-situ), ex vivo (immediately removed from fresh porcine cadaver), post-refrigeration, and post-freeze-thaw cycle spanning up to 72 hours after death. No statistically significant difference was observed in the mechanical responses due to grasping between in vivo and post-freeze conditions for porcine liver and peritoneum tissue samples (p = 0.05 for derived stiffness at grasping force values F = 5N and 6.5N). Furthermore, variance between in vivo and post-freeze conditions within each animal, was comparable to the variance of the in vivo condition between animals.
Results of this study further validate the use of preserved tissue in the design of medical simulators via observing tissue mechanical responses of post-freeze tissue comparable to in vivo tissue. Therefore, the use of thawed preserved tissue for the further study and emulation of mechanical perturbation of the liver and peritoneum can be considered. Further work in this area should investigate these trends further, particularly in regard to other tissues and the potential effects varying preservation methods may yield.
医疗保健模拟器已被证明是培训多项技术和非技术技能的宝贵资源。目前的模拟器在组织逼真度方面存在差距，这是应用的障碍；特别是对于介入性手术。模拟组织对给定手术工具运动的机械响应不准确或不现实，可能导致培训效果不佳和/或阻止学员进行活动所需的“怀疑暂停”。因此，在与培训结果相关的情况下，应该努力创建模拟组织机械响应与生物组织匹配或代表生物组织的医疗保健模拟器。从历史上看，这些数据最常来自保存（死后）组织；然而，人们担心缺乏血流的保存组织的机械性能可能缺乏足够的准确性，无法为模拟器提供必要的培训效果。
本工作通过使用定制的手持夹具来探索组织测试状态的“状态”对肝脏和腹膜组织的影响，以代表性的猪（Sus domesticus）组织在 5 只动物中进行了 5 种测试条件下的机械响应：体内、死后（原位）、离体（从新鲜猪尸体中立即取出）、冷藏后和冷冻解冻循环后，死后最长 72 小时。未观察到猪肝和腹膜组织样本因抓取而导致的机械响应在体内和冷冻后条件之间存在统计学上的显著差异（在抓取力值 F = 5N 和 6.5N 时，衍生刚度的 p = 0.05）。此外，在每个动物内，体内和冷冻后条件之间的方差与动物内体内条件的方差相当。
本研究的结果进一步验证了通过观察冷冻后组织的组织力学响应与体内组织相似，在医疗模拟器设计中使用保存组织的方法。因此，可以考虑使用解冻保存的组织进一步研究和模拟肝脏和腹膜的机械扰动。在这一领域的进一步工作应进一步调查这些趋势，特别是在其他组织和可能产生的不同保存方法的潜在影响方面。
