Bristol Veterinary School and Bristol Heart Institute, University of Bristol, Langford, Bristol, BS40 5DU, UK.
College of Veterinary Medicine, North Carolina State University, Raleigh, NC, 27606, USA.
Biomed Eng Online. 2019 Apr 16;18(1):45. doi: 10.1186/s12938-019-0664-z.
Analyze the mechanics of Finochietto-style retractors, including the responses of thoracic tissues during thoracotomy, with an emphasis on tissue trauma and means for its reduction.
Mechanical analyses of the retractor were performed, including analysis of deformation under load and kinematics of the crank mechanism. Thoracotomies in a porcine model were performed in anesthetized animals (7) and fresh cadavers (17) using an instrumented retractor.
Mechanical analyses revealed that arm motion is a non-linear function of handle rotation, that deformation of the retractor under load concentrates force at one edge of the retractor blade, and that the retractor behaves like a spring, deforming under the load of retraction and continuing to force open the incision long after crank rotation stops. Experimental thoracotomies included retractions ranging from 50 to 112 mm over 30 to 370 s, generating maximum forces of 118 to 470 N (12-50 kgf). Tissue ruptures occurred in 12 of the 24 retractions. These ruptures all occurred at retraction distances wider than 30 mm and at forces greater than 122.5 N. Significant tissue ruptures were observed for nearly all retractions at higher retraction rates (exceeding ½ rotation of the crank per 10 s).
The Finochietto-style retractor can generate large forces and some aspects of its design increase the probability of tissue trauma.
分析 Finochietto 式牵开器的力学原理，包括开胸术中胸壁组织的反应，重点关注组织创伤及其减轻方法。
对牵开器进行力学分析，包括在负载下的变形分析和曲柄机构的运动学分析。在麻醉动物（7 只）和新鲜尸体（17 只）上使用仪器化牵开器进行开胸术。
力学分析表明，臂的运动是手柄旋转的非线性函数，牵开器在负载下的变形集中在牵开器叶片的一个边缘上，牵开器的行为类似于弹簧，在回缩的负载下变形，并在曲柄旋转停止后很长时间内继续迫使切口张开。实验性开胸术包括 30 至 370 秒内 50 至 112 毫米的牵开，产生的最大力为 118 至 470 牛（12-50 千克力）。在 24 次牵开中有 12 次发生组织撕裂。这些撕裂都发生在牵开距离大于 30 毫米且力大于 122.5 牛的情况下。在较高的牵开速度（超过每 10 秒旋转曲柄半圈）下，几乎所有牵开都会发生明显的组织撕裂。
Finochietto 式牵开器可以产生很大的力，其设计的某些方面增加了组织创伤的可能性。
