外文翻译- 基于虚拟人床系统的电子护理床生物力学分析

基于虚拟人床系统的电子护理床生物力学分析人与电动护理床的关系是复杂而特殊的。本研究旨在降低使用ECB 时的失误发生率并提高舒适性。为了分析长期跟踪护理床过程中对人体施加的力分布，评价护理床新功能的可行性，我们邀请了一组老年人在三种类型的电动护理床上完成一系列实验。采用压力测图系统和虚拟人床系统对各种体位的受力进行量化，评价体位和体重的影响，探讨床运动与受力分布的关系。结果可用于改善所有体位的 ECB 病理特征，并可用于评价或预测电动护理床新增功能的可行性。第 1 部分 简介60 岁以上的人每年增长 1.9%，80 岁以上的人每年增长 3.8%。到 2030 年，全球 65 岁以上的老人比例将达到 20%。活动受限患者，如老年人和脊髓损伤患者。年龄越大，越容易受到伤害。大约 70%的溃疡发生在 70 岁以上的人身上 1。老年人的表皮变得越来越薄，对剪切力的抵抗力也越来越弱。导致溃疡的内在原因有很多，例如，心力衰竭等一些严重疾病的活动受限和合并症可明显增加溃疡的发生概率，这被认为是比老化本身更重要的原因2。溃疡的外在原因主要由褥垫系统引起。当软组织受到的接触压力超过 32mmHg 且不能经常缓解时，毛细血管小动脉肢的真皮血管会闭合，引起溃疡3。除气动床外，普通床引起的压力通常在 45mmHg-75mmHg 范围内。美国卫生保健政策和研究机构建议，压力性溃疡应根据安排的时间表重新定位至少 2 小时4。理论上，电动护理床可以帮助缓解压力并提供简单的帮助。护理任务可以减轻，而护士最危险的任务是提升或运送病人，欧洲央行在这类任务中几乎无法提供任何帮助5，因此本研究不考虑对护士的影响。如果用电动床取代传统的床，人们将被移动并长期保持许多姿势。几乎所有关于压力分布、床垫、溃疡6 和舒适性的相关结论都是基于传统床7。如果不能准确了解ECB 的力分布和动力学特征，简单设计的床会对处于易受伤害位置的患者施加不可预测的力，从而造成严重伤害。基于压力测绘系统的结果，建立了虚拟人床系统，对其进行了仿真。因为护理床是传统床和机械辅助系统的结合。丰富的相关研究可作为研究的基础。例如，卧床不起引起的慢性病，软组织的耐受性，护理任务的工作量。当用 ECB 替代传统的床位时，研究结果不能直接利用，尤其是当患者已经或已经丧失运动能力或失去意识时。设计不良的 ECB 可能会造成以下影响：（1）造成强烈和不可靠的接触压力。未缓解的压力是溃疡的主要原因。有许多方法可以处理不可靠的接触压力，定期复位，电 32mmHg 时间过长，软组织会被缺血破坏。 （2）如果人体跟随 EMCB 移动，摩擦几乎是不可避免的。可剥除角质层，为压疮等疾病提供条件。 （3）根据主观评价，将剪切效应放大。只有当力平行于表面施加时，才会发生这种情况。剪切可能使软组织变形并引起缺血。 （四）尿失禁、出汗引起的水分，软化角质层也可引起其他疾病。第 2 部分 研究方法为了探讨人床系统的生物力学特性，9 名老年人被要求使用三种 ECBS 床。 “r”值是重量 /高度（kg/cm ）的结果，床由测试人员操作。老年人信息见表 1。TABLE I. SUMMARY OF SUBJECTSR 年龄 体重/kg 身高/cm范围0.3610.4766076 6279 159176平均 0.419 63 71 174通过对居家护理的调查，根据尽可能多地替代人力的原则，选择和测量了居家护理的主要姿势。只有经常使用和保存很长时间的姿势才被选为主要姿势。根据表 1 所示的 r 值，将受试者分为三组。他们被要求悠闲地躺在床上，在接受简单训练后跟随 ECB 移动。作为压力测量系统的一部分，床垫上放置了一块特制的毯子，里面的压力传感器不足2000 个。用于记录施加在床垫上的压力。系统记录压力分布和平均压力。为了与人床刺激系统的结果进行比较，要求受试者以两种方式放置手臂，一种是自然放置，另一种是胸部折叠。TABLE II. No 动作 与床的联系1从躺着到坐起来（双腿伸直）受剪切力和摩擦的长周期压制2从躺着到坐起来（两腿并举）受剪切力和摩擦的长周期压制从一侧转向另一侧可能导致姿势以不可预测的方式发生变化，因此没有模拟转向过程。像俯卧这样笨拙的姿势也没有被模仿。极端姿势中的力分布特征主要是决定人和坏人的形状，也在一定程度上决定了运动过程。三种床的功能和结构不同，A、B 型床可以帮助患者在不考虑人体曲线的情况下坐起来。类型 C 提供了一个功能，将背部和腿部一起抬起，姿势如图 1 所示。坐骨区和大腿区的曲线与特殊设计相匹配。C 型提供了一个功能，可以将背部和腿部一起从卧位提升和旋转到坐位，然后再回到卧位。图 2 显示了整个过程中的压力值。图 1 背部和腿部一起抬起图 2.压力与时间的关系表 3. 每种姿势的持续时间躺 起身 坐起 下降 躺Time (s) 0 013 1337 3742 42在上升过程中，平均压力大大增加。在极限位置，压力达到峰值，比初始值高出 26%，随床到卧位，压力恢复到初始水平。图 3 压力与时间的关系从测量结果可以看出，超过 30%的人体表面面积被超过32mmHg 的压力挤压。躺位时压力分布最均匀，而身体再回到躺位时压力分布则不同，对于脂肪受试者（r 0.471） ，剪切力的影响增大。在腿抬高或不抬高的坐姿中，受试者在跟随 A、B 型移动时承受较大的峰值压力、剪切力和摩擦力，因为简单直床板的角部没有为臀部提供任何空间，而臀部是整个身体的主要支撑位置和旋转中心，床板移动时，整个身体移动。因此，髋关节的摩擦力和剪切力是不可避免的。更糟糕的是，如果床旋转不止一次，受试者可能会处于尴尬的位置，腰部在拐角处。建立了虚拟人体模型，模拟人体的重力分布，通过采集各姿态关键点的三维位置建立了虚拟人体。将每个体位的虚拟人体模型分为 25 个部分，每个部分的密度设为 1g/com3。由于卡车是与床的主要接口，五个部分都由不同的骨骼支撑，因此根据人体的自由度对其进行了划分，而躯干则由五个部分组成。每个部分的模型都是封闭的。整个模型先制作，然后分成若干部分。有时一些部分可以看作是一个较大的部分，例如，当模拟坐姿时，颈部和头部可以作为一个单独的部分计算。用这种方法建立的模型不仅计算简单，而且符合人体的真实形态。根据压力测量结果，确定了虚拟人体与床垫的主要接触面积。虚拟人可以发现并预测人体各部分如何与床层相互作用，可以计算出诸如剪切力之类的未知力。该结果可用于预测和量化所有体位的溃疡风险，或评估 ECB 在设计过程中新功能的可行性。为了记录人床系统中各部分的位置，建立了一个坐标系，在模型的对称平面上选择其原点，使其处于卧位，与床垂直，位于胸骨最下边缘和背部之间的长度中间。如图 4 所示。这一起源比较容易测量，相对稳定，它提供了一种根据人体特征而不是通常首先考虑的床来设计人- 床系统的方法。这种原产地选择方法有助于产品的设计完全符合人类的要求。利用质心位置和零件的重力来模拟每个零件所受的力。主要姿势主要部位数据见表四。表 4.每个姿势的时间No 姿势 部分 重力 质心位置坐标 001 胸部144329723.48, 524.48, 9.632 腰椎134703194.96, 297.91, 8.753 臀部86148963.75,102.93,3.814平躺全部725529962.95,199.96,3.275 胸部1546389884.28,358.04,339.006 腰椎1140134481.00,225.87,154.957侧躺臀部986127784.64,100.46,47.63No 姿势 部分 重力 质心位置坐标 008 总计6948102783.03,111.70,175.989 胸部151782405.77,531.24,37.0410 腰椎140734805.17,283.78,25.1311 臀部90371409.89,104.39,12.4412坐姿总计736417233.04,204.46,25.05下面是一个示例，演示如何使用模型。在图 5 中的姿势中，计算从头部到腰部，最后到臀部施加在每个部分的力。头部的摩擦忽略不计。腿提供的支撑剪力不能直接测量，也可以通过计算施加在臀部的力来知道。图 5。零件受力分析该系统具有以下优点：它易于调整和改进，即在设计过程中取得进展，而无需建立真实的模型，该系统可用于探索新姿态的可行性。该模型提供了一种更清晰的描述力效应的方法。一些不能直接测量的力可以这样计算，例如剪切力和摩擦力。在计算剪切力时，必须考虑运动过程来决定剪切力和摩擦力的方向。计算结果与压力绘图系统的结果进行了比较。两种方法的结果表明，背部和大腿是人体和床垫的主要界面，小腿在某些姿势中也很重要。肘部、手部和脚部很少引起长时间的高压，这些部位很少发生溃疡，因此这些部位被忽略了。主要姿势的压力分布如下图所示。每一点表示垂直于被测对象的一条线上的最大压力。图 6。简单坐着时的压力分布图 7。背部和腿部一起抬起时的压力分布当背部和腿部一起抬起时，平均压力明显增加，臀部成为最受压迫的部位，受试者很难调整压迫区域。在压力较大的情况下，平均压力始终大于虚拟模拟的压力结果，而压力区域保持不变，甚至增大。这意味着当身体被迫进入一个尴尬的位置时会有某种阻力。图 8。压力分布，床垫覆盖的床图 9。压力分布，取下床垫结果表明，床垫可以更均匀地分配压力，降低峰值压力，而软床垫也会产生额外的剪切力。唯一可靠的结论是胖人应该比瘦人使用更薄的床垫。第三部分 讨论通过对压力测量和虚拟人床系统的比较，发现了以下现象。受压区的分布不仅取决于重力，还取决于剪切力。在整个操作过程中，剪切力和摩擦力的方向是相反的，因此，受力区域经常发生变化，从而使受力区域放大并向剪切力的方向移动。在压力测图系统提供的图片中可以清楚地看到结果。这一现象对脂肪物体更为明显。从虚拟人床系统的受力分析可以看出，当模型跟随床板上升时，剪切力增大，以平衡躯干的重力。当床旋转时，人体臀部表面延伸超过 50%，而床 A 和床 B 的床面不能延伸到与之匹配，这就是造成摩擦力和剪切力的原因之一。另一个原因是坐着时剪切力随重力增大，床板垂直旋转 45时剪切力达到峰值。C 床使用时，由于其臀部以下的床板可随皮肤伸展，躯干重力平衡，床板上的曲线提供足够的空间容纳臀部，因此没有出现明显的受剪面积。同时由于 A、B 床不能与人体曲线相匹配，每次坐姿过程后受力分布都会发生变化，所以本应施加在髋部的压力都会变回背部，所以脊柱的压缩力会增大，躯干被迫适应一个意想不到的曲线，这对卧床病人来说是非常不舒服的。实验证明，单点平均压力随受试者体重的变化不明显。然而，很明显，肥胖的受试者与床垫的互动区域要大得多。过厚的床垫和软组织为软组织变形和剪切力提供了条件。这是从人床模拟和压力测量中知道的。畸变是缺血的原因。厚的软组织也不利于水分调节。对于“r”值小于 0.361 的瘦受试者，坐起后压力分布图几乎保持不变，但全身有一些小区域支撑，过度集中的压力是溃疡和不适的主要原因。压力比较如图 10 和图 11 所示。图 10。压力分布，r0.471图 11。压力分布，r0.361为避免溃疡，保证用户的舒适性，并改进 ECB 的设计，提出以下建议：躺着时平均接触压力最小，单纯坐着可能使平均压力增加 20%以上。与床板一起移动也会产生摩擦力和剪切力。因此，建议患者不要长时间保持坐姿，尤其是背部和腿部同时抬起的坐姿。每次改变姿势时，患者应获得帮助，使背部和臀部至少稍微抬起一点，以释放剪切力，这是令人失望的，因为这将是一项艰巨的工作和风险的保育8。坐在床上时，衣服是减少摩擦所必需的。无论是躺着还是坐着都不能完全缓解坐骨区的接触压力，因此对于卧床的病人来说，每隔一段时间将身体转向一边也是必要的。更胖的人更容易受到剪切力的威胁。瘦的人更容易承受压力峰值和不舒服的感觉。有骨支撑的薄软组织覆盖的区域容易引起溃疡9，10。床垫的设计应符合此要求。活动受限的患者在 ECB 旋转后，应帮助其他人释放剪切力。对于设计人员来说，有必要根据人体表面来设计床板，因为床板与人体曲线的不匹配可能导致意外的姿势和力分布。床板应留有足够的空间，以便臀部旋转时避免额外的压力。床板表面以下的坐骨区、背部的压力集中区应能伸缩或移动，以避免剪切力和摩擦力第四部分 结论两种方法的研究结果基本一致。只有当背部和腿部同时抬起时，测量的压力才明显大于模拟结果。这意味着可以利用模拟方法来评估和预测力的分布。在几乎所有的情况下，超过 32mmHg 的压力是不可避免的，坐起来或转过去可能会造成明显较大的压力（甚至超过 20%） ，剪切力也不能忽略。经测试的 ECB 提供的所有体位都会导致髋关节压力集中，这意味着应考虑一些其他功能，如转向一边，以消除压迫但难以缓解的部位。出于所有这些原因，可用的 ECB 可用于提供援助，但只能以推荐的方式应用，还需要其他人的定期帮助。在此基础上提出了几点建议。附：原外文文献A biomechanical analysis of electric nursing care beds basing on a virtual man-bed system 2 Author(s)Qi Wang ; Xuehua TangAbstract: Relation between human and electric care beds (ECB) is complex and special. This study aims at reducing incidence of ulcer and improve comfort when using ECB. To quantify the force distribution exerted upon human body in process of following the care beds for a long period and evaluate the feasibility of new functions of care beds, a group of old people were asked to finish a series of experiments on three kinds of electric care beds. Pressure mapping system and a virtual man-bed system were utilized to quantify the forces in all postures and assess the influences of postures and body weight, explore the relationship between bed movement and force distribution. The results can be utilized to improve the pathological characteristics of ECB in all postures, and furthermore to evaluate or predict the feasibility of new functions added to electric nursing care beds.Published in: 2009 IEEE 10th International Conference on Computer-Aided Industrial Design & Conceptual Design Date of Conference: 26-29 Nov. 2009 Date Added to IEEE Xplore: 08 January 2010 ISBN Information: INSPEC Accession Number: 11084135 DOI: 10.1109/CAIDCD.2009.5375263 Publisher: IEEE Conference Location: Wenzhou, China AdvertisementContents SECTION 1.IntroductionIndividuals over the age of 60 increase 1.9% each year and those over 80 increase 3.8%. By 2030, 20% of world population will be over 65. Mobility limited patients such as the elderly and the spinal cord injury patients. The older, the more vulnerable. Approximately 70% of ulcers occur in individuals over the age of 701. Epidermis of old people gets thinner and less resistant to shearing forces. There are many intrinsic reasons that lead to ulcer, for instance, mobility limitation and comorbidities of some serious diseases such as heart failure can increase the probability of ulcer obviously, which has been known as a much more important reason than aging itself2. Extrinsic reasons of ulcer are mainly caused by bedding system. When contact pressure exerted upon soft tissues is over 32mmHg and can not be often relieved, dermal vessels in the arteriolar limb of capillary will be closed and ulcer is caused3. Pressure caused by common beds is often in the span of 45mmHg-75mmHg except for air powered bed.It is recommended by US Agency for health Care Policy and Research that pressure ulcers should be repositioned at least 2 hours according to an arranged schedule4. Theoretically, electric care beds can help to relieve pressure and offer simple assistance. Nursing tasks can be relieved, while the most dangerous tasks for nurses are lifting or transporting patients, ECB could hardly offer any help in such tasks5, so influence to nurses is not taken into consideration in this study. If traditional beds are replaced by electric beds, people will be moved and kept in many postures for long periods. Almost all relative conclusions about pressure distribution, mattress, ulcer6 and comfort are based on traditional beds7. Were force distribution and kinetics characteristics of ECBs can not be exactly known, simply designed beds will cause great injury by exerting unpredictable forces upon patients on vulnerable positions. A virtual man-bed system was established basing on the result of pressure mapping system to simulate the situation.As the care bed is a combination of traditional bed and mechanical assistant system. Abundant relative research can be utilized as basis for the research. For example, chronics caused by bedridden, tolerance of soft tissues, work loading of nursing tasks. When traditional bed is replaced by ECB, the research results can not be utilized directly, especially when the patient has or been motion ability disabled or lost consciousness. Poor designed ECB may cause the following influences: (1) Cause intense and unrelieved contact pressure. Unrelieved pressure is the main reason of ulcer. There are many kinds of methods to deal with unrelieved contact pressure, regular reposition, electric 32mmHg for too long a period, soft tissues will be undermined by ischemia. (2) Friction is almost unavoidable if human body follows the EMCB to move. It may strip the stratum corneum and provide condition for pressure ulcer and other diseases. (3) According to subjective evaluation, effect of shear is amplified. It happens only when the forces is exerted parallel to surface. Shear may distort soft tissues and cause ischemia. (4) Moisture caused by incontinence or perspiration also cause other diseases by softening the stratum corneum.SECTION 2.MethodTo explore the biomechanical characteristics of man-bed system, 9 old people were asked to use three kinds of ECBs beds. “R” value is the result of Weight/height(kg/cm), The beds were manipulated by testers. Information of old people are shown in table 1. TABLE I. SUMMARY OF SUBJECTSRAge (year)weight (kilogram)height (cm)range0.3610.4766076 6279 159176mean 0.419 63 71 174Basing on the investigation about home care, main postures were chosen and measured basing on the discipline of replacing human force as much as possible. Only postures that are often used and kept for a long time were chosen as main postures.Subjects were divided into three groups according to the value of R shown in table 1. They were asked to lie on the beds leisurely and follow the ECBs to move after being simply trained. A specially designed blanket with less than 2000 pressure Sensors in is placed on the mattress as a part of pressure measure system. It is used to record the pressure exerted upon mattress. Pressure distribution and mean pressure were recorded by the system. To compare the result with man-bed stimulation system, the subjects were asked to put their arm in two ways, once placed naturally and again folded before chest. TABLE II. MANIPULATION PROCESSNo Action Relationship with mattress1From lying to sitting up (legs straight still)Long period pressed with shear force and friction2From lying to sitting up (legs raised together)long period pressed with shear force and frictionTurning from one side to the other may cause posture changed in unpredictable ways, so the turning process was not simulated. Awkward postures such as prone position were not simulated too. Force distribution characteristics in extreme postures is mainly decided shape of bad and man, also decided by motion process to some extend. Function and construction of the three types of beds were different, Type A, B can help patients to sit up without taking the curve of human body into consideration. Type C offers a function to lift back and leg together, the posture is shown in Fig1. Curves in ischial region and thigh region have been matched with special design. Type C provides a function to lift and rotate back and legs together from lying position to sitting position and then return to lying. Fig2 shows value of pressure during a whole process. Figure 1. Figure 1 back and legs were raised togetherView AllFigure 2. Relationship between pressure and timeView AllTABLE III. DURATION OF EACH POSTURElying raising Sitting up declining lyingTime (s) 0 013 1337 3742 42In process of being raised, mean pressure increased greatly. The pressure got to the peak which was 26% more than the original value at limit position, and then return to original level when following the bed to lying position. Figure 3. Relationship between pressure and timeView AllIt could be seen in the measurement that more than 30% of area on the surface of human body were pressed by pressure of over 32mmHg. Pressure is most evenly distributed in lying position, while the distribution has been different when the body come back to lying again, for fat subjects(R0.471), effect of shear force has been increased. In sitting positions with legs lifted or not, subjects suffered from larger peak pressure, shear force and friction when following type A, B to move, because the corner of simple straight bed board did not offer any room for hip which is the main support position and rotation center of the whole body, when the bed board moves, the whole body moves with hip, as a result, friction and shear force are unavoidable. Even worse, if the bed rotates for more than once, the subject may be kept in awkward position with lumbar on the corner.Virtual human model was established to simulate the gravity distribution of human body, the virtual human was established by collecting 3D position of critical points in all postures. The virtual human model in each posture was divided into 25 parts with density of all parts were set to be1g/com3. The parts were divided basing on the degree of freedom of human body except for the trunk which is composed of five parts because the truck is the main interface with bed and all the five parts were supported by different bones. Models of each part is closed. The whole model is made first and then divided into parts. Sometimes a few parts can be seen as a larger part, for example, neck and head can been calculated as a single part when simulating sitting postures. Models established in this way is not only easy to calculate but also comply with real shape of human body.Basing on the results of pressure measuring, main contact area between virtual human and mattress are known. The virtual human make it possible to find out and predict how the human parts are interacting with the beds, unknown forces such as shear can be calculated. The result is used to predict and quantify the risk of ulcer in all postures, or evaluate the feasibility of new functions of ECB in design process.To record the position of all parts in the man-bed system, a coordinate was set up, its origin was chosen in the symmetric plane of the model in lying posture, vertical to bed, at the middle of the length between lowest edge of sternum and back. It is depicted in Fig 4. This origin is easier to measure and relatively stable, it offers a method to design man-bed system basing on the characteristics of human body, not from bed Which is often considered first. This origin choosing method can help to design the product totally for the requirements of human. Figure 4. Position of the originView AllPosition of centroids and gravity of parts were used to simulate the force exerted on each part. Data of main parts in main postures is shown in table IV. TABLE IV. TIME OF EACH POSTURENo posture part gravityPosition of centroids (x, y, z) (cm)No posture part gravityPosition of centroids (x, y, z) (cm)1 chest 14432972 3.48, 524.48, 9.632 lumbar 13470319 4.96, 297.91, 8.753 hip 8614896 3.75,102.93,3.814lietotal 72552996 2.95,199.96,3.275 chest 15463898 84.28,358.04,339.006 lumbar 11401344 81.00,225.87,154.957 hip 9861277 84.64,100.46,47.638Lie on one sidetotal 69481027 83.03,111.70,175.989 chest 15178240 5.77,531.24,37.0410 lumbar 14073480 5.17,283.78,25.1311 hip 9037140 9.89,104.39,12.4412Sit uptotal 73641723 3.04,204.46,25.05Here is a sample to show how to use the models. In the posture in Fig5, force exerted upon each part is calculated, from head to lumbar, finally to the hip. Friction on the head is neglected. The support shear offered by leg which can not to measured directly is also known by calculating the forces exerted on the hip. Figure 5. Force analysis of partsView AllThe system has the following valuable advantages:It is easy to adjust and improve, that means making progress in design process without making real models and the system can be utilized to explore the feasibility of new postures.The model offers a much clearer description method to show the effect of forces.Some forces which can not be directly measured can be calculated in this way, for instance, shear and friction. When calculating the shear