手枪子弹冲击下有防护生物靶标多参数测量与分析

目的 研究枪弹对有防护生物靶标的致伤情况与原因,为揭示人体在防护条件下的致伤机理和医学治疗提供参考。方法 选择体重60 kg的活猪作为生物靶标,参照防护条件下单兵头部和胸部的易损情况确定生物靶标内的测试物理量和具体位置。在25 m射距下分别对防护条件下生物靶标的头部和胸部射击3发9 mm巴拉贝鲁姆手枪弹,综合测量手枪弹冲击对有防护生物靶标钝性损伤起重要作用的加速度、压力、载荷力等多个力学量。结果 （1） 手枪弹对生物靶标头部的钝性损伤使颅内产生负压脉冲并伴随产生远达效应,在其脊柱和颈动脉内出现脉冲压力;（2） 手枪弹对生物靶标胸部的钝性损伤使心脏承受高加速度冲击,肺部承受高压力波作用。结论 测量结果为定量认识手枪弹对防护条件下有生目标致伤机理提供依据。     

模拟舰船冲击对人体下肢骨骼轴向压缩损伤特性研究

目的非接触性水下爆炸在极短的时间内产生巨大的加速度，引起舰船装备的破坏和人员严重损伤，尤其是人员下肢骨骼极易受到冲击损伤，严重影响舰船战斗力。材料与方法为了研究舰船冲击运动对人体下肢主要骨骼的损伤，采用12具新鲜的下股骨骼（包括股骨、胫骨、距骨、腓骨、跟骨）人体尸体标本，模拟舰船冲击运动的特性，在冲击机上进行静态和动态压缩测试实验。结果获取人体下股骨骼在静态和动态载荷作用下的压缩特性，如破坏载荷、压缩变形等，并对数据进行分析计算，得到下肢骨骼过载加速度估算值、骨骼损伤特点、动荷系数等参数，提出现有的下肢骨骼的冲击损伤耐受性及标准。结论在人体下肢骨骼中，跟骨和股骨的破坏载荷应是最低的，其动态抗压性能也较差，这与舰船冲击伤以跟骨及股骨损伤发生率较高的实际情况相符合。     

利用有限元研究非贯穿弹道冲击防弹衣后人体躯干的力学响应

目的通过建立人体躯干有限元计算模型,对弹头非贯穿性弹道冲击下人体躯干主要脏器的力学响应进行数值模拟。方法利用正常成年男性的CT扫描数据,应用医学图像重建软件Mimics和有限元前处理工具Hy-perMesh进行人体躯干有限元建模,在显式动力有限元分析软件LS-DYNA中对速度为360 m/s的9 mm手枪弹弹头撞击装配有软质防弹衣人体躯干的压力、加速度响应进行数值计算。结果建立了包括胸廓骨骼结构、脏器、纵膈和肌肉/皮肤的人体躯干有限元模型,通过数值计算获得了心脏、肺脏、肝脏、胃的压力响应以及胸骨的加速度响应,发现不同脏器之间或同一脏器的不同位置,离弹头撞击点位置的远近决定了压力峰值的大小和出现压力峰值的时间。结论装配有软质防弹衣的人体躯干有限元计算模型可作为非贯穿弹道冲击下人体力学响应的仿真分析工具,仿真结果可为防弹衣后钝性损伤机制和防护研究提供依据。     

脊柱跟随载荷在离体生物力学应用研究中的进展

阐述跟随载荷在维持脊柱生物力学中的重要性,归纳近年来人离体脊柱标本跟随载荷模拟的各种方法及手段。通过与人体脊柱各椎体活动度、椎间盘内压等真实数据对比,从力学角度分析各类模拟手段的可行性,总结人体颈椎、胸椎、腰椎离体生物力学实验中最适合的加载载荷及扭矩,并探讨常规脊柱内固定术式对脊柱生物力学特性的影响。     

腹部枪伤时颈总动脉内血流动力学变化的模拟实验

为了探讨腹部枪伤时脑损伤的发生机制，本研究设计了模拟实验，在模拟腹部枪伤瞬间用压力传感器测试并计算了模拟总动脉内血流动力学变化。实验结果显示枪击瞬间颈总动脉内压力高，压力上升速度快，血流速度快，压差大，流量大。大量血流从颈总动脉急速涌向脑部必须导致脑部的损伤。     

颅内压低频分析

目的:临床和基础研究发现,颅内压存在波动,本工作通过动物实验模拟颅高压并研究颅内压的波动.实验方法:14条犬安置硬膜外球囊并注液制成颅高压模型,通过改变球囊内液体量来改变颅高压程度和颅内容积,由压力传感器持续记录相应压力.结果:对颅内压、腰区脑脊液压分别进行FFT分析,发现都存在一个约为0.2Hz的波动,该频率既不是心率(3Hz左右)也不是呼吸频率(0.4Hz),记为M波.分析表明:1)正常情况下,M波并不出现;2)实验开始阶段,不出现M波,当颅内压超过一定压力水平时,M波出现.随后的药物干预实验显示,采用迷走神经阻断药阿托品能明显抑制M波,而交感神经阻断药心得安效果不明显,初步说明M波与脑血管的某些调节机制有关.     

模拟不同重力环境下步态运动的足底受力分析

目的 探索不同重力环境下人体行走和跑步时的足底受力特性。方法7名健康成年男性受试者在垂直体位的减重跑台上分别在正常重力（1G）,模拟火星重力（1/3 G）和模拟月球重力（1/6 G）环境下进行3、7和10 km/h的行走和跑步活动。使用F-scan鞋垫式足底压力测量系统对运动过程中的步态时相参数、力学参数及步态平衡性等指标进行分析。结果 相同速度下,步态周期中的支撑相时间随重力下降有明显减少（P<0.01）,摆动相时间则有显著增加（P<0.01）。随着速度增加,支撑相时间明显缩短（P<0.01）,而摆动相基本不受影响（P>0.05）。最大足底受力、平均足底受力和受力积分随着重力下降有明显减少。正常重力环境下,步行速度增加可引起最大足底受力、平均受力明显增加以及受力积分显著减少（P<0.05）;但在低重力环境下,足底受力变化并不显著（P>0.05）。左右垂直冲量比在不同重力环境之间差异显著（P<0.05）,但时相对称性则并无明显差异。结论 低重力环境下,足底受力和支撑相时间等维持骨骼和肌肉结构功能的指标均显著低于正常重力环境,提示在将来设计太空飞行中防护措施和锻炼处方时需要充分考虑这一因素,以维持航天员正常的骨骼和肌肉功能。     

基于有限元模型的人体头部尺寸对颅内响应影响的探讨

本研究借助第5和第95百分位中国人头部有限元模型,通过对比小尺寸头部和大尺寸头部在相同载荷下的加速度、颅内压力和剪应力,来说明头部尺寸对其生物力学响应存在着较大的影响。在此基础上,本研究还进一步通过将大尺寸模型换算到小尺寸,将小尺寸模型换算到大尺寸,探讨了尺寸缩放方法在用于考虑头部尺寸的生物力学研究中的合理性。研究结果表明现有的采用相同头部损伤准则(HIC)值评估不同尺寸头部损伤有一定的局限性,并为更加科学地评判不同尺寸头部损伤提供了新的理论依据。     

大鼠脑组织固有频率测定

目的:确定正常及常见中枢神经损伤、外周神经损伤后大鼠脑组织的固有频率,为经颅磁刺激、经颅声波刺激等非侵入性脑刺激技术的频率选择及相关动物实验的开展提供依据。方法:24只SD大鼠随机分为正常组、坐骨神经损伤（SNI）模型组和脑缺血再灌注（MCAO）模型组,每组8只大鼠。SNI模型组行坐骨神经钳夹伤术;MCAO模型组行脑缺血再灌注损伤术;两模型组造模7 d后,3组大鼠逐步小心地打开颅骨、硬脑膜,暴露大鼠脑部。频率源输出频率,激光传感实时频谱观察、时频分析方法,得出特性曲线,确定大鼠脑组织幅值B最大时出现的固有频率。结果:每组大鼠脑组织幅值最大时的固有频率峰值较为接近,正常组大鼠为（27.04±2.12） Hz,SNI模型组大鼠为（27.57±2.19） Hz,MCAO模型组大鼠为（26.44±2.27） Hz。SNI模型组与正常组大鼠固有频率差异无统计意义（P>0.05）,MCAO模型组与正常组大鼠固有频率差异无统计意义（P>0.05）,MCAO模型组与SNI模型组大鼠比较固有频率差异无统计意义（P>0.05）。结论:脑组织的固有频率是相对稳定的,在SNI周围损伤刺激时,以及MCAO这一中枢损伤刺激时,脑组织的固有频率不会发生较大差异。     

髓核假体的四元线性黏弹模型及制备参数对模型参数的影响分析

对聚乙烯醇水凝胶髓核假体进行应力松弛性能的研究,利用四元件线性黏弹力学模型对其黏弹性力学行为进行模拟,并从模型的模拟结果分析不同制备参数对髓核假体消散压缩载荷的能力的影响。研究结果表明:四元件线性黏弹模型能够很好的模拟髓核假体的黏弹特性,拟合度达到了0．99以上,效果优于三元件线性黏弹模型。四元件线性黏弹模型的分析结果表明:溶胀率的增大可以增加髓核假体消散压缩载荷的速度,但不能改变消散压缩载荷的总量;初始PVA含量越高,髓核假体消散压缩载荷的速度和总量越小;髓核假体松弛时间与人体椎间盘的松弛时间比较接近。     

CO_2气腹对胎鼠脑超微结构和Caspase-3表达的影响

目的探讨CO2气腹对胎鼠脑组织结构及脑组织Caspase-3表达的影响。方法选择不同CO2气腹压力,建立孕鼠的CO2气腹模型,于鼠孕17 d的24 h内取胎鼠脑组织分别进行HE染色、免疫组化、电镜制片,观察胎鼠脑组织结构变化和胎鼠脑组织Caspase-3表达。结果透射电镜观察显示随气腹压力的增加,胎鼠脑组织可见细胞轻微可逆性损害。Caspase-3在实验组与对照组间胎鼠脑组织表达无明显变化（P〉0.05）,同时组间Caspase-3的表达也无显著性差异（P〉0.05）。结论 CO2气腹压力升高对胎鼠大脑细胞产生可逆性轻度损伤。     

Intracranial distension in neurosurgical pathology]

In contrast to the classic research into the problem of intracranial pressure based on the assumption that pressure in the cranial cavity is distributed uniformly, the initial methodological principle of the present work rests on the concept of the nonuniform distribution of pressure in the intracranial system both in health and disease. Comparative dynamic measurements of cerebrospinal fluid and brain tissue pressures were carried out in the early postoperative period to reveal absolute magnitudes of pressures and their correlations. Under examination were 166 neurosurgical patients with different levels of brain injury. The magnitude of cerebrospinal fluid pressure was demonstrated to depend on the level of brain injury. In the groups examined, intracerebral pressure of interstitial fluid in "normal" brain tissue was approximately the same (from -3 to +2 mm Hg). In brain edema, that pressure increased, sometimes to a considerable measure (up to 50 mm Hg). Neurosurgical pathology was shown to be characterized by nonuniform distribution of pressure in the main intracranial media: brain tissue and cerebrospinal fluid, which disturbs the physiological ratio of these pressures. It should be mentioned that some of the structures are under normal pressure whereas the other ones under elevated or lowered as compared to the physiological norm. Such a state can be correctly characterized by the term "intracranial distension" bearing in mind nonuniformity of tension in the intracranial system, a possible one-staged coexistence in the crane of the areas with elevated, normal and lowered pressures.     

自动紧急制动对公交车内儿童乘员颅脑损伤影响

目的 研究自动紧急制动(autonomous emergency braking,AEB)对公交车内儿童乘员的颅脑损伤影响。 方法 使用 Prescan 软件搭建公交车 AEB 测试场景,通过仿真得到 60 km/ h 初速度下公交车 AEB 制动工况下的减速度曲线。 基于已经验证的公交车模型和具有详细解剖学头部结构的 6 岁儿童混合有限元模型,选取车内儿童乘员典型的 4 个乘坐位置,使用 LS-DYNA 软件对公交车有、无 AEB 制动工况下儿童乘员头部损伤进行仿真。 以儿童乘员头部损伤指标 HIC15 、大脑灰质处压力、脑组织 von Mises 应力及剪切应力等生物力学响应为损伤评价指标,对儿童乘员的颅脑损伤进行分析。 结果 各组仿真试验中,位置 1 和 2 前方设置挡板时,儿童乘员大脑灰质处压力超过其损伤阈值,其余各位置儿童乘员的各项损伤指标均远小于对应的损伤阈值。 结论 AEB 能有效降低公交车内儿童乘员头部碰撞损伤,公交车内位置 3 处的儿童容易发生碰撞损伤风险,位置 1、2 处设置广告牌挡板会增加儿童乘员的颅脑损伤风险。     

对头部损伤判断准则适用性和可用性的新探索

头部损伤判断准则(Headinjury criterion,HIC)是目前较为广泛被接受的、用来衡量头部在外来载荷下安全性的一种损伤判断准则。它被应用于各国的汽车安全法规中,也是头部损伤防护装置(如头盔)设计的参考标准。然而对它的适用性和可用性也存在着不少的争议。本研究应用人类头部有限元的计算模型,通过分析两个不同大小、不同质量的头部模型在三种不同载荷下所产生的脑组织的应力和相应引出的"头部损伤判断准则"的计算值,识别影响"头部损伤判断准则"的适用性和可用性的因素,为如何更科学地评判头部受载安全性提供新的见解和结论。     

脑组织氧分压监测技术的研究与应用进展

脑组织氧分压 (brain tissue oxygen partial pressure,Pbti O2 )技术是进入 90年代后逐渐成熟起来的脑氧代谢监测方法 ,与传统的脑氧监测方法相比具有微创、安全、准确的特点。应用这一技术可以对病人进行术中及术后的长期、动态监测 ,有助于正确判断脑血流量、颅内压、脑灌注压之间的关系 ,早期判断预后。但脑组织氧分压监测所获得的信息尚需结合其他监测手段获得的数据加以综合分析 ,才能得出准确结论     

外伤后脑血肿对颅内压分布的力学分析研究

目的　根据患者CT和颅内压数据，建立外伤性脑损伤的有限元模型，分析脑血肿对颅内压产生的压力响应。 方法　采用成人头部有限元模型（GHBMC）与气体分子动力学分析脑血肿膨胀与颅内压增高的关系，提取并折叠血肿，置入有限元模型中相对应的位置，根据CT图像和颅内压值，加入肿胀曲线，进行模拟计算，得到各个部分的脑组织压力分布云图、脑组织应变的分布云图，计算脑疝多发区域的脑组织压力差。 结果　有限元模型中的压力值、中线偏离量与临床病人脑室型探头压力、CT图像中线的吻合度较好，误差率分别为4%和2%。模拟结果显示，在左侧颞枕叶矢状位上，左侧基底节区血肿病例大脑镰下方、小脑幕切迹后部压力差不显著，分别为1400 Pa和1320 Pa。但幕上颞叶压力明显大于小脑小叶的压力，分别为2504 Pa和1360 Pa。小脑前叶与后环池的压力无明显差异。左侧脑血肿患者小脑幕比右侧脑血肿患者具有更大的等效应变。 结论　左侧患者额颞基底节区的血肿更有可能导致小脑幕切迹疝。而右侧患者的脑血肿导致的压力被小脑幕的应变代偿，脑疝风险因此下降。通过本研究计算脑疝易形成区域的压力差，可更好地理解血肿造成的颅内压分布对激发脑损伤的影响，为损伤的预后提供力学依据。     

外伤后脑血肿对颅内压分布的力学分析研究

目的　根据患者CT和颅内压数据,建立外伤性脑损伤的有限元模型,分析脑血肿对颅内压产生的压力响应。 方法　采用成人头部有限元模型（GHBMC）与气体分子动力学分析脑血肿膨胀与颅内压增高的关系,提取并折叠血肿,置入有限元模型中相对应的位置,根据CT图像和颅内压值,加入肿胀曲线,进行模拟计算,得到各个部分的脑组织压力分布云图、脑组织应变的分布云图,计算脑疝多发区域的脑组织压力差。 结果　有限元模型中的压力值、中线偏离量与临床病人脑室型探头压力、CT图像中线的吻合度较好,误差率分别为4%和2%。模拟结果显示,在左侧颞枕叶矢状位上,左侧基底节区血肿病例大脑镰下方、小脑幕切迹后部压力差不显著,分别为1400 Pa和1320 Pa。但幕上颞叶压力明显大于小脑小叶的压力,分别为2504 Pa和1360 Pa。小脑前叶与后环池的压力无明显差异。左侧脑血肿患者小脑幕比右侧脑血肿患者具有更大的等效应变。 结论　左侧患者额颞基底节区的血肿更有可能导致小脑幕切迹疝。而右侧患者的脑血肿导致的压力被小脑幕的应变代偿,脑疝风险因此下降。通过本研究计算脑疝易形成区域的压力差,可更好地理解血肿造成的颅内压分布对激发脑损伤的影响,为损伤的预后提供力学依据。     

Intracranial pressure and biochemical indicators of brain damage: follow-up study

Aim

To investigate the relation between metabolic parameters of the brain tissue, as direct indicators of real metabolic conditions within the brain, and intracranial pressure, as the consequence of pathophysiological changes.

Methods

Twelve patients with closed head injuries were followed up for 24 hours after injury. A Codman parenchymal intracranial pressure and a Neurotrend electrode were inserted within 3 hours after injury to monitor parenchymal intracranial pressure, brain tissue partial oxygen pressure (P_brO₂), brain tissue partial carbon dioxide pressure (P_brCO₂), pH, and brain tissue temperature. Data detected at 8-hourly intervals were compared with repeated measures analysis of variance.

Result

At the initial observation, the mean value of intracranial pressure was 22.2 ± 3.2 mm Hg. Although it increased at the second and decreased at the third measurement, the differences between the measurements were not significant (P = 0.320). The value of P_brCO₂ was increased from the beginning (63.3 ± 6.0 mm Hg), whereas P_brO₂ was within the normal range at the first measurement (38.9 ± 6.9 mm Hg), but significantly decreased after 8 hours (P = 0.004), remaining low at later time points.

Conclusion

After brain injury, changes in P_brCO₂ are visible earlier than those in P_brO₂. Improvement in intracranial pressure values did not necessary mean improvement in the brain tissue oxygenation. In addition to intracranial pressure, P_brO_2, P_brCO₂ and pH should also be monitored, as they directly reflect the real metabolic conditions within brain tissue and may be used in predictions about the outcome and possible therapeutic approaches.In head injuries, the brain is often threatened by various secondary pathophysiological processes leading to hypoxia or ischemia of the brain tissue (1). In the acute phase after head injury, the cerebral blood flow decreases, while the oxygen consumption in the brain tissue markedly increases (2-4). Secondary neurocytotoxic processes cause brain edema and increase the intracranial pressure, which further worsens cerebral metabolism, causing new neurocytotoxic complications. To prevent this vicious circle of pathophysiological processes, it is necessary to maintain adequate oxygenation of the brain tissue, which depends on the cerebral perfusion pressure and cerebral blood flow (5).Cerebral perfusion pressure equals the difference between the mean arterial pressure and intracranial pressure. Continuous measurement of the mean arterial pressure is always possible in intensive care units (ICU), and the treatment of head injuries today routinely includes monitoring of intracranial pressure. A cerebral perfusion pressure of about 70 mm Hg can optimally supply the brain with blood; if the brain tissue partial oxygen pressure is above 35 mm Hg, normal oxygenation of the brain tissue should be assured (5,6). Continuous assessment of brain oxygenation is possible with the use of commercial sensors.It is generally accepted that intracranial pressure is the key parameter in the assessment of patients with brain injuries. Moreover, patient treatment is based on the value of intracranial pressure (7). However, biochemical parameters in the brain tissue, such as the brain tissue partial oxygen pressure (P_brO₂), brain tissue partial carbon dioxide pressure (P_brCO₂), and pH, directly reflect the real metabolic conditions in the brain, whereas intracranial pressure is merely the consequence of pathophysiological changes.In the early phase after the injury, the value of intracranial pressure may still be within the normal range, while biochemical parameters are already pathologically changed. Therefore, these metabolic parameters should be monitored in the acute phase of brain injury. Our hypothesis was that the variations of intracranial pressure values and variations of biochemical parameters were not closely related, even in cases of closed brain injury. To test this, we measured intracranial pressure, brain tissue partial oxygen (P_brO₂) and carbon dioxide (P_brCO₂) pressure, pH, and temperature of the brain tissue at different time points within the first 24 hours after injury. We also investigated the relation between the changes of intracranial pressure values and variations of each of these metabolic parameters.     

Evaluation of micro tip pressure transducers for the measurement of intracerebral pressure transients induced by fluid percussion.

We describe the application of MIKRO TIP miniature pressure transducers (MPT) for the in vivo measurement of intracerebral stresses induced by traumatic brain injury (TBI). In order to test the linearity of these transducers pressure pulses of different amplitudes (duration approximately 10ms) were generated in a closed calibration chamber. A piezoelectric pressure transducer (PPT) served as the reference measure. A linear correlation was found within the pressure range between 0.57 and 5.09 bar (R2 = 0.998). The frequency transmission characteristics of the MPTs are comparable to the PPT. In three juvenile swines (6 weeks of age) pressures within the brain tissue were induced by fluid percussion (FP) and were measured in the anterior, middle, and posterior cranial cavity as well as in the extracranial part of the medulla oblongata. The data obtained in our experiments agree with the basic biomechanics of FP known from studies in cats and rabbits. Due to their small size, MPTs can be applied in living animals. Stereotaxic positioning of these catheters at any site of the brain and spinal cord requires only minimal surgery. Therefore, MPTs are useful in evaluating animal models of brain injury and in generating input data for computational models of head injury as well as to validate the mathematical results of such models with experimental data.