【作者】 张波；

【导师】 王爱民； 赖西南；

【作者基本信息】 第三军医大学 ， 外科学， 2012， 博士

【摘要】 一、研究背景防弹衣的雏形可追溯至远古时期人们制作的人体装甲。现代防弹衣的发展开始于一次世界大战，那时出现了以蚕丝和其它天然纤维为衬里并配以钢板制成的防弹衣。防弹衣可以避免投射物(如子弹或爆炸物形成的弹片)对人体胸腹部形成的穿透伤，并降低伤员的死亡率。据统计在一次世界大战因为防弹衣的使用使英国士兵的伤亡率降低了58%。但防弹衣并不能完全消除投射物对机体的伤害，防弹衣后钝性损伤(Behindarmor blunt trauma， BABT)就是其损伤特点之一。防弹衣后钝性损伤是指投射物击中防弹衣后导致机体内脏器的非穿透性损伤。防弹衣后钝性损伤既可发生软式防弹衣也可发生在硬式防弹衣防护下的机体。投射物，尤其是高速投射物，与防弹衣碰撞后产生的能量可通过防弹衣向机体内传导并导致体内各脏器不同程度的损伤，严重时可以致死。近年来随着防弹衣和高能量武器的广泛使用，人们对防弹衣后钝性损也越来越重视，并对胸部防弹衣后钝性损伤进行了大量的研究。胸部防弹衣后钝性损伤从轻微的皮损到严重的内脏损伤，如肺挫伤、心肌挫伤和肝破裂等均有相关报道。在战斗中背部也是防护的重点，对于防弹衣防护下背部中弹后各脏器钝性损伤特点尚未见相关报道。背部的脊柱脊髓与颅骨和脑组织紧密相连，对于背部防弹衣后钝性损伤是否也会导致脊髓以及脑组织的伤害，目前尚未见相关报道。关于这种损伤形式对中枢神经(脑)功能的影响，以及伤后血清和脑脊液中特异性神经损伤标志物的表达水平也不明确。阐明这些问题不仅对背部防弹衣后钝性损伤特点有更加深刻的认识，还为背部防弹衣钝性损伤所致的中枢神经损伤的诊治和预后判断提供充分的实验依据，同时还可为致伤后作战人员的作战能力的评估提供依据。防弹衣后钝性损伤生物力学机制是什么呢？通过生物力学和计算机仿真模型研究得出防弹衣后钝性损伤与碰撞后产生的压力波与剪切力有关。但既往的研究大多局限与胸部中弹后力学传导，对背部防弹衣后钝性损伤产生的压力波在生物体内的传导规律尚无报告。关于压力波的大小与子弹动能以及损伤的关系目前也不明确。阐明这些问题可以为防弹衣的改进以及防弹衣后钝性损伤的预防提供依据。二、研究目的本实验研究目的是明确步枪弹致背部防弹衣钝性损伤后：①脊柱脊髓以及中枢神经(脑组织)损伤特点；②胸腔重要脏器的损伤特点；③实验动物的运动以及认知功能的改变；④步枪弹与防弹衣碰撞后产生的压力波在生物体内的传导规律以及产生加速度大小。在了解以上特点的基础上，探讨背部防弹衣后钝性损伤的生物力学机制。为防弹衣的改进以及防弹衣后脊柱脊髓和中枢神经(脑组织)损伤的预防、诊治和预后判断提供实验依据。三、研究内容用复合式防弹衣(软31层超高分子聚乙烯防弹衣+4.2mm Al2O3陶瓷防弹板)对实验动物的背部进行防护，以背部T8椎体部位为致伤点，在25m处用三种不同速度(590m/s，740m/s，910m/s)的某型步枪弹致伤并研究以下内容：1、致伤后中枢神经系统(脊髓及脑组织)的病理损伤特点；中枢神经系统的损伤程度与相关电生理(体感诱发电位、脑电图)以及与中枢神经损伤标志物(NSE，MBP，S-100β)表达水平的关系。2、致伤后胸腹腔重要脏器(肺、心、肝、肾)的病理损伤特点以及对相关生理功能的影响；3、不同速度枪弹致伤后对实验动物双后肢运动功能的影响；高速步枪弹(910m/s)致伤后对实验动物认知的影响。4、三种不同速度的步枪弹致伤后产生的压力波在椎旁软组织内的传导规律，致伤点附近加速度的大小；探讨压力、加速度与脊髓和脑组织损伤的关系。四、结果(一)防弹衣损伤情况：三种弹速的某型步枪弹均未击穿防弹衣，并在硬式防弹衣后形成半球形的凸起，当弹速为910m/s时，所形成凸起的高度和面积与740m/s和590m/s有显著差异(p <0.01)，740m/s组与590m/s组无显著差异。(二)实验动物损伤情况1局部皮损特点：致伤后早期，致伤区的皮肤会形成苍白区和红晕区，910m/s所形成的苍白区与590m/s有明显差异(p=0.026)，所形成的红晕区与740m/s和590m/s有明显差异(p=0.008，740m/s；p=0.000，590m/s)。740m/s和590m/s所形成的苍白区无明显差异，但红晕区面积有显著性差异(P=0.009)。皮损中心(着弹点)与T8椎体的距离分别是2.86±0.90cm (910m/s)，3.33±0.58cm(740m/s)，3.20±0.44cm(590m/s)2胸腹脏器损伤特点(1)大体损伤特点：三种速度的步枪弹均未导致椎体骨折。不同速度的步枪弹可致胸腹腔脏器不同程度的钝性损伤，其中910m/s步枪弹致伤后表现为：肺表面点片状出血(100%)，心脏瓣膜缘出血(33%)，肝包膜下出血(33%)，肾脊柱缘出血(50%)。740m/s致伤后表现为肺表面点片状出血(100%)，肾脊柱缘出血(33%)。590m/s致伤后表现为肺点状出血(40%)。(注：括号内百分数为损伤比率)(2)血压、心率、血氧饱和度损伤特点：三种速度致伤后的血压、心率和血氧饱和度在测定的时间范围内伤前伤后均无明显改变。(3)心电图损伤特点：各致伤组伤前伤后心电图无显著变化。3中枢神经系统损伤特点(1)大体及显微病理损伤特点：910m/s步枪弹致伤后表现为：脊髓挫伤和蛛网膜下腔出血(22%)；显微病理显示：脊髓神经元变性，轴突脱髓鞘改变，海马无髓神经元变性。当弹速为740m/s和590m/s时，肉眼和光镜下脊髓和脑组织未见明显损伤。(2)中枢神经损伤标志物(MBP、NSE和S-100β)变化特点：当弹速为910m/s时，中枢神经损伤标志物在脑脊液和血清中均高表达，致伤组与对照组有明显差异(p <0.01)。弹速为590m/s和740m/s时，致伤组与对照组的中枢神经损伤标志物没有明显差异。(3)脑电图损伤特点：当致伤速度为910m/s时，脑电波在伤后1min出现了抑制并在伤后3-6min内恢复。740m/s和590m/s致伤组脑电图伤前伤后无显著差异。(4)右下肢股神经诱发电位损伤特点：与致伤前相比，致伤后各组潜伏期变化无明显差异，但波幅均出现明显降低，且随着速度的增加，波幅降低越明显。各实验组波幅降低值与对照组均有显著性差异(p=0.001，910m/s；p=0.002，740m/s；p=0.023，590m/s)；910m/s与590m/s有显著性差差异(p=0.004)。(5)实验动物运动和认知功能损伤特点：速度为910m/s的步枪弹致伤后可出现双后肢肌力和感觉减退，严重时表现为双侧后肢的拖行(33%)，运动功能在48h内恢复；所有实验动物(100%)均出现记忆力障碍并在24h内恢复；740m/s的步枪弹致伤后表现为感觉和肌力减退但对实验动物的行动无明显影响；590m/s的步枪弹致伤后未见运动功能的改变。(注：括号内百分数为损伤比率)4MAIS (Maximum abbreviated injury scale)评分：910m/s组MAIS评分平均值为2.22±0.67；740m/s组MAIS评分平均值为2.00±0.00；590m/s组MAIS评分为平均值1.17±0.41。(三)生物力学损伤特点：随着弹速的增加各物理指标(压力和加速度)均不同程度的增加。在脊柱旁软组织内测定的压力大小与致伤点的距离呈指数关系，在颅内测得压力高于颈动脉内测定值(p <0.05)。通过对肢体的运动功能障碍(肌力)与相关物理参数(弹速、压力、加速度、着弹点距T8距离)进行逐步回归分析后发现：防弹衣后脊柱脊髓钝性损伤所致实验动物的运动功能障碍(y)主要与致伤点的加速度(x)有线性关系(F=137.052，p=0.000)，其线性回归方程为：y=13.282-0.002x，其中y值越小，损伤越重。五、结论在复合式防弹衣(软31层超高分子聚乙烯防弹衣+4.2mm Al2O3陶瓷防弹板)防护下，以某型步枪弹在25m远处致伤背部(T8椎体部位)后会导致多脏器的钝性损伤，具体损伤特点如下：1、胸腹腔脏器(肺、心、肝、肾)钝性损伤且主要表现为点片状出血，其损伤程度同枪弹的速度(动能)呈正比；2、高速步枪弹(910m/s)可引起致伤点下脊髓表面挫伤和蛛网膜下腔出血，脊髓神经元的变性和有髓神经纤维脱髓鞘；导致实验动物出现不同程度的肢体运动功能障碍(<48h)，严重时表现为双侧后肢拖行；3、高速步枪弹(910m/s)致伤后可导致脑组织的远达损伤，表现为脑实质的损害(海马无髓神经纤维的变性)和伤后一段时间内(<24h)认知功能(记忆力)的障碍；4、、枪弹与防弹衣碰撞后产生的压力波和加速度是导致脏器损伤的主要原因；其中椎体的加速度是评估脊髓损伤程度的主要物理参数，压力波主要通过椎体传导并导致脑组织的远达损伤。更多还原

【Abstract】 BackgroundBody armor had a long history, which was begun to use in the ancient times. Thedevelopment of modern armors originated from the World WarⅠ. Modern Armors aremainly used by army, police and guarantors. There are three kinds of body armorscategorized by materials: soft, hard and combined armors. Body armor can avoid projectiles(such as bullets or blast fragments) penetrating the chest and abdomen of human being, andlower the mortality of the wounded. It was estimated that the mortality of British soldiersdecreased by58%when the armors were applied in the World War I. But the body armorcan not completely eliminate the damage of the projectiles in the body. Behind armor blunttrauma (BABT) is one kind of typical damage. BABT can occur in the body shielded bysoft body armor or hard body armor. When the projectiles, especially high-speed projectilesimpacted with the armors, the energy generated in the course of collision could conduct tothe body through body armor, and lead to different degrees of damage in various organsunder the armor, even to death.In recent years, with the widespread application of body armors and high-energyweapons, people began to pay more attention to BABT and have been doing a lot ofresearches about the BABT on the chest. The researches ranged from minor skin lesions tosevere visceral injury, such as pulmonary contusion, myocardial contusion and rupture ofliver.However, characteristics of BABT in bullet injuries of back have not been reported.Whether spinal cord would be injured concurrent with back injuries is also not clear.Investigating of the characteristics of body armor blunt trauma in the back will contributenot only to the deep comprehension of BABT but also to the operational capabilityassessment of injured soldiers.High-speed bullets on the chest could cause BABT of the central nervous system (brain) featured by inhibition of electroencephalogram. Vertebral column is concatenatedwith skull, and spinal cord is concatenated with brain. Whether the BABT on the backcould cause damages in the brain has not been reported. It is not clear whether functionaldamage of brain and change in level of specific biomarkers in the serum or cerebrospinalfluid would occur after BABT. So, investigating the characteristics of BABT in the backwill also contribute to diagnosis, treatment and prognosis of brain injury caused by BABTon the back.What is the biomechanical mechanism of BABT? It has been reported that thepressure wave and the shear generated after the collision were the main reasons. Previousstudies are mostly confined to the injury on the chest; and there is no report on theconduction laws of pressure wave generated after BABT on the back in vivo. Therelationship between the amplitude of pressure wave and bullets kinetic energy is also notclear. Clarifying these issues can provide the basis for body armor improvements andprevention of BABT.ObjectiveTherefore, the aim of present study was to uncover the pathological characteristics ofdifferent vital organs and the biomechanical characteristics in the spine and central nervoussystem when armored animals were wounded by three different velocities bullets andinvestigate the neurological, functional characteristics of the armored animals when injuredby high-velocity bullet.ContentsThe backs of animals were protected by combined armors consisted of4.2mm Al2O3ceramic plate and ultra-high molecular polyethylene. Then the eighth thoracic vertebra (T8)was injured by bullets of three velocities (590m/s,720m/s, and910m/s) at the distance of25m. The following researches were on the basis of this animal model.1. Pathological changes of central nervous system and other vital organs in chest andabdomen were investigated after injury. Physiological changes including electrocardiogram(ECG), electroencephalogram (EEG) and somatosensory evoked potential (SEP) were alsoinvestigated after the thoracic spine injured by bullets of three velocities (590m/s,720m/s,910m/s). The level of myelin basic protein (MBP), neuron-specific enolase (NSE), and theglial cytoplasmic protein S-100β were measured in the cerebrospinal fluid (CSF) and serum.2. Motor-function changes of armored animals were evaluated when injured on thethoracic spine. Cognitive-function was evaluated when injured by high-velocity (910m/s)bullet.3. To investigate the biomechanical characteristics of pressure wave generated by theimpact, the pressure in the spine, brain and common carotid artery was measured. Theacceleration in vicinity of target point was also measured.Results1. Damages of armors: All bullets did not penetrate the ceramic armors and causedhemispheric projecture on armors. The mean height and area of projecture were significantdifferences between the group of910m/s velocity bullets and the other groups (p <0.01).2. Skin injuries: There formed a pale area surrounded by a flush area in the skin afterinjured. The flush area in the group of910m/s was statistically different compared with theother groups (p=0.008,740m/s; p=0.000,590m/s).3. Organs injuries: There were no vertebras broken in all injured animals.The injurieswere severer in a higher velocity group.When velocity was910m/s, spine cord contusion and subarachnoid hemorrhage (22%),discrete hemorrhaged areas in the lung lobes (100%), hemorrhage in the valve in theheart(33%), and hemorrhage under the envelope of liver(33%) and kidney(50%) wereobserved. The average MAIS was2.22±0.67.(The numbers in the brackets were the ratioof injured)When the velocity was740m/s, discrete hemorrhaged areas in the lung lobes (100%),hemorrhage in the kidney (33%) were observed. The average MAIS was2.00±0.00.When the velocity was590m/s, discrete hemorrhaged areas in the lung lobes (40%)were observed. The average MAIS was1.17±0.41.Pathological investigation showed neuronal degeneration and demyelination in thespinal cord and degeneration of non-medullated nerve fiber in the hippocamp when thebullets velocity was910m/s.4. Biomarkers of central nervous system: MBP, NSE, and S-100β were highlyexpressed in serum and CSF, there was significant difference between control and injuredgroup (p <0.01) when the velocity was910m/s. However there were no significant differences compared with control group when the velocity was740m/s or590m/s5. ECG investigations:. The ECG had no significant changes in each group.6. EEG investigations: The EEG showed that low frequency band decreasedsignificantly in the right frontal lobe and parietal lobe within1min after trauma andrecovered within3-6minutes when the velocity was910m/s. The EEG had no significantchanges when the velocity was740m/s or590m/s.7. Somatosensory evoked potential (right femoral nerve): The incubation period wasnot statistically different between pre-and post-injury in each group. The wave amplitudeof post-injury decreased in each group. When bullet speed was higher, the decrease ofamplitude was more significant. There were statistical differences between the injuredgroups and control group (p=0.001,910m/s; p=0.002,740m/s; p=0.023，740m/s).There was significant difference between the group of910m/s and590m/s (p=0.004).8. Motor and cognitive function: It can cause motor and cognitive dysfunction ofanimals when the bullets velocity was910m/s. The severest motor dysfunction manifestedthat the hind limbs could not support the body and only dragged (33%). The motordysfunction would last about48h. The cognitive dysfunction manifested memorydysfunction (100%), which would last less than24h.9. Biomechanical investigations: When the bullets shot on the armor, pressure wasdetected in the spine, brain and the common carotid artery. Acceleration was also detectedon the spinous process (T10). The pressure and acceleration increased with the bulletsbecome faster. The pressure detected in the brain was higher than that detected in thecarotid artery (p <0.05). The acceleration has linear relationship with the motordysfunction.ConclusionAlthough the eighth thoracic vertebra (T8) was protected by combined armors whichconsisted of4.2mm Al2O3ceramic plate and ultra-high molecular polyethylene, the highvelocity (910m/s) bullets impact from25m distance could induce degeneration of neuronand demyelination in the spinal cord, as could lead to motor dysfunction which would lastabout48h. The injury also could cause degeneration of non-medullated nerve fiber in thehippocamp, as could lead to cognitive dysfunction which would last less than24h. If thesame BABT occurred in the soldiers, it could make them incapacitation. The acceleration was perhaps the key reason responsible for the spinal cord injuryafter BABT.更多还原