The Characteristics And Mechanism Of Remote Behind Armor Blunt Brain Trauma In Swine

The small caliber and increased energy of bullets is one of focus in the modern lightweapon design and development, and the effective personal armors can greatly reduce themortality on the battlefield. However, the body armor and bullet proof-vest are not able tocompletely stop the ballistic injury. The blunt injury behind armor (BABT), thenon-penetrating injury to the human body resulting from the impact of projectiles onpersonal armors, was firstly reported by Carroll in1978. The pathological features andmechanisms of BABT have been one of the focuses of ballistics research. At presently, theBABT studies are mainly based on animal model, cadaveric subject, and simulation test inabroad, the combination of finite element analysis and validation by various experiments isthe major research tool. The most studies now days are focused on the pathology andpatho-physiology, and the mechanisms of BABT, which is subsequently used for assessmentof BABT. The current BABT criteria was made and published by the United States NationalInstitute of Justice (NIJ), which is mainly for the soft body armor, in which, the deformationcaused by bullet is measured by the plaster closely attached to the backface of bullet-proofvest, it will be considered as risk of BABT if the deformation is as deep as44mm. However,this criterion is only referred to the direct injury caused by deformation of armor, the remotetrauma resulted from the shearing waves arose by the deformation is not put into theconsideration, therefore, there is limitation on the BABT risk assessment. So far, there israrely report on BABT caused by the bullet of higher velocity and increased energycombined with a rigid armor, especially no in-depth study on the remote organ trauma, likebrain. The purpose of the current study was to investigate the feature of brain trauma behindthe armor, to establish the correlation between the trauma severity and bullet velocity, whichwill be worthwhile as a complimentary of BABT risk assessment for central nervous systemtrauma assessment. Body armor the name can cause misunderstanding may think it can resist all the bullet,in fact, body armor can’t direct pulled the block back, but the use of protective materials, thepower of the bullets into the surface of scattered a large area, its kinetic energy absorption,make it as far as possible through the human body in before the stop. In the process, willalso because the bullet deformation, and further reduce its penetration. Although bodyarmor can avoid the bullet had entered the human body caused by damage, but the body stillshot in the inevitable because the bullet’s energy absorbed by blunt, therefore blunt injuryafter the body armor is a rapid nonpenetrating damage. As a modern combat single-soldierbulletproof the important part, is widely used in modern war, and in the gulf war, the war inAfghanistan to the war in Iraq, the use of modern war a complete reversal of traditionalmode of war we know, high, refined, sharp weapon the use of equipment, and greatlyreduce the mortality rate of combat troops, even in the most brutal street fighting due to theuse of individual protective apparel, its operational personnel deaths than the traditional waris greatly reduced. According to the quality of a material body armor can be divided into thehard and soft two types, the former adopt ceramic or steel bulletproof plug-in boards canprevent the penetration of bullet step, the latter high strength of the fiber fabric absorbedbullet, hand speed the kinetic energy of projectile. Projectile hit after throughout the bodyarmor caused by damage characteristics and mechanism research has is trauma ballistics theemphasis of research, the U.S. military in Iraq and Afghanistan war,60%among thewounded there are different levels of (mTBI), most of them due to explode, and somecombat troops and not by explosive of the shock effect, is only in body armor protectiondown by the bullet shoot also appeared memory decline change, some scholars take thisform boils down to the injuries stress syndrome, if only a single stress syndrome thispsychological change and not exist on the quality of pathological changes, is worth usfurther study. At home and abroad and to ascertain the damage to animals after research andsimulation test, combining the bodies, and the finite element model analysis and test theform of complement each other, and puts forward after the body armor possibly for theenergy transfer, absorb cause as far as brain damage. But how much of the energy bodyarmor after bullets can lead to as far as brain damage, the damage to have the kind of characteristics, has not seen the report.Therefore, to illustrate how the body armor after energy bullets can cause braindamage and damage as far as what are characteristic, if there are as far as damage, so thiskind of injury biomechanics mechanism have what characteristics, in this study, we first usea certain type of military caliber rifle25m distance to three different attack speed (underthe same caliber bullets hit the energy into the different rates of, respectively for910m/s,740m/s,590m/s) simulation in lining for police Ⅱ hit level, outer NIJ Ⅲ standard forceramic bulletproof flashboard and hard of the larger white pig body armor protection areabefore the heart, observed three different speed bullet blow, hurt by electroencephalogram(EEG), electrocardiogram, before and after the arterial blood pressure, heart rate andbreathing changes. Take before the injury after injury30min,1h,2h,3h, the centrifugalartery blood, clear fluid plasma to take on brain damage detection markers, before the injuryand3h after injury with pool piercing take cerebrospinal fluid (CSF) for specific braindamage markers a Ⅱ-spectrin and calcium and activate neutral protease adhesion of a Ⅱ-SBDP detection. After injury3h for chest CT flat and thoracic bone and3d reconstructioninspection. After the injury3h bleed to death animals, observe heart, lung, liver and braininjury in the before and after pathological changes, each speed of random take2heads wastaken on brain tissue perfusion pathological microscopic and superfine check, comparingthe different speed the characteristics of the damage. In order to confirm that this as far asdamage cause of behavioral change, we in the experimental conditions remain unchanged,under the premise of hurt by1month before the larger white pig to selectively foragingtraining, use two the same size of bowl, in which a edge add two pieces of bar to changeedge as square, the bar on low voltage ac, in larger white pig feeding party basin, through tothe ac electric shock, by repeated training, hurt by larger white pig in front of a dangersignals food absolutely not tempt square and eating, hurt by the observation of injury afterpigs before and after the change of behavioral experiments. Finally, in the above modelbased on effect, establish the biomechanical testing model, in the area before the heartsubcutaneous, pericardial cavity, the left chest, the left common carotid artery andintracranial decorate biological sensors, fight larger white pig moment hurt by local and as far as brain tissue biomechanical is determined.The experimental results and conclusions1. The body armor protection, larger white pig after injury are alive, but in the shorttime after injury all have different degree of physical changes. The performance is:moments of injury, the different speed leader has a white breath stop, stop time7S--15Sdiffer, after injury within10min arterial blood pressure drops, with systolic blood pressuredrop is given priority to, among them the most obvious of decline, artery systolic bloodpressure before the injury to the third, min after gradually restored to the level before theinjury, after injury of5min speed group in eeg low frequency wave Delta, Theta wave allappear inhibition of volatility, analyzes the volatility drop between no obvious difference,5min of brain wave after back to before the injury level, after injury3h blood the midbraindamage markers S-100-B and injury in a marker of cerebrospinal fluid increased before theinjury, and a Ⅱ-SBDP spinal fluid has good specificity. When to dissect found that910m/sgroup in the brain surface of focal point there flake bleeding,740m/s group existing brainsurface patch bleeding kitchen, and590m/s group is little bleeding kitchen, the seahorseHE dyeing, armour aniline blue stain and superfine electron microscopy (sem) examinationare found to have Ca1area existing neurons, swelling, such as unclear degenerationdifferent degree change, and these changes as the bullet hit the speed of and heavier. Theabove preliminary results hint: police Ⅱ level for inner and outer for NIJ Ⅲ standardceramic bulletproof flashboard and hard body armor protection in more than590m/s bullethit step may exist as far as brain damage, low speed group in function only performancechange, such as brain electrical inhibiting, vital signs of change, change a minor in neurons,most of this change in a short time restore, and high velocity, high energy bullets have notonly the brain electrical inhibiting, vital signs of change, and also appeared relatively lowspeed group heavier pathological changes, such as small vascular rupture surface causebrain hemorrhage as focal point flake bleeding, microscopic and superfine pathological alsoappears more low speed demyelinated local group pathological changes of the heavydamage.2. Immediately after the injury to40minutes, hurt by a larger white pig before state clearly becomes poor, refuse to walk. It found that left fore walk off before the injurymuscle strength is abate, skewed to the left. While looking in selective2pig indiscriminateeating have direct danger signals basin party food, and have a head after eating party still inshock basin, have two head for square bowl2times test, but without food bowl party food,1head injury in without food, curled up in a corner piggery muscle fibrillation, all groupsare in two hours after eating recovery, and no test and eating happen.3. The bullet hit intracranial pressure moment in a very short time (one over onethousand seconds) shot up,910m/s group peak can even rise to normal intracranial pressureof40~50times, and pressure for the oscillation of the present high frequency curve,intracranial pressure and the bullet hit speed are related, the910m/s is about740m/s2times, and740m/s is about590m/s2times. Hit points and force the partial pressure withthe bullet with the increase of the speed increases.The results show that in the outer NIJ Ⅲ lining for Ⅱ level under police protection,along with the increase of the speed, in larger white pig hurt by appeared after centralnervous brain electrical suppression, blood and the specific markers of cerebrospinal fluidbrain damage increased appeared in the hippocampus experienced central neuronsdegeneration, swelling, demyelinated change, indicates that in body armor protection inmore than590m/s bullet shooting, central nervous tissue in were not under a direct hit,there are also damage, this kind of the extent of the damage is not result in larger white pigfatal, but caused larger white pig function on some of the change, and some of the minorpathological changes, also is a mild brain injury (mTBI). This kind of damage with into alsoled to the behavior changes, because larger white pig in after a month after the training tohave not danger signals bowl happen foraging behavior, but in hit with a minor after braininjury (mTBI) its behavior change and these injuries can lead to larger white pig low-levellearning and memory selective foraging error. The far reaches the brain damage its possiblebiological mechanical mechanism mainly for: in an instant, the deformation of the thoracicdynamic change, and blood direct osseous transfer, this several mechanism is not mutuallyexclusive, may be the result of joint action. The bullet hit a bulletproof compound, thekinetic energy is mostly the bulletproof material abatement, part of the energy body armor in the role of the organism, in vivo to pressure wave forms to the far end and deeptransmission, the pressure wave through the osseous transmission or cardiovascular systemof the transfer function of the brain in intracranial, cause increased intracranial pressuretransient; There are some energy into the kinetic energy of biology, cause biology highacceleration low displacement. The increased intracranial pressure with high accelerationlow displacement related, caused by high acceleration skull displacement, and brain damagecaused by relatively static acceleration brain tissue. Therefore, we can assume that, whenfighting men in body armor protection by high speed under the step the bullet shoot, canalso cause as far as brain damage and some behavior of the change.