Modeling the effect of non-penetrating ballistic impact as a means of detecting behind armor blunt trauma

BACKGROUND: According to the National Institute of Justice (NIJ) Standard 0101.04, the maximum deformation a soft armor vest can undergo without penetration is 44 mm. However, this does not take into account the effect of the pressure wave or energy transferred to the organs within the torso due to behind armor blunt trauma (BABT). Therefore, a study was undertaken to develop a finite element model (FEM) to study these effects. METHODS: A finite element model (FEM) of the human thorax; complete with musculoskeletal structure and internal organs (heart, liver, lungs and stomach), intercostal muscle and skin, has been developed in LS-DYNA. A Kevlar vest was modeled on the chest to simulate non-penetrating ballistic impact. RESULTS: Using a projectile modeled with a size and mass equivalent to a 9 mm (124 grain) bullet at 360 and 425 m/s, four impacts were simulated against NIJ Level II and Level IIIa Kevlar vests at the midsternum and right thorax. At the same velocity, the pressures decreased by a factor of 3 and the energy absorbed by the organs decreased by a factor of 6 for the NIJ Level II and Level IIIa vests, respectively. As the projectile velocity increased, the peak pressures increased by a factor of 3 while the energy absorbed by the organs increased by a factor of 4. CONCLUSIONS: The resulting pressure profiles and kinetic energy exhibited by the respective organs indicate this model may be useful in identifying mechanisms of injury as well as organs at an elevated injury risk as a result of BABT.     

Cardiac impalement from a rib after blunt trauma

Blunt chest trauma produces a variety of injuries. We present a case report of a hemodynamically stable patient after blunt chest trauma with radiographic images suggestive of the left fifth rib penetration to the heart. The diagnosis, surgical approach, and course of the patient are discussed.     

Assessing behind armor blunt trauma in accordance with the National Institute of Justice Standard for Personal Body Armor Protection using finite element modeling

BACKGROUND: To assess the possibility of injury as a result of behind armor blunt trauma (BABT), a study was undertaken to determine the conditions necessary to produce the 44-mm clay deformation as set forth in the National Institute of Justice (NIJ) Standard 0101.04. These energy levels were then applied to a three-dimensional Human Torso Finite Element Model (HTFEM) with soft armor vest. An examination will be made of tissue stresses to determine the effects of the increased kinetic energy levels on the probability of injury. METHODS: A clay finite element model (CFEM) was created with a material model that required nonlinear properties for clay. To determine these properties empirically, the results from the CFEM were matched with experimental drop tests. A soft armor vest was modeled over the clay to create a vest over clay block finite element model (VCFEM) and empirical methods were again used to obtain material properties for the vest from experimental ballistic testing. Once the properties for the vest and clay had been obtained, the kinetic energy required to produce a 44-mm deformation in the VCFEM was determined through ballistic testing. The resulting kinetic energy was then used in the HTFEM to evaluate the probability of BABT. RESULTS: The VCFEM, with determined clay and vest material properties, was exercised with the equivalent of a 9-mm (8-gm) projectile at various impact velocities. The 44-mm clay deformation was produced with a velocity of 785 m/s. This impact condition (9-mm projectile at 785 m/s) was used in ballistic exercises of the HTFEM, which was modeled with high-strain rate human tissue properties for the organs. The impact zones were over the sternum anterior to T6 and over the liver. The principal stresses in both soft and hard tissue at both locations exceeded the tissue tensile strength. CONCLUSIONS: This study indicates that although NIJ standard 0101.04 may be a good guide to soft armor failure, it may not be as good a guide in BABT, especially at large projectile kinetic energies. Further studies, both numerical and experimental, are needed to assist in predicting injury using the NIJ standard.     

Cardiac and great vessel injuries in children after blunt trauma: an institutional review

PURPOSE: The purpose of this study was to review the incidence of cardiac and great vessel injury after blunt trauma in children. METHOD: A retrospective review of 2,744 patients with injuries from blunt mechanisms was performed. RESULTS: Eleven patients sustained cardiac injury. Four patients had clinically evident cardiac contusions. All recovered. Four patients who died from central nervous system injury were found to have cardiac contusions at autopsy. None had clinical evidence of contusion before demise. One patient had a traumatic ventricular septal defect (VSD) that required operative repair. Autopsy findings showed a VSD in another patient, and a third patient was found to have a ventricular septal aneurysm that was treated medically. Two patients had great vessel injuries. One patient had a contained disruption of the superior vena cava that was managed nonoperatively. Another patient had a midthoracic periaortic hematoma without intimal disruption found at autopsy. One patient had cardiac and great vessel injuries. Discrete aneurysms of 2 coronary artery branches and the pulmonary outflow tract were identified by cardiac catheterization. This patient was treated nonoperatively. CONCLUSIONS: Cardiac and great vessel injury after blunt trauma are uncommon in children. Cardiac contusion was the most common injury encountered but had minimal clinical significance. Noncontusion cardiac injury is rare. No patient with aortic transection was identified.     

Pathophysiological changes of the central auditory pathway after blunt trauma of the head

It is the aim of the present paper to correlate clinical symptoms of auditory dysfunction (tinnitus, hyperacusis, hearing loss) one year on average after a blunt trauma of the head with objective audiological test results (otoacoustic emission and auditory brainstem response testing, impedance audiometry) and to compare these findings to controls without history of head trauma. Thirty-one patients (24-56 years) were included. They were largely female (n = 26). The clinical and otolaryngological examination (including otoscopy) of all patients revealed no pathological abnormalities. Pure-tone audiograms were normal with one exception (pre-existing noise-induced hearing loss) as well as tympanograms. The main auditory symptoms were tinnitus (n = 9), hyperacusis (n = 2) and a reported transient hearing loss immediately after the trauma (n = 16) (which had improved at the time of examination). The results of testing the central auditory pathway showed that the transiently evoked otoacoustic emissions (otoemissions) revealed statistically significant differences between amplitude differences of all patients as well as patients with tinnitus and controls in the linear, but not in the non-linear stimulation mode. A complete loss of stapedial reflex responses was found in 12 of the patients and a partial (irregular) loss (in at least more than two frequencies) in four additional patients. Auditory brainstem responses (ABR) were normal in all patients, but 76% had lowered loudness discomfort levels (LDL). Blunt trauma of the head can lead to auditory dyfunction, probably as a result of diffuse axonal injury of the central auditory pathway. An initial sensorineural hearing loss after the trauma (as a result of the inner ear fluid concussion) was transiently reported only. Auditory symptoms play a minor role in the so-called "postconcussive syndrome," but should be considered and evaluated fully.     

Management of chylothorax after blunt chest trauma

Chylothorax following blunt chest trauma is rare; we found only 19 cases reported. We describe an unusual patient with chylothorax from closed chest injury. The diagnosis is made from thoracentesis or tube thoracostomy fluid. Thoracostomy in the definitive therapeutic modality. Nonoperative or, when necessary, operative treatment of chylothorax after blunt trauma can lead to a successful outcome in 90% of cases.     

Open fixation of flail chest after blunt trauma

Progressive left chest volume loss developed in a patient with severe flail chest despite reasonable oxygenation without intubation. Because of this chest volume loss, pain, and shortness of breath, she underwent open chest wall repair using multiple metallic struts. Rapid recovery ensued, despite a perforated duodenal ulcer on postoperative day 1. Benefits of open fixation of severe flail chest are clearly demonstrated and should be considered instead of prolonged ventilation or supportive care alone for select patients.     

Infarction of extralobar pulmonary sequestration after blunt trauma

Pulmonary sequestration is a rare congenital lung malformation that occurs in either an intralobar or extralobar location and is generally asymptomatic. We report an unusual case of a child who presented with infarction of a previously asymptomatic extralobar pulmonary sequestration after blunt trauma, eventually requiring surgical excision.     

钝性胸部创伤后体内部分激素含量与血流动力学变化的关系

目的　探讨钝性胸部创伤 (BCT)后体内部分激素含量和血流动力学变化及意义。方法　随机选取兔 1 2只 ,采用BIM Ⅱ型生物撞击机致成BCT模型 ,分别在伤前、伤后 2、4、8、2 4h测定甲状腺素 (T3、T4 )、促甲状腺激素 (TSH)、肾素 血管紧张素 AⅠ、AⅡ、胰岛素及C 肽含量 ,并监测血流动力学改变。结果　BCT后 2 4hT3、T4 、TSH分别由伤前的 (1 .43± 0 .62 )nmol/L、(55 .2 0± 1 4 .60 )nmol/L、(8.34± 4 .30 )mU/L降为 (0 .54± 0 .2 8)nmol/L(P <0 .0 1 )、(32 .50± 2 .70 )nmol/L(P <0 .0 1 )、(2 .2 4± 0 .79)mU/L(P <0 .0 1 ) ;AⅠ、AⅡ、胰岛素和C肽分别由伤前的(0 .44± 0 .2 5) μg·L- 1 ·h- 1 、(48.0± 1 0 .9)ng/L、(5 .96± 2 .66)mIU/L、(0 .2 3± 0 .1 6)nmol/L增高至 (1 .38± 0 .88) μg·L- 1 ·h- 1 (P <0 .0 5)、(70 .0± 9.9)ng/L(P <0 .0 5)、(7.92± 3 .2 2 )mIU/L(P <0 .0 5)、(0 .52± 0 .0 9)nmol/L(P <0 .0 5) ;左室舒张末压 (LVEDP)和左室内压最大下降速率( dp/dtmax)增高 ;相关分析表明血清甲状腺激素、肾素 血管紧张素、胰岛素及C肽含量改变与血流动力学变化呈明显相关 (P <0 .0 5、P <0 .0 1 )。结论　BCT后体内部分激素明显改变是引起心功能障碍的原因之一。     

Significant lateralisation of supratentorial ICP after blunt head trauma

Summary After blunt head trauma simultaneous left and right hemispheric intracranial pressure (ICP) monitoring revealed a pressure gradient of about 30 mmHg persisting until the 5th day after the accident equilibrating thereafter. ICP was elevated over the radiologically more compressed hemisphere. The supratentorial space seems to allow considerable interhemispheric pressure gradients. As a consequence epidural ICP monitoring should be performed over the hemisphere with signs of greater compression.     

Successful percutaneous drainage of duodenal hematoma after blunt trauma

Duodenal hematoma after blunt trauma is usually treated nonoperatively with bowel rest, nasogastric tube suction, and intravenous hydration. We report a case in which obstructive symptoms persisted despite more than 2 weeks of conservative management. An ultrasound-guided percutaneous drain was placed, with successful resolution of symptoms.