The Development of a Tympanic Membrane Model and Probabilistic Dose-Response Risk Assessment of Rupture Because of Blast.

INTRODUCTION: There is no dose-response model available for the assessment of the risk of tympanic membrane rupture (TMR), commonly known as eardrum rupture, from exposures to blast from nonlethal flashbangs, which can occur concurrently with temporary threshold shift. Therefore, the objective of this work was to develop a fast-running, lumped parameter model of the tympanic membrane (TM) with probabilistic dose-dependent prediction of injury risk. MATERIALS AND METHODS: The lumped parameter model was first benchmarked with a finite element model of the middle ear. To develop the dose-response curves, TMR data from a historic cadaver study were utilized. From these data, the binary probability response was constructed and logistic regression was applied to generate the respective dose-response curves at moderate and severe eardrum rupture severity. RESULTS: Hosmer-Lemeshow statistical and receiver operation characteristic analyses showed that maximum stored TM energy was the overall best dose metric or injury correlate when compared with total work and peak TM pressure. CONCLUSIONS: Dose-response curves are needed for probabilistic risk assessments of unintended effects like TMR. For increased functionality, the lumped parameter model was packaged as a software library that predicts eardrum rupture for a given blast loading condition.

Simulation of Cumulative Exposure Statistics for Blast Pressure Transmission Into the Brain.

INTRODUCTION: This study develops and demonstrates an analysis approach to understand the statistics of cumulative pressure exposure of the brain to repetitive blasts events. MATERIALS AND METHODS: A finite element model of blast loading on the head was used for brain model biomechanical responses. The cumulative pressure exposure fraction (CPEF), ranging from 0.0 to 1.0, was used to characterize the extent and repetition of high pressures. Monte Carlo simulations were performed to generate repetitive blast cumulative exposures. RESULTS: The blast orientation effect is as influential as the blast overpressure magnitudes. A 75° (from the side) blast orientation can produce CPEF values exceeding traumatic brain injury pressure thresholds >0.95 while, for the same blast overpressure, a 0° (front) blast orientation results in a CPEF <0.25. Monte Carlo results for different sequences reflecting notional operational and training environments show that both mean values and standard deviations of CPEF reach the statistically equilibrium state at a finite value of n exposures for each sequence. CONCLUSIONS: Statistical convergence of the brain pressure response metrics versus number of blasts for different exposures characterizes the transitions from "low" to "high" number of blasts and quantitatively highlights the differences between operational and training exposures.

Risk assessment of lithium-ion battery explosion: chemical leakages.

Use of lithium-ion batteries has raised safety issues owing to chemical leakages, overcharging, external heating, or explosions. A risk assessment was conducted for hydrofluoric acid (HF) and lithium hydroxide (LiOH) which potential might leak from lithium-ion batteries. The inhalation no-observed-adverse-effect-level (NOAEL) for HF was 0.75 mg/kg/d. When a lithium-ion battery explodes in a limited space, HF emissions amount to 10-100 ppm. Assuming the worst-case scenario, the conversion rate was calculated to be 81.8 mg/m3, and the average daily dose (ADD) was 19.5 mg/kg/d. Consequently, the margin of exposure (MOE = NOAEL/ADD) was 0.034, a value which constitutes an unsafe inhalation exposure for HF. Conversely, skin toxicity NOAEL for LiOH was 41.35 mg/kg/d-. This LiOH value reflects the amount of lithium in the lithium-ion battery, which is generated upon contact between water and the electrolyte. The quantity of lithium in a mobile phone is approximately 295 mg, and systemic exposure dose (SED) was 4.92 mg/kg/d. Accordingly, the MOE (NOAEL/SED) value was 8.41, and skin exposure of LiOH was deemed as safe for humans. However, it is important that Energy Storage System batteries still require safety measures and technologies for next-generation batteries, to prevent any potential explosions of lithium-ion batteries.

Blast Injuries: From Improvised Explosive Device Blasts to the Boston Marathon Bombing.

Although most trauma centers have experience with the imaging and management of gunshot wounds, in most regions blast wounds such as the ones encountered in terrorist attacks with the use of improvised explosive devices (IEDs) are infrequently encountered outside the battlefield. As global terrorism becomes a greater concern, it is important that radiologists, particularly those working in urban trauma centers, be aware of the mechanisms of injury and the spectrum of primary, secondary, tertiary, and quaternary blast injury patterns. Primary blast injuries are caused by barotrauma from the initial increased pressure of the explosive detonation and the rarefaction of the atmosphere immediately afterward. Secondary blast injuries are caused by debris carried by the blast wind and most often result in penetrating trauma from small shrapnel. Tertiary blast injuries are caused by the physical displacement of the victim and the wide variety of blunt or penetrating trauma sustained as a result of the patient impacting immovable objects such as surrounding cars, walls, or fences. Quaternary blast injuries include all other injuries, such as burns, crush injuries, and inhalational injuries. Radiography is considered the initial imaging modality for assessment of shrapnel and fractures. Computed tomography is the optimal test to assess penetrating chest, abdominal, and head trauma. The mechanism of blast injuries and the imaging experience of the victims of the Boston Marathon bombing are detailed, as well as musculoskeletal, neurologic, gastrointestinal, and pulmonary injury patterns from blast injuries.

[Fire disaster due to deflagration of a propane gas-air mixture]. / Folgenschwerer Brand durch Entzündung eines Propangas-Luft-Gemisches.

On 26 Nov 2012, a serious fire occurred at Neustadt/Black Forest in which 14 persons in a sheltered workshop died and 10 other individuals were injured. The fire was caused by the unbridled escape of propane gas due to accidental disconnection of the screw fixing between a gas bottle and a catalytic heater. Deflagration of the propane gas-air mixture set the workshop facilities on fire. In spite of partly extensive burns the fatally injured victims could be rapidly identified. The results of the fire investigations at the scene and the autopsy findings are presented. Carboxyhemoglobin concentrations ranged between 8 and 56 % and signs of fire fume inhalation were present in all cases. Three victims had eardrum ruptures due to the sudden increase in air pressure during the deflagration.

[Certain theoretical-methodological problems of forensic medical expertise of the blast injury].

This article is devoted to the analysis of the theoretical problems facing forensic medical expertise of the blast injury. The original notions of the blast, injurious blast factors, and their traumatic consequences are proposed together with the classification of the blasts and their injurious factors. The principal lines of the further research on the forensic medical aspects of the blast injury are formulated.

Blast Injuries.

BACKGROUND: Blast injuries in the United States and worldwide are not uncommon. Partially due to the increasing frequency of both domestic and international terrorist bombing attacks, it is prudent for all emergency physicians to be knowledgeable about blasts and the spectrum of associated injuries. OBJECTIVE: Our aim was to describe blast physiology, types of blast injuries associated with each body system, and manifestations and management of each injury. DISCUSSION: Blast injuries are generally categorized as primary to quaternary injuries. Primary injuries result from the effect of transmitted blast waves on gas-containing structures, secondary injuries result from the impact of airborne debris, tertiary injury results from transposition of the entire body due to blast wind or structural collapse, and quaternary injuries include almost everything else. Different body systems are affected and managed differently. Despite previous dogma, multiple studies now show that tympanic membrane perforation is a poor predictor of other blast injury. CONCLUSIONS: Blast events can produce a myriad of injuries affecting any and every body system. All emergency physicians should be familiar with the presentation and management of these injuries. This knowledge may also be incorporated into triage and discharge protocols guiding management of mass casualty events.

[The role of the biological damaging factor in the explosive injury].

This article describes the specific features of the action of the biological damaging factors on the human organism associated with the explosive injury. Both the direct action of the damaging agents contained in the biological weapons and their secondary effects in the form of systemic and local infectious complications of the inflicted wounds are considered. The criteria for the evaluation of the degree of harm to the health of the victims of explosion attributable to the action of the biological damaging factor are proposed.

Sensor distribution design of travel time tomography in explosion.

Optimal sensor distribution in explosion testing is important in saving test costs and improving experiment efficiency. Aiming at travel time tomography in an explosion, an optimizing method in sensor distribution is proposed to improve the inversion stability. The influence factors of inversion stability are analyzed and the evaluating function on optimizing sensor distribution is proposed. This paper presents a sub-region and multi-scale cell partition method, according to the characteristics of a shock wave in an explosion. An adaptive escaping particle swarm optimization algorithm is employed to achieve the optimal sensor distribution. The experimental results demonstrate that optimal sensor distribution has improved both indexes and inversion stability.

The ins and outs of terrorist bus explosions: injury profiles of on-board explosions versus explosions occurring adjacent to a bus.

BACKGROUND: Terrorist explosions occurring in varying settings have been shown to lead to significantly different injury patterns among the victims, with more severe injuries generally arising in confined space attacks. Increasing numbers of terrorist attacks have been targeted at civilian buses, yet most studies focus on events in which the bomb was detonated within the bus. This study focuses on the injury patterns and hospital utilisation among casualties from explosive terrorist bus attacks with the bomb detonated either within a bus or adjacent to a bus. METHODS: All patients hospitalised at six level I trauma centres and four large regional trauma centres following terrorist explosions that occurred in and adjacent to buses in Israel between November 2000 and August 2004 were reviewed. Injury severity scores (ISS) were used to assess severity. Hospital utilisation data included length of hospital stay, surgical procedures performed, and intensive care unit (ICU) admission. RESULTS: The study included 262 victims of 22 terrorist attacks targeted at civilian bus passengers and drivers; 171 victims were injured by an explosion within a bus (IB), and 91 were injured by an explosion adjacent to a bus (AB). Significant differences were noted between the groups, with the IB population having higher ISS scores, more primary blast injury, more urgent surgical procedures performed, and greater ICU utilisation. Both groups had percentages of nearly 20% for burn injury, had high percentages of injuries to the head/neck, and high percentages of surgical wound and burn care. CONCLUSIONS: Explosive terrorist attacks detonated within a bus generate more severe injuries among the casualties and require more urgent surgical and intensive level care than attacks occurring adjacent to a bus. The comparison and description of the outcomes to these terrorist attacks should aid in the preparation and response to such devastating events.

Characterisation of explosive fragments injuring the neck.

Penetrating explosive fragments are the most common cause of neck injuries sustained by UK service personnel deployed to Afghanistan. Analysis of these fragments will enable future ballistic protective materials to be tested with appropriate projectiles. However, only a small number of fragments excised from the neck have been available for analysis and they are potentially unrepresentative. We analysed computed tomograms (CTs) of 110 consecutive UK soldiers whose necks were wounded by explosive fragments. Fragments were classified according to shape, and their dimensions used to estimate volume and mass. These calculations were then compared with the actual measurements of the excised fragments using a general linear model. The 2 most common shapes were cylinders (52%) and spheres (21%). Known and estimated masses were not significantly different (p=0.64). A fragment-simulating projectile of 0.49 g represented 85% of fragments retained in the neck. CT can accurately delineate the shape and mass of fragments, which increases the number from which the most appropriate simulated projectile can be designed. We think that this methodology should be applied to fragments retained in other parts of the body to enable broader recommendations to be made regarding the testing of ballistic materials used to protect service personnel.

[The forensic medical aspects of mechanogenesis of the blast injury].

This experimental study had the objective to elucidate the injurious action of various traumatic factors associated with explosions with special reference to the objective registration of the related high-speed processes. Most attention was given to aerial and surface bursts. Mechanogenesis and pathological morphology of the blast injuries have been most thoroughly investigated.

[The current state and prospects of the development of forensic medical expertise of the blast injury].

The analysis of the special literature and expert practice during the recent years demonstrated the scientific, practical, and social importance of the expertise of the blast injuries in the time of piece. It is emphasized that the main tasks of expert examination of blast injuries include further studies on the mechanisms of their development, simulation of various blast injuries, the development of criteria for the determination of distance from the site of explosion based on the severity of the injury, investigations into effectiveness of the protective barriers for the human body during explosions, and the creation of methods for testing means of individual body armoured protection. The provisions of a program for current and prospective forensic medical investigations into blast injuries have been formulated.

[Peculiarities of forensic medical reconstruction of the mechanism of injuries in numerous victims of the explosion of a high-capacity blasting device].

The systemic analysis of forensic medical practice in Moscow during the past 15 years has demonstrated the scientific, practical, and social significance of expertise of peace-time blast injuries resulting from many terrorist attacks with the use of improvised high-capacity explosive devices that caused multiple human victims. The authors emphasize the current lack of objective forensic medical criteria for the reconstruction of the mechanism of injuries in numerous victims of the explosion of a high-capacity blasting device. It dictates the necessity of their development and substantiation of their practical application.

Blast noise classification with common sound level meter metrics.

A common set of signal features measurable by a basic sound level meter are analyzed, and the quality of information carried in subsets of these features are examined for their ability to discriminate military blast and non-blast sounds. The analysis is based on over 120 000 human classified signals compiled from seven different datasets. The study implements linear and Gaussian radial basis function (RBF) support vector machines (SVM) to classify blast sounds. Using the orthogonal centroid dimension reduction technique, intuition is developed about the distribution of blast and non-blast feature vectors in high dimensional space. Recursive feature elimination (SVM-RFE) is then used to eliminate features containing redundant information and rank features according to their ability to separate blasts from non-blasts. Finally, the accuracy of the linear and RBF SVM classifiers is listed for each of the experiments in the dataset, and the weights are given for the linear SVM classifier.

Allocation of scarce resources after a nuclear detonation: setting the context.

The purpose of this article is to set the context for this special issue of Disaster Medicine and Public Health Preparedness on the allocation of scarce resources in an improvised nuclear device incident. A nuclear detonation occurs when a sufficient amount of fissile material is brought suddenly together to reach critical mass and cause an explosion. Although the chance of a nuclear detonation is thought to be small, the consequences are potentially catastrophic, so planning for an effective medical response is necessary, albeit complex. A substantial nuclear detonation will result in physical effects and a great number of casualties that will require an organized medical response to save lives. With this type of incident, the demand for resources to treat casualties will far exceed what is available. To meet the goal of providing medical care (including symptomatic/palliative care) with fairness as the underlying ethical principle, planning for allocation of scarce resources among all involved sectors needs to be integrated and practiced. With thoughtful and realistic planning, the medical response in the chaotic environment may be made more effective and efficient for both victims and medical responders.

Injuries from explosions: physics, biophysics, pathology, and required research focus.

BACKGROUND: Explosions cause more complex and multiple forms of damage than any other wounding agent, are the leading cause of death on the battlefield, and are often used by terrorists. Because explosion-related injuries are infrequently seen in civilian practice, a broader base of knowledge is needed in the medical community to address acute needs of patients with explosion-related injuries and to broaden mitigation-focused research efforts. The objective of this review is to provide insight into the complexities of explosion-related injury to help more precisely target research efforts to the most pressing areas of need in primary prevention, mitigation, and consequence management. METHODS: An understanding of the physics and biological consequences of explosions together with data on the nature or severity of contemporary combat injuries provide an empiric basis for a comprehensive and balanced portfolio of explosion-related research. Cited works were identified using MeSH terms as directed by subtopic. Uncited information was drawn from the authors' surgical experience in Iraq, analysis of current combat trauma databases, and explosion-related research. RESULTS: Data from Iraq and Afghanistan confirm that survivable injuries from explosions are dominated by penetrating fragment wounds, substantiating longstanding and well-known blast physics mechanisms. Keeping this factual basis in mind will allow for appropriate vectoring of funds to increase understanding of this military and public health problem; address specific research and training needs; and improve mitigation strategies, tactics, and techniques for vehicles and personal protective equipment. CONCLUSIONS: A comprehensive approach to injury from explosions should include not only primary prevention, but also injury mitigation and consequence management. Recalibration of medical research focus will improve management of injuries from explosions, with profound implications in both civilian and military healthcare systems.

Muerte por explosión: cuestiones y sistemática medico-forenses / Explosion death: medico-legal questions and systematic

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