Blast injuries

The dynamic response of human lungs due to underwater shock wave exposure

Since the 19th century, underwater explosions have posed a significant threat to service members. While there have been attempts to establish injury criteria for the most vulnerable organs, namely the lungs, existing criteria are highly variable due to insufficient human data and the corresponding inability to understand the underlying injury mechanisms. This study presents an experimental characterization of isolated human lung dynamics during simulated exposure to underwater shock waves. We found that the large acoustic impedance at the surface of the lung severely attenuated transmission of the shock wave into the lungs. However, the shock wave initiated large bulk pressure-volume cycles that are distinct from the response of the solid organs under similar loading. These pressure-volume cycles are due to compression of the contained gas, which we modeled with the Rayleigh-Plesset equation. The extent of these lung dynamics was dependent on physical confinement, which in real underwater blast conditions is influenced by factors such as rib cage properties and donned equipment. Findings demonstrate a potential causal mechanism for implosion injuries, which has significant implications for the understanding of primary blast lung injury due to underwater blast exposures.

Experimental and Numerical Study of Non-Explosive Simulated Blast Loading on Reinforced Concrete Slabs

This study presents a non-explosive method for simulating blast loading on reinforced concrete (RC) slabs. The method involves using a newly developed blast simulator to apply a speedy impact load on the slab, which generates a pressure wave similar to that of an actual blast. Both experimental and numerical simulations were carried out to evaluate the effectiveness of the method. The experimental results showed that the non-explosive method can produce a pressure wave with a peak pressure and duration analogous to those of an actual blast. The numerical simulations also showed good agreement with the experimental results. Additionally, parameter studies were conducted to evaluate the effects of the rubber shape, the impact velocity, the bottom thickness, and the upper thickness on the impact loading. The results indicate that pyramidal rubber is more suitable as an impact cushion for simulating blast loading than planar rubber. The impact velocity has the widest range of regulation for peak pressure and impulse. As the velocity increases from 12.76 to 23.41 m/s, the corresponding range of values for peak pressure is 6.457 to 17.108 MPa, and for impulse, it is 8.573 to 14.151 MPa∙ms. The variation in the upper thickness of the pyramidal rubber has a more positive effect on the impact load than the bottom thickness. With the upper thickness increasing from 30 mm to 130 mm, the peak pressure decreased by 59.01%, and the impulse increased by 16.64%. Meanwhile, when the bottom part's thickness increased from 30 mm to 130 mm, the peak pressure decreased by 44.59%, and the impulse increased by 11.01%. The proposed method provides a safe and cost-effective alternative to traditional explosive methods for simulating blast loading on RC slabs.

Defining blast loading 'zones of relevance' for primary blast injury research: A consensus of injury criteria for idealised explosive scenarios

Blast injuries remain a serious threat to defence and civilian populations around the world. 'Primary' blast injuries (PBIs) are caused by direct blast wave interaction with the human body, particularly affecting air-containing organs. Work to define blast loading conditions for injury research has received relatively little attention, though with a continued experimental focus on PBIs and idealised explosion assumptions, meaningful test outcomes and subsequent clinical applications, rely on appropriate simulated conditions. This paper critically evaluates and combines existing PBI criteria (grouped into those affecting the auditory system, pulmonary injuries and brain trauma) as a function of idealised blast wave parameters. For clinical blast injury researchers, analysis of the multi-injury criteria indicates zones of appropriate loading conditions for human-scale test items and demonstrates the importance of simulating blast conditions that are both realistic and relevant to the injury type. For certain explosive scenarios, spatial interpretation of the 'zones of relevance' could support emergency response and hazard preparedness by informing triage, patient management and resource allocation, thus leading to improved health outcomes. This work will prove useful to clinical blast injury researchers, blast protection engineers and clinical practitioners involved in the triage, diagnosis, and treatment of PBIs.

Blast Injuries

Blast injuries cause specific lesions with which the radiologist should be familiar. The mechanism of injury and the pathophysiology of this form of trauma are discussed. The clinical effects as well as the radiologic observations in various organs are presented. Most dramatic effects are observed in the thorax.

A case of Tannerite(®) target mixture causing severe blast injury

Tannerite(®) is a proprietary blend of an oxidizer, ammonium nitrate, and aluminum powder catalyst used to make homemade exploding targets. While it is currently approved for unrestricted sale in the United States, it can be used to form devices capable of inflicting major blast injury. We present here a case of close proximity exposure to detonation of the mixed Tannerite(®) blend. In our patient, the exposure lead to injuries typical of blast injury, such as tympanic membrane rupture, globe injury, and severe burns. We review here the sequelae of blast injuries that one must consider when treating a patient with close proximity exposure to Tannerite, with considerations unique to this product.

What the Intensive Care Doctor Needs to Know about Blast-Related Lung Injury

Explosions are currently the primary cause of military combat injuries. A minority of civilian trauma is also caused by explosions. People hurt by explosion are likely to present with complex injuries. The aim of the article is to explain the mechanism underlying these injuries and the associated physiology to help the intensive care clinician manage these casualties properly. The generic term ‘blast injury’ is applied to a collection of injuries caused by explosion. Components of blast injuries have precise definitions relating to the elements of the explosion that caused the injuries: primary blast injury is due to a shock wave, secondary blast injury is caused by fragments and debris colliding with the victim and tertiary blast injury is due to the casualty being thrown against solid objects. Primary blast injury results in damage principally in gas-containing organs, eg the lungs (blast lung) and can lead to impaired pulmonary gas transfer and hypoxaemia. Secondary blast injuries are often penetrating and can lead to haemorrhage while tertiary blast injuries are often blunt and involve substantial tissue damage. Survivors of explosions in confined spaces are more likely to exhibit primary blast injury than those injured in open spaces. The current military approach to immediate management is to apply the C ABC principle (arrest catastrophic haemorrhage first and then deal with airway, breathing and circulation) to achieve Damage Control Resuscitation. Early administration of blood products (plasma as well as red cells) is advocated for those suffering significant haemorrhage. Initial resuscitation is hypotensive to minimise risk of dislodging nascent clots. However, if evacuation is protracted (longer than one hour) then consideration should be given to improving blood flow / oxygen delivery by adopting a revised normotensive blood pressure target to reverse the deleterious consequences of the hypotensive shock state. Animal studies have shown that titrating FiO2 to a target SaO2 of 95% can improve survival and ‘buy time’ during hypotensive resuscitation. Ventilator strategies should use a lung-protective approach with permissive hypercapnia if necessary. Blast casualties are often a challenging group of patients needing expert, tailored, care. Outcome can be good especially in young, otherwise fit, casualties with more than 96% surviving to ICU discharge, although this figure may be lower with a mixed civilian group.

Wartime spine injuries: understanding the improvised explosive device and biophysics of blast trauma

The improvised explosive device (IED) has been the most significant threat by terrorists worldwide. Blast trauma has produced a wide pattern of combat spinal column injuries not commonly experienced in the civilian community. Unfortunately, explosion-related injuries have also become a widespread reality of civilian life throughout the world, and civilian medical providers who are involved in emergency trauma care must be prepared to manage casualties from terrorist attacks using high-energy explosive devices. Treatment decisions for complex spine injuries after blast trauma require special planning, taking into consideration many different factors and the complicated multiple organ system injuries not normally experienced at most civilian trauma centers. Therefore, an understanding about the effects of blast trauma by spine surgeons in the community has become imperative, as the battlefield has been brought closer to home in many countries through domestic terrorism and mass casualty situations, with the lines blurred between military and civilian trauma. We set out to provide the spine surgeon with a brief overview on the use of IEDs for terrorism and the current conflicts in Iraq and Afghanistan and also a perspective on the biophysics of blast trauma.

Mass-Casualty, Terrorist Bombings: Epidemiological Outcomes, Resource Utilization, and Time Course of Emergency Needs (Part I)

Introduction:

This article characterizes the epidemiological outcomes, resource utilization, and time course of emergency needs in mass-casualty, terrorist bombings producing 30 or more casualties.

Methods:

Eligible bombings were identified using a MEDLINE search of articles published between 1996 and October 2002 and a manual search of published references. Mortality, injury frequency, injury severity, emergency department (ED) utilization, hospital admission, and time interval data were abstracted and relevant rates were determined for each bombing. Median values for the rates and the inter-quartile ranges (IQR) were determined for bombing subgroups associated with: (1) vehicle delivery; (2) terrorist suicide; (3) confined-space setting; (4) open-air setting; (5) structural collapse sequela; and (6) structural fire sequela.

Results:

Inclusion criteria were met by 44 mass-casualty, terrorist bombings reported in 61 articles. Median values for the immediate mortality rates and IQRs were: vehicle-delivery, 4% (1–25%); terrorist-suicide, 19% (7–44%); confined-space 4% (1–11%); open-air, 1% (0–5%); structural-collapse, 18% (5–26%); structural fire 17% (1–17%); and overall, 3% (1–14%). A biphasic pattern of mortality and unique patterns of injury frequency were noted in all subgroups. Median values for the hospital admission rates and IQRs were: vehicle-delivery, 19% (14–50%); terrorist-suicide, 58% (38–77%); confined-space, 52% (36–71%); open-air, 13% (11–27%); structural-collapse, 41% (23–74%); structural-fire, 34% (25–44%); and overall, 34% (14–53%). The shortest reported time interval from detonation to the arrival of the first patient at an ED was five minutes. The shortest reported time interval from detonation to the arrival of the last patient at an ED was 15 minutes. The longest reported time interval from detonation to extrication of a live victim from a structural collapse was 36 hours.

Conclusion:

Epidemiological outcomes and resource utilization in mass-casualty, terrorist bombings vary with the characteristics of the event.

Mass-Casualty, Terrorist Bombings: Implications for Emergency Department and Hospital Emergency Response (Part II)

This article reviews the implications of mass-casualty, terrorist bombings for emergency department (ED) and hospital emergency responses. Several practical issues are considered, including the performance of a preliminary needs assessment, the mobilization of human and material resources, the use of personal protective equipment, the organization and performance of triage, the management of explosion-specific injuries, the organization of patient flow through the ED, and the efficient determination of patient disposition. As long as terrorists use explosions to achieve their goals, mass-casualty, terrorist bombings remain a required focus for hospital emergency planning and preparedness.

Heterotopic ossification after extremity blast amputation in a Sprague-Dawley rat animal model

OBJECTIVE

To create an animal survival model for heterotopic ossification (HO) in the residual limb of the rat after extremity blast amputation. The hypothesis was that extremity blast amputation spontaneously stimulates development of HO in the residual limb.

METHODS

Twelve Sprague-Dawley rats underwent localized exposure to a controlled, high-energy blast. Seven rats were designated for hind limb amputation and five for forelimb amputation. Our protocol produced extremity amputation through detonation of an explosive while protecting the animal proximal to the specified amputation level. Immediately after injury, the rat underwent wound management and primary surgical closure. Radiographs of the amputated limbs were obtained every 2 weeks. Heterotopic bone was radiographically classified as periosteal growth (Type A) or noncontiguous growth (Type B). A kappa statistic was calculated for interobserver strength of agreement on the presence of HO. Fisher exact test was conducted to assess the significance of the difference in hind limb and forelimb HO rates.

RESULTS

Nine of 12 animals survived the procedure. The three nonsurvivors were all hind limb amputees, and each died of various related causes. All four surviving hind limb amputees exhibited Type A HO, and three of four also exhibited Type B HO within the injured stump. One of five forelimb amputees exhibited Types A and B HO.

CONCLUSIONS

We have developed a reproducible model for HO in the residual limbs of blast-amputated rats without addition of exogenous osteogenic stimulus. Hind limb amputation demonstrated a predilection for HO formation in comparison with forelimb amputation (P < 0.05).

[Rare mechanisms of blowout fractures. Discussion of two case reports]

In the emergency room different forms of traumata with resulting insulating orbital blowout fracture are observed. The cause of accident is almost always impact to the central face with a solid object or on a hard surface. The hydraulic pressure theory and buckling force theory in terms of the pathomechanism are valid and accepted explanation models. We report two clinical cases of unusual injury mechanisms, which we discuss with reference to the available literature.

War wounds of the foot and ankle: causes, characteristics, and initial management

Foot and ankle trauma sustained in the Global War on Terror have unique causes and characteristics. At least one-quarter of all battle injuries involve the lower extremity. These severe lower extremity wounds require specialized early treatment. Ballistic mechanisms cause almost all injuries, and as such, most combat foot and ankle wounds are open in nature. Wounds are characteristically caused by blast mechanisms, but high velocity gunshot injuries are also common. The severe and polytraumatic nature of injuries sustained frequently call for damage control orthopaedics to be utilized. Cautious early treatment of irregular and highly exudative ballistic wounds with subatmospheric wound dressings may ease their early management.

Maxillofacial air-containing cavities, blast implosion injuries, and management

PURPOSE

Distinctive mechanisms of primary blast effects have produced a transitional era of facial trauma. Implosion mechanism damage is one of these. Implosion mechanism damage results in injury limited to the gas-containing structures of the auditory canal, paranasal sinuses, gastrointestinal tract, and lungs. Worldwide, the victims of explosive detonations have increased and advanced dramatically. The outcome is greater mortality and morbidity and new types of injuries, especially in the maxillofacial region. Thus, the knowledge of, and experience with, their management should be shared globally by colleagues through publications.

MATERIALS AND METHODS

The implosion and mini re-explosion of compressed air sinuses leads to skeletal crush injury to the nasal-orbital-ethmoidal, maxillary sinuses, and nasal bones. A variety of surgical approaches were used successfully under conditions of war. The assessment of the associated injuries to the lung and/or brain is the initial priority to any life-threatening blast injury. This article describes the biophysical results of blast injuries to the middle third facial skeleton and associated injuries and details the management and protection of crushed air containing paranasal spaces.

RESULTS

Easy, simple, and fast treatment and management were used successfully on the pulverized, fragmented skeletal architecture of the facial middle part without increasing morbidity and with the avoidance of unnecessary surgical trauma.

CONCLUSIONS

Injuries in one of the most difficult esthetic, physiologic, and anatomic regions of the body is best treated with an understanding of the biophysical effects of the implosion mechanism on air-containing spaces in the maxillofacial region. The introduction of new methods for the management of severe destruction of hard and soft tissue will decrease the incidence of complications and the operative time.

Blast injuries

Health-care providers are increasingly faced with the possibility of needing to care for people injured in explosions, but can often, however, feel undertrained for the unique aspects of the patient's presentation and management. Although most blast-related injuries (eg, fragmentation injuries from improvised explosive devices and standard military explosives) can be managed in a similar manner to typical penetrating or blunt traumatic injuries, injuries caused by the blast pressure wave itself cannot. The blast pressure wave exerts forces mainly at air-tissue interfaces within the body, and the pulmonary, gastrointestinal, and auditory systems are at greatest risk. Arterial air emboli arising from severe pulmonary injury can cause ischaemic complications-especially in the brain, heart, and intestinal tract. Attributable, in part, to the scene chaos that undoubtedly exists, poor triage and missed diagnosis of blast injuries are substantial concerns because injuries can be subtle or their presentation can be delayed. Management of these injuries can be a challenge, compounded by potentially conflicting treatment goals. This Seminar aims to provide a thorough overview of these unique primary blast injuries and their management.

Facing the new threats of terrorism: radiologists' perspectives based on experience in Israel

On September 11, 2001, the world changed. The vicious giant of terrorism that was dormant until that date had arisen. After the horrific mass-casualty terror attack on the United States, any and all forms of assault seem possible. Owing to the complexity of injuries encountered in terror attack victims, fast and accurate imaging plays an essential role in triage and identification of abnormalities associated with injuries. The radiologist becomes a crucial part of the first-line team of doctors treating these patients. Knowledge that the best available treatment is given to terror attack victims can enhance the strength and endurance of society against terror. On the basis of the authors' experience with terror events in Israel, the steps involved in imaging of terror attack patients include conventional radiography, focused abdominal sonography in trauma, computed tomography, and angiography, with the judicious use of supplemental imaging.

Conventional terrorism and critical care

Incidents of conventional weapons terror are increasingly part of the reality of the modern world, and in Israel, 19,948 incidents have been reported from September 2000 to December 2003. Most victims are injured in explosions resulting from suicide bombings. Exposure to the blast (primary mechanism of injury) may produce unique injuries affecting gas-containing organs, including perforation of the eardrums (most common injury); pulmonary blast injury, characterized by alveolar capillary disruption and bronchopleural fistulas; and bowel perforation, which is uncommon and may be delayed from 1 to 14 days after the injury. However, most injuries are the result of penetrating trauma (secondary mechanism) resulting from bomb fragments and nails, bolts, and steel pellets embedded in the bomb striking the victim, and blunt trauma (tertiary mechanism) sustained when the victim is propelled against an object by the blast wind. The severity of the injuries is increased when the blast occurs in a confined space. Victims of terror-inflicted injuries have a high Injury Severity Score (30% >16), a high requirement for intensive care unit admission (22.8% in Israel), and have a more prolonged hospital course and higher mortality than victims of any other form of trauma.

Gunshot and explosion injuries: characteristics, outcomes, and implications for care of terror-related injuries in Israel

CONTEXT

An increase of terror-related activities may necessitate treatment of mass casualty incidents, requiring a broadening of existing skills and knowledge of various injury mechanisms.

OBJECTIVE

To characterize and compare injuries from gunshot and explosion caused by terrorist acts.

METHODS

A retrospective cohort study of patients recorded in the Israeli National Trauma Registry (ITR), all due to terror-related injuries, between October 1, 2000, to June 30, 2002. The ITR records all casualty admissions to hospitals, in-hospital deaths, and transfers at 9 of the 23 trauma centers in Israel. All 6 level I trauma centers and 3 of the largest regional trauma centers in the country are included. The registry includes the majority of severe terror-related injuries. Injury diagnoses, severity scores, hospital resource utilization parameters, length of stay (LOS), survival, and disposition.

RESULTS

A total of 1155 terror-related injuries: 54% by explosion, 36% gunshot wounds (GSW), and 10% by other means. This paper focused on the 2 larger patient subsets: 1033 patients injured by terror-related explosion or GSW. Seventy-one percent of the patients were male, 84% in the GSW group and 63% in the explosion group. More than half (53%) of the patients were 15 to 29 years old, 59% in the GSW group and 48% in the explosion group. GSW patients suffered higher proportions of open wounds (63% versus 53%) and fractures (42% versus 31%). Multiple body-regions injured in a single patient occurred in 62% of explosion victims versus 47% in GSW patients. GSW patients had double the proportion of moderate injuries than explosion victims. Explosion victims have a larger proportion of minor injuries on one hand and critical to fatal injuries on the other. LOS was longer than 2 weeks for 20% (22% in explosion, 18% in GSW). Fifty-one percent of the patients underwent a surgical procedure, 58% in the GSW group and 46% in explosion group. Inpatient death rate was 6.3% (65 patients), 7.8% in the GSW group compared with 5.3% in the explosion group. A larger proportion of gunshot victims died during the first day (97% versus 58%).

CONCLUSIONS

GSW and injuries from explosions differ in the body region of injury, distribution of severity, LOS, intensive care unit (ICU) stay, and time of inpatient death. These findings have implications for treatment and for preparedness of hospital resources to treat patients after a terrorist attack in any region of the world. Tailored protocol for patient evaluation and initial treatment should differ between GSW and explosion victims. Hospital organization toward treating and admitting these patients should take into account the different arrival and injury patterns.

Disasters and development: Part 2: understanding and exploiting disaster-development linkages

Disasters can impede the effectiveness of development resource allocation. The damage sustained from an event can be classified into four categories: (1) Loss of resources; (2) Interruption of programs and switching of crucial resources to other, shorter-term needs; (3) Negative impacts upon investment climates; and/or (4) Disruption of the non-formal sector (local businesses). Disasters have a particularly destructive economic impact in areas in which there are few alternatives for assets that are destroyed or in areas in which the resources already are at critical levels. Development processes can both increase and/or decrease the vulnerability of a society to hazards. There are dearly established linkages between poverty, marginalization, over-population, and vulnerability. To a large extent, vulnerability derives from poverty. The poor are more likely to live in vulnerable areas (slopes prone to landslides, flood plains, marginal agricultural land), have difficulty accessing education and information, have fewer assets to invest in resources to reduce vulnerability, and are more prone to become malnourished and have chronic illnesses that predispose them to injury and death. Development may be associated with the production of new hazards accepted by a society because the perceived benefits of the development project far exceed the relative risk associated with the project. Therefore, risk assessments must be part of any program planning and evaluation. Training and education are of critical importance in preventing increased vulnerability as a result of development strategies. Development also can progress in a manner that will result in mitigation of the impacts of an event on a given society (increase absorbing capacity and/or buffering capacity, elimination of hazards or the risk of them producing a disaster). Such mitigation measures can be either structural or nonstructural. There exists a wide range of options for incorporating mitigation measures in development projects. Two case studies provide exercises that incorporate the concepts provided in this discussion: (1) The 1985 earthquake in Mexico City; and (2) Agricultural development in northern Sudan.

Mass casualty management of a large-scale bioterrorist event: an epidemiological approach that shapes triage decisions

The threat of a BT event has catalyzed serious reflection on the troublesome issues that come with event management and triage. Such reflection has had the effect of multiplying the efforts to find solutions to what could become a catastrophic public health disaster. Management options are becoming more robust, as are reliable detection devices and rapid access to stockpiled antibiotics and vaccines. There is much to be done, however, especially in the organizing, warehousing, and granting/exercising authority for resource allocations. The introduction of these new options should encourage one to believe that, in time, evolving standards of care will make it possible to rethink the currently unthinkable consequences. Unfortunately the cost of such preparedness is high and out of reach of most governments. Most of the developing world has neither the will nor the means to plan for BT events and remains overwhelmed with basic public health concerns (i.e., water, food, sanitation, shelter) that must take priority. Therefore, developed countries will be expected to respond using international exogenous resources to mitigate the effects of such a disaster. As a result, the state capacity of the effected government will be severely compromised. If triage and management of casualties is further compromised, terrorists will have met their goals. One could argue that health sciences will continue for decades to play catch up with the advanced technology driving potential bioagent weaponry. If one lesson was learned from the review of the former Soviet Union's biological weapons program, it is that the unthinkable remains an option to terrorists who have comparable expertise. It is crucial to develop realistic strategies for a BT event. Triage planning (the process of establishing criteria for health care prioritization) permits society to see cases in the context of diverse moral perspectives, limited resources, and compelling health care demands. This includes a competent and compassionate management and triage system and an in-depth and accurate health information system that appropriately addresses every level of threat or consequence. In a PICE stage I to III BT event resources will be compromised. Triage and management will be one process requiring multiple levels of cooperation, coordination, and decision-making. An immediate challenge to existing emergency medical services systems (EMSS) is the recognition that locally there will be a shift of emphasis and decision-making from prehospital first responders to community public health authorities. The author suggests that a working relationship, in most areas, between EMSS and the public health system is lacking. As priorities shift in a BT event to hospitals and public health care systems, they need to: 1. Improve their capabilities and capacities in surveillance, discovery, and in the consequences of different triage and management decisions and interventions in a BT environment, starting at the local level. 2. Develop triage and management systems (with clear lines of authority) based on public health and epidemiologic requirements, capability, and capacity (triage teams, categories, tags, rapid response, established operational priorities, resource-driven responsible management process), and link local level surveillance systems with those at the national or regional level. 3. Use a triage and management system that reflects the population (cohort) at risk, such as the epidemiologic based SEIRV triage framework. 4. Develop an organizational capacity that uses lateral decision-making skills, pre-hospital outpatient centers for triage-specific treatments, health information systems, and resource-driven hospital level pre-designated protocols appropriate for a surge of unprecedented proportions. Such standards of care, it is recommended, should be set at the local to federal levels and spelled out in existing incident-management system protocols.

Ocular injuries sustained by survivors of the Oklahoma City bombing

OBJECTIVE

The purpose of this study is to provide a review of the ocular injuries sustained by survivors of the April 19, 1995, bombing of the Alfred P. Murrah Federal Building in Oklahoma City.

DESIGN

Retrospective, noncomparative case series.

PARTICIPANTS

The authors retrospectively evaluated data collected on all surviving persons receiving ocular injuries during the bombing and on all at-risk occupants of the federal building and four adjacent buildings.

METHODS

Injury data from survivors were collected from multiple sources to include hospital medical records, a physician survey, emergency medical services run reports, written survivor accounts, building occupant survey, telephone interviews, and mail surveys.

MAIN OUTCOME MEASURES

The types of ocular injuries, the associated systemic injuries, and the location of the injured at the time of the blast were evaluated.

RESULTS

Fifty-five (8%) of the 684 injured bombing survivors sustained an ocular injury. Persons injured in the Murrah building were more than three times more likely to sustain an ocular injury than other injured persons. Seventy-one percent of ocular injuries occurred within 300 feet of the point of detonation. The most common serious ocular injuries included lid/brow lacerations (20 patients, 23 eyes), open globe injuries (12 eyes), orbital fractures (6 eyes), and retinal detachment (5 eyes). A retained intraocular foreign body accounted for only two of the injuries (4%). Glass accounted for nearly two thirds of the ocular injuries.

CONCLUSIONS

Blasts involving explosions inflict severe ocular injury, mostly as a result of secondary blast effects from glass, debris, etc. Eye injuries in bombings can probably be prevented by increasing the distance from and orientation away from windows (i.e., by facing desks away from windows). Use of such products as laminated glass, toughened window glazing, and Mylar curtains may reduce glass projectiles in the blast vicinity.

Field hospital treatment of blast wounds of the musculoskeletal system during the Yugoslav civil war

The spectrum of wounding and treatment of forty-one patients with musculoskeletal blast injuries at a U.S. military field hospital in the former Yugoslavia was reviewed. Patients underwent wound exploration, irrigation, debridement, broad-spectrum antibiotic therapy, early fracture stabilization, and appropriate reconstructive surgery. Four patients developed wound infections. Two patients died as a result of their injuries (overall mortality 5 percent). There were three below-knee amputations and five other amputations (above-knee, ankle, midtarsal, partial forefoot, and finger). Three patients sustained lumbar burst fractures from mines that exploded under their vehicles, resulting in paraplegia in one case. Our patients underwent 112 surgical procedures, an average of 2.1 per patient. Twenty-two patients (54 percent) had other injuries or conditions in addition to their orthopaedic wounds. There were wide variations in the bone and soft tissue injuries caused by detonating ordnance, and the tissue damage was qualitatively different from that caused by gunshot wounds. Early debridement, leaving wounds open, and treatment with broad-spectrum antibiotics were important factors in wound healing to allow subsequent successful reconstructive surgery in an austere field setting.

Medical consequences of terrorism. The conventional weapon threat

As long as gunpowder and explosives are used to solve disagreements between nations, ethnic groups, and individuals, victims of blast injury continue to arrive occasionally at trauma centers around the world. Bombs planted in crowded urban locations or suicide bombings continue to stress civilian EMS and urban medical systems. Although the clinical presentation depends on whether the blast occurs in open or confined quarters, open air, or water, the pattern of injury inflicted on the body is relatively consistent. The proximity to the detonating device is probably much more important than the size of the bomb. If not injured by secondary, tertiary, or other miscellaneous mechanisms of most conventional bombs with 1 to 20 kg of TNT, people at distances exceeding 6 m will probably not experience substantial blast-induced injury. Three systems are prone to injury. The first is the auditory system, with damage to the eardrum in milder cases and inner-ear injury in more severe cases. The alimentary tract with contusions, hematoma, and occasional perforation of a hollow viscus is the second system involved. Solid organs are rarely damaged in survivors of blast injury. Close proximity to the blast can impose traumatic amputation of limbs (i.e., arms and legs) and ear lobes. Most of these victims succumb to their injuries in the immediate post-injury phase, but the hallmark of blast injury is the involvement of the respiratory system. With expeditious evacuation performed by efficiently coordinated and highly skilled EMS personnel, more patients with blast injuries arrive with signs of life to the medical facility. At the medical facility, the staff need to triage many victims into urgent and nonurgent groups. Only lifesaving procedures should be performed during the initial phase. Later, medical care is directed at patients moved to ICUs. Prompt evacuation after necessary lifesaving procedures in the field; proper triage and distribution; prudent hospital triage and surgical care; and, last but not least, expert critical care provide the best possible outcome in such circumstances.

Maximal exercise performance-impairing effects of simulated blast overpressure in sheep

Lung contusion has been identified as a primary blast injury. These experiments addressed a fundamental and overt endpoint of primary blast injury, incapacitation (performance decrement). Respiration, hemodynamics, and blood gases were measured in sheep undergoing incremental exercise challenge before and 1 h after simulated blast exposure of the thorax. Pathologic examination of lung tissue was performed after exposure and exercise testing. Blast overpressure was simulated in the laboratory using a compressed air-driven shock tube. Three levels of lung injury (Levels 1-3, 'Trivial', 'Slight', and 'Moderate' injury, respectively) were examined for effects on maximal oxygen consumption (VO[2max]), an index of cardiorespiratory fitness. Resting hemodynamics and blood gases were relatively normal an hour after exposure, immediately before exercise. However, Levels 1-3 lung injury were associated with average 4.8, 29.9 and 49.3% VO(2max). decreases, respectively. These performance decrements for Levels 2 and 3 were significantly different from respective controls (non-exposed). Exercise caused significant hemoconcentration in sheep under control conditions, before exposure (resting 9.5 +/- 0.9, end-exercise 11.8 +/- 0.9 g/100 ml). Blast exposure resulted in average decreases of 4.9 +/- 3.4, 12.8 +/- 4.0, and 12.6 +/- 3.3% in exercise-induced hemoconcentration for Levels 1-3 injury, respectively. Normal exercise-induced hemodynamic increases were also attenuated after exposure. Levels 2 and 3 injury resulted in average 22.6 +/- 2.9 and 18.5 +/- 11.2% stroke volume decreases, and also 22.3 +/- 8.4 and 29.0 +/- 14.2% cardiac output decreases, respectively, during exercise. While blast lung pathology and pulmonary function changes could account for post-blast performance decrements, these experiments suggest that in sheep, early after exposure, diminished hemoconcentration and cardiac disfunction may also contribute to decreased exercise performance.

Management of primary blast injury

Blast waves are produced following the detonation of munitions, the firing of large caliber guns, or from any type of explosion. These blast waves can be powerful enough to injure the individuals exposed to them. This type of injury is called primary blast injury (PBI) and the organs most vulnerable to PBI are the gas-filled organs, namely the ear, the lungs and the gastrointestinal tract. The approach to the casualty with PBI is the same as it would be for any trauma victim, i.e. the initiation of life support measures. Attention should be directed to the common life-threatening manifestation of thoracic and abdominal PBI. Pulmonary manifestations would include hemorrhage, barotrauma and arterial air embolism, while abdominal manifestations would include hemorrhage and hollow organ rupture. Therapy is directed at the specific manifestations as well as avoiding additional iatrogenic injury.

The spectrum of pediatric injuries after a bomb blast

The spectrum of pediatric injuries seen after a bomb blast is poorly documented. The pathophysiology of blast injuries differ significantly from other forms of trauma and typically result in large numbers of distinctly patterned injuries. On April 19, 1995, a truck bomb was detonated directly adjacent to the Alfred P. Murrah Federal Building in Oklahoma City, Oklahoma. A total of 816 adults and children were injured or killed as a direct result of the blast. Twenty infants and children were seated by the window of the second floor day care center at the time of the explosion. The injuries incurred by all children involved in the blast were studied. Nineteen children, 16 of whom were in the day care center, died as a direct result of the blast. The injury patterns among the 19 dead children included a 90% (17 of 19) incidence of skull fractures, 15 of those with cerebral evisceration (skull capping); 37% with abdominal or thoracic injuries; 31% amputations; 47% arm fractures, 26% leg fractures; 21% burns; and 100% with extensive cutaneous contusions, avulsions, and lacerations. Forty-seven children sustained nonfatal injuries with only seven children requiring hospitalization. The injuries sustained by the seven hospitalized children included two open, depressed skull fractures, with partially extruded brain, two closed head injuries, three arm fractures, one leg fracture, one arterial injury, one splenic injury, five tympanic membrane perforations, three corneal abrasions, and four burn cases (1 > 40% body surface area [BSA]). After a bomb blast, pediatric patients sustain a high incidence of cranial injuries. Fractures and traumatic amputations are common. Intraabdominal and thoracic injuries occur frequently in the deceased but infrequently in survivors.

Management of unique clinical entities in disaster medicine

This article discusses the management of clinical problems encountered particularly in disasters. These include the principles of multiple-casualty triage, and field and hospital management of blast injury, crush syndrome, compartment syndrome, particulate inhalation, and traumatic asphyxiation. The indications for extraordinary measures, such as field amputation, are detailed. A brief review of the causes and epidemiology of these entities is provided, with emphasis on the clinical management in the disaster setting.

Maxillofacial blast injuries

Blast injuries cause specific lesions and occur more often than previously, because of the wide use of explosives. This is especially the case in wartime. More and more people lose their lives every day due to blast injuries. The mechanism of the injury and pathophysiology of this trauma are discussed. The clinical effects as well as management are presented. The most dramatic effects observed are fractures to the middle third of the face, reported here for the first time, with their management. New fracture lines are typically seen in fractures of the mandible due to the blast wave effects. This presentation should help in the prevention and management to save the lives of patients in future.

Emergency medicine in the Persian Gulf War--Part 3: Battlefield casualties

STUDY OBJECTIVE

To report the type and frequency of battlefield casualties and the procedures performed to treat them.

STUDY DESIGN

A prospective analysis of trauma record data incorporating anatomic categories and the Revised Trauma Score.

SETTING

Two military field trauma centers during the primary ground assault into Kuwait.

TYPE OF PARTICIPANTS

Four hundred two trauma admissions of coalition and enemy forces.

MAIN RESULTS

Forty-eight percent of casualties suffered fragmentation wounds, including 43 land mine injuries. Only 10% sustained gunshot wounds. Forty-four percent of casualties had injuries limited to the extremities; 29% had combined extremity injury and injury to another anatomic region. Extremity wounds occurred nearly twice as frequently in the lower extremities as in the upper extremities. Surgical procedures were undertaken in 164 patients, with 108 debridements for major soft tissue injuries or open fractures.

CONCLUSION

The composite casualty admitted to US Navy-Marine trauma facilities was injured by shrapnel in the lower extremity and required surgical debridement only. Soldiers with land mine injuries, as in other wars, were among those in greatest need of emergency resuscitation.

Primary blast injury after a bomb explosion in a civilian bus

A 6-kg explosive charge detonated under a seat in the center of a crowded city bus in Jerusalem, killing three passengers immediately. Of the 55 survivors, all of whom were transferred to two major medical centers, 29 were hospitalized. Among those admitted, a high rate of primary blast injuries was found, including perforated ear drums (76%), blast lung (38%), and abdominal blast injuries (14%). Two of the latter patients suffered bowel perforations, which were diagnosed with considerable delay. Eight patients (31%) had sustained life-threatening trauma, consisting of a combination of primary, secondary, and tertiary blast injuries. The overall mortality rate was 10.3%. The large number of primary blast injuries, including the unexpected finding of bowel perforations, is explained by the high amplitude of the air pressure wave (3.8-5.2 atm) and its relatively long duration (2-3 msec) resulting from the detonation of the high-energy explosive charge in the small, enclosed space of the bus. Besides the usual wounds sustained by victims of an explosion that occurs in a confined space, the possibility of primary blast injury to the abdomen and to the lungs should be taken into account by the treating surgeon.

Blast injuries from glass bottles containing dry ice

We present three cases (two incidents) of severe blast injury from the explosion of covered glass bottles containing dry ice. The first patient sustained lacerations of the face, left eye, right wrist and forearm, and abdomen with protrusion of the small bowel. The second sustained a deep laceration to her anterior neck. The third sustained multiple lacerations to her lower extremities and one to the labia majora. All three patients were taken to the operating room for surgical exploration and repair and were discharged without complications.

Oil and petrol drum explosions. Injuries and casualties by exploding oil and petrol drums containing various inflammable liquids

If ignited, an evaporated inflammable liquid remaining mixed with air in an oil or petrol drum may cause an explosion in which the top and bottom of the drum are blown off by the blast and act as projectiles causing extensive injuries to persons nearby. To analyse the occurrence of this type of accident and to study the injuries involved information was sought from all police districts in Denmark and all the departments of plastic surgery with a burns unit. The investigation revealed a total of 21 accidents caused by oil drum explosions over a period of 36 years with 16 injured within the last 5 years in a population of five million people. Fifteen accidents occurred during attempts to divide a drum with a disc grinder or a cutting blow-torch; five of the victims were welding drums or using drums as a support when welding or cleaning iron materials and one man was shifting a drum which exploded because of the heat of the sun. Five men were killed: three died from burns and two from fatal brain injuries. Two men with several facial fractures survived. Five victims received injuries to the lower limb and presented with a total of six open, comminuted fractures of the tibia. Nine men had burns covering from 2 to 50 per cent of the body surface, up to 30 per cent of the burns being full-thickness. This paper draws attention to the extreme danger of working on apparently empty oil or petrol drums with tools generating heat or sparks, unless specific precautions are taken.

Primary blast injuries

Injury from explosion may be due to the direct cussive effect of the blast wave (primary), being struck by material propelled by the blast (secondary), to whole-body displacement and impact (tertiary), or to miscellaneous effects from burns, toxic acids, and so on. Severe primary blast injury is most likely to be seen in military operations but can occur in civilian industrial accidents or terrorist actions. Damage is seen almost exclusively in air-containing organs--the lungs, the gastrointestinal tract, and the auditory system. Pulmonary injury is characterized by pneumothorax, parenchymal hemorrhage, and alveolar rupture. The last is responsible for the arterial air embolism that is the principle cause of early mortality. Treatment for blast injury is similar to that for blunt trauma. The sequalae of air embolization to the cerebral or coronary circulation may be altered by immediate hyperbaric therapy. Use of positive pressure ventilatory systems should be closely monitored as they may increase the risk of air embolism in pneumothorax. Morbidity and mortality may be increased by strenuous exertion after injury and by the wearing of a cloth ballistic vest at the time of the blast.

Disseminated intravascular coagulation and hypopotassemia associated with blast lung injury

Forty six people were injured by a large explosive charge detonated in a Jerusalem bus. Four were killed instantaneously and 22 needed hospital care. We describe our experience in five patients with blast lung injury (BLI), all of whom survived in spite of severe respiratory failure requiring mechanical ventilation. Disseminated intravascular clotting (DIC) developed in three of the five patients and significant hypopotassemia ranging from 2.2 to 2.9 mEq/L in four. These two complications have not been previously described in association with BLI. Both DIC and hypopotassemia responded to replacement therapy. Vigorous treatment of respiratory failure, early recognition, and prompt correction of hemostatic and electrolyte abnormalities may have contributed to the avoidance of fatalities among the five patients with severe blast injury.