In the decade following the September 11, 2001, terrorist attacks, Americans have become more accustomed to the threat of terrorist attacks by weapons of mass destruction (WMD). Training for response to such events is now common for first responders and medical personnel. This chapter will present practical approaches to terrorist attacks involving WMD and explosives, an overview of specific types of explosives, and strategies for dealing with blast and burn injuries in the prehospital setting.
Define terrorism, domestic and international.
Discuss specific threats to emergency responders to terrorist events.
Discuss principles and strategies relating to the approach to a possible terrorist attack.
Define the term weapon of mass destruction, and list examples.
Discuss specific issues related to emergency response to various types of WMD events.
Describe explosives and incendiaries and give examples.
Discuss specific medical conditions associated to exposure to explosives and incineraries.
Discuss signs of the possible presence of explosives on a scene (eg, pipe lengths, blasting caps, detonator cord, etc).
Terrorism is any violent act directed against people or property, which is intended to cause damage and/or death, instill fear, and disrupt normal activity among civilians while drawing attention to or furthering a specific nongovernmental group or cause.
Domestic terrorism in the United States refers to activities undertaken in the territorial jurisdiction of the United States which appear to be intended to intimidate or coerce a population or influence governmental policy by mass destruction, assassination, or kidnapping 1 [18 USC 2331(5)].
International terrorism refers to terrorist activities that would violate American criminal laws or the laws of any state and which occur outside the territorial jurisdiction of the United States or transcend national boundaries in terms of the means by which they are accomplished, the population they are meant to affect, or the locale in which the events occur or where the perpetrators seek asylum. 2
Uses of chemical, biological, radiation, nuclear, and explosive (CBRNE) resources have been well described as possible terrorist scenarios. Explosives have long been weapons of choice for international attacks due to their relative ease of use, low cost, and high impact. In the Middle East, improvised explosive devices (IEDs) and suicide bombings occur with relative frequency. Although there have been fewer explosive attacks in the United States, notable examples from the past two decades include the use of stationary IEDs in the 1993 World Trade Center attack and the Centennial Park bombing during the 1996 Olympic Games in Atlanta, Georgia. Vehicle-borne improvised explosive devices (VBIED) were used in 1995 at the Oklahoma City Murrah Building bombing and the September 11, 2001, attacks on the World Trade Center and the Pentagon. There was also an unsuccessful VBIED attempt in Times Square in 2010. Internationally, explosives were second only to firearms as the most common method of attacks against civilians in 2010 and explosives were responsible for the highest number of civilian casualties. 3 Explosives, as a method of inflicting casualties, is now the leading method of murder chosen by terrorists around the world. 4
All of these examples can be considered WMD attacks. The term weapons of mass destruction, however, has become an increasingly political term used to describe conventional and unconventional weaponry used to cause widespread damage or panic. Its connotation suggests terrorism, but it can be applied literally to many circumstances, including traditional warfare. In the immediate aftermath of an event, it may be difficult to determine if the event was intentional or accidental, and that determination may be of secondary importance. Many agencies are now using the more precise term CBRNE to describe chemical, biological, radiological, nuclear, or explosive events in an effort to devise a uniform response to such an event, regardless of its underlying nature. Accidental explosions may occur as a result of industrial accidents, compromised gas pipes, motor vehicle accidents, and many other etiologies. In many parts of the world, death or dismemberment from accidental landmine detonations are still common. 5
Unfortunately, terroristic events in the United States are not a new phenomenon. Explosives have been utilized throughout the 20th century to inflict fear in civilian populations. In 1920, a horse-drawn wagon carrying 45kg of dynamite and 230kg of iron sash weights was parked in the financial district of New York City. At noon, on September 16, the explosive-laden wagon, detonated by a timing device, exploded along Wall Street, killing 23 people and injuring 400.
Bath Township, Michigan, was site to multiple bombings in May 1927. The attacks were responsible for the deaths of 45 people. A local farmer, devastated over financial matters, used stockpiled pyrotol and dynamite to blow up his farm, the Bath Consolidated School, and finally himself.
These historical examples involve soft targets. Potential targets for a terrorist event are generally categorized as soft or hard. Soft targets are generally undefended and easier to penetrate, like train stations and buses. An attack on these locations may inflict psychological distress and some civilian casualties; however, soft target attacks do not generally result in long-term disruption of daily activity. For example, the multiple London bombings on July 7, 2005, resulted in 52 deaths but the city largely returned to normal function by the next day.
Conversely, hard targets include essential, defended, or fortified infrastructure like military installations and airports which are considerably more protected. Increased security serves both as a deterrent and makes the sites more resistant to successful attacks. 6
Nevertheless, a determined individual is all that is necessary to cause massive destruction and carnage. Would-be bombers are able to construct lethal explosives with minimal finances, resources, or expertise. Instructions to manufacture an explosive device are easily obtained via the Internet. If a bomber can obtain the necessary materials, remain inconspicuous, and transport the device, then he or she stands a good chance of deploying the device. For these reasons, it is imperative that civilian medical personnel begin to consider explosions as credible—or even likely—disasters. 7-10
Twenty-four-hour news coverage now guarantees immediate media attention, and terrorists are acutely aware of how to manipulate propaganda through the media to advance their agendas. By striking highly populated or highly publicized locations, terrorists know they can inflict more casualties and garner more attention.
TYPES OF EXPLOSIVE DEVICES
Medical responders do not have to possess an exhaustive knowledge of explosives. Law enforcement organizations are more appropriate to pursue detailed forensic work regarding explosives. It is important, however, to understand the physics of an explosive device and the resulting aftermath. Knowledge of blast wave mechanics will allow a health care provider to search out blast-related injuries.
In general, explosive materials may be categorized into two types: low grade and high grade. A low-grade explosive is similar to gunpowder including fireworks and nitrostarch. These substances deflagrate, or undergo subsonic combustion, at less than 1000 m/s. This results in a subsonic reaction without a classic blast wave. Conversely, high-energy explosives detonate at about 4500 m/s and produce a supersonic shock wave. 11 Examples of high-grade explosives include trinitrotoluene (TNT), C-4, Semtex, nitroglycerin, dynamite, or ammonium nitrate fuel oil (ANFO).
Detonation of explosive material causes chemical bonds within the material to break down, rapidly converting solid or liquid material to gas. 5 The rapid breakdown of bonds creates an exothermic reaction, resulting in a superheated ball of gas. The gas expands outward in a radial pattern, causing a shockwave that propagates through the explosive material. The outwardly expanding wave displaces the surrounding medium, causing an increase in the surrounding atmospheric pressure (the overpressure). An uninterrupted blast wave continues moving outward but dissipates quickly in an open area. Immediately behind the area of increased atmospheric pressure is a zone of negative pressure. This underpressurized area subsequently creates a vacuum (see Figure 77-1). The resulting pressure phenomenon is best summarized by the Freidlander waveform (Figure 77-2). From an explosion, victims can sustain blunt trauma, penetrating trauma, thermal burns, and severe musculoskeletal trauma including amputation. 12
Primary blast with returning shockwave.
Waveform representing ideal open air blast as described by the modified Friedlander equation. (Dewey JM. The Shape of the Blast Wave: Studies of the Friedlander Equation. Presented at the 21st International Symposium on Military Aspects of Blast and Shock, Israel 2010)
IMPROVISED EXPLOSIVE DEVICES
Improvised explosive device (IED) is a general term that encompasses a wide range of devices. IEDs may vary in size, shape, and material. In their simplest form, IEDs are essentially any explosive material wired to a trigger device. The common characteristic of all devices is they have been adapted from their original intent. 13 A vehicle-borne improvised explosive device (VBIED) is an example of such a device. A VBIED is a vehicle packed with explosive material then detonated in a crowded location or driven to a target site. A home-borne IED is a house or building packed with explosives and detonated when targets approach or enter the structure.
IEDs may also consist of manipulated blast mines, explosive formed projectiles (EFP), and suicide/homicide bombs. 14 Typically, an IED is a nonstate sponsored explosive constructed out of available materials, most often military ordinance. These devices have recently gained worldwide notoriety as a favorite tool among insurgents in Iraq and Afghanistan.
The type of device a bomber constructs depends on the target and available resources. IEDs are popular because of the ease in which they can be built and concealed. The devices can be hidden along a road or thoroughfare. 15 Instead of a single device, IEDs may be strung together in a continuous “daisy chain” formation to increase damage and casualties. 13
The explosive device may be activated remotely by the bomber or triggered by the victims themselves. An IED is triggered by tripwire, ignition fuse, mercury switch, or depressing a pressure plate. A bomb may also be detonated using a timer, radiofrequency, or cell phone, allowing the bomber to be in a location far from the explosion.
Terrorists may utilize shape charges, which add directionality to the blast. Other options include suicide/homicide bomb vest or other garment worn by the bomber, VBIEDs, and a variety of other devices to increase lethality. 16-18 Each weapon has qualities that a terrorist can take advantage of to accomplish his or her goal and escape detection.
In addition to explosives, incendiary devices may be deployed to cause damage, inflict casualties, or incite panic. An incendiary device is designed to ignite and cause fire rather than explode. Explosions rarely cause fires because oxygen is depleted during the blast. 19 Explosives may cause burns because of thermal energy released during the rapid expansion phase of a blast. However, incendiary devices are specifically meant to ignite a fire and usually burn at high temperatures.
A classic example of an incendiary device is a Molotov cocktail (Figure 77-3), which consists of a bottle partially filled with a flammable substance. A rag, doused with a flammable liquid, is shoved into the bottle opening and the rag is lit. When the bottle is thrown, it shatters against a hard surface. The flame ignites the rest of the fluid and the ensuing flames are scattered over a larger area. The resulting fire can trigger an explosion if the open flame contacts other volatile substances.
CHEMICAL, BIOLOGIC, RADIATION, NUCLEAR DEVICES
Today, one of the largest security concerns for the nation is the combination of chemical, biologic, or radioactive substances with explosives. The addition of these agents would compound the fear resulting from an explosion alone. Intelligence agencies have found plans by terrorists to attempt just such an attack. 20 In most cases, an explosion utilizing chemical, biological, or radioactive agents would not result in many casualties; yet an attack involving CRBN would have exorbitant cleanup costs, incite panic, and cause logistical complications especially if it occurs in a highly populated area like New York City. 21
A chemical substance, such as chlorine, could potentially be combined with an explosive. Chlorine, as with many chemicals, is transported by trains and trucks across the country. An explosive incident involving a chemical like chlorine could release a gas cloud into an unsuspecting populated area. In this case, because of a moving gas cloud, casualties would be located at the immediate scene, as well as downwind from the incident. This was the case in the Graniteville, SC, chlorine gas spill when a train collision released a gas cloud on January 6, 2005, killing nine people and leading to over 250 people seeking treatment for chlorine exposure. 22
If a victim is within range of the blast, they will be exposed to typical blast-related injuries as discussed later in the chapter. If a victim is located outside the blast radius, he or she may be exposed to a substances dispersed by the blast. While the effects from exposure will vary by chemical or contaminant, the most likely result will be respiratory and mucosal irritation. Decontamination and removal from the source of exposure should be done as early as possible. Bronchodilators may be beneficial for respiratory distress from pulmonary irritation.
When an explosive device is combined with any radioactive substance, it becomes a radiologic dispersal device (RDD), also referred to as a “dirty bomb.” 23 An RDD is postulated to be small enough to be portable so as to allow terrorists to remain inconspicuous. The detonation of such a device would not result in a traditional nuclear explosion but would cause panic and uncertainty as well as incur great financial cost to society because of the spread of radioactive contamination.
The effects of a blast following an RDD detonation would be confined to the immediate area and would account for most of the initial casualties. The radioactive substance, however, could be dispersed over a much larger area. 24-27 Because of their prevalence, the most likely radioactive substances to be incorporated into an RDD are Cs-137, Sr-90, Co-60, Am-241, and Pu-239. 23 Contamination occurring from the spread of radiation would hinder immediate rescue efforts and evacuation of survivors.
Victims may be grossly decontaminated through removal and disposal of their clothes and copious irrigation. Responders may minimize radiation exposure by following the International Commission on Radiological Protection recommendations including limiting time of exposure, increasing distance from primary contamination, and wearing proper protective and shielding equipment. 23,28 Victims without injuries but requiring decontamination should not be transported directly to hospitals; instead they should first be directed to a designated screening and decontamination area for proper assessment and decontamination as indicated. 29,30
CONDITIONS THAT IMPACT CASUALTIES
Many conditions influence injury severity, morbidity, and mortality. These factors include the location in which the explosion occurs, the amount and type of explosive material utilized, the physical environment, blast fragments, proximity of the victim to the blast, and how he or she is dressed. 31 Responders have no impact on any of these variables, but understanding the mitigating circumstances may help them assess the victims and the scene.
Explosive results can vary according to the properties of the materials incorporated to make the bomb. The duration of an explosion also depends on the amount of material that is utilized. As the amount of explosive material is increased, the size and strength of the resulting blast wave also increase.
Victims who are located nearest the primary blast fare worse than those who are further away. Because of the close proximity, death is often instantaneous or injuries so severe that survivability is greatly diminished. Responders must look for occult injuries in those who survive and were located near the explosion.
The pattern of injury and number of casualties depend on the environment in which the blast occurs. Arnold et al documented an immediate mortality rate of 25%, 0.8%, and 0.04% for structural collapse, enclosed blasts, and open area blasts, respectively. Structural collapse results in an increase in injury severity among casualties, as well as increased fatalities. 6,32
There are three main types of mass casualty environments. These include enclosed area, open area explosion, and structural collapse. 31 Bus or train explosions may be considered as ultraconfined and result in higher mortality than other equivalent enclosed explosions. Bus explosions are considered, by some, as a separate environment since victims are packed closely together and tend to be more proximal to the epicenter of the blast. 33
When explosions occur within an enclosure like a building or train, the damage is more severe and results in higher mortality. 34 Instead of dissipating in an exponential fashion, blast waves rebound and reverberate off surrounding walls and structures. The initial force of the wave becomes magnified when multiple reflected waves combine, resulting in an additive effect (Figure 77-4). Unlike open area blasts, increased distance from the primary explosion does not necessarily reduce injury severity. Cumulative wave forces may be two to nine times greater after reflecting off surrounding structures. 33 Survivors are more likely to sustain occult internal injuries, like blast lung. 34,35
Combined wave forces in an enclosed space. Black arrows represent primary force of blast while red arrows represent subsequent increased force from combined blast waves.
In an open-air explosion, a blast wave will dissipate more rapidly because there is nothing impeding the wave front. Barring structural interference, the force of the blast wave decreases by the cube of the distance from the site of primary explosion. In other words, victims located three times the distance from the primary site will experience a force 27 times less than those at the site of the blast. 36
The medium in which the explosion occurs, impacts how efficiently a pressure wave is transmitted. An underwater explosion will cause a blast wave that propagates faster and maintains force for a longer duration than in air. 4 The propagation of a blast wave front is dependent on the amount of force that is transmitted from molecule to molecule within the medium. Due to water's increased density, the strength of a blast wave is estimated to be three times greater in water than in open air. 36 Therefore, injuries and damage in water can be more severe at comparative distances.
When an explosion occurs, fragmented material from the bomb is hurled outward from the primary blast site. Shrapnel fragments consist of whatever material was used to construct the bomb and its casing. Bomb-makers also add additional materials to act as penetrating missiles. They may include bits of metal, screws, nails, bolts, and ball-bearings. 37 In the case of suicide bombers who wear their bombs, their bones, clothing, and accessories can also become projectiles. The force of a blast can transfer anything around the bomb into high-speed projectiles. The fragments are projected in all directions, causing additional penetrating injuries to victims. As a result, victims sustain both blunt injuries from the blast wave, and penetrating wounds from fragmentation and projectiles. 19
As with any disaster, the ability to respond to a CBRNE event begins in the planning and assessment phase with a hazards vulnerability assessment (HVA). This critical assessment includes identification of assets or potential targets, potential undesirable events, consequences and losses associated with each potential event, and risk stratification. The assessment should guide efforts at prevention, mitigation, and response. While the responsibility for implementing preventative measures usually lies primarily with law enforcement and security agencies, all first responders should be vigilant and able to function in prevention and mitigation capacities.
Should an event occur, responders in the operational setting need to be able to apply the general principles of scene safety, recognize the nature of the event, implement mass casualty management strategies, and call upon additional resources. Once an event has occurred, responders should approach the area as any hazardous materials event, keeping in mind that hazardous materials exposure and contamination could arise from an explosive dispersal device, be part of a secondary device, be released from the scene itself, or be transmitted via blood and bodily fluids originating from perpetrators or victims. The standard approach to HAZMAT scenes involves staging upwind, uphill, and upstream; accessing the scene from upwind to avoid vapor hazards; establishing hot, warm, and cold zones; ensuring safe ingress and egress routes; and decontaminating victims, responders, and equipment. Personal protective equipment should be chosen based on the responders' areas of operations, potential exposures, and detected or presumed threats. In the cold zone, level D protection in the form of uniforms, gloves, and simple respiratory masks may be sufficient. In other areas of operations, responders may require protection from multiple threats and may need to don more specialized, risk-specific PPE, such as level A or B hazmat suits, turnout gear, self-contained breathing apparatuses (SCBA), structural collapse gear, or tactical body armor, depending on the threat assessment. Only personnel trained to operate within the hot zone while wearing appropriate PPE should attempt to do so. In addition to being treated as hazmat scenes, all blast scenes should also be recognized as having the potential for continuing explosions, whether from unintentionally unexploded ordinance or from secondary devices intentionally placed to target first responders.
Oftentimes the first responders to a bombing will not have the specialized skills to detect all threats or recognize the full scope of the event, yet their initial survey can help guide the procurement of additional personnel and equipment. First responders' initial surveys can estimate the number of victims and detect additional threats such as building collapse, utility fires and explosions, and booby traps. Any indication of such threats should be passed along the chain of command to facilitate the timely deployment of medical personnel, heavy rescue equipment, search and rescue teams, structural engineers, hazmat and/or radiological teams, utility company personal, bomb squads or explosive ordnance disposal (EOD) teams, etc. After the initial assessment, medical first responders will transition into mass casualty incident (MCI) management and operations. The standardized MCI approach involves assigning a triage officer, implementing triage operations, establishing treatment and transportation areas, organizing victim evacuation, and coordinating with local hospitals. Regardless of the triage method chosen, the goal of triage is the same: maximize the likelihood of survival in the greatest possible number of victims. At a blast scene, first responders can expect to see victims with severe burns, traumatic amputations, penetrating injuries from shrapnel, blast injuries, and smoke inhalation. Posttriage management should proceed in accordance with local operating protocols, and providers should keep in mind that triage is a dynamic process and patients' conditions may deteriorate rapidly. Those patients with more severe injuries should receive priority treatment, transportation, and evacuation. While this portion of MCI response is familiar to most first responders, bombing scenes require additional considerations. Blast scenes are dynamic scenes with the potential to become rapidly dangerous due to secondary blasts, fire, hazmat release, or structural collapse. With that in mind, responders may forego triaging in place in preference for a load-and-go approach within critical zones. When operating in hot or critical zones, medical personnel should be accompanied by security personnel who can observe for hazards and/or provide tactical cover. Responders should also be cognizant of the fact that perpetrators of the event may be among the injured. They or their security escorts should perform at least a cursory assessment for weapons or unexploded ordnance, since transporting these individuals to casualty collection points or health care facilities without clearing them of weapons could have devastating consequences. 38
Accidental explosions may be caused by an electric arc or fire, but in the immediate moments after a disaster, both intentional and accidental scenes can be identical. Communities conduct extensive drills and education directed at the management of chemical, biological, radiological, and nuclear aspects of terrorism. Less investment has been made in training for pure explosion scenarios.
When a mass casualty event occurs, there are often conflicting accounts. The reports can be contradictory and confound the true details. In the moments after an explosion or fire, nonaccidental and accidental catastrophes can appear identical. When the London bombings occurred in 2005, conflicting reports included blown power transformers, underground fires, and numerous subway bombings after victims emerged from multiple train exits. 39
Locations like buses and stadiums are more likely to be terrorism targets, whereas industrial sites may seem accidental. This logic may be deceiving if an industrial site has military connections or may be considered vital infrastructure. In these cases, terrorists may target sites for symbolic value rather than the number casualties. Furthermore, any location is subject to potential terrorism if someone has a personal vendetta, like a disgruntled employee.
Standard algorithms, like Advanced Trauma Life Support (ATLS), ensure that the same format is followed each time and details are not forgotten. This minimizes confusion in disturbing situations when emotions may impair a logical thought process.
First responders must be aware of possible malicious intent and maintain a high index of suspicion for further attacks due to the unknown etiology of a disaster. Regardless of whether the disaster was nonaccidental, or purposeful, the victims and providers are in continuous danger. Threats persist until all personnel are evacuated from the scene.
Further death or injury may occur due to secondary attacks, structural damage, building collapse, leaking gas lines, or chemical exposure. In the past, responders have been killed by falling debris. 40,41 When a building is destroyed, substances that cause topical or inhalation injury may be released, as was the case during the 2001 World Trade Center attacks. Long after the wreckage has been removed from Ground Zero, questions persist regarding inhalation injuries and exposures among responders.
In the past, terrorists have increased casualties by targeting responders and bystanders. Additional victims have been injured or killed by the detonation of secondary explosive devices at the scene or being fired upon by snipers. Spending extra time to safeguard the site by verifying remaining structures are stable, securing the proper equipment (PPE) and eliminating further threats can minimize further loss of life. 32
First responders also play a preventative role by assisting in the detection of secondary explosive devices after intentional blasts. Responders should keep the blast area clear of unnecessary personnel until those with proper equipment clear the scene. The presence of a secondary explosive device can be easily overlooked among the carnage so rescuers should stay alert and aware of the environment.
Detection of further explosive devices is the responsibility of specially trained teams. They utilize equipment including robotic instruments with cameras, bomb-sniffing dogs, and sensors to detect specific chemicals. 42 Mammalian olfactory senses have been proven to be efficient detectors of explosive material and have been manipulated for such purposes. 43 It is well documented that the first wave of responders are secondary targets as well. 32 For this reason, the explosion site must be secured and any unexploded ordinances and bombs disarmed prior to evacuation and medical management of the victims.
Victims should be removed from the primary scene as quickly as possible. Any intervention necessary to stabilize the patient like a thoracostomy or intubation should be done to ensure safe transport. However, the majority of medical care should be carried out at a medical center. Rapid evacuation of responders and patients minimizes the risk of further injury to either group. Victims must be removed from the primary scene as quickly as possible without posing unnecessary risk to rescuers. Structural damage to surrounding infrastructure makes the environment dangerous for prolonged medical management on scene. 39
Experience from the frequent bombings in Israel has provided a plethora of data regarding the most efficient management of victims at a scene. Einav et al recommend an algorithm of immediate on-scene triage with minimal medical intervention followed by immediate evacuation of critically injured victims to the nearest hospital and finally evacuation of the remaining survivors to surrounding hospitals. 40,44,45
When triaging, or sorting, victims, there are four triage levels. The first requires immediate treatment and evacuation, the second group needs intervention but is presently stable, the third is described as “walking wounded” with minimal injuries and therefore requiring no immediate intervention, and the final group is likely to expire without the investment of considerable medical resources. 32 A summary of guidelines for mass-casualty medical field care as suggested by Stein et al is found in Table 77-1. 40,46
Summary of Indicated Mass-Casualty Prehospital Medical Care 40,46
||Download (.pdf) TABLE 77-1
Summary of Indicated Mass-Casualty Prehospital Medical Care 40,46
Victims who lack spontaneous respirations and palpable pulses, and those who have dilated pupils should be considered dead.
Perform airway management with C-spine control for unconscious victims and those with poor ventilation.
Perform needle thoracostomy and oxygen supplementation in the field or during transport.
Apply direct pressure and then tourniquets for extremity bleeding.
Intravenous fluid may be administered for patients who are hemodynamically unstable from blood loss if he or she can soon be stabilized in an operating facility.
Fracture reduction and splinting are indicated for patient stabilization during transport and to minimize blood loss.
Cover open wounds as soon as possible to minimize contamination.
On-scene CPR is not indicated.
As in the case of the 2005 London bombing, multiple locations may be attacked at once. The health care system is unable to prevent further mass casualty events. For this reason, as soon as a nonaccidental explosion is suspected, a central dispatch needs to be notified to prepare resources 39 A central Emergency medical services (EMS) dispatch is vital for proper resource utilization. Central coordination ensures patients are distributed appropriately among multiple healthcare facilities. 40
Victims of bombing incidents demonstrate unique injury patterns. Often, they will sustain serious injuries that involve at least three regions of his or her body. 19 Severe injuries to the head will likely result in a nonsurvivable condition. If the victim does survive, he or she may develop central nervous system disruption that presents later as a traumatic brain injury (TBI).
After an explosion, fatalities and injuries occur because of immense thermal energy, rapid expansion of gas, and a powerful shockwave that radiates outward. 5 Victims who are struck by a blast wave after an explosion will sustain variable injuries. The extent and severity of injuries depends on the factors previously discussed, for example, the victim's proximity to the blast, the type of blast, and location of the explosion.
In general, blast waves affect organ systems that consist of air-filled structures especially where there exists an air-tissue interface. 5 Such structures include the auditory, pulmonary, and gastrointestinal systems. Following an explosion, injuries may be classified as primary, secondary, tertiary, quaternary, and quinary. 47 A summary description of this classification system according to the Department of Defense (DOD) is summarized in Table 77-2. 48
||Download (.pdf) TABLE 77-2
|Blast Injury ||Mechanism ||Injury Pattern |
|I (Primary) ||Direct tissue damage resulting from impact with blast wave front ||Blunt trauma, blast lung, contusion, traumatic amputation of limbs, TM rupture, hollow organ rupture |
|II (Secondary) ||Injuries resulting from impact with fragments and projectiles ||Penetrating injuries, lacerations |
|III (Tertiary) ||Injuries resulting from the displacement of victim's body ||Acceleration/deceleration injuries, blunt injury, crush injuries |
|IV (Quaternary) ||Additional injuries resulting from contact with explosive material and blast ||Thermal burns, inhalation injury, toxic/chemical exposures |
|V (Quinary) ||Injuries or symptoms as a result of contact with contaminants within explosive device ||Bacterial exposure, biohazard exposure, radiation exposure |
Critically injured blast victims have a different pattern of mortality than nonblast-related trauma victims. Historically, nonblast-related trauma victims experience a trimodal mortality pattern, whereas blast victims demonstrate a bimodal mortality pattern. 31
Additionally, victims who were involved in structural collapse and crush-related incidents had increased rates of mortality both initially, and after 24 hours. 49
Victims, who are involved in a structural collapse, experience higher rates of inhalational complications, crush injuries, and fractures. Victims from confined blasts sustain more pulmonary injuries, solid organ injury (SOI), burns, and TM rupture. Finally, open-air blast victims tend to receive more penetrating soft tissue wounds. 31 Wounds from penetrating injuries and foreign bodies can be hidden underneath clothing. Detection of every injury is difficulty without diagnostic equipment, so a high degree of suspicion for occult injuries is warranted even when victims appear well. 37
Ocular injuries may consist of conjunctival abrasions, foreign bodies from penetrating fragments, or lens dislocation. 50 Victims can sustain burn injuries from chemical exposure or thermal heat from a blast. Blast burns occur more often on areas of exposed skin. Therefore, patterns of burn injury will be dependent on the type of clothing the victim is wearing. The most common sites that victims sustain burns are the hands and face. 51
Blunt force trauma to the chest can affect the pulmonary and cardiac systems. Cardiac contusions following blunt force trauma to the chest can lead to dysrhythmias. 50 In the immediate seconds following the blast, victims may experience a period of apnea, which usually resolves without intervention (2). Blast lung is a potentially fatal injury in which hemorrhage and edema occurs at the air-tissue interface between the capillary bed and alveoli. 52 Additionally, victims may sustain pulmonary contusions, pneumothorax, pulmonary hemorrhage, or air embolism. 50
Victims can suffer a wide variety of musculoskeletal injuries. Crush injuries with tissue destruction may occur from structural collapse of a building with subsequent entrapment. Compartment syndrome of the extremities is a concern following prolonged pressure on a body part. Fracture sites usually occur along the distal and proximal thirds of the upper and lower extremities. 5 Traumatic amputation most commonly occurs at the fracture sites of long bones.
The amount of pressure required to cause tympanic membrane (TM) damage is 2-5 PSI. 47 The absence of TM damage was once believed to be an indicator for the absence of severe occult injuries. However, Harrison et al demonstrated that the presence or absence of TM damage was not a sensitive indicator for injury severity. 53 Tinnitus and hearing loss may be temporary, but some survivors have reported permanent deafness. 5
The gastrointestinal system appears to be injured more often in underwater blasts. 4 This may be from the abdominal exposure when victims are floating prone on the surface of the water. Victims can also sustain bowel contusions and less often, perforations. 5 He or she may also suffer solid organ injuries from primary or tertiary blast effects. 19
A fetus may be protected from blast wave effects in utero. Most bodily damage occurs at an air-tissue interface. 5,47 Because the fetus is bathed in amniotic fluid, the risk of injury is reduced. However, the fetus may suffer injuries from a structural collapse, blunt trauma, and any systemic injuries that the mother may sustain.
In the process of triaging victims, one may commit errors such as over- or undertriaging. Great care should be taken to avoid these mistakes since incorrect designation may lead to misallocation of essential resources and contribute to increased mortality and morbidity.
While assessing injuries in order to triage victims after a mass casualty incident, it is important to recognize errors that might occur. Overtriage is the act of assigning noncritical patients to critical status. 35 Incorrect classification may result in the unnecessary expenditure of limited time and resources. Resources can be diverted from other, truly critical victims and detract from his or her care or even evacuation from a scene. This is acceptable during normal trauma but may contribute to increased mortality during a critical mass casualty incident. 54
Blast victims may also be undertriaged. In contrast to overtriaging, blast injuries may be overlooked and the victims therefore do not receive the care they require in a timely manner. 34 Blast injuries can be deceiving and a critical injury may not be evident until the victim deteriorates.
The proper triage assignment of blast victims is difficult to balance. Designation of triage status often occurs in intense situations where responders are easily distracted and overwhelmed. Awareness of triaging errors will help minimize the above mistakes.
The Extended Focused Assessment with Sonography in Trauma (EFAST) exam with ultrasound equipment on scene may be helpful to assess for the presence of certain life-threatening injuries. 12 Conditions that may be detected early include pneumothorax, intra-abdominal fluid, or pericardial effusion. 37
A few interventions should be considered before a victim is transported. Needle thoracostomy should be performed immediately if a pneumothorax is suspected. Endotracheal intubation on scene may be necessary for stabilization of victims with evidence of respiratory distress. Suspected pelvic fractures should undergo external stabilization before transport to minimize continued blood loss.
Long bone fractures should be splinted to avoid neurovascular damage, bleeding, and to minimize pain. Victims impaled by foreign bodies should have the objects removed only in the operating room. The object, itself, may act to tamponade a severe wound. However, it may be necessary to cut or shorten the object in order to safely transport. 49
Burns should be covered to prevent further contamination, and intravenous fluid resuscitation can begin prior to transportation. With ocular exposures, early irrigation should continue for at least 60 minutes or until the pH of the eye is neutral. 49 These interventions should not delay mobilization of the victim but should begin as early as possible.
Advances in medical technology are significant in times of war. The impetus to decrease mortality and find effective treatments on the battlefield assists in tremendous gains in civilian medicine as well. The frequent bombings in Israel, as well as the wars in Iraq and Afghanistan over the past 10 years are no exception. Managing traumatic wounds sustained from blast injuries in IED explosions has allowed medical personnel to publish a great deal of literature on the subject. As a result of improved medical care and equipment, mortality from these wars is considerably lower than past conflicts.
Every explosion incident should be considered intentional until proven otherwise.
Explosives are responsible for the highest number of civilian casualties worldwide.
Explosive materials may be categorized into two types: low grade and high grade.
High-energy explosives detonate at about 4500 m/s and produce a supersonic shock wave.
A blast causes an increase in the surrounding atmospheric pressure called the overpressure.
Blast wave physics is best summarized by the Freidlander wave.
IEDs have been adapted from their original intent and may include VBIED, HBIED, suicide vests, roadside bombs, or many other variations on the same concept.
Explosions rarely cause fires because oxygen is depleted during a blast as opposed to an incendiary device, which is intended to cause fires.
A chemical substance, such as chlorine, could potentially be combined with an explosive.
An explosive device combined with any radioactive substance is referred to as a radiologic dispersal device (RDD).
The most likely radioactive substances to be incorporated into an RDD are Cs-137, Sr-90, Co-60, Am-241, and Pu-239.
The three types of mass casualty environments are enclosed, confined, and structural collapse.
Blast fragments are mostly responsible for any fatalities and injuries.
Additional victims have been injured or killed by the detonation of secondary explosive devices at the scene or being fired upon by snipers.
The National Disaster Medical System (NDMS) was developed to assist in coordinating mass casualty operations.
Blast injuries may be classified as primary, secondary, tertiary, quaternary, and quinary.
The presence or absence of TM damage is not a sensitive indicator for injury severity.
18 U.S.C. § 2331(5) United States Code, Title 18, Section 2331.
18 U.S.C. § 2331(1) United States Code, Title 18, Section 2331.
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