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Medical Management of Disasters and Mass Casualties From Terrorist Bombings: How Can We Cope?

2002; Lippincott Williams & Wilkins; Volume: 53; Issue: 2 Linguagem: Inglês

10.1097/00005373-200208000-00001

1529-8809

Eric R. Frykberg,

Trauma, Hemostasis, Coagulopathy, Resuscitation

". . .from a terrorist perspective, the true genius of this attack is that the objective and means of attack were beyond the imagination of those responsible for Marine security."—Report of the U.S. Department of Defense Commission on Beirut Airport Terrorist Act, October 23, 1983 Since the terrorist suicide truck bombing of the U.S. Marine barracks in Beirut in 1983, the "imagination" of Americans has continued to be taxed with devastating consistency. Explosions and bombings remain the most common deliberate cause of disasters involving large numbers of casualties, especially as instruments of terrorism, yet we still have not learned how to anticipate and manage the tragic carnage they cause with any degree of effectiveness. These attacks virtually always are directed against the untrained and unsuspecting civilian population. Unlike the military, civilians are poorly equipped or prepared to handle the severe emotional, logistical, and medical burdens of a sudden large casualty load, and thus are completely vulnerable to terrorist aims. 1,2 FIGUREFig. 2: Eric R. Frykberg, MD, FACSTHE CHALLENGE The civilian medical community in the United States has been relatively indifferent in past years to the potential threat of deliberate terrorist attacks and mass casualties. 3 We have been shielded from such incidents, and thus have been spared the need to confront the unique challenges of suddenly delivering medical care to great numbers of injured victims. Our naivete and inexperience in this area have been demonstrated by the predictably confused responses to recent terrorist disasters in Oklahoma City in 1995, and in New York City, with the World Trade Center bombing in 1993 and the collapse of the World Trade Center towers on September 11, 2001. 4 Trauma physicians and trauma centers are uniquely qualified to play a leading role in the medical management of disaster victims and in the overall coordination of disaster response. They already are an integral part of the prehospital emergency medical system and public health efforts of many communities, and their infrastructure, training, and experience are specialized for the comprehensive evaluation and treatment of injury. 5–7 However, the U.S. trauma community has not at all taken the lead in the development of disaster planning or education, which has largely defaulted to other medical specialties and administrative and public safety organizations, and has become more of a paper drill than a realistic guide for dealing with actual disasters. Very few physicians have any experience with true mass casualty events, or disasters, which by definition involve such large numbers of victims, or such severe or unique injuries, that local medical resources cannot fully handle them. This is a very different situation from multiple casualty events, as we see on a typical busy weekend night in an urban trauma center, in which multiple patients are handled by existing personnel and facilities, even if strained. 8 Predictably and logically, medical response to terrorist disasters tends to be most sophisticated and most effective in those countries that most commonly are exposed to them, or among those groups who regularly train for these contingencies, such as the military. A large body of published data now exists from these unusual medical experiences that can serve as a valuable learning tool for medical communities, such as ours, in which such experience is sparse, but in which the potential for terrorist activity is on the rise. 2,9–12 Military medical forces are well prepared and well trained to cope with true mass casualty events, even though they actually deal with such events as infrequently as the civilian sector. This training, and the systematic planning for orderly triage, stabilization, and evacuation of casualties through a chain of treatment stations and hospitals in times of war (Table 1), have allowed them to cope with massive casualty burdens that would overwhelm the ordinary civilian community. In the Battle of the Somme in 1916, the British military medical command was confronted with the heaviest casualty load ever documented in war, with 123,908 wounded managed by three armies in the month of July alone, 26,675 wounded seen in one 24-hour period, and 5,346 wounded soldiers treated in a single day by one casualty clearing station. 13 The fact that these victims were handled in an orderly manner, even though severely straining the system, demonstrates the importance of training and preparation. The generally untrained and unprepared civilian sector must learn from this resource and from those who have handled mass casualties, because it is the civilian medical community that typically is confronted by terrorist acts.Table 1: Casualty Flow in DisastersDifferent types of disasters, such as fires, shootings, floods, infectious or chemical agents, radiation, or earthquakes, result in very different patterns of injury and medical needs. The purpose of this review is to define those principles that are applicable to the effective delivery of medical care after bombings and explosions, as this is the method that most commonly has been used by terrorists, and is most likely to result in the largest numbers of casualties and destruction of property. 2 It also is a scenario that requires the immediate presence of surgeons and other specialists with an expertise in the management of trauma. A knowledge of the patterns of injury, and barriers to care, associated with these events, as derived from the experience of those who have been involved in true disasters, is essential to a proper response to current disasters, and to provide a template for maximizing casualty survival in the future. LEARNING FROM THE PAST Biology of Explosive Injury There are three forms of bodily injury induced by explosive blasts—primary, secondary, and tertiary blast injuries. Primary blast injury is caused by the shock wave that spreads radially outward from an explosion, at the speed of sound, and is transmitted more rapidly and powerfully, and over a longer distance, in water than in air. In air, this shock wave dissipates rapidly, in relation to the cube of the distance from the blast. The more powerful the blast, the greater the distance at which damage may occur. 2,14,15 When the shock wave passes through the body, tissues are disrupted at air-liquid interfaces in a process called "spalling," and the ears and lungs are most commonly injured. The bowels are damaged only in the most powerful blasts, most typical of underwater blasts. The degree of tissue injury is directly related to the magnitude and the duration of the peak overpressure of the blast shock wave. After this is a longer phase of negative pressure, when implosion may occur, and then a major movement of air known as "blast wind."12,16–18 Most victims of primary blast lung injury from explosions are killed immediately, as the vital organs are likely to be fatally injured in anyone who is close enough to the blast to be hit by the shock wave before it dissipates. Death is often caused by massive cerebral and coronary air embolism, as well as the most powerful forms of secondary and tertiary injuries this close in to the explosion. Late deaths among the small number of survivors with primary blast lung injury are caused by progressive pulmonary insufficiency, which has all the radiographic and pathologic signs of parenchymal hemorrhage, similar to blunt contusions. 19,20 Indoor detonations tend to cause more severe primary blast injuries than open-air bombings outdoors, because the blast wave is magnified, rather than dissipated, as it is reflected off walls, floors, and ceilings. Leibovici and coworkers documented a 7.8% mortality among 204 casualties involved in open-air bombings in Jerusalem, and a 49% mortality among 93 victims of detonations inside buses. 12,21 Secondary blast injury is caused by debris set in motion by the shock wave that impacts the body. Tertiary blast injury involves the actual displacement of the victim's body to crash into other objects. These two forms of explosive injury cause typical bodily trauma, and it is these injuries that predominate among survivors of bombings. 12,22,23 Profile of Past Explosive Disasters Two major urban explosions in the 20th century, both accidental, serve to illustrate the enormous problems faced by the civilian medical community in caring for mass casualties. On December 6, 1917, a Belgian ship, the Imo, collided with the French munitions ship Mont Blanc in Halifax harbor, Nova Scotia, causing 35 tons of benzene to ignite on the top deck of the latter ship in a major fire. Fifteen minutes later, this fire ignited a cargo below decks consisting of 2,300 tons of picric acid, 10 tons of gun cotton, 300 rounds of ammunition, and 200 tons of trinitrotoluene (TNT), to cause the largest nonnuclear man-made explosion in history. The ship itself was blown 1 mile high, and its 2-ton anchor was found 2 miles away. Over 2.5 km2 of the city was leveled by the blast and subsequent 150-foot-high tidal wave, also wiping out hundreds of firefighters and onlookers who responded to the initial fire. The blast shattered windows 100 km away. There were 2,000 deaths, 9,000 injured, and 20,000 left homeless, in a city of only 50,000 population. 24 On April 16, 1947, the ship Grand Camp caught fire in the port of Texas City, Texas. Twenty minutes later, its cargo of ammonium nitrate fertilizer exploded, shooting a column of smoke 2,000 feet into the air, and hurling the ship's 1.5-ton anchor 2 miles away. Shortly after this was another more powerful blast, followed by a 150-foot-high tidal wave and numerous fires throughout the area. There were 600 deaths in a city of only 16,000 population, including, once again, the loss of the city's entire fire department and dozens of onlookers who responded to the initial fire. 25 These disasters demonstrate how a typical community's medical resources would be overwhelmed by such large casualty loads, especially if medical facilities also were destroyed. Medical management of such great numbers must depend on help from outside, and on the ability to evacuate victims to other facilities and other locations for definitive care (Table 1). 7 The panic, chaos, and emotional trauma of such disasters can magnify the loss of life, and are best combatted by prompt and vigorous leadership, and a preexisting plan for the immediate rescue, disposition, and treatment of casualties. 26 Also demonstrated was the importance of protecting medical assets by keeping them away from the explosion scene and areas at high risk of further attack and damage. The "second-hit" principle was well illustrated in these incidents, involving the attraction of first responders and onlookers by an initial fire or explosion, who then are wiped out by a subsequent blast or other force. Terrorists have learned to exploit this to great effect, and this has become a common pattern in terrorist bombings to maximize injury and fear. The fact that first responders typically include firefighters, police, and medical personnel, who are trained to help victims, emphasizes the danger of this phenomenon to subsequent rescue and care efforts, and the importance of avoiding it by restricting the initial response. 2,5 Terrorism is the unlawful exercise of random and ruthless violence against property or individuals, usually innocent civilians, to intimidate governments or societies for political or ideologic purposes. 27 The devastation caused by explosions has led to this becoming the most common deliberate weapon of terrorism. The first recorded terrorist bombing occurred in Antwerp, Belgium, in 1585, when 7 tons of gunpowder were detonated to destroy a bridge on the River Schelt, reportedly killing 1,000 soldiers, among whom ". . .some dropped dead without any wounds, sheerly from concussion."3 This is probably the first known description of primary blast injury. The number and destructive power of bombings reached a zenith in the 20th century. There was a 10-fold increase in terrorist bombing incidents worldwide between 1968 and 1980, with 5,075 events documented between 1973 and 1983, causing 3,689 deaths and 7,991 injuries. 28 Even in the United States, there were 12,216 bombing incidents just between 1980 and 1990. This trend continued increasing during the 1990s, with 1,582 bombings causing 222 injuries and 27 deaths in the United States in 1990 alone. 3,11,29 However, Americans have continued to feel immune to any significant impact from bombings until relatively recently (Table 2).Table 2: Prominent Terrorist Bombings Since 1969The first major loss of American lives from this form of attack occurred with the truck-bombing of the U.S. Marine barracks in Beirut, Lebanon, in October 1983. The detonation of an ammonium nitrate fuel-air bomb resulted in an explosive force equivalent to 6 tons of TNT, the largest nonnuclear man-made explosion ever detonated deliberately. This caused the complete collapse of the four-story building, with 346 casualties, including 234 (68%) immediate deaths and 112 survivors. The onshore battalion aid station was located on the fourth floor, and its physician and several corpsmen were killed. Initial rescue efforts were hampered by hostile sniper fire. Sixty-five survivors were treated by an on-site U.S. Navy surgical team aboard a ship located offshore in the first 6 hours after the incident. A total of 86 survivors were then evacuated to Germany, Italy, and Cyprus for definitive care. 30–32 Analysis of the patterns of injury and death from this event demonstrates some important principles relating to disaster management. Most survivors had noncritical injuries. Nineteen survivors (17%) were critically injured (Injury Severity Score [ISS] > 15), among whom seven (37%) deaths ultimately occurred days to weeks later. Six of these deaths (86%) were in victims who were rescued and treated more than 6 hours after the blast (2 had severe burns), whereas only 1 occurred, from blast lung injury, among all 65 survivors rescued early. This emphasizes the importance of a short interval between injury and treatment, and early aggressive resuscitation, as a prognostic factor for survival. 1,32 The high immediate death rate (68%), and the high dead/wounded ratio of > 2:1 (which is a reversal of the 1:2–1:5 ratio typical of military combat in conventional wars) was probably because of the extreme magnitude of the explosive force and the added impact of building collapse. Both of these are major prognostic factors of terrorist bombings that affect casualty outcome. 28 The high death rate among the critically injured survivors (7 of 19 [37%]) also can be attributed to these factors. This "critical mortality rate" more accurately reflects the magnitude of the disaster and results of medical management than the overall mortality rate of 6.3% (7 of 112), as it measures deaths among only those truly at risk of death. The overall mortality rate is falsely diluted by the majority of noncritical survivors. 32,33 Most survivors of the Beirut bombing suffered soft tissue and musculoskeletal injuries, which were relatively mild and not life threatening. Head trauma was the most common injury among immediate (71%) and late deaths (57%), but only 11% (4 of 37) of those with head injuries died. 30 Chest trauma (including blast lung) and burns occurred in only a small number of survivors, but were major contributors to late deaths (29% each), and had the highest specific mortalities (15% and 40% mortality, respectively, among all survivors with these injuries). These data indicate the importance of anatomic site and nature of injury as a prognostic factor among bombing victims, and may be useful in comparing different bombing disasters with respect to medical needs and how medical care may affect outcome. Also demonstrated in this incident were the dangers of placing medical assets in front-line high-risk areas, the potential for first responders to be killed by a second-hit phenomenon (in this case, sniper fire), and the need to triage and manage casualties at a site distant from the disaster scene. 5 The importance of an immediate presence of surgical capability, and an established evacuation plan, were other lessons learned in the Beirut experience. Survivors of bombings can be expected to have a variety of injuries from secondary and tertiary blast effects, for which surgery is likely to be necessary in the most seriously wounded. Two laparotomies were performed within hours of the bombing by the on-site surgical team in Beirut, and most evacuated survivors required rapid resuscitation and surgery over the next 3 days. 32 These factors undoubtedly saved lives among the most critically injured survivors. Several other terrorist bombings that primarily involve indoor detonations have been documented in the published literature (Table 3). It is worthwhile to review the results of these events to confirm the importance of the lessons learned in Beirut, and delineate any other factors that may impact on the effective delivery of medical care in these unique circumstances.Table 3: Primarily Indoor Terrorist BombingsIn August 1980, the railroad terminal in Bologna, Italy, was bombed during rush hour with an explosive device of 20 kg of TNT, causing a partial building collapse. There were 291 casualties, 73 (25%) of which were immediately killed. Although 83% of the 218 survivors were hospitalized, only 48 (22%) were critically injured, in which group 11 deaths occurred (6% overall mortality, 23% critical mortality rate). 23 The occurrence of building collapse, and an injury pattern of largely noncritical soft tissue and musculoskeletal trauma, were similar to the Beirut bombing. The percentage of critically injured survivors was also similar. The ISS distributions of survivors from both events were remarkably similar, with a mean ISS in both incidents of approximately 11. 32 The lower immediate death rate, and the lower but still substantial critical mortality rate, in the Bologna incident, were probably because of the weaker explosive force and the building collapse affecting only a portion of the casualties, with much of the blast dissipated through the open air of the spacious building. The large casualty load was the result of the large number of people in the building at the time. A series of 11 terrorist bomb explosions occurred in Paris, France, during a 10-month period in 1986, all but one occurring indoors. Five events produced more than 30 casualties each. A total of 268 casualties occurred, with 13 immediate deaths (5%) and 205 of the 255 survivors hospitalized. Forty survivors were critically injured (16%), among whom seven died (17.5% critical mortality, 3% overall mortality). The average ISS of all survivors was 14.8, but among the seven late deaths it was 39.8. 28 An explosive device of 10 kg of TNT was detonated during the noon meal in a U.S. military mess hall in Cu Chi, Vietnam, in 1969, resulting in 46 casualties, including 12 immediate deaths (26%). Twelve of the 34 survivors were evacuated to U.S. Army hospitals (35%), among whom 3 (25%) died. 34 In 1994, a seven-story building in Buenos Aires, Argentina, which housed the Argentine Israeli Mutual Association (AMIA), was leveled by the detonation of an ammonium nitrate fuel-air explosive device with a blast force equivalent to 660 lb of TNT. 35 There were approximately 286 total casualties and 82 (29%) immediate deaths. Among the 204 survivors, 41 (20%) were hospitalized, 14 (7%) were critically injured, and 4 of these died, for an overall late mortality of 3.4% and a critical mortality rate of 29%. The most severely injured were those within the building at the time of the bombing. In 1995, an ammonium nitrate bomb designed as a fuel-air explosive (similar to the explosions in Texas City, Beirut, and Buenos Aires) was detonated in front of the Murrah Federal Building in Oklahoma City, Oklahoma, with a blast force equivalent to 2 tons of TNT. 36 This caused a partial collapse of the building and damage to several surrounding buildings. There were 759 total casualties, 162 (21%) immediate deaths, 83 (14%) hospitalized survivors, and 52 (9%) critically injured survivors, among whom there were 5 late deaths (0.8% overall mortality among all 597 survivors, 9.6% critical mortality rate). As in the AMIA bombing, the highest mortality and most severe survivor injuries occurred in the victims in the collapsed portion of the building (Table 4).Table 4: Impact of Building Collapse on Outcome in Oklahoma City Terrorist Bombing, 1995*The collapse of the twin towers of the World Trade Center in New York City on September 11, 2001, was devastating in terms of how unexpected it was, and the realization of how vulnerable the United States is to such attacks. The jetliner crashes into these buildings, quite analogous to bombings, are estimated to have imparted the equivalent of 12,500 tons of force. The subsequent building collapse is estimated to have released the equivalent explosive force of 900 tons of TNT, 37 resulting in approximately 3,000 deaths, and several hundred survivors with predominantly noncritical injuries (dead/wounded ratio of 5:1). With only a few survivors rescued from the collapsed buildings, the immediate death rate among those in the buildings was over 99%. Complete information on severity of injuries and mortality among survivors is not yet available. The published casualty figures and outcomes from several bombings that were primarily outdoors 10,12,18,38–42 all demonstrated similar patterns of predominantly noncritical injuries, but had relatively low immediate and late mortality. 33 Analogous results were reported after the bombing at the 1996 Olympics in Atlanta, Georgia, 43 although the major injuries from this incident were penetrating wounds from strewn shrapnel, somewhat different from the blast-related blunt trauma of most other bombings. All these events occurred in major urban settings, with several nearby hospitals and extensive medical resources available, and involved relatively small bombs with rapid blast dissipation within a short distance in the outdoor environment. These are probably the major factors contributing to the low critical injury and mortality rates of these incidents. Patterns of Injury, Severity, and Mortality It is important to distinguish the two goals of terrorist attacks: casualty generation, or the total number injured and killed from the single use of a weapon; and lethality, or the proportion of casualties killed. The magnitude of an explosion, and the number of people in the vicinity, primarily determine casualty generation, whereas indoor location and building collapse maximize lethality. 3 Analysis of past bombing disasters reveals definite patterns of injury and mortality, which provide the opportunity to plan and prepare for future events. Immediate deaths, or those who die before reaching medical care, appear related to the magnitude of the explosion, the occurrence of building collapse, and an indoor location (Table 3). A comparison of those bombings involving a major component of building collapse shows substantial rates of immediate deaths, and relatively constant critical mortality rates among survivors, with widely varying explosive forces (Table 5). Those incidents involving an additional component of indoor location were associated with the highest immediate death rates. This suggests that building collapse is the most important determinant of outcome among these variables. Indoor blasts not only magnify the destructive power of the primary blast shock wave but also promote complete building collapse, which maximizes both casualty generation and lethality of a bombing. 12,18,21,34,42Table 5: Relation of Explosive Force and Building Collapse to Casualty Outcome*A greater magnitude of explosive force tends to maximize casualty generation, even in outdoor locations, but the rapid dissipation of the shock in open air reduces lethality, with a lower level of critical injuries among survivors. The open-air bombings at Old Bailey, the Tower of London, and Jerusalem in the 1970s, and at the 1996 Olympics, support this observation. 11,40,41,43 This was also illustrated in the Oklahoma City bombing in 1995, in which a very large 2-ton TNT equivalent blast was primarily directed through the air because the truck-borne bomb was placed outside the target building. This resulted in 759 casualties, but only 9% suffered critical injuries, and there was only a 9.6% critical mortality rate. 36 However, those casualties within the collapsed portion of the building suffered significantly higher mortality and morbidity (Table 4). The virtually 100% immediate death rate of casualties within the collapsed World Trade Center towers clearly showed the relative importance of building collapse, over and above explosive force, as a prognostic variable. The magnitude of explosive force has its greatest impact on lethality, rather than only casualty generation, when it is applied to building collapse, and when greater than a 1-ton TNT equivalent. The largest buildings, containing the greatest numbers of potential casualties, require the largest levels of explosive force to collapse. In both Buenos Aires and Oklahoma City, mortality was highest on the upper floors of the collapsed building. 35,36 Building collapse is also maximized by placing the bomb completely within the building, as occurred in Beirut, Bologna, and Buenos Aires, rather than outside to result in partial collapse, as in Oklahoma City. Another determinant of mortality among victims of bombings is the availability of medical resources at the disaster scene. One reason for the high immediate death rate and critical mortality rate in Beirut was its isolated location in a hostile country without an established prehospital system of transport and care, and without secure definitive care facilities, requiring a long time interval for rescue and transport of survivors to British and American military hospitals in Cyprus, Italy, and Germany. 31,32 This same problem occurred in the Cu Chi mess hall bombing in Vietnam. 34 In contrast, bombings in major urban areas with extensive and sophisticated prehospital systems and medical facilities, which allow rapid rescue and transport to definitive care, tend to have lower mortality rates. 12,23,28,35,36,38,42,43 Most critical body system injuries are found among those immediately killed after terrorist bombings. Although all fatalities suffered multiple injuries, head injuries tend to be most common in this group, as was shown in Beirut. 30 Data from 305 fatalities from the Northern Ireland bombings in the 1970s 12,18,38 showed that primary blast lung was found in 47%, abdominal injuries in 34%, and other chest injuries in 25% of all immediate deaths. These are the same body systems that most commonly cause death in all other forms of trauma. Among survivors, soft tissue and musculoskeletal injuries, and blast injuries of the ears and eyes, predominate in up to 80% of cases, but are mostly noncritical in severity, and contribute virtually nothing to mortality. 23,32,33,36 Although over 50% of deaths among immediate survivors of bombings have head injury, most survivors with head injuries are noncritical, as only 1.5% of those with head injuries die. 18,30,33 The most critical cases are selected out by the initial blast, succumbing to immediate death. Chest and abdominal injuries, including blast lung, and traumatic amputations, occur very infrequently among bombing survivors for the same reason. 2 However, the few surviving cases of these injuries have a substantial specific mortality, with 19% of all surviving abdominal injuries, 15% of chest injuries, and 11% of blast lung cases and traumatic amputations succumbing to late death despite medical care. 2,10,18,28,33 These injuries should be recognized as prognostic markers of severity, and need immediate care to optimize survival. Burns also are relatively infrequent among survivors of bombings, and tend to be mild flash burns, with low mortality. 33 In some bombings, however, burns have been more severe and a larger contributor to mortality, as in Beirut, where 40% of burned survivors died. 32 Over 20 survivors of the World Trade Center disaster on September 11, 2001, were transported to a burn center with severe burns. The anatomic distribution of injuries among bombing victims tends to be out of proportion to the total body surface area. Head injuries occur more frequently than would be predicted on the basis of the 12% body surface area of the head and neck exposed to the environment, whereas torso and extremity trauma occur less frequently than their relative surface areas would suggest. This has been explained by clothing distribution, with covered areas of the body being less exposed to some of the forces of injury, such as flash burns. 10–12,23,33,44–46 Emotional shock is a common consequence of terrorist bombings, especially among female survivors. Although it is not as lethal as physical injury, there is significant potential for long-term psychological disability. This should be considered in the same category as other major injuries with respect to the need for treatment. Disaster planning should include provisions for emotional evaluation and rehabilitation of casualties. 10,38,44 One of the most consistent injury patterns noted among survivors of terrorist bombings is the overwhelming predominance of relatively minor, noncritical injuries that are not life-threatening. 9,23,32,33,35,36,43,47 The incidence of critical injuries among survivors varies between 9% and 22% (Table 3). The planning for medical management of casualties must revolve around this basic lesson learned from prior bombing disasters, as medical resources must be allocated acco