Disaster and Mass Casualty

Eric R. Frykberg and William P. Schecter

INTRODUCTION

The term disaster is subject to a variety of interpretations and misperceptions that typically relate to one’s background and experience, but there are specific characteristics on which most would agree. An essential feature of a disaster involves a major disruption of the infrastructure of a community or geographic region and its inhabitants. Another is that the magnitude of destruction exceeds that of routine emergency situations to such an extent that the response to it must be entirely different in order to restore some semblance of order and normalcy. Approaching a disaster with the mindset of simply doing more of the same, using the same methods as routine emergencies, is generally doomed to failure and tends to extend rather than curtail the adverse consequences.¹

True disasters are rare. Very few events in a century result in more than 1,000 casualties, and only about 10–15 events each year throughout the world result in more than 40 casualties.² Because they are rare, as well as unpredictable, random, sudden, and unexpected, their successful management requires established and well-rehearsed plans that anticipate necessary consequences, procedures, and needs.^2–4

The feature that best distinguishes the medical response to a disaster from the routine medical care of patients is that resources are overwhelmed by the casualty load. The receiving hospital is therefore unable to provide each casualty with the optimal level of care that is standard in routine medical management.^5,6 External assistance is necessary to manage the event. This has significant impact on the approach to medical care and the associated ethical considerations, as, by definition, the limited resources must be rationed according to who most merits care so as to avoid squandering these resources and leaving many other casualties without care that may be more effectively applied in terms of overall casualty salvage. This means that some casualties who would ordinarily be treated may have to be denied full care for the sake of saving many more. These altered standards of care that must prevail in true disasters tend to be unfamiliar and morally repugnant to health care providers, and they are not taught in medical or nursing schools or residency training. This emphasizes the necessity of education and training in these principles if a medical response is to succeed.⁷ This response cannot just be more of the same, but an entirely different approach to care. The longer it takes to learn this as a medical response unfolds, the more property and lives will be lost unnecessarily.¹

A multiple casualty event is one in which hospital resources are strained, but not overwhelmed, by the patient load, as we experience on busy nights in urban trauma centers and emergency rooms. All patients are ultimately fully treated according to our standard principle of the greatest good for each individual, although the costs include extra personnel, financial losses, delays in care, and difficulty in finding beds, operating rooms (ORs), and equipment. A mass casualty event is distinctly different, referring to casualty loads that overwhelm available resources, preventing optimal individual care. This requires a paradigm shift in focus on a new principle of the greatest good for the greatest number. A disaster response must revolve around the population rather than the individual, with all the difficult ethical implications of rationed care.^7,8 The average medical provider may never see a true mass casualty disaster in an entire career, which all the more emphasizes the importance of education and training to prepare for them.

CLASSIFICATION OF DISASTERS

Several classification schemes (Table 8-1) have been applied to disasters.³ The number of casualties is often used to define a mass casualty event and its severity, although it is a relative measure that does not necessarily reflect the magnitude of an event. Five victims of a motor vehicle crash could be handled easily at a major urban trauma center, while this could overwhelm a small rural hospital and be seen there as a true mass casualty disaster. Classification according to mechanism, such as tornados, hurricanes, earthquakes, fires, floods, shootings, or bombings, natural or man-made, allows identification of distinct patterns of damage, injury, and logistical demands. Classification according to injury type similarly allows distinction of these patterns to facilitate response planning, such as burns, blast injuries, and chemical or radiation poisoning.

TABLE 8-1 Disaster Classification Schemes

Extent and timing of a disaster may be a useful means of classification in view of the very different types of response required for specific geographic and time course considerations. A closed disaster refers to a single event occurring in a specific location, with a clearly defined scene, such as a building collapse. Closely related to this are finite disasters, which occur within a defined and usually short period of time with a clear beginning and end, such as tornados or terrorist bombings. The response challenges in terms of resources and personnel would be quite different in open disasters occurring over a wide geographic area, such as hurricanes, and in ongoing disasters, in which destruction occurs over a prolonged and uncertain time period, such as aftershocks following an earthquake, disease pandemics, or armed conflicts and wars.

The most useful classification scheme groups events according to the level and extent of response and resources necessary to manage the destruction of people and property. A common system involves three levels of response, from local to regional to statewide, national or international. This tends to work best and is widely used because it corresponds to the most basic disaster characteristic of overwhelmed resources, and magnitude is reflected by the extent of external assistance that is needed.

PLANNING

Plans are nothing. Planning is everything.

Dwight David Eisenhower

The word disaster is derived from the Latin words for “evil star,” suggesting that these events are random and unpredictable acts of God for which anticipation and preparation is futile. In fact, the very rarity and unpredictability of disasters make advance preparations essential for a successful response to occur, as the complexity and very different approaches of such a response tend to be counterintuitive and cannot be cobbled together at the time of the event. Furthermore, there are patterns of property damage, bodily injury, behavior, response elements, and pitfalls that are common to all disasters. Once such patterns can be identified (Fig. 8-1), preparation and planning are entirely possible, and moreover are the most essential factors that lead to a successful outcome in terms of minimizing the loss of infrastructure and lives.^4,9–12

FIGURE 8-1 Graphic comparison of the range of Injury Severity Scores (ISS) of survivors of the terrorist bombings of the train station in Bologna, Italy, in 1980 and the U.S. Marines barracks in Beirut, Lebanon, in 1983,^6,19,63 showing the common pattern seen in most disasters of only a minority with critical injuries. (From Frykberg ER. Disaster and mass casualty management. In: Britt LD, ed. Acute Care Surgery. 2007:235, Fig. 16-2, with kind permission of Springer Science+Business Media.)

Disaster planning begins with education. Knowledge of the abundant published reports of past disasters and of basic principles of disaster response is necessary for the formulation of a realistic and workable disaster plan. The plan must be based on valid assumptions derived from actual experience so as to accurately anticipate the most likely injury patterns, resource requirements, human behavior, and threats.¹³ Without this knowledge, plans tend to be based on imagination rather than reality. It is common for plans to assume model behavior, rather than incorporate how people actually behave in this setting.^2,13

The problems and lessons learned in past disasters serve as an important planning tool that allows the plan to avoid their repetition (Table 8-2), and to thus be more useful in future events. Failure of communications has been the most common and consistent pitfall of disaster responses, due to damage to telephone, cellular phone, and radio infrastructure, and to overloading of that infrastructure by overuse. Communication is the thread that weaves the complex fabric of a disaster response together. Its breakdown impairs the coordination and interoperability of this response. Without redundant systems in place to maintain this interoperability, the response will falter. Another major pitfall of most disaster responses is the uncertainty of who is in charge, which must be designated and understood by all responders in advance to avoid a loss of command and control. Failure of security at the disaster scene and in the hospital increases the dangers to casualties, responders, and medical providers. The system of medical care for mass casualties must be workable to optimize their outcomes. The control of volunteers, the worried well, families, and the media is necessary to prevent confusion of roles, misinterpretation of instructions and messages, and mass confusion by these well-meaning but uninformed and untrained entities. Finally, the original disaster plan has consistently been found to be unworkable very early into the response of virtually every reported disaster, demonstrating a widespread failure of valid and effective planning.¹⁴

TABLE 8-2 Common Pitfalls in Disaster Response

Disaster plans and the process of planning must integrate the many multidisciplinary entities that will contribute to the disaster response and work toward the common goal of recovery (Table 8-3). Plans should be developed by the people who will be executing them. The formulation of a plan should begin with an assessment of the most likely threats that may give rise to a disaster event in any given community or region, which is known as a hazards vulnerability analysis (HVA). The plan should then be built around such threats. Examples include radiation leaks from a nearby nuclear reactor, airplane crashes near airports, floods near major bodies of water, frequent clusters of large numbers of people such as in a sports stadium or theme park, and common weather events such as tornados or hurricanes.

TABLE 8-3 Key Stakeholders in Disaster Planning

Disaster plans should follow an all-hazards approach, which refers to the creation of only one generic plan encompassing those factors common to all disasters. This is far more effective than multiple plans for each specific type of disaster, as these are unlikely to all be read and remembered by responders and providers. A robust all-hazards plan will have the necessary flexibility to adapt to the unique challenges of each specific event. An example of how to provide such flexibility is to attach appendices to the generic plan for such categories as burns, radiation or chemical poisoning, and blast injuries. The basic premise of all-hazards planning is that all disasters should have the same broad principles of response.⁴

The planning process is more important than the written plan, which often sits on a shelf unread. The collective interaction of the many different response elements in this process allows all participants to understand the capabilities and needs of each other, and thus how everyone fits into the overall disaster response (see Table 8-3). This provides flexibility and adaptability to the unique exigencies of any specific event, which is independent of the written plan and allows a response to proceed despite an unrealistic written plan. This process helps to prevent the paper plan syndrome, or the false sense of complacency that a written plan may confer even though it is not read or tested.

Once formulated, disaster plans must be tested regularly through both hospital drills of a single facility and community-wide exercises that integrate multiple response elements. These simulations are meant to test the plan for its ability to guide the response to actual events, and should be as realistic as possible in order to confirm its effectiveness and uncover weaknesses that should be improved.^4,15

A postevent analysis of all drills and actual disasters is another essential element of disaster planning. This should involve all key participants in the response and should occur within 24–48 hours of the event while memories are fresh. Documentation of all parts of the disaster response should be objectively and comprehensively reviewed to identify those things that worked and those that did not. The plan should then be revised and strengthened accordingly to make it more workable and successful the next time. Disaster planning must be a dynamic process. It is also important to disseminate the lessons learned so as to extend the existing knowledge base.¹⁴ Such a postevent critique of the New Orleans response to Hurricane Katrina in 2005 showed a number of weaknesses in the disaster plan despite its thoughtful formulation and testing.¹⁶

COMMAND AND CONTROL

In order to coordinate the complex structure of a disaster response, there must be a recognized prevailing authority to exert command and control. The absence of clear authority is one of the most common barriers to a successful disaster response (see Table 8-2), as each of the many participating agencies and personnel tends to believe that it is in charge, and is reluctant to yield its individual missions, agendas, and independence to an overriding command element. This, of course, prevents the smooth coordination and interoperability of all these entities that is necessary to achieve a common goal, as none of these entities have the perspective to appreciate the “big picture.” It is clear that the longer it takes to exert effective command and control of a disaster scene, the longer will chaos, and destruction of property and lives, persist.^9,14,17,18

An effective disaster response command structure incorporates three widely recognized command principles. Unity of command refers to a designated hierarchy in which all personnel have specific roles and responsibilities with regard to the common goal. Chain of command refers to the reporting process in this hierarchy, in which each person reports to one supervisor, and no more than five to seven people report to one person (span of control). Unified command refers to the consolidation of all response elements under a single authority who determines the overall mission and objectives toward which all efforts are directed in a coordinated fashion. Deviation from these principles, such as bypassing the chain of command, weakens the structure as a whole by impairing the commander’s situational awareness, and thus the ability to properly execute the mission. This weakness has manifested in a number of major disasters. In New York City on September 11, 2001, no clear authority existed to coordinate the independent actions of multiple response elements following the collapse of the World Trade Center. This same problem was evident following Hurricane Katrina in New Orleans in 2005, and following the earthquake in Haiti on January 12, 2010. The result in these and many similar events was large-scale confusion over the roles of responders, loss and waste of equipment and supplies, lack of enforcement of safety precautions with exposure of responders and medical providers to safety risks, and delays in provision of food, water, shelter, and medical care.

Following a series of wildfires in California in the 1970s, the problem of poor coordination of multiple response units from multiple jurisdictions was identified. The Incident Command System (ICS) was developed as a management tool to address these command and control issues in the setting of major disasters, by incorporating all response elements under a single Incident Commander (IC). ICS is based on functional requirements that are allocated among five major management activities carried out by a general staff—command, planning, logistics, operations, and finance/administration. The operations section is directly responsible for the nuts and bolts of the response, including casualty care, and all other sections support this element. A command staff directly supports the IC with interaction with the media and the public, assurance of safety, and facilitating coordination of all elements, through a Public Information Officer, a Safety Officer, and a Liaison Officer, respectively. The ICS incorporates the three command principles described above to be highly flexible and adaptable to any form of disaster or emergency (Fig. 8-2). Its success and effectiveness is demonstrated by its adoption as the official model for disaster response in the United States and many other countries. All participants in a disaster response must learn this system and their specific role within it.¹⁸

FIGURE 8-2 The structure and major functional elements of the Incident Command System.

TRIAGE

The sorting and prioritization of casualties according to their needs is known as triage. This is generally a minor consideration in routine medical care, where there are essentially unlimited resources and all may be provided optimal treatment. However, in austere environments and in mass casualty events, the process of triage assumes major importance because, by definition, resources are limited, and must therefore be allocated, or rationed, according to the principle of the greatest good for the greatest number. This is a major departure from routine standards of medical care, as necessary considerations of salvageability and resource availability must enter into these decisions.⁷ The most severely injured casualties with the lowest chance of survival, yet with the greatest resource requirements, may have to be put aside and treated last, if at all, rather than first, in order to conserve the limited resources for the greater number who will most benefit. Rapid identification of this expectant category of casualties provides the best opportunity for maximizing casualty salvage.^{3,6,9,19–22}

Triage Accuracy

The challenge of triage lies in the very consistent pattern of injury severity found in most mass casualty disasters (see Fig. 8-1), in which a large majority of survivors are not critically injured and therefore do not require immediate care or even hospitalization.^6,19,21,23 The rapid identification of that small minority (10–20%) who are critically injured is vitally important in order to direct the limited resources where they are most needed, and not squander them on those not in need. This is the key challenge of health care providers.

The two errors of triage include undertriage, or the inappropriate assignment of critically injured casualties to a delayed, nonurgent category, and overtriage, or the assignment of noncritical casualties to immediate, urgent care. Undertriage is always considered a medical problem that results in preventable mortality, because necessary care is delayed. In routine medical care, overtriage is more of a logistical, economic, and administrative problem, resulting in strained financial, personnel, supply, and equipment resources, but does not impact patient outcomes. However, in a mass casualty setting, when large numbers inundate a hospital all at once, overtriage impairs the ability to detect the critically injured minority who require early lifesaving interventions, and could therefore be as much a threat to casualty survival as undertriage. Hirshberg et al. have provided data to support this contention with a computer modeling study of mass casualty events²⁴ that demonstrates a diminishing capability to optimally care for critical casualties as the rate of overtriage, or influx of noncritical casualties, increases (Fig. 8-3). They have extended this finding with another recent computer model²⁵ showing an improvement in the ability of hospital trauma teams to manage an increasing influx of critically injured mass casualties as triage accuracy increases (Fig. 8-4). That this degradation in care may lead to increased mortality among critically injured mass casualties, as most appropriately measured by the critical mortality rate (CMR), is suggested by a meta-analysis of published data from 14 major terrorist bombing disasters comprising 3,105 casualties (Table 8-4).^6,19,23,26 Graphic depiction of these data confirms a highly consistent linear relationship (r = 0.92) between overtriage and CMR (Fig. 8-5).

FIGURE 8-3 Effect of increasing overtriage (arrival rate of noncritical casualties, non-cm³/h) on hospital capability to optimally care for arriving critical casualties, or surge capacity (cm³/h). (From data in Hirshberg A, Scott BG, Granchi T, et al. How does casualty load affect trauma care in urban bombing incidents? A quantitative analysis. J Trauma. 2005;58:686–695, with permission of Lippincott Williams & Wilkins.)

FIGURE 8-4 Computer model of mass casualty hospital management showing improving surge capacity (arrival rate of critical casualties) at which trauma teams can provide optimal care (time to saturation of teams) with improving triage accuracy (% correct decisions), with reference surge capacity at 6 critical casualties/h. (From Hirshberg A, et al. Triage and trauma workload in mass casualty: a computer model. J Trauma. 2010;69:1074–1081. Wolters Kluwer Health, Lippincott Williams & Wilkins, with permission.)

FIGURE 8-5 Relationship of overtriage and critical mortality rate in mass casualties from 14 terrorist bombing events (in black) and 3 nonbombing events (in red), from data in Table 8-4. (Adapted from Frykberg ER. Medical management of disasters and mass casualties from terrorist bombings: how can we cope? J Trauma. 2002;53:201–212, Wolters Kluwer Health, Lippincott Williams & Wilkins, with permission.)

TABLE 8-4 Relation of Overtriage to Critical Mortality in Survivors of 14 Terrorist Bombings and 3 Nonbombing Mass Casualty Events

This same relationship holds true with the application of data from 3 additional nonbombing mass casualty disasters with a total of 301 surviving casualties—the 1987 Keystone, Colorado, chairlift accident,²⁷ the 2003 Station nightclub fire in Rhode Island,¹² and the 2007 mass shooting at Virginia Tech.^28,29 This overall analysis of 3,406 casualties from 17 disasters (see Table 8-4 and Fig. 8-5) demonstrates that the adverse effect of overtriage is not confined to any one disaster mechanism, but relates to the common pattern of all disasters, regardless of mechanism, in which the inundation of hospitals with a sudden large casualty load interferes with the delivery of urgent medical care.

It is clear that triage accuracy, which involves minimizing both undertriage and overtriage, is essential to the success of a disaster medical response. In fact, it is the one element of a disaster response in which medical providers can directly impact casualty outcomes in the initial aftermath of a disaster. The triage officer who makes these decisions therefore has an important role in this setting. This person must be experienced in the types of injuries that each disaster is likely to cause, and should also be trained in the unique standards that must be applied to mass casualty care in order to optimize triage accuracy, and thus casualty survival. Who should be designated as the triage officer is dependent more on training and experience than on professional background, and it need not even be a physician. It is important to recognize that this position involves only decision making and not treatment, and therefore any physician or surgeon in this role is being removed from casualty care. Available resources must thus impact the decision as to who should be in this position. In some events, nurses or prehospital personnel may best perform this duty. In unconventional disasters, such specialists as infectious disease or public health personnel, radiation biologists, or toxicologists may be the most appropriate triage officer. However, most disasters result in bodily injury, in which setting surgeons and emergency medicine physicians are best in this role because of their experience with the acute care of trauma victims.^{5,6,9,12,17,21,30} Whoever assumes this role must have the leadership qualities to exert authority and make prompt and firm decisions that will be followed, and must have situational awareness of evolving conditions and resource constraints to make accurate decisions.

Triage Decisions

Triage decisions must be rapid as well as accurate in order to move casualties along to accommodate the continuing influx of more casualties. The greater the casualty load, the more rapid must this process be. Therefore, these decisions must be as simple and abbreviated as possible. It should not be surprising that the many complex triage methodology schemes currently in vogue, which require assessment of multiple physiologic and anatomic parameters on each casualty, prove unworkable in true disasters.³¹ Those who are most experienced in mass casualty triage consistently assert that decisions must derive from no more than a clinical judgment, or gestalt, after a quick look at the victim for a few seconds.^5,17,32–36 Casualty dispositions must also be simple. In the prehospital sector, all that is necessary is to determine if a casualty is alive or dead, and, if alive, whether hospitalization is warranted or not. Those judged to require hospitalization are then moved on, and at the hospital the decision is made as to entrance or not. Once in the hospital, the basic decision is whether the casualty requires one of the critical resources of OR, intensive care unit (ICU), or not. Further segregation into delayed and minimal categories may be made at this point, but it should be noted that if minimally injured casualties are in the hospital, there was a failure in the triage process to keep them out, as they should not be burdening this critical resource. Those casualties judged as expectant should also be kept out of the hospital to avoid wasting resources. The dead should be recognized and segregated from the living to avoid unnecessary application of resources on their resuscitation.¹⁷

What constitutes an expectant casualty cannot be specifically defined in advance, as it will differ for each specific disaster according to such variables as casualty numbers, type and severity of injuries, and available resources. The leaders of the medical care operations should agree on this determination in the earliest phases of the disaster response, when the magnitude and needed resources can best be assessed. Examples of determining factors include the number of mechanical ventilators, availability of electrical power, the presence of toxic contamination, and the number of available ORs and surgeons.^9,20–22

Triage must be a dynamic process that involves continued reassessment at each successive echelon of care, precisely because injury is dynamic and the status of casualties could change over time. Casualties put aside into delayed or expectant categories should be closely monitored for changes that may warrant reassignment to other levels of urgency. This monitoring is an essential backup mechanism for any triage errors made by the triage officer at any point along the casualty care continuum. Errors must be expected in major mass casualty events, but anticipating them, and instilling flexibility in the system to mitigate their adverse consequences, creates error tolerance. Once the casualty influx subsides, resources can be reevaluated, and expectant and delayed casualties may be reconsidered for immediate treatment or other change in status.^5,17

MEDICAL CARE OF CASUALTIES

Prehospital Considerations

Disaster responses typically evolve through four phases—chaos, initial reorganization, site clearing, and recovery.¹⁷ The initial chaos that characterizes all disaster scenes is brought to order with the arrival of the first responders and their establishment of command and control. Protection of first responders must be the priority at this point, to prevent them from becoming secondary casualties

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