Overview of Disaster Medicine
More than 4 million people worldwide have lost their lives and hundreds of millions have suffered due to natural and man-made disasters during the past 30 years. The dollars lost in damages and reconstruction costs are staggering. Hundreds of billions have gone to rebuild the infrastructure and to replace the personal property damaged or lost as a result of these disasters. Ongoing assistance may be required many years after the disasters to sustain and reconstruct the lives of those affected.
Disaster medicine and prevention is a system of study and medical practice encompassing the disciplines of emergency medicine and public health. The multidisciplinary nature of disaster planning and response has traditionally resulted in various definitions of disasters and events that cause mass casualties. Some commonality in terminology has evolved in the organizational aspects of emergency medical disaster response:
- Austere medicine: Medicine practiced on-location without the amenities provided by an organized medical system. Austere medicine is often practiced in temporary shelters, with quite limited equipment. The goal is to provide temporary “fixes” to restore functionality or save life.
- Disaster: Any event that overwhelms the emergency medical system resources available at a given time in a given jurisdiction. This may be a city/county, a region, a state, or even a country.
- Incident Command System (ICS) and Incident Management System (IMS): Initially used by the military and fire departments. ICS has evolved over the past two decades into the current disaster management tools of choice for disaster command, operations, planning, logistics, and finance from the federal to local level.
- Multiple (or Mass) Casualty Incident (MCI): Any event that causes a large number of individuals to become ill or injured. Sometimes called Multiple Victim Incident (MVI).
- Medical disaster: Any event that causes a large number of individuals to become ill or injured and overwhelms the medical system resources available at a given time in a given jurisdiction.
- Mutual aid: Agreements between neighboring communities to provide support and assistance in the event of a disaster.
- National Response Framework (NRF): This is the current evolution of the US government national response plan. The ability for augmenting flexibility continues to be the driving force for the current version of the NRF. National or federal framework for coordinating the population and infrastructure of our nation including federal, state, local, tribal, and private sector resources in the event of a disaster.
- Mitigation: Critical foundation in the effort to reduce the loss of life and property from natural and/or man-made disasters by avoiding or lessening the impact of a disaster and providing value to the public by creating safer communities. Mitigation seeks to fix the cycle of disaster damage, reconstruction, and repeated damage. These activities or actions, in most cases, will have a long-term sustained effect.
Disaster Cycle
Disasters follow a pattern of development and have a distinguishable life cycle of various durations. This sequence of events has been termed the disaster life cycle (Figure 4–1). Disaster planning, response, and research may be simplified by using the disaster cycle as a model for complex events. Five phases supplement the disaster life cycle.
The interdisaster period is where there is a sequence of events that lead to the occurrence of a disaster. Evaluation of local hazards that may lead to a disaster or augment the destructive effects of a disaster is paramount to risk assessment strategies.
The warning phase develops next and marks the time during which a particular event is likely to occur. Historically, weather and seismic prediction models have allowed for public warnings and protection modalities to be implemented such as sheltering and evacuations to occur long before the inciting event occurs.
This is the event. This phase may be relatively short or prolonged. The magnitude of damage, prioritization, and identification of injured and required resources is determined. Planning and preemptive actions will have the greatest effect on mitigation of the impact phase.
This phase represents the response to the emergency, the period where immediate time-sensitive action will save lives.
Categories of Disaster and Mass Casualty Events
Disasters are generally thought of in terms of being natural or man-made. Technically, however, all disasters are man-made. A palm tree felled by a hurricane is a natural event caused by a natural hazard. When the society builds a high-rise hotel on the same shore and the hurricane destroys the hotel, it is the same natural event, but because men built the hotel knowing the risks entailed in this location, it is now potentially a disaster.
Specific types of disasters produce different patterns and numbers of injuries and have different effects on the social and physical environment. It is important to be familiar with these disaster categories in terms of scope, scale, and historical impact.
An earthquake is the most likely large-scale event in the United States. Earthquake intensity is commonly measured by the Richter scale, a logarithmic scale that measures the intensity of seismic waves. An earthquake of 2.0 magnitude is barely felt, whereas an 8.0-magnitude event is greatly destructive. There have been six major earthquakes greater than 8.0 on the Richter scale in the history of the United States. An earthquake of a given magnitude may produce varying amounts of destruction, depending on a complex interaction of many factors, including the type of ground underlying a structure, the degree of ground failure (eg, landslide, soil failures), and the construction quality of overlying structures.
Injuries are most often due to structural collapse, the degree of which will also depend heavily on local structural engineering standards. Illness also occurs as a result of disruption of existing community infrastructure (eg, food supply, power, sanitation, ongoing support for persons with chronic disease). Predictably, the patterns of injury seen among casualties include severe orthopedic, neurologic, and thoracic crush injuries, lacerations, tetanus and dysentery infections, environmental exposure, and exacerbations of chronic medical problems.
Current problematic areas for earthquake activity include the Enriquillo fault line in the Caribbean in which lies Haiti and the New Madrid fault of the mid-eastern United States.
Tropical cyclones (hurricanes in the United States and Atlantic, typhoons in the eastern Pacific, tropical cyclones elsewhere) are a circulating mass of clouds, rain, and wind around a clear central area of extreme low barometric pressure. They occur most commonly in the late summer months.
The intensity of tropical cyclones is rated on a 5-point scale. For hurricanes approaching the United States, this information is available from the National Weather Service, which can also provide information about a storm’s probable path. Damage is due to high winds, which can exceed 150 mph, storm surges, tornadoes, and inland flooding. Of these four, inland flooding causes more property damage and loss of life.
Casualties may be caused by trauma from flying debris or structural collapse; by drowning; by famine related to damaged agriculture and food distribution systems; by disease related to loss of power, water, and sanitation; and occasionally by violence related to loss of public safety. Casualties may be significantly reduced by early warning systems and evacuation efforts.
Annually in the United States, tornadoes and severe thunderstorms are the most common cause of death due to natural disasters. Approximately 100,000 severe storms (eg, involving thunder, high winds, and hail) occur each year in the United States, including 1000 tornadoes. Most commonly affected are the states in “tornado alley,” the area between the Rocky Mountains and Appalachian Mountains. No state is completely free of the risk of tornado. Tornadoes usually occur during the summer months and during late afternoons. Only about 3–4% of all tornadoes produce injury, and most deaths occur in a small number of highly destructive events. Casualties are related to trauma from structural collapse, flying debris, or being knocked to the ground or thrown. Head injuries, crush injuries, fractures, contusions, and lacerations are common.
As with all disasters, secondary illness and injury may occur, although tornadoes most commonly tend to produce random, isolated groups of casualties wherever they touch down, rather than diffuse area-wide casualties and destruction to community infrastructure. Multitornado storms such as occurred in Moore, Oklahoma, during 1999 can cause widespread damage. Casualty mitigation through early warning and evacuation is hard to manage because tornadoes are difficult to predict and the time frame for evacuation or protective cover is brief.
Floods can be divided into riverine floods, hurricane (storm) flooding, flash floods, and tsunamis. Riverine floods are typically seasonal and result from excessive rains or snow melts that lead to rivers overflowing their banks in a floodplain area. Flash floods occur in areas where rainfall produces surface water that exceeds the runoff or absorptive capacity of the soil. Storm flooding as a result of hurricanes is covered above. Tsunamis are caused by earthquakes or volcanic eruptions at sea. Rarely, flooding can be caused by failure of a dike or dam, usually due to heavy rains.
In the United States, the number of deaths each year from floods is small and sporadic. Property damage can be considerable, as are secondary effects on crops, sanitation, and vector-borne infections. When casualties occur, they are usually due to drowning. Mitigation (eg, through watershed engineering projects and limiting development on floodplains) and early warning are the most effective means of reducing deaths.
Tsunamis or tidal waves occur during sudden geologic events occurring at sea, such as earthquakes and volcanic eruptions. The tsunami will be worse if the epicenter of the seismic event resides in relatively shallower water. The giant wave of water may travel from the epicenter at hundreds of miles per hour. The onset is often heralded by a sudden ebb of water that exposes the seafloor and is followed in minutes by a wall of water that may rise to 100 ft. Massive damage occurs to the shore and structures; casualties are due to drowning. Mitigation through early warning is the most effective means of reducing casualties. Sea walls and locating structures on high ground can provide some additional relief.
Volcanoes are channels of molten rock (magma) from deep in the earth that vent to the surface in one of several forms. They may cause eruptions of molten rock (lava) or spew ash and debris. Volcanoes tend to be localized to the boundaries of tectonic plates (eg, the Pacific Rim). Injury is most commonly due to falling debris, collapse of structures under the weight of ash, being buried in mudslides or lava flows, or toxic effects of gases (eg, carbon dioxide, hydrogen sulfide). Effects on agriculture and property can be extensive. In many cases, early warning, although imprecise, can allow evacuation and mitigate casualties.
A winter storm can range from a moderate snow over a few hours to blizzard conditions with blinding wind-driven snow that lasts several days. Some winter storms may be large enough to affect several states, while others may affect only a single community. Many winter storms are accompanied by sustained low temperatures and heavy winds.
Frostbite and hypothermia are of main concerns with trapped motorists, homeless people, and those trapped at home, without utilities or other services. Incorrect venting of heating devices and/or generators is a major cause of carbon monoxide poisoning during disasters. Fires are common with use of inappropriate alternative heating devices. Of course, trapped without heat or proper clothing, people may suffer hypothermia or cold injuries. Property damage may occur due to pipeline freezing with subsequent building flooding, structural overload with snow and/or ice, and falling tree limbs or trunks. Automobile accidents are common.
A disease epidemic occurs when there are more cases of that disease than normal. A pandemic is a worldwide epidemic of a disease. A pandemic may occur when a disease appears against which the population has little or no immunity. With the increase in worldwide transport and urbanization and crowded conditions in some countries, epidemics due to a new disease or novel organism are more likely to occur around the world. The World Health Organization has defined six phases of a pandemic to provide a global framework to aid countries in preparedness and response planning for a possible pandemic (Figure 4–2). Pandemics can be either mild or severe in the illness and death they cause, and the severity of a pandemic can change over the course of that pandemic. Examples of pandemics and plagues are listed in Table 4–1.
| Event | Years |
|---|---|
| Black Death (probably bubonic plague) | 1300s |
| Typhus | 1501–1587 |
| Influenza | 1732–1733, 1775–1776, 1857–1859, 1889–1892 |
| Cholera | 1816–1826, 1829–1851, 1852–1860, 1863–1875, 1899–1923 |
| Bubonic plague | 1855 |
| Spanish flu (avian flu) | 1918–1920 |
| El Tor (Vibrio cholerae) | 1960s |
| HIV/AIDS | 1980s to present |
| Swine flu (H1N1) | 2009–2010 |
Agents such as anthrax, plague, and smallpox may be used as biologic weapons. This may differ little from epidemics and plagues, but is caused by the deliberate efforts of man.
Agents such as ricin, chlorine, and nerve agents can be used as weapons or may be the result of release of chemical agents from industrial sources. Industrial accidents that cause large-scale disasters most commonly result in the release of a hazardous material. The most notorious occurred in 1984 in Bhopal, India, where a release of methyl isocyanate killed more than 2000 and injured up to 200,000.
Injuries vary depending on the nature of the agent. Asphyxia, respiratory distress, skin and eye irritations, neurologic abnormalities, or teratogenic effects may occur. In addition, explosive effects are not uncommon in industrial accidents.
Release of radiation from dirty bombs, nuclear blasts, or reactor accidents can be associated with major disasters. In nuclear accidents, injuries are due to the immediate blast effects, exposure to toxic chemicals used at reactor sites (eg, sulfuric acid, chlorine, ammonia), and radiation exposure. Aside from the atomic explosions in Japan in World War II, few deaths have resulted from nuclear disasters, although several significant incidents have occurred. The most deadly was the 1986 Chernobyl reactor explosion in the former Soviet Union, in which 27 people died and 135,000 were evacuated, many of whom were exposed to high radiation levels. The Chernobyl radiation release is considered the worst nuclear power plant accident in history. Over 400 times more radioactive material was released from the power plant explosion than the atomic bomb that was dropped on Hiroshima.
Explosions, blasts, and injuries causing mass casualties may be industrial, agricultural (grain elevators), or terrorism. The patterns of injury include direct blast injuries, fragment wounds, injuries sustained by the force of the blast, and injuries from the chemical products of the explosive.
Collectively, fires produce approximately 5000 deaths and 300,000 injuries each year in the United States, although the number has been on a steady decline since the 1950s. Under the right conditions, hot gases can produce winds that collect in a rotating cyclone (called a fire storm). Most deaths are due to asphyxiation from carbon monoxide and other toxic gases and due to burns. When exits are blocked, casualties from both fire and inhalation of toxic gases and crowd-related injuries may occur.
Transportation accidents are the most common incidents producing multiple casualties in the United States. Airplane crashes produce a high ratio of fatalities to total injuries; highway accidents have the opposite characteristic. Railway accidents may produce significant injuries if passengers are involved and also have resulted in release of hazardous materials. Ship and ferry accidents are often complicated by adverse weather conditions.
Transportation accidents are the prototypical geographically localized multicasualty events practiced in most communities’ disaster drills. They are realistically apt to occur, and they lend themselves to management within the jurisdiction and structure of local emergency medical services (EMS). The patterns of injury are well known to most emergency workers and consist of fractures, contusions, lacerations, and head and thoracoabdominal blunt injury.
Structural failure of a building or man-made structure can be precipitated by natural forces (eg, earthquake) or may occur unexpectedly (eg, the Hyatt skywalk collapse in Kansas City, 1981; 113 dead and 200 injured). However, most such events in the United States have been limited in scope and have not produced many casualties. Injuries are predictable and consist of head injuries, fractures, lacerations, and blunt thoracoabdominal injuries.
Historically, acts of violence in the civilian arena are usually limited to a small number of casualties. Explosives are by far the most common modality used in modern terrorist attacks. Given the September 11, 2001, attack on the World Trade Center, the prior bombing there in the parking structure, the bombing of the Murrah Federal Building in Oklahoma City in 1995, the sarin gas attack in Tokyo, and the 2001 anthrax scare, it is obvious that acts of terrorism can strike close to home and affect a hospital’s ability to properly care for a large influx of patients.
The 2001 anthrax scare in the United States and known world stockpiles and instability of biologic and chemical warfare programs around the world have demonstrated that bioterrorism is a very real threat. Hospital surveillance requires a high level of suspicion. A bioterrorism event that goes unrecognized or may be dismissed as a natural epidemic may compromise hospital staff and patients not associated with the disaster. Establishing an effective response requires hospital, local, state, and federal cooperation and training. An effective response should include the following four steps: detection and diagnosis, declaration of need, defense, and drug therapy.
