Management of unique clinical entities in disaster medicine

Blast Trauma: The Fourth Weapon of Mass Destruction

Injury from blast is becoming more common in the non-military population. This is primarily a result of an increase in politically motivated bombings within the civilian sector. Explosions unrelated to terrorism may also occur in the industrial setting. Civilian physicians and surgeons need to have an understanding of the pathomechanics and physiology of blast injury and to recognize the hallmarks of severity in order to increase survivorship. Because victims may be transported rapidly to the hospital, occult injury to gas and fluid containing organs (particularly the ears, bowel and lungs) may go unrecognized. Information surrounding the physical environment of the explosion (whether inside or outside, underwater, associated building collapse, etc) will prove useful. Most of the immediate deaths are caused by primary blast injury from the primary blast wave, but secondary blast injury from flying debris can also be lethal and involve a much wider radius. Liberal use of X-ray examination in areas of skin punctures will help to identify a need for exploration and/or foreign body removal. Biologic serum markers may have a role in identifying victims of primary blast injury and assist in monitoring their clinical progress. Tertiary blast injury results from the airborne propulsion of the victim by the shockwave and is a source of additional blunt head and torso trauma as well as fractures. Miscellaneous (quaternary) blast injury include thermal or dust inhalation exposure as well as crush and compartment syndromes from building collapse. Any explosion has the potential to be associated with nuclear, biologic or chemical contaminants, and this should remain a consideration for healthcare givers until proven otherwise.

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

Introduction:

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

Methods:

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

Results:

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

Conclusion:

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

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

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

Field Triage and Patient Maldistribution in a Mass-Casualty Incident

Introduction:

Management of mass-casualty incidents should optimize outcomes by appropriate prehospital care, and patient triage to the most capably facilities. The number of patients, the nature of injuries, transportation needs, distances, and hospital capabilities and availabilities are all factors to be considered. Patient maldistributions such as overwhelming individual facilities, or transport to facilities incapable of providing appropriate care should be avoided. This report is a critical view of the application of the START triage nomenclature in the prehospital arena following a train crash in Los Angeles County on 26 January 2005.

Methods:

A scheduled debriefing was held with the major fire and emergency medical services responders, Medical Alert Center staff, and hospitals to assess and review the response to the incident. Site visits were made to all of the hospitals involved. Follow-up questions were directed to emergency department staff that were on duty during the day of the incident.

Results:

The five Level-I Trauma Centers responded to the poll with the capacity to receive a total of 12 “Immediate” patients, 2.4 patients per center, the eight Level-II Trauma Centers responded with capacity to receive 17 “Immediate” patients, two patients per center, while the 25 closest community hospitals offered to accept 75 “Immediate” patients, three patients per hospital. These community hospitals were typically about one-half of the size of the trauma centers (average 287 beds versus 548, average 8.7 operating rooms versus 16.6). Twenty-six patients were transported to a community hospital >15 miles from the scene, while eight closer community hospitals did not receive any patients.

Conclusions:

The debriefing summary of this incident concluded that there were no consistently used criteria to decide ultimate destination for “Immediates”, and that they were distributed about equally between community hospitals and trauma centers.

Hemoconcentration caused by microvascular dysfunction after blast injuries to the chest and abdomen of rabbits

BACKGROUND

One of the important causes of death after blast injuries is reduced blood volume, which typically results from hemorrhage but may also result from nonhemorrhagic causes. Hemoconcentration is one such alternate cause of reduced blood volume, but its mechanism is unclear. Because blood is condensed after chest-abdomen blast injuries in rabbits, a series of experiments was conducted to clarify this phenomenon.

METHODS

Chest-abdomen blast injuries from different distances (10 cm, 15 cm, 20 cm, and 30 cm) were induced in male rabbits. ¹²⁵I-albumin was injected into the blood, and its concentration in different organs was tested at various times after the blast injury. The residual radioactivity in different organs and the pre- and postinjury hematocrit was also tested. Histologic evaluations were conducted to detect the injuries to the different organs.

RESULTS

After injury, ¹²⁵I-albumin leaked out of the vessels into organs such as the lungs, liver, and kidneys. The volume of leakage was highly correlated with the distance from the blast. At a distance of 10 cm, the rate of leakage was the highest. The hematocrit was higher for 30 minutes and 3 hours after the injury; 6 hours after the injury, the hematocrit began to return to normal levels. The residual radioactivity of ¹²⁵I-albumin was increased in the heart, brain, lungs, and kidneys, especially at a distance of 10 cm. Histologic evaluation results showed that the cells, microvessels, and organelles of the microvessel endothelial cells in the vital organs, such as the kidneys, were damaged.

CONCLUSION

The preliminary results indicate that microvessels in the lungs and kidneys are the key targets of blast injuries. The damage to the microvessels leads to leakage of albumin, which is one of the important reasons for hemoconcentration in the absence of active bleeding after a blast injury. Treatment should be initiated in victims of blast injuries who are severely wounded as soon as possible after the explosion during the earliest stages of the injury to avoid the occurrence of shock or other severe complications.

Disasters and mass casualties: II. explosive, biologic, chemical, and nuclear agents

Terrorists' use of explosive, biologic, chemical, and nuclear agents constitutes the potential for catastrophic events. Understanding the unique aspects of these agents can help in preparing for such disasters with the intent of mitigating injury and loss of life. Explosive agents continue to be the most common weapons of terrorists and the most prevalent cause of injuries and fatalities. Knowledge of blast pathomechanics and patterns of injury allows for improved diagnostic and treatment strategies. A practical understanding of potential biologic, chemical, and nuclear agents, their attendant clinical symptoms, and recommended management strategies is an important prerequisite for optimal preparation and response to these less frequently used agents of mass casualty. Orthopaedic surgeons should be aware of the principles of management of catastrophic events. Stress is less an issue when one is adequately prepared. Decontamination is essential both to manage victims and prevent further spread of toxic agents to first responders and medical personnel. It is important to assess the risk of potential threats, thereby allowing disaster planning and preparation to be proportional and aligned with the actual casualty event.

Surge capacity: a proposed conceptual framework

There is a need for emergency planners to accurately plan for and accommodate a potentially significant increase in patient volume in response to a disaster. In addition, an equally large political demand exists for leaders in government and the healthcare sector to develop these capabilities in a financially feasible and evidence-based manner. However, it is important to begin with a clear understanding of this concept on a theoretical level to create this capacity. Intuitively, it is easy to understand that surge capacity describes the ability of a healthcare facility or system to expand beyond its regular operations and accommodate a greater number of patients in response to a multiple casualty-producing event. The way a response to this need is implemented will, of course, vary dramatically depending on numerous issues, including the type of event that has transpired, the planning that has occurred before its occurrence, and the resources that are available. Much has been written on strategies for developing and implementing surge capacity. However, despite the frequency with which the term is used in the medical literature and by the lay press, a clear description of surge capacity as a concept is lacking. The following article will provide this foundation. A conceptual framework of surge capacity will be described, and some new nomenclature will be proposed. This is done to provide the reader with a comprehensive yet simplified view of the various elements that make up the concept of surge capacity. This framework will cover the types of events that can cause a surge of patients, the general ways in which healthcare facilities respond to these events, and the categories of people who would make up the population of affected victims.

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

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

Mass casualties and triage at a sporting event

When a sports medicine doctor provides coverage for a sporting event with a large number of athletes and spectators, he or she should always be aware that the potential for a large number of injuries exists. In the event of a mass casualty incident that overwhelms the available medical resources, he or she may be the most qualified professional present to triage and organise patient care. Certain basic rules of triage in a disaster situation should be followed, the goal being to save as many lives as possible. Special circumstances, such as crush injuries, lightning strikes, and blast injuries, may affect the triage and initial care of injured patients.

Practical points in evaluation and resuscitation of the injured child

The ultimate goal of resuscitation of an injured child is delivery of oxygen to intracellular organelles in order to maintain aerobic metabolism. This can be obtained by following ATLS protocols with immediate attention to the "ABCDE's" and compulsive reevaluation of the adequacy of resuscitation maneuvers. After stabilization, seriously injured children should be transferred to trauma centers with established pediatric trauma programs utilizing preexisting transfer agreements and protocols. Pediatric trauma is indeed a team endeavor, requiring the coordinated expertise and teamwork of prehospital EMS providers, trauma team members, and the pediatric trauma and rehabilitation centers. With careful and compulsive communication and coordination, injured children can be returned to their families in better mental and physical condition than pre-injury with reasonable expectation of a full and productive life.

Tornado at Pine Lake, Alberta — July 14, 2000: Assessment of the emergency medicine response to a disaster

Les programmes de médecine et de résidence négligent souvent l’enseignement de la médecine de catastrophe, mais lorsqu’une catastrophe se produit, c’est le personnel de médecine d’urgence qui se retrouve au front. Les médecins d’urgence doivent se familiariser avec le plan de sinistre de leur hôpital et être prêts à participer à l’opération de sauvetage.

Helicopter emergency medical services roles in disaster operations

Rotor-wing aircraft have previously proven utility in disaster operations, but recent expert reviewers have identified areas of potential improvement in integration of helicopter emergency medical services (HEMS) resources into disaster planning and management. This paper discusses salient points regarding helicopter operations in disaster management, using prior reports regarding rotor-wing aircraft utilization as a basis upon which to provide a concise review of HEMS operations in disasters.

Recovery from blast lung injury: one-year follow-up

BACKGROUND

Blast injury to the lung is one of the devastating threats facing victims of an explosion. Although the pathogenesis of blast injury has been studied, little is known about the long-term effects on lung function in survivors.

OBJECTIVE

To examine the pulmonary function of survivors 1 year after sustaining a blast injury.

DESIGN

Prospective study.

SETTING

Pulmonary function test laboratory at Hadassah Medical Center, Jerusalem.

PARTICIPANTS

Eleven surviving victims of a blast injury sustained during a bus terrorist explosion.

MEASUREMENTS

Twelve months after the injury, physical examinations, lung function tests, and progressive cardiopulmonary exercise examinations were conducted, and chest radiographs were obtained.

RESULTS

The average age was 28 +/- 9.8 years. Most of the victims had multiple injuries in addition to the lung injury. Ten patients received mechanical ventilation, and 6 patients required chest drainage. All patients were treated in the ICU, with an average stay of 11.8 +/- 9 days. The patients were discharged to their homes or to a rehabilitation center 32.4 +/- 27. 3 days after the explosion. One year later, none had any pulmonary-related complaints. Physical examination of the lungs was normal. Most of the patients demonstrated normal lung function tests and complete resolution of the chest radiograph findings.

CONCLUSION

Most patients who survive lung blast injury will regain good lung function within a year.