Decontamination is the "process of removing or neutralizing a hazard from the environment, property or a life form."1 Triage is a method of rationing care in a mass casualty scenario when resources are limited. After an attack on civilians using a weapon of mass destruction, triage, decontamination, and treatment may need to be initiated while there is still uncertainty regarding the agent and extent of exposure. Even amidst such uncertainty, health care professionals should be ready to begin triage and decontamination to prevent morbidity and mortality. This article outlines common principles in managing the exposure of children to weapons of mass destruction and describes the adaptations for individual agent types.
A single fixed-response plan cannot meet all of the potential mass casualty scenarios, and many factors necessitate flexibility in the response. For instance, the anthrax attacks of 2001 used a white powder that was easily recognized. Essentially, this attack was approached like other hazardous material problems. It is likely that future biological attacks will be unannounced and initially unnoticed. The type or combination of agents (thermomechanical, biological, chemical, radiological) is critical for determining whether and how decontamination is accomplished. Other considerations in the event of an attack using a weapon of mass destruction include the number of victims, the state of the agent (liquid versus vapor versus powder), and the setting of the exposure (inside versus outside).
Institutions must have well-rehearsed basic emergency response plans with an effective communication infrastructure, information management system, and decision-making apparatus that will allow for adaptation in a crisis. Several detailed reviews exist to help administrators prepare an institutional plan for response.13
Despite our awareness of a threat, many institutions still do not have personnel or procedures in place to respond to a weapon of mass destruction. A study of hospitals in the Philadelphia area found that among 54 emergency departments, only 10% of physicians had adequate training and only 16% were able to decontaminate more than 10 patients per hour.4 No studies on the capabilities for pediatric-specific decontamination have been performed.
CHILDREN AND WEAPONS OF MASS DESTRUCTION
An imperative consideration in the event of a mass casualty weapon incident is the presence of children. Even in the workplace, disasters and terrorism can affect children. In the terrorist bombing of the Alfred P. Murrah Federal Building in Oklahoma City, 10% of the casualties were children and infants; 31% of the pediatric casualties died compared to 21% of the adult casualties.5 In Bhopal, India, a large-scale industrial disaster resulted in the release of methyl isocyanate in a densely populated urban area. On the first day, 20% of the admissions to one hospital were younger than age 15.6
Because of the particular vulnerabilities of children to the pathophysiological and psychological effects of weapons of mass destruction, there may be a disproportionate number of pediatric victims. After a test nuclear weapon detonation in 1954, children in the Marshall Islands were exposed to significant doses of whole-body gamma rays and fallout. One report indicated that compared to adults children experienced more nausea, vomiting, and depression in leukocyte counts as well as more widespread bums.7 In the Chernobyl accident of 1986, although no children suffered from acute radiation syndrome, many were hospitalized for other related illnesses.8
The key to management of any mass casualty scenario is rapid and efficient triage, with the goal being to save as many lives as possible. In a mass casualty event such as a chemical agent attack, casualties must first be triaged before decontamination. Both military and civilian models have been described regarding methods of triage for victims of mass casualty weapons.912 One should understand the difference between the military and civilian models. In an austere battlefield environment, the goals of triage are to identify the extent of injury, to return the minimally injured to their mUitary mission, and to apply the limited medical resources to those most likely to survive. The battlefield is a resource-poor environment.
In a resource-poor environment mass casualty victims can be classified into one of four categories: (1) immediate victims require immediate care to save life or limb; (2) delayed victims can have definitive care delayed for some defined period without increased risk of loss of Ufe or limb; (3) minimal victims have non-life-üireatening injuries that require minimal care or even may be self-care; and (4) expectant victims have medical requirements that may exceed the immediate capabilities, who may require heroic efforts, or who are likely to die regardless of efforts. While this is not a model for providing routine medical care, its use may be necessary in a scenario of limited medical resources with an overwhelming casualty flow.
A civilian mass casualty scenario, however, shifts from being initially resource-poor to resource-rich as regional and national resources are applied. Thus, given the same clinical scenario, one might first classify a victim in one category and in another category when resource-rich. Triage should be repeated as the clinical status of a victim changes and as medical resources become more, or less, available.
In a mass casualty event, a triage officer (ideally an experienced emergency medical technician, nurse, or physician) is challenged with identifying a small number of seriously ill individuals interspersed among a large number of casualties who may have suffered mild or no effects. Further complicating the event are psychiatric casualties or those individuals who falsely believe they have been a direct victim of an attack; the ratio of psychiatric casualties to actual wounded may be 5:1 or higher.13 Although the number of psychiatric casualties may be significant, the responder should be aware that the effects of many chemical agents and secondary physiological derangements (eg, hypoxia) can resemble psychiatric symptoms.
GENERAL PRINCIPLES OF DECONTAMINATION
Expeditious decontamination must follow once victims have been triaged. The first rule in decontamination is that the individuals involved in primary triage and initial decontamination must protect themselves with the appropriate personal protective equipment. In a mass casualty event, medical resources (facilities and personnel) cannot be compromised by cross-contamination from victims. Thus, the goals of a health care facility for decontamination include eliminating or neutralizing agents harmful to victims, preventing secondary exposures among health care workers, and eliminating or containing contaminated clothing, equipment, and waste products, thereby preventing contamination of the health care facility.
Figure 1 . Adaptation of the US Army's basic personnel decontamination station.
Decontamination is a stressful activity that requires intense labor and large amounts of material. Personal protective equipment worn by those engaged in decontamination activities is cumbersome, retains heat and moisture, and accelerates fatigue. Decontamination teams may be limited in the number of victims they can process. One simulation at a hospital-based decontamination center in Sweden with a staff of 13 in full personal protective equipment achieved a rate of 16 victims an hour with two thirds on stretchers.14 If ten such decontamination teams - approximately 130 people - were deployed in a scenario similar to the Tokyo subway attacks (where approximately 5500 victims presented for care), it would take approximately 28 hours to decontaminate all the victims fully if the decontamination teams processed 20 victims per hour. This optimistic calculation illustrates the need to limit the number of victims requiring full decontamination.
Creating a "Decori" Zone
There is no ideal plan for a decontamination zone, and institutions have adapted basic principles to their mission and physical plant. Depending on the individual hospital emergency response plan, decontamination may take place in portable tents, ambulance bays, or parking lots. Essential elements, however, include a dirty contaminated zone where victims enter and are decontaminated that is separate from a clean decontaminated zone where decontaminated victims may exit to enter the health care facility. Traffic is one-way to prevent cross-contamination. In addition, the facility should allow for decontamination of both ambulatory and nonambulatory patients. An adaptation of the US Army's basic personnel decontamination station is provided in Figure 1 (page 263).
Entry to the health care facility is blocked except for those who are in the clean zone. A hot-line is an arbitrarily established demarcation separating dirty and clean zones in a decontamination area. Security personnel should be assigned to ensure that contaminated individuals (victims or medical personnel) do not breach this line.
Selecting the Appropriate Decontaminant Agent
Hypochlorite. Many sources have adapted US military doctrine for civilian use. At times, using this doctrine may be harmful for children. Current military doctrine advocates the use of a carbonaceous adsorbent powder and dilute (0.5%) hypochlorite solution for decontamination. Hypochlorite solution is easily available as household bleach (5%-6% hypochlorite) and is inexpensive. Given enough time, it neutralizes most biological and chemical weapons. It may be used as a 5% solution to decontaminate equipment such as vehicles but needs to be diluted 10-fold (to 0.5%) when used for personnel decontamination.
Plain water. Hypochlorite is not, however, the gold standard for decontamination. It may effectively neutralize many biological agents (except toxins) on the skin, but its use otherwise is limited. For chemical agents such as mustard and nerve agents, a minimum of 20 minutes of exposure to hypochlorite is required for chemical decontamination, rendering it impractical. In addition, even at low concentrations, hypochlorite can be irritating or damaging to skin.15
Because of the relatively thin skin of a child, increased susceptibility to irritation would be expected if bleach were used as a decontaminant in a child. Fortunately, plain water has been shown to be a very effective decontaminant. A US Army study showed the relative benefits of copious water as a wet decontaminant compared to bleach.16 In this study, 5% bleach actually increased mortality in rabbits when compared to those who underwent no decontamination at all.
There is debate about the advantages of warm versus cold water for decontamination. Although warm water can encourage spontaneous hydrolysis of toxins, it also can encourage dilation of superficial blood vessels, thus potentially increasing systemic absorption of the toxin. Cold water, in contrast, prevents dermal absorption by vasoconstriction but also may cause hypothermia. In a real-life scenario, however, time is critical in decontamination. Therefore, one should use the first available water at a comfortable temperature.
A major problem of liquid decontamination is its use in cold weather. At an ambient temperature of 65°F, most individuals complain of discomfort due to cold. To address this problem, with the additional reticence of victims to disrobe and shower, use of indoor sprinkler systems might be considered. Other plans for cold weather are available.13 Responders need to be especially vigilant for the effects of hypothermia in children and infants. Following liquid decontamination, shelter from the elements and cold should be provided immediately.
Dry decontaminants. The use of dry decontaminante also has been described. An adsorbent, dry material reduces the amount of chemical toxin available without introducing liquids that may traumatize tissues or activate other agents such as sulfur mustard. In an emergency situation, household powders may work as well. A Swedish study of in vitro and in vivo preparations illustrated the benefits of flour or talcum powder followed by wet-tissue paper for removing sarin.17 Flour has been shown to be an effective adsorbent for soman, VX, and mustard agent. Scraping gross amounts off with a Popsicle stick will even confer benefit.18 These studies re-iterate the importance of physical removal of the toxin to minimize toxic exposure, thus reducing morbidity and mortality.
SPECIAL CONSIDERATIONS FOR DECONTAMINATION IN CHILDREN
In a mass casualty scenario, most children are not likely be attended by a pediatrician. For an emergency response team that has focused on preparing for the generic adult victim, the child victim will challenge the system. An efficient and accurate triage system might disintegrate when unprepared responders and health care professionals must manage uncooperative or nonverbal children.
Lack of experience with weight estimation, selection of equipment and ventilation parameters, and the calculation of drug doses - integral to a pediatric practice - can slow expeditious triage, decontamination, and treatment designed to accommodate adults. The resultant inefficiencies may contribute to increases in overall morbidity and mortality as responders struggle to improvise.
Children may be exceptionally vulnerable to agents that require decontamination. The vapor density of nerve agents or toxic industrial chemicals concentrates exposure on those closest to the ground. Children's increased minute ventilation also increases their inhaled exposure dose of vapor agents.
Similarly, the large surface-to-volume ratio in children places them at risk for increased absorption of any cutaneous toxin or agent. By weight considerations alone, a lethal dose of a toxin for a child might be one half to one third or less than that for an adult. Thus, a parent and child pair at the same location during a chemical exposure may suffer vastly different medical effects.
In addition, mild and early symptoms may be missed due to a child's inability to communicate symptoms of pain or discomfort. Triage of children, especially young children, is quite different from adults. (For suggested levels of triage for nerve agent casualties, see Table 1 on page 244.)
Parents of infants or small children may be reluctant to separate at a time of crisis. Keeping a mother with a child may be helpful for supervision and may assist with thermoregulation of infants who are affected. Teams should consider how to best decontaminate parentchild pairs.
To help address the specific problems of decontamination and assessment of children, a special pediatric area within the triage and decontamination zone should be considered. In a review of an Israeli hospital response plan, the authors described how a separate zone for pediatric triage and monitoring is established once decontamination has been achieved.19 One report of a domestic organophosphate mass poisoning described the psychosocial utility of a unique area for observing asymptomatic children.20 A pediatric-specific zone would allow for specialized care, concentration of pediatric resources, and attention to pediatric behavioral issues.
Other nonmedical issues also arise, especially for institutions that do not routinely see a large number of children. There will be the added demands of child supervision during triage, decontamination, and medical care. This requires extra personnel to supervise and provide psychological care for children. At a minimum, children will require a change of clothing, frequent feedings on unique diets, and diaper changes.
Unaccompanied children will face issues of parental identification and appropriate temporary custodial care. In preparation for hours of treatment and observation, one should consider having toys or other diversions available in addition to basic materials for feeding and hygiene. Methods for recording data and identification should be instituted, as children may present unaccompanied by a guardian. These are all issues that need to be considered in a mass casualty response plan.
AGENT-SPECIFIC ASPECTS OF DECONTAMINATION
The type of agent, route of exposure (skin versus inhalation), state of the agent (liquid versus vapor), and individual vulnerabilities determine the speed of onset and severity of clinical manifestations. Of the chemical agents, surface contamination with vesicants (eg, mustard) and nerve agents are of primary concern. Small amounts are readily absorbed and highly toxic. Timely and thorough decontamination after exposure to these agents can prevent morbidity and mortality. In contrast, cyanide is highly volatile, and pulmonary agents (eg, phosgene) are nonpersistent gasses and thus do not present the same topical hazard or require the same urgent attention to decontamination.
In an event in which the agent is unidentified or without a reliable witness who can attest to the route of exposure, caution might dictate a more thorough decontamination. For a child, it may be difficult for the triage officer to take a definitive history, and more children may require definitive decontamination.
When an individual is exposed to a nerve agent or to cyanide in vapor form, evacuation to a low-risk, well-ventilated area may be the only initial response that is needed. Clothing and hair of victims may release small amounts of nerve agent vapors, and hospital personnel should be aware of the potential for secondary contamination of health care workers. In the attacks on the Tokyo subway, significant numbers of hospital personnel and responders experienced symptoms related to exposure to vapor trapped in the air cells of the victims' clothing.21 Consequently, although a full decontamination may not be necessary, a change of clothes and a shower may be indicated at the first opportunity.
In a liquid exposure, one should quickly remove any agent that may be on clothing and skin (gross decontamination) with any kind of absorbent material. Full removal of clothing is necessary, as the agent may collect under garments. Asymptomatic victims awaiting decontamination should be observed for changes in clinical status. Even after decontamination, individuals with a suspected cutaneous exposure to nerve agent liquid should be observed for 18 to 24 hours to ensure no delayed effects of an absorbed agent.
Health care providers should be aware that thin butyl rubber gloves provide at least 60 minutes of protection from chemical agents in aqueous base. Chemical agents traverse latex gloves much more readily, and double latex gloves should be changed every 20 minutes.19
RADIOLOGICAL AGENT DECONTAMINATION
Individuals who have been exposed to radiation energy only do not require decontamination. However, victims of radiation exposure who have surface contamination with radioactive particulate matter or internal contamination from inhaled or ingested particles are a hazard to themselves and potentially to other medical personnel. The risk of secondary exposure of response personnel is far less than with chemical agents.
In the prehospital setting, it is reasonable to attend to immediate life-threatening injuries (thermal bums or blastrelated injuries) in radiation victims prior to assessing the radioactive contamination status and to completing thorough decontamination. Once patients are stabilized, decontamination should proceed as with chemical agents along a prescribed unidirectional route. In the situation in which it is uncertain if there is residual radioactive material, technicians with appropriate detection equipment are necessary, and samples of skin surface, urine, stool, and nasal swabs should be analyzed.
Gross decontamination is achieved by brushing off loose particulate matter and removing clothing and shoes. This alone removes 90% to 95% of the contaminant.22 Washing uncovered skin with soap and water achieves a level of 98% decontamination from radioactive particulate matter. If radioactivity persists in the hair or scalp, further washing or cutting of hair may be necessary. Treatment of internal decontamination with cathartics or gastric lavage should be considered if significant ingestion has occurred.
Medical personnel should consult with local radiation safety officers regarding the necessary protective gear. However, personnel should at least wear gowns, rubber gloves, and masks. All clothes and personal gear from victims and health care personnel should be collected, identified, sealed, and stored in a remote location.
BIOLOGICAL AGENT DECONTAMINATION
Biological attacks are more likely to occur as a covert release of infectious agents, followed days or even weeks later by clinical manifestations. During the intervening incubation period, most victims will have self-decontaminated through ordinary hygiene practices. In addition, most biological agents (with the exception of mycotoxins) are not absorbed through the skin. Consequently, full decontamination procedures are rarely indicated.
In the few situations where decontamination may be of value, biological agents can be decontaminated using mechanical means (eg, soap and water rinse) or chemical media (eg, hypochlorite solution). The desire to use hypochlorite solutions should be tempered by its caustic nature and by the risk of iatrogenic topical chemical injury, as mentioned earlier.
Open wounds in victims present unique problems. One should assume that open wounds have been exposed to toxic agents through the traumatized area. Especially if exposed to liquid mustard or nerve agents, these individuals should be monitored for systemic effects. Wound dressings and foreign bodies can act as depots for toxic agents and radioactive contamination. Consequently, all dressings should be removed from contaminated patients and the wound flushed with standard irrigating solutions (eg, normal saline) and then redressed to prevent further contamination.
The intact margins of the wound can be decontaminated with standard materials, but decontaminating agents should not be introduced into the wound itself. In one study using the vesicant sulfur mustard in an animal model, wounds that were left contaminated had fewer lesions than those treated with dilute hypochlorite or water.21 Hypochlorite also should not be used in the eyes, brain, spinal cord, or open abdominal wounds.
Time is essential in preventing morbidity and mortality following an attack with a weapon of mass destruction. As medical professionals, our assistance will be sought in the immediate aftermath. We must rush deliberately to help by carefully considering the type of agent and the exposures, implementing basic and sensible measures (such as gross decontamination), recognizing when complete decontamination is necessary to reduce the continuing hazard to the victim or response personnel, and seeking the assistance of subject matter experts as it becomes available.
Effective planning will benefit all of our patients. Many primarily adult-oriented institutions are not aware that they will be required to treat victims of all ages following an attack with a weapon of mass destruction and to support them until relief is available. Pediatric providers should consider if their local plans truly meet the needs of those they intend to serve.
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