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7
Patient Decontamination
and Mass Triage

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     Decontamination is defined as the process of removing or neutralizing a hazard from the environment, property, or life form. The principal objectives of this process are to prevent further harm and optimize the chance for full clinical recovery or restoration of the object exposed to the dangerous hazard. The triage process is the initial step taken to meet the primary objectives of a disaster response, which involves sorting the injured by priority and determining the best utilization of available resources (e.g., personnel, equipment, medications, ambulances, and hospital beds). This chapter includes a review of decontamination and mass triage with an emphasis on the research and development needs in these areas of disaster response.

     Fire departments and hazardous material teams have traditionally described the decontamination processes with two terms--"technical decon" and "medical" or "patient decon." "Technical decon" is the process used to clean vehicles and personal protective equipment (PPE) and "medical" or "patient decon" is the process of cleaning injured or exposed individuals.

     Technical decon is most commonly performed using a sequential nine-step process originally developed by Noll and Hildebrand (1994). The steps are listed below.

In the Exclusion Zone (Hot Zone--dangerous concentrations of the agent are likely)

1. Contaminated tools and equipment drop onto a plastic sheet

2. Contaminated trash drop

In the Contamination Reduction Zone (Warm Zone)

3. Primary garment wash/rinse (boots, outer gloves, suit, SCBA, and mask)

4. Primary garment removal

5. Secondary garment wash/rinse (decontaminate inner protective garment and inner gloves)

6. Face piece removal/drop (can be combined with stations 7 and 8)

7. Boot drop

8. Inner glove removal

In the Support Zone (Clean Zone)

9. Shower and clothing change

     This process is well known and extensively utilized by the public safety community. Cleaning is done using water in conjunction with one of four cleaning solutions, (solutions known as A, B, C, D), depending on the type of contaminant. Solution "A" contains 5 percent sodium bicarbonate and 5 percent trisodium phosphate and is used for inorganic acids, acidic caustic wastes, solvents and organic compounds, plastic wastes, polychlorinated biphenyls (PCBs), and biologic contamination. Solution "B" is a concentrated solution of sodium hypochlorite. A 10 percent solution is used for radioactive materials, pesticides, chlorinated phenols, dioxin, PCB, cyanide, ammonia, inorganic wastes, organic wastes, and biologic contamination. Solution "C" is a rinse solution of 5 percent trisodium phosphate. It is used for solvents and organic compounds, PCB and polybrominated biphenyls (PBB), and oily wastes not suspected to be contaminated with pesticides. Solution "D" is dilute hydrochloric acid. It is used for inorganic bases, alkalis, and alkali caustic wastes.

     Once the decon process is completed, the equipment is most often returned to service, unless the item(s) cannot be completely decontaminated (as determined by using available detection devices). However, current research does not provide an answer to the question, "how clean is clean?" Some communities will depend on disposable equipment as an alternative to trying to assure that each item has been thoroughly decontaminated. Other communities may not be able to afford the replacement cost and depend on using available technology or best guess to determine when these items are "clean." It will be important for emergency responders to know when technical decontamination has been achieved, if the equipment is to be reused. It is vital when personal protective clothing or equipment is involved.

     Patient decontamination, which Hazmat teams have to undertake much less often than technical decon, is to be performed when the contaminant poses a further risk to the patient or a secondary risk to response personnel. Fire and EMS publications frequently describe how patient decontamination can be done, but few of the recommendations are based on empirical research. Because little scientific documentation exists for when and how patient decontamination should be performed expeditiously and cost effectively, prehospital and hospital providers are left to doing what they think is right, rather than doing what has been proven to work best. Generally, the process involves three stages; gross, secondary, and definitive decontamination.

Gross Decon

1. Evacuate the patient(s) from the high-risk area.

2. Remove the patient's clothing.

3. Perform a one-minute quick head-to-toe rinse with water.

Secondary Decon

1. Perform a quick full-body rinse with water.

2. Wash rapidly with cleaning solution from head to toe.

3. Rinse with water from head to toe.

Definitive Decon

1. Perform thorough head-to-toe wash until "clean".

2. Rinse with water thoroughly.

3. Towel off and put on clean clothes.

     As noted above, among the first steps in the decontamination process is the removal and disposal of clothing. Cox (1994) estimates that 70 to 80 percent of contaminant will be removed with the patient's clothes. Little scientific data exist to support this assertion, however. The ideal skin decontaminant would remove and neutralize a wide range of hazardous chemicals, be cheap, readily available, rapid acting, and safe. For most civilian applications, water has been the choice; the technical decontaminant solutions cannot be safely used to clean the skin or mucous membranes. The armed forces have assessed a wide variety of skin decontaminants, including flour, Fuller's earth, and absorbent ion-exchange resin for environments where water is not available. A fresh solution of 0.5 percent sodium hypochlorite appears to be the state-of-the-art liquid decontaminating agent for personnel contaminated with chemical or biological agents (Chemical Casualty Care Office, 1995). The half-life of sarin in undiluted household bleach, which is 5.0 percent sodium hypochlorite and generally too harsh for use on skin, is on the order of 3 seconds (Kingery and Allen, 1995).

     Civilian Hazmat teams generally have basic decontamination plans in place, though proficiency may vary widely. Very few, if any, teams are manned, equipped, or trained for mass decontamination, however. Again, water is the principal decontamination solution, with soap recommended for oily or otherwise adherent chemicals. Some teams suggest that initial mass decontamination be accomplished by fire hose (operated at reduced pressure), which has the advantage of being possible even before the Hazmat team arrives on scene (the MMST equipment list includes hoses specifically for this purpose). Shower systems with provisions for capturing contaminated runoff are commercially available and may provide some measure of privacy in incidents involving only a handful of victims (they generally accommodate only one person at a time). However, the availability of trained personnel in appropriate personal protective clothing is likely to be a limiting factor, even when larger shower units or multiple smaller ones are available. The CBIRF and MMST have much larger shower units, capable of decontaminating dozens to hundreds of victims with sodium hypochlorite solution, and are staffed at much higher levels than local Hazmat teams. However, neither will be immediately available unless predeployed (as was done, for example, at the Atlanta Olympics and State of the Union Address). Harsh weather, intrusive media, and the willingness of ambulatory patients to disrobe in less than private surroundings will also affect the conduct of field decontamination. Where there are very large numbers in need of decontamination, crowd control measures will be necessary to keep panicky or merely impatient victims at the scene long enough to complete decontamination.

     The degree to which a patient is decontaminated in the prehospital setting depends on the decon plan, available resources, the weather, and patient volume. At minimum, every patient presenting a risk of secondary contamination risk should receive gross decon before departing for the hospital. These patients should be transported to a hospital (by properly protected EMTs and paramedics). The receiving hospital should be equipped and staffed to perform secondary and definitive decon, if not already done in the field.

     Patients requiring additional medical attention, such as attention to the ABCs (airway, breathing, and circulation), antidotes, or other emergency treatment, may receive that care during or after the decontamination process depending on the severity of the agents' effects and the ability of the decon team and available medical personnel to render that care. Nonambulatory patients pose much more of a decontamination and treatment burden than ambulatory patients, because most portable decontamination chambers require a person to stand. Decontamination and treatment planning must also address how to deal with the pediatric patient and the elderly.

     Although hospitals are required by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) to be prepared to respond to disasters, including hazardous material accidents, few have undertaken realistic planning and preparation. Some hospitals have decontamination facilities; however, very few have outdoor facilities or an easy way of expanding their decontamination operations in a mass-casualty event (Cox, 1994; Levitin and Siegelson, 1996). Often their initial response to an incident will be to contact the local fire department or Hazmat team for assistance. This will not be a viable solution if the incident is large or nearby. Unannounced ambulance or walk-in patients who are contaminated may create havoc and harm before "outside" help arrives to address the situation or internal resources can be organized to respond. If assistance from the local public safety agency is not available, the hospital is left to fend for itself and, if unprepared, the response is likely to place the patient, staff, and facility at great risk. There is little financial incentive for a hospital to be prepared for a "once in a lifetime" event, and proper equipment and training may be perceived as too expensive under the circumstances. Generally, hospitals that are prepared are usually capable of handling only a few patients an hour. What happens when a large number of patients begin to arrive? Currently, the medical literature does not contain sufficient research findings to assist hospitals with cost-effective Hazmat or terrorist response planning. The Agency for Toxic Substances and Disease Registry recently released a series of guidelines to help local emergency departments, communities, and other policymakers develop their own response plan or hazardous materials incidents (U.S. DHHS, 1994a), and the Centers for Disease Control and Prevention's Planning Guidance for the Chemical Stockpile Emergency Preparedness Program (CSEPP) provided recommendations for civilian communities near chemical weapons depots (U.S. DHHS, 1995b). Although helpful, the outlines are very generic, do not address how to actually perform mass decon, and do not contain information on many of the agents which are likely to be seen in a terrorist incident. Since planning is left to the local jurisdictions, the success of any national initiative is dependent upon cooperation at the local level.

     Aside from the issues related to effective decontamination procedures, training of emergency department personnel must also be considered. There are few courses emergency department personnel may attend to improve their level of preparation for decontamination of large numbers of people.

     Much has been learned about patient decontamination and mass triage in recent years from the process to the equipment. The following section highlights some of these advances and identifies needs for additional research and development.

     Further research is needed to determine when decontamination is really warranted and the most effective way to establish and correctly conduct the decon process both in the field setting as well as in the hospital. Both U.S. Army (Chemical Casualty Office, 1995) and FEMA (Federal Emergency Management Agency) guidance suggest that decontamination is unnecessary when dealing with agents in nonpersistent (vapor) form. Under these circumstances, removal of the patient from the source of the vapor is all that should be necessary, and decontamination would needlessly delay evacuation and treatment. In practice, a number of extra-scientific reasons can be adduced for making decon routine: the agent(s) cannot always be identified immediately, medical personnel may be endangered by very small amounts of agent present on each of a long series of patients, and to protect the psychological well-being of both victims and emergency workers.

     Recent reports on the Tokyo subway incident of 1995, which involved the nonpersistent nerve agent sarin, provide some support for this position (Okumura et al., 1998a,b). No field decontamination was performed onsite, and emergency medical technicians (EMT) transported 688 victims to hospitals by ambulance. Ten percent of 1,364 EMT showed symptoms and had to receive treatment at the hospital themselves. Once the hospitals (at least St. Luke's) learned that nerve agent was suspected, the most seriously ill patients were directed to a shower upon arrival. Their clothes were placed in plastic bags and sealed up. Despite these precautions, and the use of surgical masks and gloves, 110 hospital staff (23 percent) complained of acute poisoning symptoms on a follow-up questionnaire.

     To perform patient decontamination safely and correctly requires a response plan, proper equipment, and trained personnel. Military procedures, and adaptations thereof for use in the CSEPP provide generic guidance for some highly specific situations, but to date there is no detailed national guideline on how to set up and conduct a massive decontamination process in the civilian setting. Ideally, this guideline would address areas such as site management and crowd control, cleaning ambulatory and nonambulatory victims, handling the special needs of pediatric and geriatric populations, and a standardized patient assessment and triage process to be initiated by personnel wearing PPE to determine viability and need for decontamination.

     Besides the need for a step-by-step process for performing decon in the field setting and in the emergency department, there is no good way to determine when a patient is "clean." Few chemical or biological agents can be readily seen on the skin or quickly assayed to determine whether any residual product remains after washing. Existing technology is either not available, too expensive, or does not provide the needed versatility to be used in the civilian environment. In the absence of knowing "when clean is clean enough," prehospital and hospital personnel are left to process certification (we followed the SOP, so the person or item must be clean) or using their best clinical judgment as to when the decon process can be terminated--an inefficient, and potentially unsafe, practice in many instances. Affordable, accurate, and durable detection devices that are able to reliably establish that no further clinical risk remains to the patient need to be developed so that emergency personnel will know when a patient is "clean." Of course, once the guidelines and technology are in place, issues of funding for EMS and hospital personnel training will need to be addressed.

     The ideal cleaning agent is inexpensive and nontoxic, is rapidly applied and effectively removes the entire contaminant from personnel, equipment, and vehicles. At this time, more is known about technical decon than patient decon, which, as mentioned above, generally involves the use of either soap and water or sodium hypochlorite (0.5 percent). Little research exists to show which soap is best and how long a body surface area must be scrubbed before it is properly cleaned. However, a recent review of the literature by Hurst (1998) suggests that under certain conditions bleach, even at the 0.5 percent level, may actually increase the toxicity of some nerve agents. The M258A1 and M291 are individual skin decontamination kits used by the military and are not routinely available or familiar to the civilian population. Their applicability for use in the civilian setting or in mass decon efforts has not been studied. Current military research on the use of foams, gels, catalytic solvents, and Fenton reagents may have some application for performing technical decontamination in the civilian setting, but more research is needed to determine which agent(s), if any, are suitable for use on civilian patients of all ages and what advantages they have over water or hypochlorite.

     The equipment currently used by many EMS and hospital personnel during decon is very rudimentary and often "home made." Commercially available equipment is often expensive and designed for technical decon rather than patient decon. For example, containment basins often do not have sufficient size or depth to accommodate patients who are supine on backboards, shower systems correctly wash only standing patients, and patients often stand or lie in the product just washed off them. Patient modesty and protection from the environment are two other problems seen in performing prehospital decon. While some hospitals advertise they have a decon room, often it is too small, or ill equipped to meet its intended purpose. Obtaining large supplies of tepid water can be a challenge for prehospital and hospital decon systems. High-pressure systems require less volume, which helps control runoff as well, but low-pressure, high-volume spray nozzles should theoretically be used to avoid vasodilatation of superficial vessels during rinsing that could enhance agent absorption. However, the necessity of their use has never been scientifically proven. Research on the application of military decon strategy and equipment in the civilian setting has also never been reported. Although the commercial market can certainly produce needed decontamination hardware, development of more standardized methods for conducting patient decon will spur improvements in the suitability and cost of the equipment.

     While the exact number of hazardous material accidents occurring each year may not be known, available data does suggest that for most incidents there are few, if any, injuries (Sullivan and Krieger, 1992). However, terrorists' use of a chemical or biological weapon is likely to lead to scores of injuries and fatalities. The rapid implementation of effective triage and initiation of decon will be vital to optimizing victim survivability and responder safety. But how these two processes should be conducted is neither well known nor extensively studied in the civilian setting. Most hazardous material teams and hospitals have limited experience, usually with five or fewer patients at a time. How they can handle 50, 500, or 5,000 patients in a rapid, efficient, and safe fashion is a critical question being asked across the country. The utilization of an MMST to assist local responders may be part of the answer, but emergency planners and incident commanders must keep in mind it will be 90 minutes or longer before this team (which, in Washington, D.C., for example, consists of 43 members) and its equipment arrives. Federal assistance from DoD will likely take even longer to arrive. Interim solutions will have to be found. Some public safety agencies are using specially designed tractor-trailers to decon multiple patients simultaneously (e.g., New York City). These units can provide protection from the environment as well as privacy from onlookers in addition to deconning multiple patients at a time. However, these trailers are expensive and cannot always be placed in desirable locations within the warm zone. Easily inflatable tents are used as shelters. They provide some of the benefits of trailers and are less expensive, but generally take some time to assemble and cannot handle large numbers of patients at a time. Local communities will need to have a primary decon plan that the first personnel on the scene can rapidly implement and a secondary plan to employ when additional personnel and equipment become available.

     Critical to managing the decontamination of large numbers of patients is gaining control of the crowd. Repeatedly giving definitive instructions on what to do over loud speakers is important, along with having an adequate number of properly protected personnel directing the victims through the decon process. Providing verbal instructions may be all that is needed to care for the ambulatory populations, but nonambu-latory victims will require more assistance and equipment (e.g., back-boards). There is virtually no research being conducted on how to effectively organize and manage such a mass decontamination effort. The military model primarily addresses how to handle young healthy soldiers already wearing protective clothing and respiratory protection, and is not directly applicable to a heterogeneous, unprotected, and undisciplined population. The similar mass decon process envisioned by the MMST has not been utilized except in drills.

     Patient resistance to removing their clothing because of modesty or bad weather is a potential problem, but there is no research that validates this issue or its impact. Some suggestions have been made to simply leave the patients' clothing on and spray the crowd with water from hoses located on top of fire apparatus. The effectiveness of this approach, which might actually increase agent-skin contact, has not been studied either.

     Organizing a large decon corridor to handle inordinate numbers of patients is another vital concern. Research is needed to determine the optimal responder/patient ratio, how large an area is needed to decon 50, 500, and 5,000 people, what level of medical training is required for the personnel performing decon, and how much medical care should be given in the warm zone as opposed to the cold zone or at the hospital. Delaying or improperly conducting decontamination increases the danger to the patient as well as the health care provider.

     No less important is the hospital's ability to process large numbers of victims in a timely fashion. Hospitals need to know how their decon systems should be organized and equipped, whether decon is best done inside or outside of the facility, what PPE emergency department personnel should wear, how the system should accommodate both walk-in and ambulance-delivered patients, and the patient volume that should be manageable in an emergency department that has 10,000, 25,000, or 60,000 visits a year. Another issue is how the cost for being prepared could be recovered by the hospital. Unlike other modernization efforts, a decontamination unit is not going to pay for itself with new patients and fees for the hospital.

     Biological warfare agents on the skin and clothing of patients pose only minimal risk to medical personnel from aerosolization ("off-gassing") if standard precautions (gown, gloves, eye protection, and careful handling of needles and other "sharps") are observed. Dermal exposure to a suspected agent should nevertheless be treated immediately with soap and water, followed, after a thorough rinse, with a 0.5 percent hypochlorite solution, which will neutralize any remaining microorganisms within 5 to 10 minutes. As noted in the previous section, hypochlorite is contraindicated for decontamination of eyes or in cases of wounds involving brain, spinal cord, or the abdominal or thoracic cavities. Equipment used in caring for potentially contaminated or infected patients should receive special attention in view of the likelihood of its subsequent use with other patients. Normal sterilization with dry heat or autoclaving is ideal, but 30 minutes soaking in a 5.0 percent hypochlorite solution (undiluted household bleach) will serve as a field expedient.

     Additional attention will need to be paid to how to decontaminate any facilities contaminated by a release. This may prove to be a bigger undertaking than dealing with the human exposure risks, as there is little experience in the literature on how to most cost effectively accomplish this task. Gases or liquids in aerosol form (e.g., formaldehyde) combined with surface disinfectants are often used to ensure complete decontamination. Gels and foams being pursued by scientists at Sandia National Laboratory (Zelikoff, 1998) can help in carrying and holding disinfectant to walls and ceilings. Curry and Clevenger (1997) recently reviewed promising research on biological decontamination by eight different "electrotechnologies." These include electron beams, X-rays, pulsed electric fields, microwaves, and UV light. Of these, only UV light is likely to be feasible for patient decontamination, and then only with low-power UV in conjunction with a photosensitizer like hydrogen peroxide. Contaminated terrain often needs no decontamination other than natural drying and solar UV radiation, but exceptionally persistent organisms like anthrax need to be decontaminated using a spray mixture of chlorine-calcium, formalin, or lye solutions. In some locations seawater may serve as an expedient and less hazardous substitute (Manchee and Stewart, 1988).

     The psychological impact of being exposed to a poison is not well studied. Whether crowds will listen to instructions or panic, what they need to be told and how that message should be given, whether they will take off their clothes in the absence of an obvious immediate danger, whether they will shower with persons they have never met before, and how best to control or avoid hysteria are among the issues that need to be addressed.

     The three primary objectives of a disaster response are: (1) do the greatest good for the greatest number of victims; (2) effectively utilize personnel, equipment, and health facilities; and (3) do not relocate the disaster from one location to another by poor command, control, or communication practices.

     The triage process is the initial step taken to meet the primary objectives of a disaster response. The purpose of triage is to sort the injured by priority and determine the best use of available resources (e.g., personnel, equipment, medications, ambulances, and hospital beds). Many EMS agencies have in place a triage plan to implement in the event of an airplane crash, train derailment, or school bus accident. Traditional triage centers around the use of diagnosis-based criteria or involves the evaluation of each patient's respiration, perfusion, and mental status findings in order to determine whether they should be classified as urgent, delayed, or deceased. Both triage approaches require the examiner to see the patient and obtain certain clinical data by verbal communication and tactile examination. In a chemical terrorist incident the victim(s) may suffer from the effects of poison, trauma, or both. In a more conventional disaster, unless they are in danger, the patients can usually remain in place until directed to relocate. Their evacuation and treatment priority is indicated on a triage tag or colored ribbon. Unlike military triage protocols, where the focus is on successful completion of the "mission," the emphasis in the civilian sector is on saving as many persons as possible.

     There are several differences between the triage done for the traditional disaster scenario and that for a hazardous material incident or a chemical/biological terrorist event. Time demands, patient volume, and the PPE being worn by response personnel in the hot and warm zones may preclude normal life-saving measures being rendered quickly, if at all. For example, verbal communication may not be possible because of the responder's PPE. A tactile examination may not be possible for the same reason. Additionally, the whole concept of traditional triage (treating the most seriously injured first) may not be applicable in a chemical or biological incident. Those walking around may need to be among the first to be decontaminated and evacuated because they have the best chance of survival. It is not desirable that victims remain in place in the hot zone until examined. Rather, immediate evacuation efforts should be undertaken and the victims directed towards the decon process established in the warm zone. Also, there will be little, if any, time to indicate a patient's priority on a triage tag in the hot or warm zones. Additionally, the patient data recorded on a triage tag is at risk of getting defaced when the tag becomes wet during decontamination.

     Psychological issues also play a part in triage after a mass chemical or biological terrorist attack. Among the most important directions given to victims of nonhazmat incidents is how to evacuate the area, stop bleeding, and stay warm. The mixture of men with women and young and old together in this circumstance poses psychological problems.

     A comprehensive national training program on the medical management of patients injured by weapons of mass destruction (WMD) should be developed for prehospital and hospital personnel. The curriculum should include the following:

• site management/crowd control,

• triage,

• providing medical care while wearing PPE,

• set-up of mass decon areas in the field and at hospitals,

• performing mass decon on ambulatory and nonambulatory patients of all ages, and

• proper recognition and management of the psychological aspects of undergoing decontamination and exposure to WMD.

Little empirically based information exists in these areas, but it appears to the committee that equipment needs are secondary to information about procedures and methods.

7-1 The committee therefore recommends that research and development efforts in decontamination and mass triage be concentrated on operations research on procedures and techniques for effective decontamination of large numbers of people. Such research should include:

the physical layout, equipment, and supply requirements for performing mass decon for ambulatory and nonambulatory patients of all ages and health in the field and in the hospital;

a standardized patient assessment and triage process for evaluating contaminated patients of all ages;

optimal solution(s) for performing patient decon, including decon of mucous membranes and open wounds;

the benefit vs. the risk of removing patient clothing;

effectiveness of removing agent from clothing by a showering process;

how much contact time for showering is necessary to remove a chemical agent;

whether high pressure/low volume or low pressure/high volume spray is more effective for patient decontamination;

the best methodology to employ in determining if a patient is "clean"; and

the psychological impact of undergoing decontamination on all age groups.