Chemical Release - Major Incidents - @ JEMS.com


Chemical Release

Response & decontamination for large-scale chemical events

 

 
 
 

Mark A. Kirk, MD | From the Disaster & Terrorism Preparedness Issue


Faced with a large number of people exposed to a chemical warfare agent or a toxic industrial chemical, EMS responders should remember a simple rule of thumb: Consider the victims to be on fire and act with the same urgency. Jarring as it may seem, such practical guidance can help first responders prioritize and provide the best care for the most people.

Medical management following a large-scale chemical release requires a sequence of steps to remove patients from a toxic environment, decontaminate them on scene and deliver them to a hospital setting. However, the first EMS personnel to arrive at the scene of a chemical incident must not become sidetracked in setting up a multi-step process for patient decon. Knowing what to do in such a disaster begins with understanding that every second counts and that patient decon is, above all, a first aid procedure.

When performed swiftly and with the proper techniques, decon limits adverse health effects. It also protects responders in the field and providers in hospitals from secondary contamination.

Preparedness is critical because the threat is real. In 1995, the infamous sarin attack on several lines of the Tokyo subway killed around a dozen people, injured hundreds and prompted thousands to seek medical care. In 2005, two trains collided in Graniteville, S.C., rupturing a tank car that released about 60 tons of chlorine gas. Nine people died and more than 500 others were treated for chemical exposure.

When it comes to decon, EMS personnel can benefit from knowing the fundamentals of toxicology. Fortunately, the basics are straightforward. They center on the two concepts of routes of exposure and dose response.

Toxicology Fundamentals
Hazardous chemicals can enter the body through contact with the skin or the two pathways of inhalation, called routes of exposure. Decon should focus on the removal of hazardous substances that have come into contact with skin and clothing.

The term dose response refers to the escalating harmful effects that occur as the amount of the contaminant increases. To better understand the phenomenon, consider what happens when someone drinks one, five or 10 beers. The more a person consumes, the more severe the intoxicating effects.

The same holds true for inhalation and skin exposure. The dose, which influences the harmful effects, is determined by the duration and concentration of the exposure.

Toxic liquids splashed on the skin typically cause tissue damage in the form of chemical burns or blisters. Strong acids and bases, which are known for their corrosive effects, can be especially harmful. The quicker the removal of toxic substance that is in contact with the skin, the less absorption will occur and the less severe the health effects will be.

Beyond injury from direct contact, many chemicals can penetrate the skin and enter the circulatory system. For instance, hydrofluoric acid may cause systemic toxicity and eventual cardiac arrest. Similarly, organophosphate insecticides and nerve agents may cause vomiting, copious pulmonary secretions, respiratory distress, muscle paralysis, seizures and coma.

The route of exposure helps determine the decon procedure. Gases and vapors pose inhalation risks, but many do not cause contamination. For example, carbon monoxide may cause severe central nervous system and cardiac effects but poses no skin absorption risk.

However, some vapors can condense on the skin and clothing and pose a risk. Additionally, some chemicals can penetrate the skin easily; their unique properties determining how readily they may be absorbed.

In cases of slow absorption, patients may fall ill hours after exposure. Each incident is unique and the incident commander must evaluate many variables when determining the need for decon.

Executing Decontamination
Consequences of ineffective decon include resource demands on all facets of the response system, degrading medical care, and potential delays in transport to hospitals as well as in administering life-saving antidotes.

Once on scene, responders may need to focus on those requiring immediate medical care and those grossly contaminated. Victims will self-evacuate before responders are able to fully assess the scene and before thorough decon equipment is ready to use. Responders must persuade patients to stay in the immediate vicinity until decontaminated.

Responders arriving at the scene will face three types of victims:
1. Those with toxic effects or contaminants on skin or clothes;
2. Those exhibiting mild symptoms or without obvious contamination on skin or clothes who are potentially contaminated; and
3. Those at low risk for significant exposure and without symptoms who are concerned about their exposure.

The immediate first decon action is clothing removal. This is followed by flushing with copious amounts of water. Emergency response personnel must do these two things within two minutes of recognizing contaminated patients. They should also instruct ambulatory patients to begin removing clothing on their own and aid those in need of assistance. These steps will decrease the contact time of chemicals and limit absorption, reducing the dose a person would otherwise sustain. Following these initial steps, a more thorough process ensures patients are sufficiently decontaminated for safe handling without high-level PPE and safe to transport away from the scene. These additional steps isolate contamination and prevent its spread to such critical response resources as responders, ambulances and hospitals.

Conclusion
The Department of Homeland Security (DHS) established the Chemical Defense Program in 2011 to help build preparedness and response capabilities.(1) The program provides guidance with respect to rapid detection, decision-making and life-saving actions. It also recognizes the critical role of decon in emergency response and promotes publications with detailed best practices, such as the Occupational Safety and Health Administration’s “Best Practices for Protecting EMS Responders during Treatment and Transport of Victims of Hazardous Substance Releases.”(2)

Researchers need to develop a “standard of care” as well as a universal decon protocol that is not specific for any chemical. Such a protocol would reduce confusion, minimize delays and save lives. To help close the knowledge gaps, DHS and Health and Human Services are leading a working group on mass human chemical decon with the involvement of the White House Office of Science and Technology Policy. The group seeks to translate science into best practices and identify the best method of patient decon in large-scale events where resources are limited.(3)

Until guidance with a stronger scientific basis is available, responders must remember in the wake of a major chemical release that patient decon is primarily a first aid procedure and that, in treating patients, they face a race against time.

Editor’s Note: Go to the online version of this supplement at jems.com/supplements for a comprehensive list of tips for first responders.

References
1. U.S. Department of Homeland Security. (July 15, 2011). Science & Technology Directorate Chemical & Biological Division. In Department of Homeland Security. www.dhs.gov/xabout/structure/gc_1224531303278.shtm.
2. Federal Emergency Management Administration. (Nov. 18, 2009). Responder Knowledge Base. In FEMA Responder Knowledge Base. www.rkb.us/contentdetail.cfm?content_id=226784.
3. Franco C, Bouri N. (2012). Environmental Decontamination Following a Large-Scale Bioterrorism Attack: Federal Progress and Remaining Gaps. In Center for Biosecurity of UPMC. www.upmc-biosecurity.org/website/resources/publications/2010/2010-04-07-environmental_decontamination.html.



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Related Topics: Major Incidents, WMD and Terrorism, toxic inhalation. chemical release, decontamination, decon, chemical warfare agent

 

Mark A. Kirk, MDMark A. Kirk, MD, is currently medical director of Medical Simulation Center and associate professor of emergency medicine at the University of Virginia.

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