137 Chemical and Nuclear Agents
Key Points• Decontamination should take place immediately, before initial treatment and evacuation of exposed patients.
• For patients exposed to nerve agents, atropine and pralidoxime chloride should be administered rapidly.
• Treatment of blast injuries and emergency medical conditions should precede specific treatment of radiation exposure.
Epidemiology
Tens of thousands of chemicals are manufactured, transported, and used every day. The 1984 Bhopal, India, disaster revealed the dangers posed by chemical agents. A 2008 U.S. Department of Health and Human Services database of 14 states reported more than 15,000 chemical-related events and over 4500 casualties.1 Since World War I, chemical agents have also been used intentionally on civilian and military personnel, most recently in Japan in 1994-1995, in Russia in 2002, and in Iraq in 2007. Of the 13 categories of chemical agents recognized by the U.S. Centers for Disease Control and Prevention, the four principal categories are nerve, vesicant, blood, and pulmonary agents2 (Box 137.1).
Box 137.1
Categories of Chemical Agents
From U.S. Centers for Disease Control and Prevention. Chemical categories. Available at http://www.bt.cdc.gov/agent/agentlistchem-category.asp.
Perspective
Casualties involving chemical and radiologic or nuclear agents have traditionally been associated with military armed conflicts. However, over the past 25 years, with the increased production and distribution of industrial chemicals, as well as the escalating threat of terrorist use of weapons of mass destruction, management of casualties from chemical, biologic, radiologic, nuclear, and high-yield explosive events has increasingly become the responsibility of the EP.3
Initially approved in 1999 and revised in 2006, the American College of Emergency Physicians (ACEP) issued a clinical policy statement that recognized the risk posed by accidental or intentional release of chemical and nuclear hazardous material (HAZMAT).4 In another clinical policy statement, the ACEP also encouraged EPs to assume a primary role in the medical aspects of planning, management, and patient care during disasters, including those involving chemical, radiologic, and nuclear agents.5
Basic Principles of Managing Contaminated Patients
Communication and Mobilization
Most events involving chemical or radioactive agents are rapidly identified by emergency services. Notification of health care facilities of a HAZMAT incident and casualties must also take place rapidly because 50% to 80% of the acute casualties will arrive at the closest health care facilities within 90 minutes following an event.6 Some casualties may leave the scene under their own power and go to a nearby health care facility, even before other patients arrive via emergency medical services.7,8
Decontamination
Decontamination should take place immediately, before initial treatment and evacuation of exposed patients. Although decontamination is usually completed at the scene before transportation, exposed and potentially contaminated patients may go on their own to nearby health care facilities.9 In addition to requiring primary decontamination and triage, these patients may secondarily contaminate existing patients and medical personnel and thus create additional casualties and diminish the response by the affected facility.7,9,10
Removal of contaminated clothing can eliminate 70% to 90% of HAZMAT.11,12 Once completed, patients should shower—or be showered if incapacitated—with copious amounts of tepid water. Several adjuncts, such as hypoallergenic liquid soap, may be helpful. Other adjuncts, including hard brushes and dilute additives such as bleach, are unlikely to provide additional benefit and, in some scenarios, could be harmful. Contaminated clothing and special items such as valuables and firearms should be labeled and securely contained to prevent accidental or continued secondary contamination, as well as for possible forensic analysis during a HAZMAT or criminal investigation.12–16
Security
Security personnel at health care facilities should be engaged promptly because their primary responsibility is to protect existing patients, staff, and the health care facility from contamination and distraction from avoidable crowds by controlling all access points to the facility. This responsibility may entail limiting visits from arriving friends, family, and other third parties, as well as sequestering contaminated patients.17
Security personnel should control traffic flow to and within the facility. Incoming patients should be directed to designated triage and decontamination sites, and the arrival of hospital personnel should be expedited. Patients awaiting further evaluation and disposition may be directed to secondary triage, holding, and treatment areas. Security personnel should coordinate with law enforcement and government agencies, safeguard valuables, and maintain the chain of custody of firearms and forensic evidence.9,10,17
Chemical Agents
Nerve Agents
Pathophysiology
Absorbed through inhalation and skin contact, nerve agents irreversibly bind and inactivate acetylcholinesterase (AChE) receptors, thereby leading to excessive accumulation of acetylcholine and overstimulation of nicotinic and muscarinic receptors. Though dose dependent, the effects from inhalation begin within seconds and peak within minutes, whereas the effects from skin exposure may take minutes to hours to become evident.18–20
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