Multi-specialty panel presents consensus guidelines for prehospital management of mass casualties from chemical warfare agents
The release of chemical weapons by terrorists would present an enormous challenge for the medical and public safety communities. EMS personnel would be confronted with a large volume of patients displaying atypical medical conditions, such as wide-spread chemical burns, blistering, blurred vision or blindness.
Although the probability of an attack is small, improper patient handling because of inaccurate, presumptive diagnoses can lead to contamination of health-care providers. Therefore, the availability of clear and specific guidelines for prehospital care providers will help ensure prompt treatment of victims if and when a chemical attack occurs.
Most clinical publications regarding chemical warfare agents have been scholarly reviews. Although this format has an important role, a review does not lend itself to practical clinical application. Thus, the guidelines developed by this consensus process focus on critical actions rather than a review of the topic. The guidelines are for the treatment of patients exposed to nerve agents, chlorine, cyanide, phosgene and sulfur mustard agentsƒthe five chemical substances commonly designated as potential terrorist warfare agents.
Development of treatment guidelines
These important triage guidelines were developed under a grant from the Office of Public Health Emergency Preparedness in the U.S. Department of Health and Human Services, using evidence from the published medical literature and from the clinical knowledge of a national consensus panel with expertise in chemical warfare agents.
The panel conducted an extensive literature search (of 1966Ï2002 Medline data), including articles from all languages. The medical subject headings for the literature search consisted of each agent name with sub-headings "toxicity,""poisoning" and "adverse effects"; text word searches consisted of each agent name paired with "poisoning,""toxicity,""ingestion" or "inhalation." The authors also searched bibliographies of the collected articles and current toxicology textbooks for additional citations, including those prior to 1966.
Articles chosen for inclusion contained patient data from human exposure to the agent of focus. Reviews, chapters, editorials and commentaries were included only if they documented the diagnosis, management or outcome of at least one patient exposed to the particular agent of focus.
Despite our extensive search, we found little data regarding the prehospital treatment of victims of chemical warfare in the medical literature. The original search identified a total of 1,011 articles, of which 364 included patient data: 212 involved hospital management, and„ involved prehospital management (see Table 1).
We assessed each article for data relevant to diagnosis, assessment or treatment of a patient in the prehospital setting by a physician reviewer not involved in the consensus process. The non-voting panel chair drafted each outline algorithm to include these questions:„„
a. What critical historical information should be collected during prehospital care?
b. What critical components of the physical exam should be performed during prehospital care?
c. Is there other critical assessment information that should be collected during prehospital care?
2. Should treatment be performed during prehospital care?„
a. What are the indications for treatment?
b. What is the dosage and dosing schedule?
c. How should the patient's response be monitored?
The consensus process (Figure 1) involved an initial meeting of the entire panel, followed by a modified Delphi approach using an electronic communication process based on electronic mail, which included structured information flow, feedback to the participants and anonymity for the participants.
The panel was asked to employ its expertise when responding to each round of the draft guidelines and to provide comments and pertinent additional literature citations. Near the end of the process, a final meeting of the panel participants was held to evaluate remaining issues and achieve final panel consensus. The panel approved a final version of each guideline by vote.
Each guideline begins with diagnosis of a chemical exposure and provides specific clinical guidelines that address the initial care of the poisoned patient, typically until the patient has completed the emergency phase of care. Each guideline also includes a clear decision point when the diagnosis is reconsidered: "Evidence of [agent name] exposure present?" If the answer to this question is negative, the user is directed to consider alternative diagnoses.
Table 2 (PDF) presents the guidelines for prehospital treatment of patients exposed to nerve agents. Additional guidelines for the treatment of patients exposed to chlorine, cyanide, phosgene and sulfur mustard agents can be downloaded from„www.jems.com/terrorism-wmdresponse.
A large volume of literature has emerged concerning decontamination of the chemically contaminated patient, but many have concluded that simple decontamination by disrobing and copious flushing with water, with or without soap, is appropriate and adequate for nearly all chemical casualties.
The ability of EMS or an emergency department (ED) to accommodate patients could vary substantially depending on several factors, such as institutional level of preparedness, time of day and staffing at the time of presentation. To address this, we created the concepts of "capacity adequate" and "capacity exceeded" for each guideline to identify essential recommendations for when EMS or an ED cannot accommodate the volume and severity of patients presenting for care.„
One limitation regarding guidelines based on the chemical agent involved is that the agent may be unidentified or misidentified. It's also possible that multiple agents could be involved simultaneously. An acronym for assisting the emergency responder in conducting a thorough, systematic assessment of a poisoned casualty ƒ ASBESTOS (agent, state of agent, body sites, effects, severity, time course, other diagnoses and synergism) ƒ has been previously described. We included a step for the responder to assess the patient's clinical manifestations in the context of the presumed clinical agent and, if there are inconsistencies, to consider alternative diagnoses.„
It is the objective of this panel that these guidelines will be used to consolidate and advance our preparedness efforts against terrorism in communities across the nation. We encourage readers to download the additional algorithms at„www.jems.com/terrorism-wmdresponse and share them within their EMS agencies and with other preparedness response partners. An effective EMS response is a critical first step in responding to casualties of chemical agent exposures, and these guidelines are another tool to assist EMS responders.
The authors are members of the consensus panel convened to develop these guidelines or those that supported their efforts. Their complete credentials and affiliations are available at„www.jems.com/terrorism-wmdresponse.
Acknowledgement: Sponsorship and partial financial support for this project was provided by the Office of Public Health Emergency Preparedness, United States Department of Health and Human Services.