Pediatric emergency medicine trisk 4558 4558
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The physical forms of CWAs are dictated by their chemical structures and by
properties such as volatility (speed of evaporation), which is inversely related to
environmental persistence. Nonpersistent agents are gases (such as chlorine and
phosgene) or volatile liquids (such as cyanide and the G-series nerve agents) at
ambient temperatures. Persistent agents, which can be either solids or lowvolatility liquids, include sulfur mustard and the V- and A-series nerve agents and
can pose a high risk of secondary contamination from the environment or from
contaminated casualties. Routes of exposure to CWAs are primarily inhalational
and dermal; ocular, enteral, and parenteral (from contamination of wounds) are
less common. Inhalation is the typical route of exposure for volatile,
nonpersistent agents, although aerosolized liquids and solids, even those of low
volatility, can also be inhaled. Effects following exposure may be local (at or near
the sites of exposure), systemic (at body sites remote from the sites of exposure),
or both. Although CWAs may begin damaging tissue immediately upon exposure,
with inhaled phosgene or dermal exposure to sulfur mustard, VX, or the A-series
NTAs the onset of signs and symptoms may be delayed for several hours or even
longer.
This section of the chapter focuses on the extremely potent nerve agents but
will also detail other categories of toxic CWAs and several industrial chemicals.
General principles of supportive care for poisoned patients are detailed in Chapter
102 Toxicologic Emergencies ; these principles also apply largely to the general
support of CWA victims.
Goals of Treatment
The goals of emergency therapy are prompt recognition of chemical casualties,
immediate decontamination, acute supportive care, and administration of specific
antidotes and other medical countermeasures, as applicable, while protecting
medical providers and hospital infrastructure from secondary contamination.
Clinical Considerations
Clinical Recognition
Chemical attacks can generate large numbers of casualties with a common
exposure history, but the recognition of even isolated cases is important. Perhaps
the most critical emergent decision for ED staff is to distinguish cyanide from
nerve-agent poisoning because the immediate antidotal therapies are quite
different. In both cases victims may present with sudden collapse, coma, and
seizures, with many deaths occurring rapidly. However, nerve-agent casualties
will more likely exhibit miosis, cyanosis, copious oral and nasal secretions,
