Physical properties

CWAs generally are stored and transported as liquids and deployed as either liquid aerosols or vapors. Victims usually are exposed to agents via one or more of 3 routes: skin (liquid and high vapor concentrations), eyes (liquid or vapor), and respiratory tract (vapor inhalation).

CWAs are characterized by 2 inversely related physical properties: volatility (ie, tendency of liquids to vaporize, which directly increases with temperature) and persistence (ie, tendency of liquids to remain in a liquid state).

In general, volatile liquids pose the dual risk of dermal and inhalation exposure, while persistent liquids are more likely to be absorbed across the skin. The effects of vapors largely are influenced by ambient wind conditions; even a slight breeze can blow nerve agent vapor away from its intended target. Effects of vapor are enhanced markedly when deployed within an enclosed space.

Clinical effects

Depending on the agent and the type and amount (concentration) of exposure, CWA effects may be immediate or delayed. Large inhalation exposures to nerve agents or mustards are likely to be lethal immediately. Small dermal exposures to nerve agents and mustards are particularly insidious and generally require expectant observation for variable periods because of possible delayed effects. Specific clinical effects of CWAs are as varied as the agents.

Medical management

To appropriately manage CWA exposures, emergency care personnel are required to protect themselves by performing the following:

• Using PPE
• Decontaminating patients immediately
• Providing supportive care
• Providing specific antidotes when indicated

Personal protective equipment

The primary responsibility of those who treat victims of CWAs is to protect themselves by wearing adequate PPE. First responders are at serious risk from the chemically contaminated environment (hot zone), either from direct contact with persistent liquid or from inhaling vapor. First responders and emergency care providers also are at risk from handling skin and clothing of victims contaminated with liquid CWAs (secondary skin and inhalation exposure). Conversely, providing care to those exposed only to vapor CWAs poses little risk to emergency care providers outside the hot zone. Regardless, until identification of the substance is made and it is deemed nontoxic, responders should wear their PPE.

Standard protective garments are inadequate for most CWAs. Double layers of latex gloves are useless against liquid nerve and blister agents, and surgical masks and air-purifying respirators are inadequate against nerve agent vapors.

Date: 2015-01-12; view: 821