Chapter 132

• Nerve agents cause death by respiratory failure, primarily from the muscarinic effects of bronchorrhea and bronchospasm.
• The antidote atropine can counteract the muscarinic effects of nerve agents.
• Removing all clothing and jewelry will most likely constitute adequate decontamination of victims exposed to nerve agent vapor.

Planning for a medical response to terrorism has primarily focused around the needs of healthy military recruits or the population as a whole. There as been little discussion pertaining to vulnerable populations such as children. Unfortunately, entire communities are now at risk for terrorism. Children are even more susceptible than adults to the effects of chemical weapons, especially those that are inhaled or absorbed through the skin.1 There are several reasons for this such as, a child's surface area relative to his or her body mass is greater than that of an adult, increasing effective dermal absorption of chemical agents, as well as the risk of fluid loss and hypothermia. The child's higher metabolic and respiratory rates would increase uptake of inhaled vapors. Metabolic pathways that detoxify or eliminate poisons may be underdeveloped. Many chemical agents, such as vesicants and the nerve agents, are heavier than air, producing increased concentrations closer to the ground. In addition, aspects of disaster planning and response such as mass decontamination of children and dosing of antidotes in the pediatric population would pose unique challenges.

Nerve agents are highly toxic organophosphate compounds first developed in the years leading up World War II. They are, essentially, much more potent versions of the organophosphate insecticides. Although commonly called “nerve gases”, these agents are actually liquids with variable volatility at room temperature. Nerve agents that have been manufactured and stockpiled in the past include tabun, sarin, and soman. VX is the most potent of these agents, with a potentially fatal liquid exposure involving as little as one drop applied to the skin of an adult; this lethal amount would be proportionally much less in children.

Nerve agents are powerful inhibitors of the enzyme acetylcholinesterase (AChE). This enzyme normally serves to modulate the actions of acetylcholine, a neurotransmitter that is found throughout the peripheral and central nervous systems. With the enzyme blocked, acetylcholine accumulates and the cholinergic receptors become overstimulated in an uncontrolled manner. There are three major classifications of cholinergic receptors and actions:

### Muscarinic

These receptors are found at the neuromuscular junction of smooth (involuntary) muscles of the respiratory and gastrointestinal tracts, as well as in secretory glands. As acetylcholine builds up in these locations, smooth muscle contracts spasmodically and glands secrete uncontrollably. A convenient mnemonic to help remember the muscarinic actions of nerve agents is DUMBELS:

•     Diaphoresis, Diarrhea
•     Urination
•     Miosis
•     Bronchorrhea, Bronchospasm
•     Emesis
•     Lacrimation
•     Salivation, Sweating

Victims of nerve gas exposure die from respiratory failure, primarily because of bronchorrhea ...

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