Pediatric emergency medicine trisk 4581 4581
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Riot-control agents, also called lacrimators (“tear gas”), include several
compounds, the most important of which are CS (o-chlorobenzylidene
malononitrile), CN (1-chloroacetophenone, also marketed as Mace), and OC
(oleoresin capsicum, or pepper spray). All three are solids and are typically
dispersed as an aerosol of fine particles (e.g., smokes) or droplets (e.g., sprays).
These agents are widely available, cause significant incapacitating effects in
closed spaces, and could conceivably be used in a terrorist attack.
CS and CN generate bradykinins leading to pain without significant tissue
injury; OC binds to VR1 (TRPV1) receptors on sensory neurons and causes the
release of substance P, which leads to neurogenic inflammation with vasodilation,
hyperemia, and plasma extravasation as well as pain. All these agents can cause
transient ocular burning sensation, tearing, blepharospasm, and photophobia;
irritation of the nose, throat, and upper airway; and skin burning, erythema, and
sometimes vesication. A few riot-control agents, such as Adamsite (DM), are
referred to as vomiting agents because they cause pronounced vomiting in
addition to delayed-onset irritation of the eyes and the upper airway.
Most victims under usual circumstances of exposure become symptomatic
within seconds from the traditional lacrimating agents (irritation after exposure to
DM may take up to 20 minutes to develop) but remain so for only 20 to 60
minutes. However, high concentrations in closed spaces or after discharge of
agent close to the victim’s face have been associated with serious medical
complications, including severe ocular toxicity, dermal burns, and pulmonary
failure. A few lethal cases have been described in which death was caused by
severe tracheobronchitis with pseudomembrane formation and pulmonary edema.
Management includes careful ocular and dermal decontamination. The skin
should be washed with soap and water, although this may cause transient
increased pain. Hypochlorite solution should not be used because it may
exacerbate dermal burns via the creation of toxic by-products. The eyes should be
thoroughly irrigated after a single dose of topical anesthetic.
Respiratory complications must be managed supportively, as previously
described for mustard and pulmonary-agent toxicity. Because severe respiratory
effects may not manifest for 12 to 24 hours, patients with dyspnea or any
objective findings should probably be observed in the hospital. Severe respiratory
complications from exposure to riot-control agents have been described in at least
two young infants, one of whom was in a house into which CS was sprayed. A
canister of pepper spray was accidentally discharged directly into the face of the
other infant. Both survived with prolonged care, the latter requiring ventilatory
support, including 5 days of extracorporeal membrane oxygenation. A few cases
