Pediatric emergency medicine trisk 1143
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management of suspected FGA exposures differs from the approach used for
traditional nerve agents. All individuals suspected of having been exposed need to
be identified, decontaminated, and observed, with serial determinations of RBC
cholinesterase or plasma cholinesterase as well as heart rate and temperature
monitoring. Meanwhile, epidemiologic clues may lead to the identification of
additional possibly exposed individuals.
A-series agents are difficult to treat once victims have gone into cholinergic
crisis; aggressive treatment with atropine and an oxime is needed along with
scopolamine (initially 1 mg IV in adults; the dose may be scaled down for
children). During the latent period, victims need to be decontaminated thoroughly
as soon as possible, although decontamination may be effective even an hour or
two after exposure. Heart rate, core temperature, and cholinesterase levels in the
blood or plasma (or both) should be monitored. Pyridostigmine bromide (PB) 30
mg orally every 8 hours in adults (lower doses scaled to body weight are
appropriate for children) should be considered; this is normally given as a
pretreatment for nerve-agent exposure and is not given after the onset of
cholinergic crisis. PB is a carbamate anticholinesterase used in anesthesia and in
the treatment of conditions such as myasthenia gravis. At the time of the 1990
Gulf War, the U.S. FDA approved it as a pretreatment to be given before
exposure in situations in which the risk of exposure to the traditional nerve agent
soman (GD) was high. (PB is a pretreatment , or pre-exposure antidotal
enhancement, not prophylaxis ; it helps antidotes to work better, but the antidotes
still have to be given.) Subsequently, the FDA extended that approval for
conditions in which exposure to any nerve agent was likely. PB pretreatment is
not normally a consideration outside military scenarios, but because of the long
latent periods with FGAs, administration of PB during the latent period, when the
outside of the body has technically been exposed but the target organs (the CNS,
skeletal muscles, smooth muscles, and exocrine glands) have not yet been
exposed, could theoretically be of use. If a provider–patient relationship exists,
PB might be considered when given under informed consent. PB will predictably
depress cholinesterase levels, but the drop is only about 30% from the
preadministration values; if cholinesterase levels drop precipitously during the
latent period, or if the heart rate or core temperature decreases by more than 25%
from baseline, the patient should be treated for full-blown cholinergic crisis.
TABLE 132.4
PRIMARY THREAT CHEMICAL AGENTS OF TERRORISM
TABLE 132.5
AUTOINJECTOR ADMINISTRATION OF NERVE-AGENT
ANTIDOTES FOR INITIAL THERAPY OF SEVERELY AFFECTED
MASS CASUALTIES OR IN PREHOSPITAL SETTING
Atropine
Approximate age
Approximate weight (kg)
Autoinjector size (mg) a
<6 mo
<7.5
0.25
6 mo–4 yrs
7.5–18
0.5
5–10 yrs
18–30
1
10 yrs
>30
2 (adult size)
Pralidoxime b (or combination pralidoxime/atropine c )
Approximate age
(yrs)
Approximate weight (kg)
Number of autoinjectors
3–7
13–25
1
8–14
26–50
2
14
>50
3
Diazepam (10 mg each, for seizures, or severe exposure)
Approximate age
(yrs)
Number of autoinjectors
5–Adolescent
Adolescent and
older
1
2
a Administer
one autoinjector of each size indicated.
autoinjectors (e.g., 2 mg of atropine, 600-mg pralidoxime, combination of 2.1-mg atropine
and 600-mg pralidoxime or 10-mg diazepam), while not approved for pediatric use, might be considered as
initial treatment in dire (especially prehospital) circumstances, for children with severe, life-threatening
nerve-agent toxicity who lack intravenous access, and for whom more precise, mg/kg IM dosing (as per
Table 132.4 ) would be logistically impossible. Suggested pralidoxime dosing guidelines are offered: Note
potential excess of initial dose for age/weight, although within general guidelines for recommended total
over first 60–90 min of therapy of severe exposures.
c The combination autoinjectors may also be used for children in these age and size categories, as noted, to
replace both atropine and pralidoxime for initial therapy in severe cases. Such use will result in moderate
excess dosage of both antidotes, but again, generally within the guidelines for recommended total over the
first 60–90 min of therapy for severe exposures.
b Adult-intended
Adapted from Henretig FM, Cieslak TJ, Eitzen EM Jr. Biological and chemical terrorism. J Pediatr
2002;141:311–326. Copyright © 2002 Elsevier. With permission
FIGURE 132.7 Autoinjector-packaged pralidoxime can be injected into an empty vial for
subsequent reuse in small pediatric patients. (Reprinted from Henretig FM, Mechem C, Jew R.
Potential use of autoinjector-packaged antidotes for treatment of pediatric nerve agent toxicity.
Ann Emerg Med 2002;40:405–408. Copyright © 2002 American College of Emergency
Physicians. With permission.)
Specific Pediatric Considerations. The thinner skin of children might make
them more susceptible to dermal absorption of chemical toxins in comparison to
adults ( Table 132.2 ). Likewise, the immature blood–brain barrier in infants
might increase the relative risk of CNS toxicity. Children have smaller airway
diameters, anatomic subglottic narrowing, and higher respiratory rates as well as
exhibit limited endurance of the accessory muscles of breathing; these
characteristics could predispose to earlier and more severe respiratory effects
from nerve agents. In addition, children have a greater susceptibility to seizures.
Although OP-pesticide poisoning in children may certainly manifest by dramatic
muscarinic findings, including respiratory compromise (see Chapter 102
Toxicologic Emergencies ), one case series of anticholinesterase pesticide
poisoning in children found that depressed sensorium and muscle weakness and
flaccidity were more prominent than muscarinic findings. Nevertheless, more
than half of these patients did demonstrate miosis (80%), tearing and excess
salivation (60%), and GI findings (52%). Other studies have shown an absence of
