476 Emergency Medicine
423.The answer is d.(Rosen, pp 2010-2019.)The patient sustained a
low-voltage (< 1000 V) electrical injuryfrom the wall socket. All patients
sustaining such an injury warrant an ECGandcardiac monitoringin the
ED. In the United States, household wiring has 120 V of alternating current
with a frequency (number of switches from positive to negative) of 60 Hz.
Alternating current causes continuous muscle contraction and stimulation
that may cause ventricular fibrillation. Direct current usually just causes a
single muscle spasm and is the less dangerous of the two, depending upon
the voltage. The current is equal to the voltage over the resistance (Ohm’s
law). This patient sustained a superficial thermal burn and most likely did
not become part of the circuit given that there were not any clear entry or
exit wounds as seen in direct-contact injuries. Disposition of this patient
should include localized wound care, close follow-up, and instructions to
return if there are any worsening symptoms.
(a and b)Although a urinalysis to screen for myoglobin and a basic
metabolic panel to check renal function might be performed, it is not neces-
sary given the nature of this child’s injury. (c and e)A chest x-ray and arterial
Doppler will not prove efficacious given the clinical examination.
424.The answer is c.(Rosen, pp 797-799.)This patient sustained an injury
from a venomous marine animal.Approximately 50,000 such incidents
occur yearly. Marine animals may be divided into two classes: stingers and
nematocysts.Stingers include sea urchins, stingrays, catfish, cone shells, and
starfish. Radiographs may be useful in delineating the calciferous material
deposited in the skin for removal. Nematocysts are much more prevalent
and account for the majority of envenomations and most likely account for
this patient’s distress. This class includes jellyfish, fire corals, Portuguese
man-o-war, and anemones. These creatures have spring-loaded venomous
glands that discharge upon mechanical or chemical stimulation. The number
of nematocysts on a tentacle can number in the thousands. These stinging cells
can remain activated after weeks of the animal being beached. The venom
containsvarious peptides and enzymes that may cause progression of symp-
toms including nausea, muscle cramps, dyspnea, angioedema, and anaphy-
laxis. The preferred treatment is vinegar,which deactivates the nematocyst.
In cases where medical attention cannot be sought in a timely manner,
urine has been shown to be just as efficacious. An attempt may be made to
shave off nematocysts after proper analgesia. Patient should be given tetanus
prophylaxis and antihistamines as needed.