478 Emergency Medicine
which causes cell denaturing upon contact. Ammonia (c)is present in many
household cleaners, as a cooling agent in refrigerator units, and as a fertilizer
owing to its high nitrogen content and may act differently depending in what
form it is in. For example, it may freeze skin on contact or affect breathing
because of its vapors. Formic acid (d)is a caustic organic acid used in many
industries that causes a coagulation necrosis. Treatment for exposure to all
of these chemicals includes copious irrigation and observation for systemic
side effects.
427.The answer is b.(Rosen, pp 775-776.)Cat bitesinvolvepuncture
woundsoften extending down through skin into tendons and bones owing
to the nature of the animals’ sharp teeth. The reported incidence of infection
from these bites may be as high as 30% to 50%, with many patients presenting
only after an infection has incurred. It is important to note that cat bites
have a higher infection rate compared to dog bites, given the typical puncture
wound that inoculates bacteria down the track deep into tissue and becomes
enclosed.Pasteurella multocidais a strong gram-negative, facultative anaerobic
rod found in the oral cavity of the majority of healthy cats and may cause
severe systemic infection, especially in the immunocompromised. Patients
need to be followed closely as these infections may seed deep into joints
and tissue requiring debridement.
(a)First-generation cephalosporins have proven to be only minimally
effective. The organism is resistant to (d)vancomycin and (c)clindamycin.
(e)Antibiotic topicals, such as bacitracin, would be inappropriate given the
high virulence of this organism.
428.The answer is c.(Rosen, pp 801-812.)This patient sustained a
second-degree burn involving 2.25% of her body surface area (BSA),
according to the rule of nines. The rule of nines aids in estimating the area
of involvement as seen below. In the adult, each anterior or posterior sur-
face of the upper extremity and head are equal to 4.5%. Each surface of the
lower extremity is equal to 9%. Each surface of the chest and torso is equal
to 18%.Perineal areas account for 1% of BSA. Children and infants have
increased total BSA relative to their weight, thereby requiring different fluid
requirementsand area estimation. More percentage is dedicated to the
head given their larger head-to-body ratios (7% in children and 9% in
infants). The treatment for this patient involves silver sulfadiazine dress-
ings and close follow-up.Prophylactic antibiotics are not warranted in
these cases, given the chance of increased future resistance rates. For areas
of greater involvement and inhalation burns, fluid resuscitation may