Environmental Exposures Answers 485patients with a history of altitude illness as prophylaxis. It works to decrease
the formation of bicarbonate by inhibiting carbonic anhydrase. This diuretic
action counters the fluid retention in acute mountain illness. It also decreases
bicarbonate absorption in the kidney, causing a metabolic acidosis, which
stimulates hyperventilation. This compensatory mechanism is turned off
when the pH is close to the physiologic range of 7.4. It’s this hyperventilation
that counters the altitude-induced hypoxemia, thereby relieving symptoms.
Dexamethasone(b)works to decrease vasogenic edema and decrease
intracranial pressure. It is generally used as adjunctive therapy in high-altitude
cerebral edema. Nifedipine (c)works by decreasing pulmonary artery pres-
sure in high-altitude pulmonary edema as does the diuresis resulting from
(d)furosemide. Morphine (e)is thought to reduce pulmonary blood flow
and decrease hydrostatic forces in pulmonary edema.
439.The answer is b.(Rosen, pp 2010-2019.)This patient sustained a direct
lightning injury,as evidenced by the typical fern-like patternexhibited.
These injuries may inflict fractures, cardiovascular collapse, burns, blunt
abdominal injuries, and neurologic damage. Tympanic membrane ruptures
are a common associated injury caused by the outflow tract of the lightning
strike and it is important to check for blood in the ear canals of these patients.
It is important to quickly assess the ABCs of these patients and establish an
airway. Immobilization of the cervical spine is often indicated as well as close
ECG monitoring. Patients should be admitted for observation after obtaining
a complete blood count (CBC), creatinine kinase with MB fraction, basic
metabolic panel, and appropriate radiographs of involved areas. Although
50 to 300 people die because of lightning strikes each year in the United
States, most injuries sustained are not lethal.
440.The answer is c.(Rosen, pp 793-794.)Fire antshave proven to be a
real threat to humans. Ninety-five percent of clinical cases result from the
Solenopsis invictaspecies, another member of the Hymenoptera,which was
imported from Brazil in the 1930s. This ant is found in many of the southern
states given that it cannot survive long winters and is slowly replacing the less
dangerous species native to North America. It is small and light-reddish to
dark brown and its venom is 99% alkaloid, which is unique to the animal
kingdom. This causes hemolysis, membrane depolarization, local tissue
destruction, and activation of the complement pathway all of which could
be especially dangerous in this patient with facial injuries. The sting usually
produces a pustule within 24 hours. Local burning, erythema, and pruritus are