Environmental Exposures Answers 481An STD (a)is unlikely. Descent barotrauma (c)include sinus, ear, and
skin squeeze. Divers who hold their breath upon descent may also develop
lung squeeze. Ascent barotrauma (d)involves similar conditions in addition to
pneumomediastinum and pneumothorax. Nitrogen narcosis (e),also known
as “rapture of the deep,” is an interesting phenomenon in which prolonged
dives produce a euphoric effect upon the diver because of the collection of
nitrogen gas in the tissues. This may prove dangerous in the face of an emer-
gency, given a false sense of security and impaired motor skills.
432.The answer is d.(Rosen, p 2025.)Being a rookie diver, this patient
ascended to the surface too quickly. As in decompression sickness, nitrogen
gas bubbles form and subsequently travel to the arterial system through the
pulmonary veins into the cardiac chambers. Arterial gas embolismmay
also occur in patients with an underlying patent foramen ovale. Symptoms
are usually sudden and dramatic. Divers, who may have been thought to
drown, actually passed out during ascent because of an underlying embolism.
Treatment includes hyperbaric oxygen therapy and the avoidance of air
transport.
Although cardiac ischemia (b)may occur because of this, it is not the
precipitating event. Pulmonary embolism (a)in otherwise healthy individuals
with no risk factors is low probability as the inciting event. Transient ischemic
attacks(c)may present in a variety of ways, but given this clinical scenario,
a serious diving-related cause must be investigated first. (e)Nitrogen narcosis
occurs secondary to breathing gasses at higher than normal atmospheric
pressure. It occurs as the diver descends to depths greater than 70 ft. Clinically,
patients appear as if they are ethanol intoxicated. The condition clears with
resurfacing.
433.The answer is a.(Rosen, pp 786-792.)This patient suffered a venomous
snakebite.Pit vipers, such as rattlesnakes, copperheads, and water moccasins, are
the most prevalent and are present in all states except Alaska, Maine, and
Hawaii. Coral snakes are the second most prevalent and are present mainly
in the southern states. Red on yellow, kill a fellow; red on black, venom lack
is a commonly used phrase to help remember which snakes are dangerous.
Venomous snakes can also be recognized by their triangular heads, elliptical
pupils, fangs, and the presence of a pit between the eye and nostril—
characteristicsthat may not be noticed by the victim initially. Therefore,there is a
snakebitegrading system, which requires antivenin with progressive symp-
toms of edema, coagulopathy, and neurologic manifestations. The amount of