Travel Reference
In-Depth Information
Consuming water alone can lead to the condition known as exercise-induced hy-
ponatremia (low blood sodium), so in addition to drinking water, individuals should eat,
particularly salty foods, or drink one of the sport beverages that contain salt.
Heat Syncope and Heat Exhaustion
Heat illnesses range in severity from very mild to lethal. Typical patterns of illness have
been given specific names, but the types of heat injury must be recognized as different
manifestationsofthesamebasicdisorder.Mildheatillnesseshavethepotentialforbecom-
ing severe and must be treated with care.
Heat syncope and heat exhaustion are milder forms of heat illness. Heat syncope is a
disorder similar to ordinary fainting (syncope) except for its cause. In an effort to increase
heat loss, the blood vessels in the skin dilate to such an extent that the blood supply to the
brain is diminished. Reduction in blood volume by dehydration contributes to the lower
cerebral blood flow. Initially a person with heat syncope feels faint and is usually aware of
a rapid heart rate. Nausea, vomiting, headache, dizziness, and restlessness, even brief loss
ofconsciousness, are not uncommon. Skin color and the presence ofsweating are variable.
Heat exhaustion is a more severe disorder. Some investigators have separated these two
disorders on the basis of body temperature, which is normal with syncope but elevated to
102° to 104°F (39° to 40°C) with heat exhaustion. Heavy sweating is present, and symp-
toms such as nausea, vomiting, and headache tend to be more severe. Individuals with heat
exhaustion have faster respirations and a fast heart rate.
Heat syncope should be treated just like fainting. An individual who recognizes prelim-
inary symptoms should lie down, or at least sit down, to avoid injury and, if lying down,
shouldelevatethefeet.Acoolerenvironmentisdesirable,andtheindividualshouldatleast
beprotectedfromdirectsunlight.Thepersonshouldbegivenfluids,particularlyfluidslike
thesportsbeveragesthatcontainsalt,andshouldnotengageinvigorousactivityforatleast
the rest of that day. Only after complete restoration of body fluids and resumption of a nor-
mal urine output should exercise in a hot environment be cautiously resumed.
An individual with heat exhaustion should be treated in the same way, but body temper-
ature must be closely monitored. If the temperature is above 104°F (40°C), or continues to
climb after the person has been taken out of the sun and is at rest, active cooling should be
started. If a clinical thermometer is not available and the individual feels warmer than oth-
ers do, active cooling should be started and maintained until the person feels comfortable.
Individuals with heat exhaustion have an even greater fluid deficit that must be corrected,
which may be difficult if the individual is nauseated or vomiting. Such persons must be
very careful about resuming physical activity and usually should be examined by a physi-
cian before doing so.
Heat Stroke
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