Page 58 - Athletic Health Handbook
P. 58
that may cause hypertension and
tachycardia thereby lowering the
susceptibility to heat illness. These
risk factors all have the potential to
affect the heat load on the body or
the body’s ability to dissipate heat
(Table 1). Knowledge of risk factors
may help in identifying athletes predis-
posed to heat stroke and assist in
counseling both coaches and players
on actions that can be implemented
to diminish the risk of heat stroke.

Pathophysiology stroke typically affects elderly patients Diagnosis
with co-morbid medical conditions
The basic mechanism of heat stroke who present with hyperpyrexia, An elevated core body temperature
is a heat load on the body greater than mental status changes, and anhidrosis greater than 104°F is always associated
the body’s ability to dissipate the heat. (lack of sweating). Exertional heat with heat stroke, but necessitates
The source of heat can be exogenous, stroke occurs in younger patients rectal temperature. Axillary, tympanic,
endogenous, or, most often, a combi- without chronic medical conditions, and oral sites are not accurate meas-
nation of the two. During exercise, most notably athletes and laborers. ures of core body temperature. Since
blood flow is shunted to active The primary differentiating sign is the brain is extremely sensitive to
muscles. As muscle temperature that, unlike victims with classic heat temperature elevation, confusion is
elevates with activity, warmed blood stroke, patients with exertional heat usually the first sign of heat stroke.
can lead to an increase in core body stroke continue to sweat. Mental status changes range from
temperature. In an attempt to dissi- confusion and dizziness to delirium
pate this heat, blood is delivered to Risk Factors and coma. In addition to the central
the skin where sweat is evaporated nervous system malfunction, other
and heat is lost. During exercise, The major risk factors for heat stroke organ systems may be affected and
excessive sweating and inadequate are: (1) Environmental conditions require prompt medical attention.
fluid intake can lead to volume such as temperature, humidity, cloth- Tachycardia is usually present, with
depletion. The body attempts to ing, and activity level, (2) Prescription hypotension and cardiovascular
maintain a normotensive state by medications and over-the-counter collapse occurring late. Coagulopathy
delivering less blood to the skin, which supplements such as Ephedra, and may occur with purpura, hemoptysis,
results in less dissipation of heat. (3) Medical conditions such as sickle and hematuria. Acute renal failure
cell trait, dehydration, recent febrile secondary to acute tubular necrosis
Classification illness, sleep deprivation, sunburn, may also develop. Rhabdomyolysis is
and obesity. Ephedra belongs to the common as a result of muscle contrac-
Heat stroke may be classified as either class of sympathomimetic alkaloids tion and rigidity. Liver involvement
classic or exertional. Classic heat usually is associated with central
lobular necrosis and cholestasis.4
Progression of symptoms may lead
to seizure, coma, or death.

Differential Diagnosis

The differential diagnosis of heat
stroke includes heat exhaustion,
cardiac abnormalities, exertional
hyponatremia, epilepsy, and hypo-
glycemia. Cardiac arrhythmias can be
detected or excluded by careful auscul-
tation. Exertional hyponatremia is

ON-THE-FIELD MANAGEMENT OF HEAT STROKE 58
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