Definitions and Epidemiology
Heat illnesses exist on a spectrum of seriousness. An athlete need not experience symptoms of mild then moderate then severe heat illness to have heat stroke. The exact epidemiology is poorly defined and varies widely dependent on the study population and environmental conditions.
Definitions, pathogenesis, clinical presentations, and key principles of treatment of heat-related illnesses are summarized in Table 38-1.1–8
Table 38-1. Heat-Related Illnesses |Favorite Table|Download (.pdf)
Table 38-1. Heat-Related Illnesses
Swelling of the distal extremities when exposed to exercise in a warm environment. Usually transient and subsides within the first few days of the acclimatization period.
Neuroendocrine system response to real or relative decreased plasma volume early in the period of exposure to exercise in a warm environment. It is believed that this decrease causes increased secretion of aldosterone and therefore leads to sodium retention.
Swelling and puffiness, more notable in the ankles, and less commonly the hands. Typically in the first few days in heat exposure. Heat edema is uncommon in the face and therefore any facial edema should be evaluated accordingly.
Elevation of the swollen extremities. Self limiting and resolves within the few first days of heat exposure.
Transient hypovolemia, orthostatic hypotension that usually affects an unacclimatized athlete. Likely related to dehydration and venous pooling secondary to vasodilatation in the body's attempt to regulate core body temperature.
Explained by the vasodilation. As the athlete decreases activity the resulting decreased cardiac output along with possible dehydration, results in hypotension. This, in turn, leads to vasovagal insufficiency and cerebral hypoperfusion.
Manifests in the early acclimatizing period as a sudden fainting that resolves shortly after the young athlete comes to rest on the ground. Occurs after completion of a sustained activity, and typically in the first few days of exposure to the warm environment.
Evaluate for injuries secondary to the syncopal episode, including head and neck injuries. The athlete should be moved to a cool environment and re-hydrated. Evaluate need for cardiac workup prior to the return to activity.
Involuntary spasms of the muscles, commonly affecting the lower extremity but may occur in the arms or abdomen; occurring during or after the physical activity.
Multiple theories including alterations in spinal neural reflex activity, local electrolyte abnormalities, and exertional muscle damage.
Can occur at any ambient temperature; more common in warmer environments. Present as uncontrolled and involuntary contractions of the muscles, most commonly the lower extremity. Abdominal, back and upper extremity may be involved. Common with longer duration sports as the muscle approaches fatigue.
Cessation of the activity, gentle stretching, massage, and oral hydration. With severe cramping, intravenous hydration with normal saline may be required. When the cramping resolves, and provided the athlete re-hydrates, he/she can generally return to activity.
Exertional heat exhaustion
Inability to sustain exercise that has occurred during heavy exertion ...