Heat Illnesses Part I

Since we are in the southern route, heat is a major concern and should be addressed. You should know that heat illnesses are preventable, but many deaths occur every year. I just learned on Facebook that a girl in marching band with me passed away on a hiking trip in Arizona and was most likely heat related. It's a real tragedy, so please take the heat seriously.

So from Athletic Management, all you want to know about heat illnesses.

An ever-present concern of practicing or competing in a hot humid environment is the problem of hyperthermia. Hyperthermia refers to an increase in body temperature. In recent years, particularly among football players and wrestlers, a number of deaths have been caused by hyperthemia. It is vitally important to understand when environmental heat and humidity are at a dangerous level and to act accordingly. Remember that an individual does not have to be in the south to experience heat-related illnesses. Heat and humidity occur in every geographic region of the United States, and anyone who supervises athletes that practice and compete in these environmental conditions must be able to recognize the clinical signs of heat stress and manage them properly.

Regardless of the level of physical conditioning, extreme caution must be taken when exercising, particularly in hot, humid weather. Prolonged exposure to extreme heat can result in heat illness. Heat stress is certainly preventable, but each year many athletes suffer illness and occasionally, death from some heat-related cause. Athletes who exercise in hot, humid environments are particularly vulnerable to heat stress. The physiological processes in the body can continue to function only as long as body temperature is maintained within a normal range. Maintenance of normal temperature in hot environment depends on the ability of the body to dissipate heat. Heat can be dissipated from the body through four mechanisms: conduction (direct contact with a cooler object); convection (contact with a cooler air or water mass); radiation (heat generated from metabolism); and evaporation (sweat evaporating from the skin surface). It must be added that the body can also gain heat through conduction, convection, and radiation if the surrounding environment is hotter than the body temperature or if the body is exposed to direct sunlight. By far most of the heat that is dissipated from the body is through the process of evaporation.

Sweat glands in the skin allow water to be transported to the suface where it evaporates, taking large quantities of heat with it. When the temperature and radiant heat of the environment become higher than body temperature, loss of body heat becomes highly dependent on the process of sweat evaporation. THe sweat must evaporate for heat to be dissipated. But the air must be relatively free of water for evaporation to occur. Heat loss through evaporation is severely impaired when the relative humidity reaches65 percent and virtually stops when the humidity reaches 75 percent. The heat index takes both ambient air temperature and relative humidity into account and attempts to determine how hot it actually feels to the human body.

It must be emphasized that, while heat illness is most likely in occur in a hot, humid environment, it is possible that heat illnesses can also occur in colder environments when the athlete allows himself or herself to become dehydrated and the body cannot dissipate heat through sweating.

It should be obvious that heat-related problems have the greatest chance of occuring on days when the sun is bright and the temperature and relative  humidity are high. But it is certainly true that various forms of heat illness, including heat syncope and exertional heat cramps, heat exhaustion, heatstroke, or hyponatrmia can occur whenever the body's ability to dissipate heat is impaired.

Heat Syncope

Heat syncope, or heat collapse, is associated with rapid physical fatigue during overexposure to heat. It is usually caused by standing in heat for long periods or by not being accustoed to exercising in the heat. It is caused by peripheral vasodilation of superficial vessels, hypotension, or a pooling of blood in the extremities, which results in dizziness, fainting, and nausea. Heat syncope is quickly relieved by laying the athlete in a cool environment and replacing fluids.

Exertional Heat Cramps

Heat cramps are extremely painful muscle spasms that occur most commonly in the calf or abdomen, although any muscle can be involved. The occurance of heat cramps is related primarily to excessive loss of water and loss of electrolytes, particularly sodium. Electrolytes are ions (sodium, chloride, potassium, magnesium, and calcium) that are essential elements in muscle contraction.

Profuse sweating involves losses of large amounts of water as well as electrolytes, thus destroying the balance in concentration of theses elements within the body. This imbalance ultimately results in painful musle contractions and cramps. The person most likely to get heat cramps is one who is fairly good condition who simply overexerts in the heat.

Heat cramps may be prevented by adequate replacement of fluids and increased intake of sodium. The immediate treatment for heat cramps is ingestion of large quantities of fluid and sodium and mild stretching with ice massage of the muscle in spasm. An athlete who experiences heat cramps will generally not be able to return to practice or competition for the remainder of the day because cramping is likely to reoccur.

Exertional Heat Exhaustion

Heat exhaustion results from inadequate replacement of fluids lost through sweating. Clinically, the victim of heat exhaustion collapses and manifests profuse sweating, pale skin, mildly elevated temperature (102 degrees F), dizziness, hyperventilation, and rapid pulse.

It is sometimes possible to spot athletes who are having problems with heat exhaustion. They may begin to develop heat cramps. They may become disoriented and light-headed, and their physical performance will not be up to their usual standards when fluid replacement has not been adequate. In general, persons in poor physical condition who attempt to exercise in the heat are most likely to get heat exhaustion.

Immediate treatment of heat exhaustion requires ingestion and eventually intravenous replacement of large quantities of fluids. It is essential to obtain an accurate core temperature. Temperature can be measured in the ear with a tympanic membrane thermometer. However, a rectal temperature is most accurate indicator of core temperature to differentiate heat exhaustion from heatstroke. In heat exhaustion the core temperature will be around 102 degrees F. If possible, the athlete should be placed in a cool environment, although it is more critical to replace fluids.

Exertional Heatstroke

Unlike heat cramps and heat exhaustion, heatstroke is a serious, life-threatening emergency. The specific cause of heatstroke is unknown; however, it is clinically characterized by sudden collapse with loss of consciousness; flushed, hot skin; less sweating than is seen with heat exhaustion; shallow breathing; a rapid, strong pulse; and, most important, a core temperature of 104 degrees F or higher. Basically heatstroke is a breakdown of the thermoregulatory mechanism caused by excessively high body temperature; the body loses the ability to dissipate heat through sweating.

Heatstroke can occur suddenly and without warning. the athlete may or may not show signs of heat cramps or heat exhaustion. The possibility of death from heatstroke can be significantly reduced if body temperature is lowered to normal within 45 minutes. The longer the body temperature is elevated to 104 degress F or higher, the higher the mortality rate.

It is imperative that the victim be transported to a hospital as quickly as possible. Every first-aid effort should be directed to lowering body temperature. Get the athlete into a cool environment. Strip all clothing off the athlete. It is most effective to immerse the athlete in ice water. Alternatives would be to place ice bags in the armpits, groin, and neck, or sponge him or her down with cold water, and fan with a towel. The replacement of fluid is not critical in initial first aid.

Exertional Hyponatremia

Hypornatremia is a condition involving a fluid/electrolyte disorder that results in an abnormally low concentration of sodium in the blood. It is most often caused by ingesting so much fluid before, during, and after exercise that the concentration of sodium is decreased. It alse can occur due to too little sodium in the diet or in ingested fluids over a period of prolonged exercise. An individual with a high rate of sweating and a significant loss of sodium, who continues to ingest large quantities of fluid over a several hour  period of exercise (as in a marathon or triathlong), is particularly vulnerable to developing hyponatremia. Hyponatremia can be avoided completely by making certain that fluid intake during exercise does not exceed fluid loss and that sodium intake is adequte.

The signs and symptoms of exertional hyponatremia may include a progressively worsening headache; nausea and vomiting; swelling of the hands and feet; lethargy, apathy, or agitation; and low blood sodium. Ultimately, a very low concentration of sodium can compromise the central nervous system creating a life-threatening situation.

It hyponatremia is suspected and blood sodium levels cannot be determined onsite, measures to rehydrate the athlete should be delayed and the athlete should be transported immediately to a medical facility. At the medical facility the delivery of sodium, certain diuretics, or intravenous solutions may be necessary. A physician should clear the athlete before he or she is allowed to return to play.