Hyperthermia

Hyperthermia, also known as heat stroke or sunstroke, is an acute condition which occurs when the body produces or absorbs more heat than it can dissipate. It is usually due to excessive exposure to heat. The heat-regulating mechanisms of the body eventually become overwhelmed and unable to effectively deal with the heat, and body temperature climbs uncontrollably. This is a serious medical emergency that requires immediate hospitalization. more...

Progression

Body temperatures above 40 °C (104 °F) are life-threatening. At 41 °C (106 °F), brain death begins, and at 45 °C (113 °F) death is nearly certain. Internal temperatures above 50 °C (122 °F) will cause rigidity in the muscles and certain, immediate death.

Heat stroke may come on suddenly, and usually follows a less-threatening condition commonly referred to as heat exhaustion or heat prostration.

Signs and symptoms

One of the body's most important methods of temperature regulation is perspiration. Evaporation of water is endothermic; therefore, perspiration is an efficient way to rid the body of excess heat. When the body becomes sufficiently dehydrated to prevent the production of sweat, this avenue of heat reduction is closed. Thus, the first symptom of a serious heat stroke may be the loss of sweating. When the body is no longer capable of sweating, core temperature begins to rise, immediately, and swiftly.

The victim will become confused, hostile, and may seem drunk. Because the body is so dehydrated, blood pressure will drop significantly, leading to possible fainting or dizziness, especially if the victim stands suddenly. As blood pressure drops, heart rate and respiration rate will increase (tachycardia and tachypnea) as the heart attempts to supply enough oxygen to the body. The skin will become red as blood vessels dilate in an attempt to increase heat dissipation. As heat stroke progresses, the decrease in blood pressure will cause blood vessels to contract, resulting in a pale or bluish skin color. Complaints of feeling hot may be followed by chills and trembling, as is the case in fever. Some victims, especially young children, may suffer convulsions. Acute dehydration such as that accompanying heat stroke can produce nausea and vomiting; temporary blindness may also be observed. Eventually, as body organs begin to fail, unconsciousness and coma will result.

Under very rare circumstances, a person may exhibit symptoms similar to heat stroke without but not suffer a heat stroke.

First aid

As with any emergency, the first step is to call the local emergency telephone number. Heat stroke is a medical emergency requiring immediate hospitalization.

The body temperature must be lowered immediately, and the victim must be hydrated by drinking water or by administration of intravenous fluids. Other substances may be used in place of water if absolutely necessary; however, alcohol and caffeine should be avoided, because of their diuretic properties.

The victim should be removed into a cool area (indoors, or at least in the shade). Excess clothing should be removed. The person may be bathed in cool water, or wrapped in a cool wet towel. A fan may be used to aid in evaporation of the water. Use of a bathtub is to be avoided for an unconscious victim; if there is no alternative, the victim's head must be held above water. Cold compresses to the head, neck, and groin will help cool the victim. Ice and very cold water can produce hypothermia; they should not be used to lower the victim's body temperature, and the victim's temperature should be monitored continuously to avoid this danger. Similarly, alcohol rubs will cause further dehydration and must be avoided. Nothing should be given by mouth, including medication and water, until the victim's condition has been assessed and stabilized by trained medical personnel. The victim's heart rate and breathing should be monitored, and CPR may be necessary if the victim goes into cardiac arrest.

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