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Hyperthermia (hyperpyrexia), in its advanced state referred to 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 medical emergency that requires immediate medical attention.
Hyperthermia can be created artificially by drugs or medical devices. In these instances it may be used to treat cancer and other conditions. Malignant hyperthermia is a rare complication of some types of general anesthesia.
Hyperthermia is the opposite of hypothermia.
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, but usually follows a less-threatening condition commonly referred to as heat exhaustion or heat prostration.
Signs and symptomsEdit
Heat prostration, or heat exhaustion, is characterized by mental confusion, muscle cramps, and often nausea or vomiting. At this stage the victim will likely be sweating profusely. With continued exposure to ambient heat, which sometimes is facilitated by the mental confusion, temperature may rise into the 39 to 40 °C range (103 to 104 °F), and lead to full-blown heat stroke.
One of the body's most important methods of temperature regulation is perspiration. This process draws heat from inside, allowing it to be carried off by radiation or convection. Evaporation of the sweat furthers cooling, since this endothermic process draws yet more heat from the body. When the body becomes sufficiently dehydrated to prevent the production of sweat this avenue of heat reduction is closed. When the body is no longer capable of sweating core temperature begins to rise swiftly.
Victims may become confused, may become hostile, often experience headache, and may seem intoxicated. , Blood pressure may drop significantly from dehydration, leading to possible fainting or dizziness, especially if the victim stands suddenly. Heart rate and respiration rate will increase (tachycardia and tachypnea) as blood pressure drops and 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. The decrease in blood pressure will cause blood vessels to contract as heat stroke progresses, resulting in a pale or bluish skin colour. 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 suffering a heat stroke.
Difference between hyperthermia and feverEdit
A fever is when the body recognizes its normal core temperature at a higher temperature, mainly by the “pre-optic region” of the anterior hypothalamus, as to optimize the efficiency of bodily operations. One example of this is when one gets a bacterial/viral disease, where the body raises its temperature to let the immune system work better and to deteriorate the condition of the invaders. Meanwhile, hyperthermia is when the body temperature is raised without the consent of the heat control centers.
Heat stroke is a medical emergency requiring 