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| '''Hyperthermia''' 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 overview|Overview]]== |
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| 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 pathophysiology|Pathophysiology]]== |
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| Hyperthermia is the opposite of [[hypothermia]].
| | ==[[Hyperthermia differential diagnosis|Differentiating Hyperthermia from other Diseases]]== |
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| ==Progression== | | ==[[Hyperthermia epidemiology and demographics|Epidemiology and Demographics]]== |
| Body temperatures above 40[[Celsius|°C]] (104 [[Fahrenheit|°F]]) are life-threatening. This compares to normal body temperature of 36-37°C (97-98°F). 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.
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| Heat stroke may come on suddenly, but usually follows a less-threatening condition commonly referred to as ''heat exhaustion'' or ''heat prostration''.
| | ==[[Hyperthermia risk factors|Risk Factors]]== |
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| ==Signs and symptoms== | | ==[[Hyperthermia natural history, complications and prognosis|Natural History, Complications and Prognosis]]== |
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| ''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''.
| | ==Diagnosis== |
| | [[Hyperthermia history and symptoms|History and Symptoms]] | [[Hyperthermia physical examination|Physical Examination]] | [[Hyperthermia laboratory findings|Laboratory Findings]] | [[Hyperthermia other diagnostic studies|Other Diagnostic Studies]] |
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| 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 [[dehydration|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.
| | ==Treatment== |
| | [[Hyperthermia medical therapy|Medical Therapy]] | [[Hyperthermia primary prevention|Primary Prevention]] | [[Hyperthermia cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Hyperthermia future or investigational therapies|Future or Investigational Therapies]] |
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| 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 vessel]]s 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.
| | ==Case Studies== |
| | | [[Hyperthermia case study one|Case #1]] |
| Under very rare circumstances a person may exhibit symptoms similar to heat stroke without suffering a heat stroke.
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| ==First aid== | |
| Heat stroke is a medical emergency requiring hospitalisation, and the local emergency services should be notified as soon as possible.
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| The body temperature must be lowered immediately. The victim should be moved to a cool area (indoors, or at least in the shade) and clothing removed to promote heat loss (passive cooling). Active cooling methods may be used: The person is bathed in cool water, a hyperthermia vest can be applied, or the person may be wrapped in a cool wet towel. Cold compresses to the [[torso]], [[head]], [[neck]], and [[groin]] will help cool the victim. A fan may be used to aid in evaporation of the water (evaporative method). Ice and very cold water can produce [[hypothermia]]; they should be used only when there are means to monitor the victim's temperature continuously.
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| Immersing a victim into a bathtub of cold water (immersion method) is a recognized method of cooling. This method requires the effort of 4-5 persons and the victim should be monitored carefully during the treatment process. This should be avoided for an unconscious victim; if there is no alternative, the victim's head must be held above water.
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| Hydration is of paramount importance in cooling the victim. This is achieved by drinking [[water]] (Oral rehydration). Commercial [[isotonic]] drinks may be used as a substitute. [[Alcohol]] and [[caffeine]] should be avoided due to their [[diuretic]] properties. Some [http://www.bt.cdc.gov/disasters/extremeheat/heat_guide.asp authorities] are opposed to giving any fluids, except by emergency personnel. Intravenous hydration (via a drip) is necessary if the victim is confused, unconscious, or unable to tolerate oral fluids.
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| Alcohol rubs will cause further dehydration and impairment of consciousness and should be avoided. The victim's condition should be reassessed 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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| The victim should be placed into the [[recovery position]] to ensure that their [[airway]] remains open.
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| ==Prevention==
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| The risk of heatstroke can be reduced by observing precautions to avoid overheating and dehydration. Light, loose-fitting clothing will allow perspiration to evaporate. Wide-brimmed hats in bright colour keep the sun from warming the head and neck; vents on a hat will allow perspiration to cool the head. Strenuous exercise should be avoided during daylight hours in hot weather; so should remaining in enclosed spaces (such as automobiles). People who must be outside should be aware that humidity and the presence of direct sunlight may cause the heat index to be 10 °C (18 °F) hotter than the temperature indicated by a thermometer.
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| In hot weather people need to drink plenty of liquids to replace fluids lost from sweating. Thirst is not a reliable sign that a person needs fluids. A better indicator is the color of [[urine]]. A dark yellow color indicates dehydration. While alcoholic beverages, tea, and coffee may help somewhat in restoring lost fluids, their [[diuretic]] effect in these situations is counterproductive. Water or sports drinks are more effective.
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| === Especially susceptible populations ===
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| While anyone can be affected by hyperthermia, some populations are especially susceptible to heat illness and injury. As noted by Joseph Rampulla in the ''The Health Care of Homeless Persons'' :<ref>{{cite web |url= http://www.bhchp.org/BHCHP%20Manual/pdf_files/Part2_PDF/Hyperthermia.pdf|title= Hyperthermia & Heat Stroke: Heat-Related Conditions|accessdate=2007-02-22 |author= Joseph Rampulla, MS,APRN,BC|year= 2004 |month= June|format=pdf |work= The Health Care of Homeless Persons |publisher= Boston Health Care for the Homeless Program |pages= pp.199-204| }}</ref> :
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| <blockquote>Heat illness most seriously affects the poor, urban-dwellers, young [[children]], those with chronic physical and mental illnesses, substance abusers, the elderly, and people who engage in excessive physical activity under harsh conditions.</blockquote>
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| ==Clinical applications==
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| Hyperthermia can be intentionally produced for medical purposes. [[Thermotherapy]], or therapy by induced hyperthermia, may be used as a [[cancer]] treatment to kill or weaken [[tumor]] cells, with negligible effects on healthy cells.
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| ==Related Chapters== | | ==Related Chapters== |
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| [[Category:Emergency medicine]] | | [[Category:Emergency medicine]] |
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| == References ==
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| <references/>
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| {{Consequences of external causes}} | | {{Consequences of external causes}} |
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