Hypothermia

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Hypothermia refers to any condition in which the temperature of a body drops below the level required for normal metabolism and/or bodily function to take place. In warm-blooded animals, core body temperature is maintained at or near a constant level through biologic homeostasis. When the body is exposed to colder temperatures, however, its internal mechanisms may be unable to replenish the heat that is being lost to the body's surroundings. Hypothermia is the opposite of hyperthermia. Because the words sound alike, they are easily confused.

Stages of Hypothermia in Humans

Stage 1

Body temperature drops by 1°C - 2°C below normal temperature C (1.8°-3.6°F, or between 96.8°F - 95°F). Mild to strong shivering occurs. Unable to perform complex tasks with the hands; the hands become numb. Blood vessels in the outer extremities contract, lessening heat loss to the outside air. Breathing becomes quick and shallow. Goose bumps form, raising body hair on end in an attempt to create a insulating layer of air around the body (a vestigial response, but useful in other species).

Stage 2

Body temperature drops by 2°C - 4°C (3.6°F - 7.2°F, or between 95°F - 91.4°F). Shivering becomes more violent. Muscle miscoordination becomes apparent. Movements are slow and labored, accompanied by a stumbling pace and mild confusion, although the victim may appear alert. Surface blood vessels contract further as the body focuses its remaining resources on keeping the vital organs warm. Victim becomes pale. Lips, ears, fingers and toes may become blue.

Stage 3

Body temperature drops below approximately 32°C or 90°F (normal is 37°C or 98.6°F). Violent shivering persists; difficulty speaking, sluggish thinking, and amnesia start to appear; inability to use hands and stumbling are also usually present. Cellular metabolic processes shut down. Below 86°F (30°C) shivering stops and the exposed skin becomes blue and puffy, muscle coordination very poor, walking nearly impossible, and the victim exhibits incoherent/irrational behavior or even a stupor. Pulse and respiration rates decrease significantly. Major organs fail. Clinical death occurs. Because of decreased cellular activity in stage 3 hypothermia, the body will actually take longer to undergo brain death.

First aid

• If any symptoms of hypothermia are present, especially confusion or changes in mental status, the local emergency service should be immediately contacted.
• If the person is unconscious, check their airway, breathing, and circulation. If necessary, begin rescue breathing or CPR. If the victim is breathing less than 6 breaths per minute, begin rescue breathing.
• Take the person inside to room temperature and cover him or her with warm blankets. If going indoors is not possible, get the person out of the wind and use a blanket to provide insulation from the cold ground. Cover the person's head and neck to help retain body heat.
• Once inside, remove any wet or constricting clothes and replace them with dry clothing.
• Warm the person. If necessary, use your own body heat to aid the warming. Apply warm compresses to the neck, chest wall, and groin. If the person is alert and can easily swallow, give warm, sweetened, nonalcoholic fluids to aid the warming.
• Stay with the person until medical help arrives.
• Assume that you should obtain a doctor if the victim has been exposed for 24 hours or more.
• DO NOT assume that someone found lying motionless in the cold is already dead.
• DO NOT use direct heat (such as hot water, a heating pad, or a heat lamp) to warm the person.
• DO NOT give the person alcohol.^{[citation needed]}

Hospital Treatment

In a hospital, warming is accomplished by external techniques (blankets, warming devices) for mild hypothermia and by more invasive techniques such as warm intravenous fluids or even lavage (washing) of the bladder, stomach, chest and abdominal cavities with warmed fluids for severely hypothermic patients.^{[citation needed]} These patients are at high risk for arrhythmias (irregular heartbeats), and care must be taken to minimize jostling and other disturbances until they have been sufficiently warmed, as these arrhythmias are very difficult to treat while the victim is still cold. An important tenet of treatment is that a person is not dead until they are warm and dead. Remarkable accounts of recovery after prolonged cardiac arrest have been reported in patients with hypothermia. This is presumably because the low temperature prevents some of the cellular damage that occurs when blood flow and oxygen are lost for an extended period of time.

Prevention

In air, most heat is lost through the head [1]; hypothermia can thus be most effectively prevented by covering the head. Having appropriate clothing for the environment is another important prevention. Fluid-retaining materials like cotton can be a hypothermia risk; if the wearer gets sweaty on a cold day, then cools down, they will have sweat-soaked clothing in the cold air. For outdoor exercise on a cold day, it is advisable to wear fabrics which can "wick" away sweat moisture. These include wool or synthetic fabrics designed specifically for rapid drying.

Heat is lost much more quickly in water. Children can die of hypothermia in as little as two hours in water as warm as 16°C (61°F, 289 K), typical of sea surface temperatures in temperate countries such as Great Britain. Many seaside safety information sources fail to quote survival times in water, as well as the consequent importance of diving suits. This is possibly because the original research into hypothermia mortality in water was carried out in wartime Germany on unwilling subjects. There is an ongoing debate as to the ethical basis of using the data thus acquired.

There is considerable evidence, however, that children who suffer near-drowning accidents in water near 0°C (32°F, 273 K) can be revived up to two hours after losing consciousness. The cold water considerably lowers metabolism, allowing the brain to withstand a much longer period of hypoxia.

Medically Induced

See induced hypothermia

See also

• Hyperthermia
• Cryonics
• First aid
• Frostbite
• Hibernation
• Mountain rescue
• Torpor
• Winter sport
• Brown adipose tissue allows babies higher chance of survival by converting fat into heat (from a Discovery Channel documentary on Survival)

References

External links

• Emergency Insulation http://furtech.typepad.com/blizzard_insulation
• CanyonWiki:Hypothermia
• Canadian rescue workers internet site (hypothermia division)
• Hypothermia
• Hypothermia in the elderly
• http://www.hypothermia.org/
• Windchill chart in km/h windspeeds and °C temperature measures
• Help the Aged charity (United Kingdom) - hypothermia in the elderly, death information, advice, downloads etc.
• Table of hypothermia effects at different water temperatures