2013年10月13日星期日
Tomsawyers online mens dark black jackets windbreaker Definition of frostbite
Definition of frostbite and frostnip in the medical dictionary Frostbite and
frostnip definitionfrostbite is the term for damage to the skin and other
tissues caused by freezing.Frostnip is a mild form of cold injury. Descriptionin
north america, frostbite is largely confined to alaska, canada, and the northern
states.Recent years have witnessed a substantial decline in the number of cases,
probably for several reasons, including better winter clothing and footwear and
greater public understanding of how to avoid cold-Weather dangers.At the same
time, the nature of the at-Risk population has changed as rising numbers of
homeless people have made frostbite an urban as well as a rural public health
concern.The growing popularity of outdoor winter activities has also expanded
the at-Risk population. Causes and symptomsfrostbiteskin exposed to temperatures
a little below the freezing mark can take hours to freeze, but very cold skin
can freeze in minutes or seconds.Air temperature, wind speed, and moisture all
affect how cold the skin becomes.A strong wind can lower skin temperature
considerably by dispersing the thin protective layer of warm air that surrounds
our bodies.Wet clothing readily draws heat away from the skin because water is a
potent conductor of heat.The evaporation of moisture on the skin also produces
cooling.For these reasons, wet skin or clothing on a windy day can lead to
frostbite even if the air temperature is above the freezing mark. The extent of
permanent injury, however, is determined not by how cold the skin and the
underlying tissues become but by how long they remain frozen.Consequently,
homeless people and others whose self-Preservation instincts may be clouded by
alcohol or psychiatric illness face a greater risk of frostbite-Related
amputation because they are more likely to stay out in the cold when prudence
dictates seeking shelter or medical attention.Alcohol also affects blood
circulation in the extremities in a way that can increase the severity of
injury(As does smoking).A review of 125 saskatchewan frostbite cases found a tie
to alcohol in 46% and to psychiatric illness in 17%.Other risk factors
identified by researchers include inadequate clothing, previous cold injury,
fatigue, wound infection, atherosclerosis(An arterial disease), and
diabetes.Driving in poor weather can also be dangerous:Vehicular failure was a
predisposing factor in 15% of the saskatchewan cases. Three nearly simultaneous
physiological processes underlie frostbite injury:Tissue freezing, tissue
hypoxia, and the release of inflammatory mediators.Tissue freezing causes ice
crystal formation and other changes that damage and eventually kill cells.Much
of this harm occurs because the ice produces pressure changes that cause
water(Crucial for cell survival)To flow out of the cells.Tissue hypoxia(Oxygen
deficiency)Occurs when the blood vessels in the hands, feet, and other
extremities narrow in response to cold.Among its many tasks, blood transfers
body heat to the skin, which then dissipates the heat into the environment.Blood
vessel narrowing is the body way of protecting vital internal organs at the
expense of the extremities by reducing heat flow away from the core.However,
blood also carries life-Sustaining oxygen to the skin and other tissues, and
narrowed vessels result in oxygen starvation.Narrowing also causes acidosis(An
increase in tissue acidity)And increases blood viscosity(Thickness).Ultimately,
blood stops flowing through the capillaries(The tiny blood vessels that connect
the arteries and veins)And blood clots form in the arterioles and venules(The
smallest arteries and veins).Damage also occurs to the endothelial cells that
line the blood vessels.Hypoxia, blood clots, and endothelial damage lead, in
turn, to the release of inflammatory mediators(Substances that act as links in
the inflammatory process), which promote further endothelial damage, hypoxia,
and cell destruction. Frostbite is classified by degree of injury(First,
second,Third,OrFourth), or simply divided into two types,
superficial(Corresponding to first-Or second-Degree injury)And
deep(Corresponding toThird-OrFourth-Degree injury).Most frostbite injuries
affect the feet or hands.The remaining 10% of cases typically involve the ears,
nose, cheeks, or penis.Once frostbite sets in, the affected part begins to feel
cold and, usually, numb;This is followed by a feeling of clumsiness.The skin
turns white or yellowish.Many patients experience severe pain in the affected
part during rewarming treatment Tomsawyers
online mens classic black jackets down vest and an intense throbbing
pain that arises two or three days later and can last days or weeks.As the skin
begins to thaw during treatment, edema(Excess tissue fluid)Often accumulates,
causing swelling.In second-And higher-Degree frostbite, blisters
appear.Third-Degree cases produce deep, bloodfilled blisters and, during the
second week, a hard black eschar(Scab).Fourth-Degree frostbite penetrates below
the skin to the muscles, tendons, nerves, and bones.In severe cases of frostbite
the dead tissue can mummify and drop off.Infection is also a possibility.
Frostniplike frostbite, frostnip http://tomsawyers.co.uk/ is associated
with ice crystal formation in the tissues, but no tissue destruction occurs and
the crystals dissolve as soon as the skin is warmed.Frostnip affects areas such
as the earlobes, cheeks, nose, fingers, and toes.The skin turns pale and one
experiences numbness or tingling in the affected part until warming begins.
Diagnosisfrostbite diagnosis relies on a physical eXamination and may also
include conventional radiography(X rays), angiography(X-Ray examination of the
blood vessels using an injected dye to provide contrast), thermography(Use of a
heat-Sensitive device for measuring blood flow), and other techniques for
predicting the course of injury and identifying tissue that requires surgical
removal.During the initial treatment period, however, a physician cannot judge
how a case will progress.Diagnostic tests only become useful three to five days
after rewarming, once the blood vessels have stabilized.
Treatmentfrostbiteemergency medical help should always be summoned whenever
frostbite is suspected.While waiting for help to arrive, one should, if
possible, remove wet or tight clothing and put on dry, loose clothing or wraps.A
splint and padding are used to protect the injured area.Rubbing the area with
snow or anything else is dangerous.The key to prehospital treatment is to avoid
partial thawing and refreezing, which releases more inflammatory mediators and
makes the injury substantially worse.For this reason, the affected part must be
kept away from heat sources such as campfires and car heaters.Experts advise
rewarming in the field only when emergency help will take more than two hours to
arrive and refreezing can be prevented. Because the outcome of a frostbite
injury cannot be predicted at first, all hospital treatment follows the same
route.Treatment begins by rewarming the affected part for 15-30 minutes in water
at a temperature of 104-108(40-42.2 This rapid rewarming halts ice crystal
formation and dilates narrowed blood vessels.Aloe vera(Which acts against
inflammatory mediators)Is applied to the affected part, which is then splinted,
elevated, and wrapped in a dressing.Depending on the extent of injury, blisters
may be debrided(Cleaned by removing foreign material)Or simply covered with aloe
vera.A tetanus shot and, possibly, penicillin, are used to prevent infection,
and the patient is given ibuprofen to combat inflammation.Narcotics are needed
in most cases to reduce the excruciating pain that occurs as sensation returns
during rewarming.Except when injury is minimal, treatment generally requires a
hospital stay of several days, during which hydrotherapy and physical therapy
are used to restore the affected part to health.Experts recommend a cautious
approach to tissue removal, and advise that 22-45 days must pass before a
decision on amputation can safely be made. Frostnipfrostnipped fingers are
helped by blowing warm air on them or holding them under one armpits.Other
frostnipped areas can be covered with warm Tomsawyers Outlet UK hands.The injured
areas should never be rubbed. Alternative treatmentalternative practitioners
suggest several kinds of treatment to speed recovery from frostbite after
leaving the hospital.Bathing the affected part in warm water or using contrast
hydrotherapy can help enhance circulation.Contrast hydrotherapy involves a
series of hot and cold water applications.A hot compress(As hot as the patient
can stand)Is applied to the affected area for three minutes followed by an ice
cold compress for 30 seconds.These applications are repeated three times each,
ending with the cold compress.Nutritional therapy to promote tissue growth in
damaged areas may also be helpful.Homeopathic and botanical therapies may also
assist recovery from frostbite.Homeopathic hypericum(Hypericum perforatum)Is
recommended when nerve ending are affected(Especially in the fingers and
toes)And arnica(Arnica montana)Is prescribed for shock.Cayenne pepper(Capsicum
frutescens)Can enhance circulation and relieve pain.Drinking hot ginger(Zingiber
officinale)Tea also aids circulation.Other possible approaches include
acupuncture to avoid permanent nerve damage and oxygen therapy. Prognosisthe
rapid rewarming approach to frostbite treatment, pioneered in the 1980s, has
proved to be much more effective than older methods in preventing tissue loss
and amputation.A study of 56 first-, second-,And third-Degree frostbite patients
treated with rapid rewarming in 1982 found that 68% recovered without tissue
loss, 25% experienced some tissue loss, and 7% needed amputation.In a comparison
group of 98 patients, treatment using older methods resulted in a tissue loss
rate of nearly 35% and an amputation rate of nearly 33%.Although the comparison
group included a higher proportion of second-And third-Degree cases, the
difference in treatment results was determined to be statistically significant.
The extreme throbbing pain that many frostbite sufferers endure for days or
weeks after rewarming is not the only prolonged symptom of frostbite.During the
first weeks or months, people often experience tingling, a burning sensation, or
a sensation resembling shocks from an electric current.Other possible
consequences of frostbite include skin changes, nail deformation or loss, joint
stiffness and pain, hyperhidrosis(Excessive sweating), and heightened
sensitivity to cold.For everyone, a degree of sensory loss lasting at least four
years sometimes a lifetime inevitable. Preventionwith the appropriate knowledge
and precautions, frostbite can be prevented even in the coldest and most
challenging environments.Appropriate clothing and footwear are essential.To
prevent heat loss and keep the blood circulating properly, clothing should be
worn loosely and in layers.Covering the hands, feet, and head is also crucial
for preventing heat loss.Outer garments need to be wind and water resistant, and
wet clothing and footwear must be replaced as quickly as possible.Alcohol and
drugs should be avoided because of their harmful effects on judgment and
reasoning.Experts also warn against alcohol use and smoking in the cold because
of the circulatory changes they produce.Paying close attention to the weather
report before venturing outdoors and avoiding unnecessary risks such as driving
in isolated areas during a blizzard are also important.
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