Hypothermia Misc.

First Aid & Emergencies - Hypothermia Treatment (www.emedicinehealth.com)

Treating Hypothermia (www.hypothermia.org)

Alaskan Protocol (Brief) - Full Text (www.hypothermia.org)

JAMA Protocol (Brief) - Full Text (www.hypothermia.org)

Hypothermia Field Rescue (www.hypothermia-ca.com)

Airway Rewarming (www.hypothermia-ca.com)

Hypothermia Survival on Land & on Water (www.hypothermia-ca.com)

Special Situations of Hypothermia (www.hypothermia-ca.com)

Hypothermia

Hypothermia

Physiology, Signs, Symptoms and Treatment Considerations

As you know, hypothermia is a temperature related disorder. Therefore, it is necessary to understand human physiology as it pertains to temperature stress.
Man is considered to be a tropical animal. Normal functioning of the human animal requires a body temperature of 37 degrees Celcius (98.6 degrees Fahrenheit). Comfortable human survival using only that protection from temperature stress which is provided physiologically at birth would therefore require an environment providing a temperature of 37 degrees Celcius, plus or minus perhaps 1 degree.
The body can self-compensate for small upward or downward variations in temperature through the activation of a built-in thermoregulatory system, controlled by temperature sensors in the skin.
The response to an upward variation in body temperature is the initiation of perspiration, which moves moisture from body tissues to the body surface. When the moisture reaches the surface it evaporates, carrying with it a quantity of heat. The explanation for a person becoming thirsty when exposed to a hot environment for a period of time is that fluids lost due to perspiration must be replaced.
The response to a downward variation in body temperature is shivering, which is the body's attempt to generate heat. Shivering is an involuntary contraction and expansion of muscle tissue occurring on a large scale. This muscle action creates heat through friction.
Now that the necessary groundwork has been laid we can delve into the intricacies of hypothermia and it's treatment.

THE DISORDER

Hypothermia is defined as a core temperature of less than 35 degrees Celcius. Hypothermia is also considered the clinical state of sub-normal temperature when the body is unable to generate sufficient heat to efficiently maintain functions.
Many variables contribute to the development of hypothermia. Age, health, nutrition, body size, exhaustion, exposure, duration of exposure, wind, temperature, wetness, medication and intoxicants may decrease heat production, increase heat loss, or interfere with thermostability.
The healthy individual's compensatory responses to heat loss via conduction, convection, radiation, evaporation and respiration may be overwhelmed by exposure. Medications may interfere with thermoregulation. Acute or chronic central nervous system processes may decrease the efficiency of thermoregulation.

Let's look at the definitions of the aforementioned causes of heat loss.
Conduction:
direct transfer of heat by contact with a cooler object - conduction of heat to the cooler object
Convection:
cool air moving across the surface of the body, heat transferred to the cool air, warming it and cooling the body
Radiation:
heat radiated outward from the warm body to the cooler environment
Evaporation:
the loss of heat through the process of removing water from the surface of the body through vaporization
Respiration:
inspired air raised to body temperature and then exhaled

Each of these causes of heat loss can play a large or small role in the development of hypothermia, depending on clothing, head cover, wind, weather, etc.
Once hypothermia develops, the heat deficit is shared by two body compartments, the shell and the core. The shell consists of the outer 1.65 mm of skin and has an average area of 1.8 square meters. This constitutes approximately 10% of a 70 kg mass. The remainder of the body is the core.
However, when we speak of Core Temperature it is the thoracic, or critical core we are concerned with, mainly the area of the heart, lungs and brain.

RECOGNITION OF SIGNS AND SYMPTOMS

Impending Hypothermia:
Due to physiological, medical, environmental, or other factors the person's core temperature has decreased to 36 degrees Celcius. The person will increase activity in an attempt to warm up. The skin may become pale, numb and waxy. Muscles become tense, shivering may begin but can be overcome by activity. Fatigue and signs of weakness begin to show.

Mild Hypothermia:
The person has now become a victim of hypothermia. The core temper-ature has dropped to 35 - 34 degrees Celcius. Uncontrolled, intense shivering begins. The victim is still alert and able to help self, however movements become less coordinated and the coldness is creating some pain and discomfort.

Moderate Hypothermia:
The victim's core temperature has now dropped to 33 - 31 degrees Celcius. Shivering slows or stops, muscles begin to stiffen and mental confusion and apathy sets in. Speech becomes slow, vague and slurred, breathing becomes slower and shallow, and drowsiness and strange behavior may occur.

Severe Hypothermia:
Core temperature now below 31 degrees Celcius. Skin is cold, may be bluish- gray in color, eyes may be dilated. Victim is very weak, displays a marked lack of coordination, slurred speech, appears exhausted, may appear to be drunk, denies problem and may resist help. There is a gradual loss of consciousness. There may be little or no apparent breathing, victim may be very rigid, unconscious, and may appear dead.

TREATMENT PREFACE

Treatment of cold injuries has long been controversial.
Hippocrates, Aristotle and Galen mention various cold injury treatments. Cold has had major impacts on military history. Hannibal lost nearly half his army of 46,000 crossing the Alps in 218 BC. Baron Larrey, Napoleon's chief surgeon, reported only 350 of the 12,000 men in the Twelfth Division survived the cold. He observed that those soldiers placed closest to the campfire during that retreat from Russia died. The winter of 1777 took its toll on Washington's troops. There were large losses to cold injuries in the Crimean and both world wars. About 10% of the United States casualties in Korea were cold related.
Be aware that hypothermia may masquerade as a variety of conditions, including death, in a variety of situations and seasons.
Always act on the premise that "no one is dead until warm and dead".
Patients cold, stiff and cyanotic, with fixed pupils and no audible heart tones or visible thoracic excursions have been successfully resuscitated. One patient recovered completely in the morgue.
The only certain criterion for death in hypothermia is irreversibility of cardiac arrest when the patient is warm.
Conclusions regarding the potential reversibility of coexisting conditions should be withheld until the patient is rewarmed. Resuscitation, including CPR if necessary, should be continued until either failure after hospital rewarming to 35 degrees Celcius or danger through exposure to rescuers exists.
The sole consensus regarding prehospital treatment is that all patients at some point should be rewarmed.
Initial management principles emphasize prevention of further heat loss, rewarming as soon as is safely possible at a "successful" rate and rewarming the core before the shell, in an attempt to avoid inducing lethal side effects during rewarming. This treatment goal is important, since hypothermia itself may not be fatal above 25 degrees Celcius core temperature.
Hypothermia causes several reactions within the body as it tries to protect itself and retain its heat. The most important of these is vasoconstriction, which halts blood flow to the extremities in order to conserve heat in the critical core area of the body.
When core temperature exceeds 30 degrees Celcius the major source of heat production is shivering thermogenesis.
This maintains peripheral vasoconstriction, which minimizes the severity of vascular collapse during rewarming. Induction of vasodilation in these patients may precipitate rewarming shock and metabolic acidosis.
Rapid shunting of cold blood from the periphery to the core as the direct result of vasodilation may cause the core temperature to drop. This phenomenon of a drop in temperature after initiation of therapy is termed core temperature after-drop.
Prevention of vasodilation is the reason why it is imperative that the patient's extremities not be rewarmed before the core. If vasodilation occurs, cold blood returning to the heart may be enough to put the patient into ventricular fibrillation.
The patient must also be handled very gently and not be allowed to exercise, as muscular action can pump cold blood to the heart.
Certain assumptions permit safe treatment. If the patient is unresponsive and not shivering, one should presume severe hypothermia.
At temperatures below 32 degrees Celcius, one should expect an irritable myocardium, a temperature gradient between the core and periphery, and relative hypovolemia (abnormally decreased volume of circulating blood in the body).
The patient is in a "metabolic ice-box", and sudden thawing may be disastrous to the cardiovascular system.

TREATMENT FOR THE DIFFERENT LEVELS OF HYPOTHERMIA

Impending Hypothermia:
Seek or build a shelter to get the person out of the cold, windy, wet environment.
Start a fire or get a cookstove going to provide warmth. Provide the person with a hot drink (no alcohol, coffee or tea).
Halt further heat loss by insulating the person with extra clothes, etc. This person should recover from the present condition quite quickly.

Mild Hypothermia:
Remove or insulate the patient from the cold environment, keeping the head and neck covered. This prevents further heat loss and allows the body to rewarm itself.
Provide the patient with a warm, sweetened drink (no alcohol, coffee or tea) and some high energy food. Limited exercise may help to generate some internal heat, but it depletes energy reserves.

Moderate Hypothermia:
Remove or insulate the patient from the cold environment, keeping the head and neck covered. Apply mild heat (comfortable to your elbow) to the head, neck, chest, armpits and groin of the patient.
Use hot water bottles, wrapped Thermo-Pads, or warm moist towels.
It is possible that you may have to continue this treatment for some time. Offer sips of warm, sweetened liquids (no alcohol, coffee or tea) if the patient is fully conscious, beginning to rewarm and is able to swallow. Patient should be seen by a physician.

Severe Hypothermia:
Place patient in a prewarmed sleeping bag with one or two other people. Skin to skin contact in the areas of the chest (ribs) and neck is effective. Exhale warm air near the patient's nose and mouth, or introduce steam into the area.
Try to keep the patient awake, ignore pleas of "leave me alone, I'm ok". The patient is in serious trouble, keep a close, continuous watch over the patient.
Apply mild heat, with the aim of stopping temperature drop, not rewarming.
If patient has lost conciousness be very gentle, as by now the heart is extremely sensitive. Always assume the patient is revivable, do not give up.
Check for pulse at the carotid artery. If, after two minutes you find no pulse check on the other side of the neck for two minutes.
If there is any breathing or pulse, no matter how faint, do not give CPR but keep very close watch for changes in vital signs.
If no pulse is found begin CPR immediately, stopping only when the heart begins to beat or the person applying CPR can not carry on any longer without endangering himself.
Medical help is imperative, hospitalization is needed.

CONCLUSION
Treatment of hypothermia should be approached with knowledge and care.
It is altogether too easy to cause more harm than good by using the wrong treatment. If one can not distinguish the level of hypothermia through visible signs and symptoms then he should assume severe hypothermia.
Through recent research and clinical findings it has come to be concluded that the safest and most effective method of treating hypothermia is through inhalation rewarming. The necessary equipment for providing inhalation rewarming therapy in the field is now readily available. However, this equipment may not be available when it is needed and people who may end up in the position of having to provide treatment must know the alternative methods which have been described here.
Always remember, gentle handling, insulation, no alcohol, coffee or tea, and don't try to rewarm a patient in a hurry.
Any method which will rewarm a patient in a hurry in the field will likely cause further complications, if not death.

Hypothermia

Background

Hypothermia describes a state in which the body’s mechanism for temperature regulation is overwhelmed in the face of a cold stressor. Hypothermia is classified as accidental or intentional, primary or secondary, and by the degree of hypothermia.

Accidental hypothermia generally results from unanticipated exposure in an inadequately prepared person; examples include inadequate shelter for a homeless person, someone caught in a winter storm or motor vehicle accident, or an outdoor sport enthusiast caught off guard by the elements. Intentional hypothermia is an induced state generally directed at neuroprotection after an at-risk situation (usually after cardiac arrest, see Therapeutic Hypothermia). Primary hypothermia is due to environmental exposure, with no underlying medical condition causing disruption of temperature regulation. Secondary hypothermia is low body temperature resulting from a medical illness lowering the temperature set-point.

Many patients have recovered from severe hypothermia, so early recognition and prompt initiation of optimal treatment is paramount.

Systemic hypothermia may also be accompanied by localized cold injury (see Frostbite).

Pathophysiology

The body’s core temperature is tightly regulated in the “thermoneutral zone” between 36.5°C and 37.5°C, outside of which thermoregulatory responses are usually activated. The body maintains a stable core temperature through balancing heat production and heat loss. At rest, humans produce 40-60 kilocalories (kcal) of heat per square meter of body surface area through generation by cellular metabolism, most prominently in the liver and the heart. Heat production increases with striated muscle contraction; shivering increases the rate of heat production 2-5 times.

Heat loss occurs via several mechanisms, the most significant of which, under dry conditions, is radiation (55-65% of heat loss). Conduction and convection account for about 15% of additional heat loss, and respiration and evaporation account for the remainder. Conductive and convective heat loss, or direct transfer of heat to another object or circulating air, respectively, are the most common causes of accidental hypothermia. Conduction is a particularly significant mechanism of heat loss in drowning/immersion accidents as thermal conductivity of water is up to 30 times that of air.

The hypothalamus controls thermoregulation via increased heat conservation (peripheral vasoconstriction and behavior responses) and heat production (shivering and increasing levels of thyroxine and epinephrine). Alterations of the CNS may impair these mechanisms. The mechanisms for heat preservation may be overwhelmed in the face of cold stress and core temperature can drop secondary to fatigue or glycogen depletion.

Hypothermia affects virtually all organ systems. Perhaps the most significant effects are seen in the cardiovascular system and the CNS. Hypothermia results in decreased depolarization of cardiac pacemaker cells, causing bradycardia. Since this bradycardia is not vagally mediated, it can be refractory to standard therapies such as atropine. Mean arterial pressure and cardiac output decrease, and an electrocardiogram (ECG) may show characteristic J or Osborne waves (see Media file 1). While generally associated with hypothermia, the J wave may be a normal variant and is seen occasionally in sepsis and myocardial ischemia.

Atrial and ventricular arrhythmias can result from hypothermia; asystole and ventricular fibrillation have been noted to begin spontaneously at core temperatures below 25-28°C.

Hypothermia progressively depresses the CNS, decreasing CNS metabolism in a linear fashion as the core temperature drops. At core temperatures less than 33°C, brain electrical activity becomes abnormal; between 19°C and 20°C, an electroencephalogram (EEG) may appear consistent with brain death. Tissues have decreased oxygen consumption at lower temperatures; it is not clear whether this is due to decreases in metabolic rate at lower temperatures or a greater hemoglobin affinity for oxygen coupled with impaired oxygen extraction of hypothermic tissues.

The term "core temperature after drop" refers to a further decrease in core temperature and associated clinical deterioration of a patient after rewarming has been initiated. The current theory of this documented phenomenon is that as peripheral tissues are warmed, vasodilation allows cooler blood in the extremities to circulate back into the body core. Other mechanisms may be in operation as well. Some believe that after drop is most likely to occur in patients with frostbite or long-standing hypothermia.

• Mild hypothermia (32-35°C)
  • Between 34°C and 35°C, most people shiver vigorously, usually in all extremities.
  • As the temperature drops below 34°C, a patient may develop altered judgment, amnesia, and dysarthria. Respiratory rate may increase.
  • At approximately 33°C, ataxia and apathy may be seen. Patients generally are stable hemodynamically and able to compensate for the symptoms.
  • In this temperature range, the following may also be observed: hyperventilation, tachypnea, tachycardia, and cold diuresis as renal concentrating ability is compromised.
• Moderate hypothermia (28-32°C)
  • Oxygen consumption decreases, and the CNS depresses further; hypoventilation, hyporeflexia, decreased renal flow, and paradoxical undressing may be noted.
  • Most patients with temperatures of 32°C or lower present in stupor.
  • As the core reaches temperatures of 31°C or below, the body loses its ability to generate heat by shivering.
  • At 30°C, patients develop a higher risk for arrhythmias. Atrial fibrillation and other atrial and ventricular rhythms become more likely. The pulse continues to slow progressively, and cardiac output is reduced. J wave may be seen on ECG in moderate hypothermia.
  • Between 28°C and 30°C, pupils may become markedly dilated and minimally responsive to light, a condition that can mimic brain death.
• Severe hypothermia (<28°c)
  • At 28°C, the body becomes markedly susceptible to ventricular fibrillation and further depression of myocardial contractility.
  • Pulmonary edema, oliguria, coma, hypotension, rigidity, apnea, pulselessness, areflexia, unresponsiveness, fixed pupils, and decreased or absent activity on EEG are all seen.

Hypothermia

LINKS
http://emedicine.medscape.com/article/770542-overview
http://www.merck.com/mmpe/sec21/ch319/ch319d.html

Hypothermia (General Overview)

Hypothermia

By Mayo Clinic staff

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Original Article:http://www.nlm.nih.gov/medlineplus/hypothermia.html

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• Definition
• Symptoms
• Causes
• Risk factors
• Complications
• Tests and diagnosis
• Treatments and drugs
• Prevention

Definition

Hypothermia is a medical emergency that occurs when your body loses heat faster than it can produce heat, causing a dangerously low body temperature. Normal body temperature is around 98.6 F (37 C). Hypothermia (hi-po-THUR-me-uh) occurs as your body temperature passes below 95 F (35 C).

When your body temperature drops, your heart, nervous system and other organs cannot work correctly. Left untreated, hypothermia eventually leads to complete failure of your heart and respiratory system and to death.

Hypothermia is most often caused by exposure to cold weather or immersion in a cold body of water. Primary treatments are methods to warm the body back to a normal temperature.

Symptoms

Shivering is your body's automatic defense against cold temperature — an attempt to warm itself. Constant shivering is a key sign of hypothermia. Signs and symptoms of hypothermia include:

• Shivering
• Clumsiness or lack of coordination
• Slurred speech or mumbling
• Stumbling
• Confusion or difficulty thinking
• Poor decision making, such as trying to remove warm clothes
• Drowsiness or very low energy
• Apathy, or lack of concern about one's condition
• Progressive loss of consciousness
• Weak pulse
• Shallow breathing

A person with hypothermia usually isn't aware of his or her condition, because the symptoms often begin gradually and because the confused thinking associated with hypothermia prevents self-awareness.

Hypothermia not related to the outdoors
Hypothermia isn't always the result of exposure to extremely cold outdoor temperatures. An older person may develop mild hypothermia after prolonged exposure to indoor temperatures that would be tolerable to a younger or healthier adult — for example, temperatures in a poorly heated home or in an air-conditioned home.

In such cases, mild hypothermia may result in vague symptoms, and the typical shivering may not be present at all. Symptoms of mild hypothermia not related to extreme cold exposure may include:

• Confusion
• Lack of coordination
• Dizziness
• Nausea or vomiting
• Fatigue

Hypothermia in infants
Typical signs of hypothermia in an infant include:

• Bright red, cold skin
• Very low energy

When to see a doctor
Call 911 or your local emergency number if you see someone exhibiting signs of hypothermia or if you suspect a person has had unprotected or prolonged exposure to cold weather or water. If possible take the person inside, remove wet clothing and cover him or her in layers of blankets.

Causes

Hypothermia occurs when your body loses heat faster than it produces it. The most common causes of hypothermia are exposure to cold weather conditions or cold water, but prolonged exposure to any environment colder than your body can lead to hypothermia if you aren't dressed appropriately or can't control the conditions. Specific conditions leading to hypothermia include:

• Wearing clothes that aren't warm enough for weather conditions
• Staying out in the cold too long
• Unable to get out of wet clothes or move to a warm, dry location
• Accidental falls in water, as in a boating accident
• Inadequate heating in the home, especially for older people and infants
• Air conditioning that is too cold, especially for older people and infants

How your body loses heat
The mechanisms of heat loss from your body include the following:

• Radiated heat. Most heat loss is due to heat radiated from unprotected surfaces of your body. Your head has a large surface area and accounts for about half of all heat loss.
• Direct contact. If you're in direct contact with something very cold, such as cold water or the cold ground, heat is conducted away from your body. Because water is very good at transferring heat from your body, body heat is lost much faster in cold water than in cold air. Water that is 65 F (18 C) — a relatively mild air temperature — can lead to hypothermia very quickly. Similarly, heat loss from your body is much faster if your clothes are wet, as when you're caught out in the rain.
• Wind. Wind removes body heat by carrying away the thin layer of warm air at the surface of your skin. A wind chill factor is important in causing heat loss. For example, if the outside temperature is 32 F (0 C) and the wind chill factor is minus 15 F (minus 26 C), your body loses heat as quickly as if the actual temperature outside were minus 15 F (minus 26 C).

Risk factors

A number of factors can increase the risk of developing hypothermia:

• Older age. People age 65 and older are more vulnerable to hypothermia for a number of reasons. The body's ability to regulate temperature and to sense cold may lessen with age. Older people are also more likely to have a medical condition that affects temperature regulation. Some older adults may not be able to communicate when they are cold or may not be mobile enough to get to a warm location.
• Very young age. Children lose heat faster than adults do. Children have a larger head-to-body ratio than adults do, making them more prone to heat loss through the head. Children may also ignore the cold because they're having too much fun to think about it. And they may not have the judgment to dress properly in cold weather or to get out of the cold when they should. Infants may have a special problem with the cold because they have less efficient mechanisms for generating heat.
• Mental impairment. People with a mental illness, dementia or another condition that impairs judgment may not dress appropriately for the weather or understand the risk of cold weather. People with dementia may wander from home or get lost easily, making them more likely to be stranded outside in cold or wet weather.
• Alcohol and drug use. Alcohol may make your body feel warm inside, but it causes your blood vessels to dilate, or expand, resulting in more rapid heat loss from the surface of your skin. The use of alcohol or recreational drugs can impair your judgment about the need to get inside or wear warm clothes in cold weather conditions. If a person is intoxicated and passes out in cold weather, he or she is likely to develop hypothermia.
• Certain medical conditions. Some health disorders affect your body's ability to regulate body temperature. Examples include underactive thyroid (hypothyroidism), malnutrition, stroke, severe arthritis, Parkinson's disease, trauma, spinal cord injuries, burns, disorders that affect sensation in your extremities (for example, nerve damage in the feet of people with diabetes), dehydration and any condition that limits activity or restrains the normal flow of blood.
• Medications. A number of antipsychotic drugs and sedatives can impair the body's ability to regulate its temperature.

Complications

If left untreated, hypothermia leads to complete failure of the heart and respiratory system and to death.

People who develop hypothermia because of exposure to cold weather or cold water are also vulnerable to other cold-related injuries, including:

• Frostbite, or freezing of body tissues
• Gangrene, decay and death of tissue resulting from an interruption in blood flow (possible complication of frostbite)
• Chilblains, damage to nerves and small blood vessels, usually in the hands or feet after prolonged exposure to above-freezing, cold temperatures
• Trench foot (immersion foot), damage to nerves and small blood vessels due to prolonged immersion in water

Tests and diagnosis

The diagnosis of hypothermia is usually apparent based on a person's physical signs and the conditions in which the person with hypothermia became ill or was found.

A diagnosis may not be readily apparent, however, if the symptoms are mild, as when an older person who is indoors has symptoms such as confusion, lack of coordination and impaired speech. In such cases, a part of the diagnostic workup will include a temperature reading with a rectal thermometer that reads low temperatures.

Treatments and drugs

Seek immediate medical attention for anyone who appears to have hypothermia. Until medical help is available, follow these hypothermia treatment guidelines.

First-aid care

• Be gentle. When you are helping a person with hypothermia, handle him or her gently. Limit movements to only those that are necessary. Don't massage or rub the person. Excessive, vigorous or jarring movements may trigger cardiac arrest.
• Move the person out of the cold. Move the person to a warm, dry location if possible. If you're unable to move the person out of the cold, shield him or her from the cold and wind as much as possible.
• Remove wet clothing. If the person is wearing wet clothing, remove it. Cut away clothing if necessary to avoid excessive movement.
• Cover the person with blankets. Use layers of dry blankets or coats to warm the person. Cover the person's head, leaving only the face exposed.
• Insulate the person's body from the cold ground. If you're outside, lay the person on his or her back on a blanket or other warm surface.
• Monitor breathing. A person with severe hypothermia may appear unconscious, with no apparent signs of a pulse or breathing. If the person's breathing has stopped or appears dangerously low or shallow, begin cardiopulmonary resuscitation (CPR) immediately if you're trained.
• Share body heat. To warm the person's body, remove your clothing and lie next to the person, making skin-to-skin contact. Then cover both of your bodies with blankets.
• Provide warm beverages. If the affected person is alert and able to swallow, provide a warm, nonalcoholic, noncaffeinated beverage to help warm the body.
• Use warm, dry compresses. Use a first-aid warm compress (a plastic fluid-filled bag that warms up when squeezed), or a makeshift compress of warm water in a plastic bottle or a dryer-warmed towel. Apply a compress only to the neck, chest wall or groin. Don't apply a warm compress to the arms or legs. Heat applied to the arms and legs forces cold blood back toward the heart, lungs and brain, causing the core body temperature to drop. This can be fatal.
• Don't apply direct heat. Don't use hot water, a heating pad or a heating lamp to warm the person. The extreme heat can damage the skin or induce cardiac arrest.

Medical treatment
Depending on the severity of hypothermia, emergency medical care for hypothermia may include one of following interventions to raise the body temperature:

• Blood rewarming. Blood may be drawn, warmed and recirculated in the body. A common method of warming blood is the use of a hemodialysis machine, which is normally used to filter blood in people with poor kidney function.
• Warm intravenous fluids. A warmed solution of salt water may be injected into a vein to help warm the blood.
• Airway rewarming. The use of humidified oxygen administered with a mask or nasal tube can warm the airways and help raise the temperature of the body.
• Cavity lavage. A warm saltwater solution may be used to warm the stomach, bladder or colon. To deliver the warm solution, a small tube is inserted down the throat to reach the stomach, through the urethra to the bladder or through the rectum to the colon.

Prevention

Staying warm in cold weather
Before you or your children step out into cold air, remember the advice that follows with the simple acronym COLD — cover, overexertion, layers, dry:

• Cover. Wear a hat or other protective covering to prevent body heat from escaping from your head, face and neck. Cover your hands with mittens instead of gloves. Mittens are more effective than gloves because mittens keep your fingers in closer contact with one another.
• Overexertion. Avoid activities that would cause you to sweat a lot. The combination of wet clothing and cold weather can cause you to lose body heat more quickly.
• Layers. Wear loosefitting, layered, lightweight clothing. Outer clothing made of tightly woven, water-repellent material is best for wind protection. Wool, silk or polypropylene inner layers hold body heat better than cotton does.
• Dry. Stay as dry as possible. Get out of wet clothing as soon as possible. Be especially careful to keep your hands and feet dry, as it's easy for snow to get into mittens and boots.

Keeping children safe outdoors
The American Academy of Pediatrics suggests the following tips to help prevent hypothermia when children are outside in the winter:

• Dress infants and young children in one more layer than an adult would wear in the same conditions.
• Limit the amount of time children spend outside in the cold.
• Have children come inside frequently to warm up.

Winter car safety
During cold-weather months, keep emergency supplies in your car in case you get stranded. Supplies may include several blankets, matches, candles, a first-aid kit, dry or canned food, and a can opener. Travel with a cell phone if possible. If you're stranded, put everything you need in the car with you, huddle together and stay covered. Run the car for 10 minutes each hour to warm it up. Make sure a window is slightly open and the exhaust pipe isn't covered with snow while the engine is running.

Alcohol consumption
If you drink, do so in moderation. Take the following precautions to avoid alcohol-related risks of hypothermia. Don't drink alcohol:

• If you're going to be outside in cold weather
• If you're boating
• Before going to bed on cold nights

Cold-water safety
Water doesn't have to be extremely cold to cause hypothermia. Any water that's colder than normal body temperature causes heat loss. The following tips may increase your survival time in cold water, if you accidentally fall in:

• Wear a life jacket. If you plan to ride in a watercraft, wear a life jacket. A life jacket can help you stay alive longer in cold water by enabling you to float without using energy and by providing some insulation. Keep a whistle attached to your life jacket to signal for help.
• Get out of the water if possible. Get out of the water as much as possible, such as climbing onto a capsized boat or grabbing onto a floating object.
• Don't attempt to swim unless you're close to safety. Unless a boat, another person or a life jacket is close by, stay put. Swimming will use up energy and may shorten survival time.
• Position your body to minimize heat loss. Use a body position known as the heat escape lessening position (HELP) to reduce heat loss while you wait for assistance. Hold your knees to your chest to protect the trunk of your body. If you're wearing a life jacket that turns your face down in this position, bring your legs tightly together, your arms to your sides and your head back.
• Huddle with others. If you've fallen into cold water with other people, keep warm by facing each other in a tight circle.
• Don't remove your clothing. While you're in the water, don't remove clothing. Buckle, button and zip up your clothes. Cover your head if possible. The layer of water between your clothing and your body will help insulate you. Remove clothing only after you're safely out of the water and can take measures to get dry and warm.

Help for at-risk people
For people most at risk of hypothermia — infants, older adults, people who have mental or physical impairments, or people who are homeless — community outreach programs and social support services can be of great help. If you're at risk or know someone at risk, contact your local public health office for available services, such as the following:

• Check-in services to see if you and your home are warm enough during cold weather
• Assistance for paying heating bills
• In-home or community meal programs to help maintain good nutrition
• Homeless shelters
• Community warming centers, safe and warm daytime locations where you can go during cold weather
• Safety bracelets for people with dementia who may wander or get lost easily