What are the effects of hypothermia: Hypothermia – Symptoms and causes

24.03.201913.04.2021 by alexxlab

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Hypothermia – Symptoms and causes

Overview

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-poe-THUR-me-uh) occurs as your body temperature falls below 95 F (35 C).

When your body temperature drops, your heart, nervous system and other organs can’t work normally. Left untreated, hypothermia can lead to complete failure of your heart and respiratory system and eventually to death.

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

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Symptoms

Shivering is likely the first thing you’ll notice as the temperature starts to drop because it’s your body’s automatic defense against cold temperature — an attempt to warm itself.

Signs and symptoms of hypothermia include:

Shivering
Slurred speech or mumbling
Slow, shallow breathing
Weak pulse
Clumsiness or lack of coordination
Drowsiness or very low energy
Confusion or memory loss
Loss of consciousness
Bright red, cold skin (in infants)

Someone with hypothermia usually isn’t aware of his or her condition because the symptoms often begin gradually. Also, the confused thinking associated with hypothermia prevents self-awareness. The confused thinking can also lead to risk-taking behavior.

When to see a doctor

Call 911 or your local emergency number if you suspect someone has hypothermia.

While you wait for emergency help to arrive, gently move the person inside if possible. Jarring movements can trigger dangerous irregular heartbeats. Carefully remove his or her wet clothing, replacing it with warm, dry coats or 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
Being unable to get out of wet clothes or move to a warm, dry location
Falling into the water, as in a boating accident
Living in a house that’s too cold, either from poor heating or too much air conditioning

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.
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. 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.

Risk factors

Risk factors for hypothermia include:

Exhaustion. Your tolerance for cold diminishes when you are fatigued.
Older age. The body’s ability to regulate temperature and to sense cold may lessen with age. And some older adults may not be able to communicate when they are cold or to move to a warm location if they do feel cold.
Very young age. Children lose heat faster than adults do. 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.
Mental problems. People with a mental illness, dementia or other conditions that interfere with 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 expand, resulting in more rapid heat loss from the surface of your skin. The body’s natural shivering response is diminished in people who’ve been drinking alcohol.
In addition, the use of alcohol or recreational drugs can affect 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 an underactive thyroid (hypothyroidism), poor nutrition or anorexia nervosa, diabetes, stroke, severe arthritis, Parkinson’s disease, trauma, and spinal cord injuries.
Medications. Some drugs can change the body’s ability to regulate its temperature. Examples include certain antidepressants, antipsychotics, narcotic pain medications and sedatives.

Mayo Clinic Minute: Why the risk of frostbite is greater than you think

Show transcript for video Mayo Clinic Minute: Why the risk of frostbite is greater than you think

As winter drags on and temperatures drop way down, your risk of cold-related injury like frostbite can go way up.

“Literally think of it as freezing of the tissues,” Dr. Sanj Kakar Mayo Clinic Orthopedic hand and wrist surgeon says frostbite is more common than many people think.

“We tend to see frostbite, for example, when the temperature is 5 degrees Fahrenheit with minimal windchill,” Dr. Kakar explains.

If the windchill drops below negative 15 degrees Fahrenheit, not unheard of in the northern half of the U.S., frostbite can set in within half an hour.

The most vulnerable areas of frostbite are your nose, ears, fingers and toes.

“Initially [with] the milder forms, you can get some pain and some numbness of the tips, but the skin can change its color,” Dr. Kakar says. “It can be red. It can be white. Or it can be blue. And you can get these blisters on your hands. And it can be a very serious injury.”

The worst cases, the tissue can die, and you may need surgery to remove it.

So who’s most at risk?

“[Those most at risk are] certain patients with diabetes, patients who have previous history of frostbite are prone to it, the elderly or your very young children, and also, for example, if you’re dehydrated,” he says.

Complications

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

Freezing of body tissues (frostbite)
Decay and death of tissue resulting from an interruption in blood flow (gangrene)

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.
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 from the cold

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.
Bring children indoors if they start shivering — that’s the first sign that hypothermia is starting.
Have children come inside frequently to warm themselves when they’re playing outside.
Don’t let babies sleep in a cold room.

Winter car safety

Whenever you’re traveling during bad weather, be sure someone knows where you’re headed and at what time you’re expected to arrive. That way, if you get into trouble on your way, emergency responders will know where to look for your car.

It’s also a good idea to keep emergency supplies in your car in case you get stranded. Supplies may include several blankets, matches, candles, a clean can where you can melt snow into drinking water, a first-aid kit, dry or canned food, a can opener, tow rope, booster cables, compass, and a bag of sand or kitty litter to spread for traction if you’re stuck in the snow. If possible, travel with a cellphone.

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

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 posture (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 because it helps to insulate you from the water. Buckle, button and zip up your clothes. Cover your head if possible. Remove clothing only after you’re safely out of the water and can take measures to get dry and warm.

Help for people most at risk

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

Assistance for paying heating bills
Check-in services to see if you and your home are warm enough during cold weather
Homeless shelters
Community warming centers, safe and warm daytime locations where you can go during cold weather

Hypothermia: Symptoms, treatment, and stages

Share on PinterestHypothermia happens when the body cannot produce enough energy to keep warm. Older people and children are especially susceptible.

Hypothermia is a severe condition in which the body temperature drops to an abnormally low level. It occurs when the body is unable to produce enough heat to counter the heat that it is losing.

The part of the brain that controls body temperature is called the hypothalamus. When the hypothalamus recognizes changes in body temperature, it initiates body responses to bring the temperature back in line.

The body produces heat during routine metabolic processes in cells that support vital bodily functions. Most heat leaves the body through the skin’s surface by the processes of convection, conduction, radiation, and evaporation.

If the environment becomes colder, the body shivers. This increase in muscle activity generates more heat. However, if the body loses heat more quickly than it can make it, the core temperature will fall.

As the temperature falls, the body shunts blood away from the skin to reduce the amount of heat that escapes.

Instead, it directs blood flow to the vital organs of the body, such as the heart, lungs, kidney, and brain. The heart and brain are most sensitive to lower temperatures, and electrical activity in these organs slows down when they become cold.

If the body temperature keeps falling, the organs begin to fail, ultimately leading to death.

Hypothermia is the opposite of hyperthermia, which involves an elevated body temperature and can present as heat exhaustion or heat stroke.

As hypothermia sets in, it becomes more challenging to think, move, and take preventive action. This is dangerous because it means that people who have hypothermia will not seek to keep themselves warm and safe.

The body starts to slow down as the temperature drops. If the person stops shivering, it can be a sign that their condition is getting worse.

The individual is at risk of lying down, falling asleep, and dying. In some cases, people will paradoxically remove their clothes just before this occurs.

Treatment depends on the degree of hypothermia, but the aim will be to make the person warm.

Treatments include the following:

First aid treatment

Anyone with symptoms of hypothermia will need immediate medical assistance.

Until medical assistance arrives, taking the following action can help:

moving the person to a warm, dry place, if possible, or sheltering them from the elements
removing wet clothing, cutting items away if necessary
covering their whole body and head with blankets, leaving only the face clear
putting the individual on a blanket to insulate them from the ground
monitoring breathing and carrying out CPR if breathing stops
providing skin-to-skin contact, if possible, by removing clothing and wrapping yourself and the individual in the blanket together to transfer heat
providing warm drinks, if the individual is conscious, but no alcohol or caffeine

It is vital not to use direct heat, such as heat lamps or hot water, as this can damage the skin. It can also trigger irregular heartbeats and, potentially, lead to cardiac arrest.

Do not rub or massage the person either, as these potentially jarring movements could also cause cardiac arrest.

Clinical treatment

According to an article published in the American Family Physician (AFP), the journal of the American Academy of Family Physicians (AAFP), the following techniques can help treat hypothermia.

Passive external rewarming: This uses the individual’s heat-generating ability. It involves removing their cold, wet clothing, ideally replacing it with adequately insulated, dry clothing, and moving them to a warm environment.

Active external rewarming: This involves applying warming devices, such as hot-water bottles or warmed forced air, externally to truncal areas of the body. For example, the individual could hold a hot-water bottle under each arm.

Active core rewarming: This uses warmed, intravenous fluids to irrigate body cavities, including the thorax, peritoneum, stomach, and bladder. Other options include getting the individual to inhale warm, humidified air, or applying extracorporeal rewarming by using a heart-lung machine.

Do not give a person alcohol if they have signs of hypothermia, and avoid giving any drinks to an unconscious person.

A person with severe hypothermia may not seem to have a pulse or be breathing. If they appear to be dead, the CDC advise bystanders to give CPR while keeping the person warm and waiting for emergency help. It is possible that this may resuscitate them.

Hypothermia generally progresses in three stages from mild to moderate and then severe.

According to the AAFP, the signs and symptoms of these stages are as follows:

Stage	Body temperature	Signs and symptoms
Mild	90°F to 95°F (32.2°C to 35°C)	High blood pressure, shivering, rapid breathing and heart rate, constricted blood vessels, apathy and fatigue, impaired judgment, and lack of coordination.
Moderate	82.4°F to 90°F (28°C to 32.2°C)	Irregular heartbeat, a slower heart rate and breathing, lower level of consciousness, dilated pupils, low blood pressure, and a decrease in reflexes.
Severe	Less than 82.4°F (28°C)	Labored breathing, nonreactive pupils, heart failure, pulmonary edema, and cardiac arrest.

Additional symptoms of hypothermia may include:

Mild:

dizziness
hunger and nausea
difficulty speaking

Moderate to severe:

shivering may stop
slurred speech
significant confusion
drowsiness
apathy or lack of concern
weak pulse

When a person has severe hypothermia, they may no longer know what they are doing, due to a change in mental consciousness.

Paradoxical undressing

Back in 1979, researchers described a phenomenon known as paradoxical undressing.

In paradoxical undressing, people remove their clothes despite the cold. As a result of doing this, they lose more body heat, which can be fatal. This can happen during the later stages of hypothermia as the person becomes disoriented, confused, and possibly combative.

Although there is a lack of research on this situation, anecdotal evidence suggests that 20–50 percent of deaths from hypothermia are due to paradoxical undressing.

In infants

Infants lose body heat more easily than adults, and they cannot shiver to keep warm.

Infants with hypothermia may have:

bright red skin
cold skin
very low energy
a weak cry

Infants should not sleep in a cold room. Using extra blankets is not a solution as there is a risk that these can smother the infant.

The CDC suggest making alternative arrangements if it is not possible to maintain a warm space where an infant can sleep.

Understanding and being prepared for hypothermia is integral to its prevention.

People are at higher risk if they:

work outdoors in cold weather
practice snowsports, watersports, or other outdoor activities
are at home during winter weather, especially older people
are stranded in a vehicle in severe winter conditions
are sleeping rough
have other medical conditions
use alcohol or illicit drugs

At home

To prevent hypothermia indoors, the National Institute on Aging (NIA) recommend the following:

heating the room you are using to 68–70°F and closing off other rooms to save on heating bills
insulating your home, by either making building improvements or laying down rolled-up towels to stop drafts
arranging for someone to check on you regularly if you live alone

Stranded in a motor vehicle

Anyone who becomes stranded in a motor vehicle should move everything they need from the trunk into the vehicle.

They should run the car for 10 minutes every hour, making sure that snow is not covering the exhaust pipe and keeping the window open a crack to prevent a buildup of fumes.

People should also consider creating a winter survival kit to keep in the car. The kit should contain nonperishable food, blankets, a first aid kit, water, and necessary medications.

Outdoor activities

Tips for avoiding hypothermia when outdoors include:

checking the weather conditions in advance and preparing accordingly
wearing multiple layers of clothing with the innermost layers made of wool, silk, or polypropylene because these materials retain heat better than cotton
layering clothing to trap multiple layers of air

Overexertion will not help, as this can lead to exhaustion and result in sweat-drenched clothing, both of which contribute to heat loss.

A person who begins to experience or show signs of mild hypothermia should retreat to a warmer place immediately to prevent progression to a life-threatening condition.

Other tips

Other tips for a cold environment include:

wearing a hat or thick scarf on the head, even indoors
avoiding alcohol
eating a sufficient number of calories, as additional fat under the skin can protect against cold during a winter weather spell

Hypothermia in summer

Hypothermia can happen in summer too. Excessively cool air-conditioning or water-based activities pose a risk, especially for infants and older people who may not be able to express how they are feeling.

The National Institutes of Health (NIH) recommend keeping room temperatures at 68°F (20°C) or above and closing off rooms that are not in use.

Observing symptoms and taking a person’s temperature with a thermometer can show whether or not they are experiencing hypothermia.

The BMJ define hypothermia as when a person’s body temperature below 95°F (35°C).

An oral thermometer may not show a temperature this low. In either case, it is vital to seek urgent medical attention.

Hypothermia can result from a chronically cold environment, such as during winter, or it can happen suddenly, for example, if a person falls into cold water.

The CDC stress that temperatures do not have to be excessively cold for hypothermia to develop. If the air temperature is 40°F (4.4°C) and a person is wet, they can develop hypothermia.

Hypothermia in water

People lose heat more quickly in water than on land. Water temperatures that would be comfortable as outdoor air temperatures can lead to hypothermia.

According to an article published in Scientific American, people in water that is 41°F (5°C) can lose muscle strength and coordination in as little as 10 minutes.

Even at 79°F (26°C), a person spending an extended period in the water may be at risk of hypothermia.

Indoor causes

Indoors, a lack of heating, excessive air conditioning or taking an ice bath can result in hypothermia.

Indoor hypothermia often has a poor outcome, because it tends to affect older people, and the diagnosis often comes at a late stage.

Vulnerable populations

Results of a study published in 2018 showed that 75 percent of people who received medical treatment in New York City hospitals for cold-related illness were outdoors when this happened.

Around half were sleeping rough, and another 25 percent had no heating at home. Substance abuse or having a mental or physical health condition increased the risk.

Most of the deaths and illnesses did not occur during periods of extreme cold.

The researchers noted, “Although the climate is warming, cold exposure is an ongoing concern during the winter.”

Medical causes

Other causes of hypothermia include metabolic disorders that result in a lower basal metabolic rate. These disorders cause the body to generate less heat internally.

Exposure to toxins and dysfunction of the thyroid, adrenal, or pituitary glands may also be underlying causes.

Q:

My elderly neighbors live alone. I’m not sure they heat their house or eat very well in winter, but they always say they are OK. When the cold weather comes, how often should I check on them and what other help can I offer?

A:

This sounds like a very difficult situation. I am sure your neighbors appreciate your concern.

During the winter time, you should check on your neighbors every few days. When temperatures are below freezing, you should check on them daily. Consider donating a space heater to your neighbors and even some extra blankets, warm clothes, or both.

Alana Biggers, MD, MPHAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

Hypothermia: Symptoms, treatment, and stages

Share on PinterestHypothermia happens when the body cannot produce enough energy to keep warm. Older people and children are especially susceptible.

Hypothermia is a severe condition in which the body temperature drops to an abnormally low level. It occurs when the body is unable to produce enough heat to counter the heat that it is losing.

As the temperature falls, the body shunts blood away from the skin to reduce the amount of heat that escapes.

If the body temperature keeps falling, the organs begin to fail, ultimately leading to death.

Hypothermia is the opposite of hyperthermia, which involves an elevated body temperature and can present as heat exhaustion or heat stroke.

The body starts to slow down as the temperature drops. If the person stops shivering, it can be a sign that their condition is getting worse.

The individual is at risk of lying down, falling asleep, and dying. In some cases, people will paradoxically remove their clothes just before this occurs.

Treatment depends on the degree of hypothermia, but the aim will be to make the person warm.

Treatments include the following:

First aid treatment

Anyone with symptoms of hypothermia will need immediate medical assistance.

Until medical assistance arrives, taking the following action can help:

moving the person to a warm, dry place, if possible, or sheltering them from the elements
removing wet clothing, cutting items away if necessary
covering their whole body and head with blankets, leaving only the face clear
putting the individual on a blanket to insulate them from the ground
monitoring breathing and carrying out CPR if breathing stops
providing skin-to-skin contact, if possible, by removing clothing and wrapping yourself and the individual in the blanket together to transfer heat
providing warm drinks, if the individual is conscious, but no alcohol or caffeine

It is vital not to use direct heat, such as heat lamps or hot water, as this can damage the skin. It can also trigger irregular heartbeats and, potentially, lead to cardiac arrest.

Do not rub or massage the person either, as these potentially jarring movements could also cause cardiac arrest.

Clinical treatment

According to an article published in the American Family Physician (AFP), the journal of the American Academy of Family Physicians (AAFP), the following techniques can help treat hypothermia.

Do not give a person alcohol if they have signs of hypothermia, and avoid giving any drinks to an unconscious person.

Hypothermia generally progresses in three stages from mild to moderate and then severe.

According to the AAFP, the signs and symptoms of these stages are as follows:

Stage	Body temperature	Signs and symptoms
Mild	90°F to 95°F (32.2°C to 35°C)	High blood pressure, shivering, rapid breathing and heart rate, constricted blood vessels, apathy and fatigue, impaired judgment, and lack of coordination.
Moderate	82.4°F to 90°F (28°C to 32.2°C)	Irregular heartbeat, a slower heart rate and breathing, lower level of consciousness, dilated pupils, low blood pressure, and a decrease in reflexes.
Severe	Less than 82.4°F (28°C)	Labored breathing, nonreactive pupils, heart failure, pulmonary edema, and cardiac arrest.

Additional symptoms of hypothermia may include:

Mild:

dizziness
hunger and nausea
difficulty speaking

Moderate to severe:

shivering may stop
slurred speech
significant confusion
drowsiness
apathy or lack of concern
weak pulse

When a person has severe hypothermia, they may no longer know what they are doing, due to a change in mental consciousness.

Paradoxical undressing

Back in 1979, researchers described a phenomenon known as paradoxical undressing.

Although there is a lack of research on this situation, anecdotal evidence suggests that 20–50 percent of deaths from hypothermia are due to paradoxical undressing.

In infants

Infants lose body heat more easily than adults, and they cannot shiver to keep warm.

Infants with hypothermia may have:

bright red skin
cold skin
very low energy
a weak cry

Infants should not sleep in a cold room. Using extra blankets is not a solution as there is a risk that these can smother the infant.

The CDC suggest making alternative arrangements if it is not possible to maintain a warm space where an infant can sleep.

Understanding and being prepared for hypothermia is integral to its prevention.

People are at higher risk if they:

work outdoors in cold weather
practice snowsports, watersports, or other outdoor activities
are at home during winter weather, especially older people
are stranded in a vehicle in severe winter conditions
are sleeping rough
have other medical conditions
use alcohol or illicit drugs

At home

To prevent hypothermia indoors, the National Institute on Aging (NIA) recommend the following:

heating the room you are using to 68–70°F and closing off other rooms to save on heating bills
insulating your home, by either making building improvements or laying down rolled-up towels to stop drafts
arranging for someone to check on you regularly if you live alone

Stranded in a motor vehicle

Anyone who becomes stranded in a motor vehicle should move everything they need from the trunk into the vehicle.

They should run the car for 10 minutes every hour, making sure that snow is not covering the exhaust pipe and keeping the window open a crack to prevent a buildup of fumes.

People should also consider creating a winter survival kit to keep in the car. The kit should contain nonperishable food, blankets, a first aid kit, water, and necessary medications.

Outdoor activities

Tips for avoiding hypothermia when outdoors include:

checking the weather conditions in advance and preparing accordingly
wearing multiple layers of clothing with the innermost layers made of wool, silk, or polypropylene because these materials retain heat better than cotton
layering clothing to trap multiple layers of air

Overexertion will not help, as this can lead to exhaustion and result in sweat-drenched clothing, both of which contribute to heat loss.

A person who begins to experience or show signs of mild hypothermia should retreat to a warmer place immediately to prevent progression to a life-threatening condition.

Other tips

Other tips for a cold environment include:

wearing a hat or thick scarf on the head, even indoors
avoiding alcohol
eating a sufficient number of calories, as additional fat under the skin can protect against cold during a winter weather spell

Hypothermia in summer

The National Institutes of Health (NIH) recommend keeping room temperatures at 68°F (20°C) or above and closing off rooms that are not in use.

Observing symptoms and taking a person’s temperature with a thermometer can show whether or not they are experiencing hypothermia.

The BMJ define hypothermia as when a person’s body temperature below 95°F (35°C).

An oral thermometer may not show a temperature this low. In either case, it is vital to seek urgent medical attention.

Hypothermia can result from a chronically cold environment, such as during winter, or it can happen suddenly, for example, if a person falls into cold water.

The CDC stress that temperatures do not have to be excessively cold for hypothermia to develop. If the air temperature is 40°F (4.4°C) and a person is wet, they can develop hypothermia.

Hypothermia in water

People lose heat more quickly in water than on land. Water temperatures that would be comfortable as outdoor air temperatures can lead to hypothermia.

According to an article published in Scientific American, people in water that is 41°F (5°C) can lose muscle strength and coordination in as little as 10 minutes.

Even at 79°F (26°C), a person spending an extended period in the water may be at risk of hypothermia.

Indoor causes

Indoors, a lack of heating, excessive air conditioning or taking an ice bath can result in hypothermia.

Indoor hypothermia often has a poor outcome, because it tends to affect older people, and the diagnosis often comes at a late stage.

Vulnerable populations

Results of a study published in 2018 showed that 75 percent of people who received medical treatment in New York City hospitals for cold-related illness were outdoors when this happened.

Around half were sleeping rough, and another 25 percent had no heating at home. Substance abuse or having a mental or physical health condition increased the risk.

Most of the deaths and illnesses did not occur during periods of extreme cold.

The researchers noted, “Although the climate is warming, cold exposure is an ongoing concern during the winter.”

Medical causes

Other causes of hypothermia include metabolic disorders that result in a lower basal metabolic rate. These disorders cause the body to generate less heat internally.

Exposure to toxins and dysfunction of the thyroid, adrenal, or pituitary glands may also be underlying causes.

Q:

A:

This sounds like a very difficult situation. I am sure your neighbors appreciate your concern.

Alana Biggers, MD, MPHAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

Signs, Symptoms, Causes, and Treatment

What Is Hypothermia?

Hypothermia is a potentially dangerous drop in body temperature, usually caused by prolonged exposure to cold temperatures. The risk of cold exposure increases as the winter months arrive. But if you’re exposed to cold temperatures on a spring hike or capsized on a summer sail, you can also be at risk of hypothermia.

Normal body temperature averages 98.6 degrees. With hypothermia, core temperature drops below 95 degrees. In severe hypothermia, core body temperature can drop to 82 degrees or lower.

How Does Cold Exposure Cause Hypothermia?

During exposure to cold temperatures, most heat loss — up to 90% — escapes through your skin; the rest, you exhale from your lungs. Heat loss through the skin happens primarily through radiation and speeds up when skin is exposed to wind or moisture. If cold exposure is due to being immersed in cold water, heat loss can occur 25 times faster than it would if exposed to the same air temperature.

The hypothalamus, the brain’s temperature-control center, works to raise body temperature by triggering processes that heat and cool the body. During cold temperature exposure, shivering is a protective response to produce heat through muscle activity. In another heat-preserving response — called vasoconstriction — blood vessels temporarily narrow.

Continued

Normally, the activity of the heart and liver produce most of your body heat. But as core body temperature cools, these organs produce less heat, in essence causing a protective “shut down” to preserve heat and protect the brain. Low body temperature can slow brain activity, breathing, and heart rate.

Confusion and fatigue can set in, hampering a person’s ability to understand what’s happening and make intelligent choices to get to safety.

What Are the Symptoms of Hypothermia?

Hypothermia symptoms for adults include:

Shivering, which may stop as hypothermia progresses (shivering is actually a good sign that a person’s heat regulation systems are still active. )
Slow, shallow breathing
Confusion and memory loss
Drowsiness or exhaustion
Slurred or mumbled speech
Loss of coordination, fumbling hands, stumbling steps
A slow, weak pulse
In severe hypothermia, a person may be unconscious without obvious signs of breathing or a pulse

Hypothermia symptoms for infants include:

Cold-to-touch, bright red skin
Unusually low energy

What Causes Hypothermia?

Possible causes of hypothermia include:

Cold exposure. When the balance between the body’s heat production and heat loss tips toward heat loss for a prolonged period, hypothermia can occur. Accidental hypothermia usually happens after cold temperature exposure without enough warm, dry clothing for protection. Mountain climbers on Mount Everest avoid hypothermia by wearing specialized, high-tech gear designed for that windy, icy environment.

However, much milder environments can also lead to hypothermia, depending on a person’s age, body mass, body fat, overall health, and length of time exposed to cold temperatures. A frail, older adult in a 60-degree house after a power outage can develop mild hypothermia overnight. Infants and babies sleeping in cold bedrooms are also at risk.

Other causes. Certain medical conditions such as diabetes and thyroid conditions, some medications, severe trauma, or using drugs or alcohol all increase the risk of hypothermia.

What Are the Risk Factors for Hypothermia?

People at increased risk for hypothermia include:

The elderly, infants, and children without adequate heating, clothing, or food
People with mental illness
People who are outdoors for extended periods
People in cold weather whose judgment is impaired by alcohol or drugs

How Is Hypothermia Diagnosed?

Recognizing the symptoms is the first step in diagnosing hypothermia. A specialized thermometer, available in most hospital emergency rooms, can detect very low core body temperatures and confirm a diagnosis.

Temperatures for mild, moderate, and severe hypothermia generally range from:

Mild hypothermia: 90-95 degrees Fahrenheit

Moderate hypothermia: 82-90 degrees Fahrenheit

Severe hypothermia: Lower than 82 degrees Fahrenheit

Because response to hypothermia varies among individuals, temperatures may differ.

What Is the Treatment for Hypothermia?

Hypothermia is a potentially life-threatening condition that needs emergency medical attention.

If medical care isn’t immediately available:

Remove any wet clothes, hats, gloves, shoes, and socks.
Protect the person against wind, drafts, and further heat loss with warm, dry clothes and blankets.
Move gently to a warm, dry shelter as soon as possible.
Begin rewarming the person with extra clothing. Use warm blankets. Other helpful items for warming are: an electric blanket to the torso area and hot packs and heating pad on the torso, armpits, neck, and groin; however, these can cause burns to the skin. Use your own body heat if nothing else is available.
Take the person’s temperature if a thermometer is available.
Offer warm liquids, but avoid alcohol and caffeine, which speed up heat loss. Don’t try to give fluids to an unconscious person.

Continued

If the hypothermic person is unconscious, or has no pulse or signs of breathing, call for emergency help right away. CPR (cardiopulmonary resuscitation) should be given immediately if a pulse can’t be felt and there is no sign of breathing. Feel for the pulse for up to a whole minute before starting CPR, because the heart rate may be extremely slow and you should not start CPR if there is any heartbeat present.

CPR should be continued, in the absence of signs of breathing or a pulse, until paramedics arrive or the person is taken to a hospital.

In cases of advanced hypothermia, hospital treatment is required to rewarm the core temperature. Hypothermia treatment may include warmed IV fluids, heated and humidified oxygen, peritoneal lavage (internal “washing” of the abdominal cavity), and other measures. Complications during recovery can include pneumonia, heart arrhythmias, ventricular fibrillation (a dangerous “fluttering” rhythm of the heart), cardiac arrest (a sudden stopping of the heartbeat), and death.

Seek immediate medical help for anyone with hypothermia. Call 911 if you suspect severe hypothermia.

Hypothermia – Better Health Channel

Hypothermia occurs when the body’s temperature falls below 35 °C. The human body has a number of systems that maintain a constant core temperature of around 37 °C. A person doesn’t have to be in sub zero temperatures to risk hypothermia – it only requires the environmental temperature to be less than the body temperature and a person will “donate” heat to the atmosphere.

If the heat generated by the body – and people are constantly generating heat through metabolic processes and muscle movements – is less than that lost to the environment, then their temperature will begin to fall.

The four ways that the human body loses heat include:

conduction – by direct transfer from the body to an object that is cooler than the body (for example, lying on a cold surface will pass body warmth to the surface away from the body)
convection – air or liquid flow across the skin drawing off heat (for example, wind will increase heat loss, as will water that is cooler than body temperature)
radiation – electromagnetic waves distribute heat into the ambient environment (for example, exposed skin will allow heat to be drawn off if the air temperature is less than the body – the exposed head of a person is a strong source of heat loss, particularly in children)
evaporation – fluid on the skin turns to vapour, drawing off heat (moist skin will lose heat more rapidly, such as in someone who is wet, clammy or has exposed moist skin, such as burns).

Sometimes, medical conditions can lead to hypothermia. For example, someone suffering a stroke or a person with diabetes suffering a hypoglycaemic episode may end up lying immobile for a period of time, unable to protect themselves from hypothermia.

The natural response to becoming cold is two-fold, including:

Behavioural – the person will try and move around to generate heat, and seek shelter from further heat loss.
Physiological – the body shunts blood to the core to keep it warm, hair stands on end to trap a layer of warm air around us (goose bumps), we shiver to make more heat and our body releases hormones to speed up our metabolism to create more heat.

If these measures don’t work, hypothermia will result.

Symptoms of hypothermia

Hypothermia can be distinguished into three stages – mild, moderate or severe. The signs and symptoms of hypothermia can be approximately grouped with the temperature ranges of the different stages:

For mild hypothermia (35-32 ^oC), signs and symptoms include:

pale and cool to touch as blood vessels constrict in the skin
numbness in the extremities
sluggish responses, drowsiness or lethargic
shivering
increased heart rate and breathing.

For moderate hypothermia (32-28 ^oC), signs and symptoms include:

decreasing conscious state
may have been incontinent of urine as a result of an increased workload on the kidneys related to blood being shunted to the major organs
no longer shivering
slowed heart rate, breathing rate and low blood pressure.

For severe hypothermia (below 28 ^oC), signs and symptoms include:

unconscious and no longer responding
the heart beats more slowly and may become irregular before ultimately stopping if the person gets too cold
no response to light in the pupil of the eye
rigid muscles – the person might feel like they are in rigor mortis
pulses and respiratory effort may be present but hard to detect.

Myth about hypothermia

One hypothermia myth is that you lose more heat through your head than any other part of your body. This is not true. Heat loss occurs through any area of skin exposed to the environment. An adult head is approximately 10 per cent of the surface area of their whole body.

Most of the time, the rest of our bodies are covered, with the possible exception of our hands (which together only make up about four per cent of our surface area), so we feel cold, because our head is cold compared to the rest of our insulated body.

If a person had to expose another part of their body – for example, their abdomen, which also makes up about 10 per cent of an average adult body – then they would lose as much heat through that as their exposed head.

Parents are often advised to keep children’s heads covered to stop them getting cold, but this isn’t to do with any special heat-losing properties of the head. It has more to do with the relative size of the head to the body. At birth, a baby’s head makes up over 20 per cent of their total surface area, so exposing that skin leads to increased heat loss, putting them at risk of hypothermia much quicker than an adult, if they were to both have their heads uncovered.

Risk factors for hypothermia

Factors that may increase a person’s susceptibility to hypothermia include:

Children – small children are at risk of hypothermia because they are unable to protect themselves in varied environmental conditions. They also have a faster rate of heat loss than adults, generally speaking. Due to their large head relative to their body, they also need their heads covered to prevent significant heat loss.
Old age – in the elderly, the ability to notice changes in temperature is impaired due to the loss of nerve endings to the skin. They also have less fat, which has an insulating function, and a lower metabolic rate, and so generate less heat themself. Social factors also play a part, as the elderly are more likely to be reluctant to use heating for economic reasons, and they may be socially isolated so can be alone for long periods of time with no one noticing as they deteriorate.
Dementia or immobilising illness – anybody who is unable to look after themselves independently, either physically or cognitively, is at risk of hypothermia. People with dementia can be particularly at risk if they wander off in cold conditions without having protected themselves with appropriate clothing first.
Alcohol and other drugs – alcohol makes people feel cosy because it relaxes the blood vessels, allowing more blood to flow near the skin, providing a flushed appearance and a warm sensation. This also puts people who are drunk at significant risk of hypothermia if they are outside in cold weather, as this increases the rate of heat loss. It also slows down the metabolism, so slows down internal heat generation. Alcohol also impairs judgement, so the person is less likely to recognise the environment and their own physical condition, and less likely to take protective measures against heat loss. This is also a concern with any other mind-altering substance.
Water immersion – people who spend any time immersed in water that is colder than body temperature will suffer significant heat loss. The other person at risk is anyone who may have been in wet clothes for a prolonged period of time, either due to incontinence or sweating.

Severe hypothermia is life-threatening

Mild hypothermia (32–35 °C body temperature) is usually easy to treat. However, the risk of death increases as the core body temperature drops below 32 °C.

If core body temperature is lower than 28 °C, the condition is life-threatening without immediate medical attention. Under this temperature, a person will be very cold to touch, unresponsive, rigid, not breathing, have no pulse, and their pupils will be fixed (they will not respond to light changes). They will appear to be dead, but they may not be.

First aid for severe hypothermia

First aid steps for severe hypothermia include:

In an emergency, call triple zero (000).
While waiting for help to arrive, monitor the person’s breathing. If they have severe hypothermia, their breathing may become dangerously slow or shallow, or they may cease breathing.
Begin cardiopulmonary resuscitation (CPR) immediately if the person shows no signs of life – if they are not breathing normally, are unconscious or unresponsive, or not moving.

Never assume a person is dead. A person with severe hypothermia may only take one breath per minute, with a heart rate of less than 20 beats per minute. Always assume they are alive.

First aid for all cases of hypothermia

The first aid tips that apply to all stages of hypothermia include:

The first step in all cases of hypothermia is to prevent any further heat loss. This is done by removing the four ways that heat loss occurs mentioned earlier, including:
- Conduction – remove the person from a cold surface if possible. Ideally, place them onto a warm surface, or at least a dry one that will prevent further heat loss.
- Convection – remove the person from a windy or wet environment. Covering with blankets is good, but the aim must be to get them to shelter.
- Radiation – Cover as much of the person as possible to avoid radiant heat loss. Particularly cover the head of a younger child.
- Evaporation – wet and sweaty people will suffer evaporative heat loss. Dry skin where possible and remove wet clothing as soon as practicable.
Don’t massage or rub the person – and do not allow them to help you. Keep them still because, particularly below 32 ^oC, they risk a cardiac arrest.
Move the person out of the cold – if this is not possible, protect them from wind, cover their head and insulate their body from the cold ground. If the person is moderately or severely hypothermic, move them as gently as possible. Below approximately 30 ^oC the heart is very vulnerable and there are case studies of simple movements like rolling the person over prompting a cardiac arrest.
Remove wet clothing – replace with a dry covering, preferably warm. Cover the person’s head.
Try to warm the person – do not use hot water immersion. Make sure that the person is dry. Insulate them from the environment to retain whatever heat they are producing. Use whatever heat source is available – heaters, hot water bottles, heat packs, an electric blanket – to begin slowly warming the person. The heat source should not be too hot or too close to the person. A slow and gradual warming is ideal and whatever heat source is used only has to be warmer than the person to be donating heat. When applying heat close to the skin – such as with hot water bottles or heat packs – be careful not to make them too hot, as the person may have impaired sensation to their skin and is at risk of suffering burns. If using multiple small sources of heat, such as heat packs, preferentially pack them around the torso, into armpits and the groin to focus warming on the central area.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 bodies with a blanket or get into a sleeping bag if possible.
Don’t give alcohol– it lowers the body’s ability to retain heat. If the person is alert and is able to swallow, have them drink warm, non-alcoholic beverages. Do not offer liquids if they are vomiting.
Do not leave the person alone– stay with them at all times.
Continually monitor breathing–if the person’s breathing stops, start cardiopulmonary resuscitation (CPR) immediately if you are trained. If unsure, dial triple zero (000) – operators will advise you what to do. Continue CPR until the person starts breathing on their own or until medical help arrives.
Don’t assume the person is dead – CPR can be lifesaving for a person with severe hypothermia who may appear to be dead. They may not be breathing, have no pulse, be cold to touch, have fixed pupils and be rigid – but they may still be alive.

Preventing hypothermia when outdoors

Exposure to cold weather, even for a short time, can be dangerous if you are not prepared. Shivering and feeling cold or numb are warning signs that the body is losing too much heat.

Simple ways to prevent hypothermia include:

Avoid prolonged exposure to cold weather.
Be alert to weather conditions that may increase the risk of hypothermia and act accordingly. For example, seek shelter during a snowstorm.
If driving through a cold weather environment, particularly if there is a risk of ice or snow on the road increasing the chances of a crash, do not rely on the vehicle heater to stay warm while driving. Dress for the weather outside the car and leave the heater turned down so that in the event that you are incapacitated by an accident or snowstorm, you have a better chance of avoiding hypothermia.
Wear several layers of clothing to trap body heat, rather than just one bulky layer. Natural fibres like wool are better at holding heat.
Use a weatherproof outer layer to stay dry.
Use gloves, scarves and socks, with spares to replace when wet.
Wear insulated boots.
Wear warm headgear.
Make sure your clothes and boots aren’t too tight. If your blood circulation is restricted, you are more prone to hypothermia.
Drink plenty of fluids.
Eat regularly.
Take regular breaks to reduce the risk of physical fatigue.
Keep your eye on exact body temperature by taking a clinical thermometer in your first aid kit.
Change out of wet clothes straight away.
Avoid alcohol, cigarettes and caffeine.
Make sure your kit includes a good supply of waterproof matches.

Use a buddy system

When participating in any outdoor activity that has the potential risk of hypothermia, such as bushwalking or mountaineering, use the ‘buddy system’ and check each other for warning signs. You may not be able to recognise your own symptoms of hypothermia due to mental confusion. First aid training is strongly advised.

Hypothermia at home

Hypothermia can occur in the home. The elderly and some people with medical conditions are more susceptible to hypothermia. The risk can be reduced by:

making sure there is adequate heat in the home
seeking assistance from government agencies for help with heating, food and clothing if necessary
having regular medical check-ups.

Where to get help

In an emergency, call triple zero (000)
Your doctor
The emergency department of your nearest hospital

Cold truths about hypothermia

Every Minnesotan is familiar with piling on coats, hats, mittens and other clothing to stay protected from the elements during the winter months. Hypothermia — literally meaning “low (body) temperature” — occurs when too much heat escapes the core of the body and cannot be replaced quickly enough. It can affect someone’s mental and physical abilities and eventually be fatal if not treated. Hypothermia sets in very slowly, so those affected often do not realize they need help or medical attention.

No one plans to become hypothermic; car trouble, walking home from a party, or a slip and fall on the ice are just a few ways people inadvertently get over-exposed to the harsh cold.

According to HCMC emergency physician and hypothermia specialist Dr. Doug Brunette, hypothermia can set in within minutes, depending on the conditions and the patient.

Dr. Doug Brunette

“Heat is lost rapidly if the patient is wet, like if they fall through the ice on a lake. And the body size of the patient matters as well. Thin patients will lose heat faster; and infants – who have a higher body surface area relative to adults – can become hypothermic in a matter of minutes if exposed to severe heat losing environmental conditions. ”

We have all experienced bone-chilling cold at some time or another, but how can you tell if it’s hypothermia?

“Confusion and disorientation are telltale signs that someone may be having problems, and if someone is suspected of prolonged cold exposure and is found unconscious, he or she needs immediate medical care,” says Dr. Brunette.

Depending on the severity of hypothermia, treatment in the emergency department includes aggressive, supportive critical care that may require that the patient is placed on a ventilator. Re-warming is a key part of the medical management. This is accomplished using a variety of techniques that include both external and internal rewarming methods.

“Severe hypothermia can result in organ damage and permanent medical issues,” warns Dr. Brunette, “however, if the patient didn’t have a respiratory or cardiac arrest, there’s a good chance for complete recovery without long-term effects.”

Few would argue against the logic of staying warm and comfortable by wearing protective clothing and avoiding extreme cold temperatures; however, poor or impaired decision-making increases the chances of hypothermia and frostbite. Alcohol use, for example, impairs judgment and puts people at risk for life and limb-threatening cold exposure. It can also cause dehydration, which can accelerate symptoms of hypothermia and frostbite.

“No one plans to be stranded in the cold, but it can and does happen,” says Dr. Brunette.

Here are some reminders of what you can do to be safe:

Wear layered – and dry – clothing and outerwear. Always wear a hat, gloves, and warm shoes or boots.
Avoid being outdoors on those brutally cold days and nights when temperatures are low and the winds are high. Stay inside if you can!
Anticipate problems and dress appropriately – car trouble, late buses/trains, icy/slippery conditions might have you being outside longer than planned
Keep a winter emergency kit in your vehicle that includes a blanket, matches, candle, flashlight, snacks and other comfort items
Share your travel plans with someone else so they’ll know when you’ll arrive at your destination
Carry a cell phone
Stay alert – avoid or limit alcohol use

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Author

James Li, MD Former Assistant Professor, Division of Emergency Medicine, Harvard Medical School; Board of Directors, Remote Medicine