Hypothermia is a dangerous condition involving low body temperature. Symptoms such as shivering, pale skin, and fast heart rate indicate a person’s core body temperature has dropped below normal.
Keep reading to learn more about the treatment, symptoms, prevention, diagnosis, and causes of hypothermia.
What is hypothermia?
Hypothermia is an abnormally low body temperature of below 95°F (35°C)Trusted Source. This happens when a person experiences cold temperatures for a prolonged period.
While normal metabolic processes in the body generate heat, wintry weather can cause the body to lose more heat than it generates. When this occurs, the core temperature drops.
A structure in the brain called the hypothalamus regulates body temperature. FindingsTrusted Source show that when someone is exposed to cold, the hypothalamus raises body temperature through measures such as increasing muscle tone and shivering.
However, if exposure to cold continues, it will eventually overwhelm the body, and shivering will stop. At this point, multiple organs may stop functioning, which ultimately leads to death. This is why hypothermia is an extremely dangerous condition.
Symptoms in stages
Symptoms in babies differ from symptoms in adults, note the Centers for Disease Control and Prevention (CDC)Trusted Source. Babies may have very low energy and bright red, cold skin.
Mild hypothermia
Symptoms in this stage include:
body temperature of 90–95°F (32–35°C)
tiredness
shivering
hunger
nausea
skin that is dry and paler than usual
fast heart rate
increased muscle tone
increased blood pressure
decline in memory, judgment, and thinking ability
unclear speech
loss of control of body movements
frequent urination
Moderate hypothermia
Typically, shivering stops between 86–90°F (30–32°C). Other symptoms of moderate hypothermia include:
body temperature of 82–90°F (28–32°C)
continued decline in thinking ability
lethargy
enlarged and less responsive pupils
low blood pressure
slow heart rate
slow breathing rate
paradoxical undressing, or removal of clothes
increased susceptibility to abnormal heart rhythms
Severe hypothermia
Infographic by Yaja Mulcare
Symptoms of this stage include:
body temperature of less than 82°F (28°C)
continued decline in blood flow to the brain, leading to unresponsiveness
continued decline in blood pressure, heart rate, and heart output
increased susceptibility to abnormal heart rhythms
congestion in lungs
production of a very small amount of urine
loss of reflexes
ultimately, failure of heart and lung function
Treatment
Treatment depends on the degree of hypothermia, but the aim is to make the person warmer. It involves first aid and clinical treatment.
First aid
moving the person to a warm, dry place, if possible, or sheltering them from the elements
taking off any wet clothing
covering the person with an electric blanket, if available, or dry layers of towels, clothing, or blankets
making skin-to-skin contact with another individual
having the person drink a warm beverage, excluding alcohol, if they are not unconscious
avoiding moving or jostling the person, as doing so can trigger a fatal heart rhythm abnormality
If someone has severe hypothermia, they may be unconscious. They may also appear not to have a pulse or be breathing. If this occurs, a bystander should perform CPR and continue it until help arrives. Sometimes people with hypothermia who appear to be dead can resuscitate.
Clinical treatment
Passive external rewarming: This entails removing the person’s wet clothing and covering them with layers of insulation.
Active external rewarming: This involves methods such as water immersion and using a heating unit to transfer heat through convection. However, water immersion poses the danger of triggering collapse of the heart and blood vessels.
Active core rewarming: This involves irrigating body cavities with warm, intravenous fluids. Other options include the use of warming that originates from outside the body, such as hemodialysis, which is filtering of the blood with a machine that acts as an artificial kidney.
Prevention
Check the weather forecast before going outdoors, and dress appropriately.
Avoid drinking alcoholic and caffeinated beverages, as they increase heat loss.
Wear multiple layers of clothing, including a hat, scarf, and gloves.
Set the home thermostat to 68°F (20°C) or higher, and dress warmly.
Keep space heaters, which are an acceptable indoor heat source, away from flammable objects and ensure smoke and carbon monoxide detectors work.
Place rolled towels underneath home doors to prevent drafts.
Check on elderly neighbors, and make sure they have enough heat and food.
Dress babies warmly, and limit their exposure to cold temperatures.
In winter, unexpected events can occur that pose a danger of hypothermia, such as home power outages and running out of gas while driving. To offset the risk of these events, experts recommend keeping winter survival kits at home and in the car.
Certain medications, specifically psychiatric medicationsTrusted Source, may increase a person’s risk of hypothermia. An individual may consider asking their doctor or pharmacist whether their medication could increase their risk of hypothermia.
Home survival kits may include:
extra food and water
an emergency heating source
a fire extinguisher and smoke detector
Car survival kits may include:
sleeping bags and blankets
high calorie, nonperishable food
extra clothing to keep dry
water container
waterproof matches
Diagnosis
When doctors examine a person, the key symptoms and signs below indicate a diagnosis of hypothermia:
body temperature below 95°F (35°C)
shivering
impaired mental state
frostbite, which is injury to body tissues resulting from freezing
Other telltale symptoms inlude:
frequent urination
fast heart rate, fast breathing, and high blood pressure in mild hypothermia
slow heart rate, slow breathing, and low blood pressure in moderate hypothermia
a long pause in breathing or coma in severe hypothermia
blood sugar
electrolytes, such as sodium and potassium
substances that show kidney function
Doctors may order an electrocardiogram (ECG) to assess heart function. They may also use imaging tests, such as X-rays, to assess the effects of a stroke or trauma that led to prolonged exposure to cold. Additionally, a doctor may use other lab studies and tests to detect potential complications and underlying causes of hypothermia.
Causes
Exposure to cold temperatures or falling into cold water can cause hypothermia.
extremes of age
low blood sugar
malnutrition
skin disorders, such as burns and psoriasis
stroke
endocrine disorders, such as hypothyroidism and adrenal insufficiency, which are conditions affecting parts of the body that produce hormones
substance use disorder
neurodegenerative disorders, such as dementia
dilated blood vessels due to conditions such as spinal cord injuries
sepsis, which is an extreme response to infection