Hypothermia is a condition that occurs when your body temperature drops below 95°F(35°C). This happens when a person experiences cold temperatures for a prolonged period. Normal body temperature is 98.6°F. Major complications can result from this drop in temperature, including death.
How does Hypothermia happens?
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.
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.
Stages & Symptoms –
As hypothermia progresses through the stages, symptoms become more severe and dangerous.
• Mild Hypothermia
Symptoms in this stage include:
• body temperature of 90–95°F (32–35°C)
• 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
• 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
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
Hypothermia symptoms for infants include:
• Cold-to-touch, bright red skin
• Unusually low energy
Exposure to cold temperatures or falling into cold water can cause hypothermia. The temperatures do not have to be excessively cold for hypothermia to develop. If the air temperature is 40°F (4.4°C) and someone is wet, they can develop hypothermia.
Risk Factors –
Risk factors for hypothermia include:
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.
• 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.
• 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.
• 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.
Some drugs can change the body’s ability to regulate its temperature. Examples include certain antidepressants, antipsychotics, narcotic pain medications and sedatives.
If left untreated, hypothermia can lead to cardiac arrest and death.
When doctors examine a person, the key symptoms and signs mentioned above indicate a diagnosis of hypothermia.
Evidence shows that the diagnostic process should also include blood tests to measure:
• 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.
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
Anyone with symptoms of hypothermia needs immediate medical attention. Until help arrives, the following actions are recommended –
• 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
Clinical treatment may include the following options:
• 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.
When it is cold, you should wear a hat that covers the ears and warm, dry clothing.
Older people and children should take extra care to prevent hypothermia by:
• Dressing in layers and keeping warm clothes nearby
• Keeping homes at a temperature above 68° F
• Moving around when you feel cold so you can increase your body temperature
• Eating and drinking warm foods and beverages
• Wearing appropriate clothing outdoors, including hats, mittens, coats and footwear
• Taking regular breaks and coming inside to warm up whenever spending time outside
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