Hypothermia

"Normal" body temperature is actually a range between 97°F and 99°F (or 36.1°C and 37.2°C). So if your body temperature is usually below 98.6°F but above 97°F, then that is your normal body temperature and not hypothermia.

In hypothermia, body temperature drops below 95°F, which is a cause for concern. Hypothermia in adults is divided as:

• Mild hypothermia: When the body temperature is between  95°F and 89.6°F (35°C to 32°C).
• Moderate hypothermia: When the body temperature is between 89.6°F and 82.4°F ( 32°C to 28°C)
• Severe hypothermia: When the body temperature drops below 82.4°F (28°C) 

Newborns and infants have larger body surface as compared to their body weight, which makes them lose energy at a much faster rate than adults. The World Health Organization (WHO) has suggested different temperature values for hypothermia in infants:

• Mild hypothermia: When the body temperature is between 96.8°F and 97.5°F (36.0°C to 36.4°C)
• Moderate hypothermia: When the body temperature is between 89.6°F and 96.6°F (32.0°C to 35.9°C)
• Severe hypothermia: When the body temperature drops below 89.6°F (32°C).

On the basis of the duration of hypothermia, it is classified as:

• Acute hypothermia: This type of hypothermia occurs when your body temperature drops suddenly due to exposure to an extremely cold environment such as getting stuck in snowfall or getting wet in the cold. 
• Chronic hypothermia: This type of hypothermia occurs when your body temperature drops over a long period of time. It is usually seen in people who are not able to control their body temperatures, like in the case of elderly people and babies.

On the basis of the cause, it is classified as:

• Exhaustion hypothermia: In this type, the body gets exhausted by producing heat and causes a sudden drop in temperature. This is usually seen in people with underlying medical conditions.
• Perioperative hypothermia: In this type, the body temperature drops after surgery as the body cannot maintain temperature after receiving anaesthesia.

Hypothermia symptoms vary, depending on the type. Here's a quick look at how each type of hypothermia presents in terms of symptoms:

Mild hypothermia

The mild symptoms of hypothermia are seen when body temperature is between  95°F and 89.6°F (35°C to 32°C). The mild symptoms of hypothermia are:

• Shivering of hands and feet 
• Unclear speech due to chattering teeth
• Slow movements 
• Extreme exhaustion
• Clumsiness, making the person prone to falling
• Dizziness
• Racing heart rate (tachycardia)
• Rapid breathing (tachypnea)
• Pale skin
• Confusion
• Excessive urination

Moderate hypothermia

Moderate hypothermia is seen when the body temperature is between 89.6°F to 82.4°F (32°C to 28°C). The signs that are seen in moderate hypothermia are:

• No shivering
• Stiffness of muscles 
• Expanded pupils of the eye
• Bluish colour of the skin
• Low heart rate and breathing rate 
• Slurring of speech
• Low blood pressure
• Weak reflexes
• Confusion and unaware of the surroundings
• Loss of consciousness

Severe hypothermia

Severe hypothermia occurs when the body temperature drops below 82.4°F (28°C). The signs of severe hypothermia are:

• Absence of reflexes
• Extremely low blood pressure
• Absence of heartbeats or breathing

A person can slip into a coma or even die due to severe hypothermia.

Some infants or children may show signs of hypothermia as a bright red colour of the skin with extreme dizziness. An infant with chronic hypothermia would show a persistent decrease in body weight. This can even prove fatal for the baby.

Anyone who comes in contact with extremely cold conditions is prone to get hypothermia. However, there are some people who are at a higher risk: 

• Elderly people: With advancing age, the body loses its ability to control its temperature. However, as older people tend not to spend much of their energy, their body uses that energy to keep them warm. But this increases their risk of hypothermia as they will not be able to understand when the temperature becomes too low.
• Children: Young children spend more energy than adults as they keep playing and jumping around all day. This leaves their body with a very little amount of stored energy, thus making them prone to hypothermia. 
• Babies and infants: Infants do not have energy reserved in their body which makes them prone to hypothermia. Also, they don’t even show similar signs of feeling cold as adults do, which makes it difficult to understand if a baby is feeling cold until their skin starts changing colour to bright red. 
• Inexperienced travellers: People who visit a new place for vacation without proper research and are outdoor adventure seekers such as hikers and hunters, may not be prepared for the cold and wet conditions they may encounter.
• Homeless people: People who do not have a house can get hypothermia in cold and wet conditions. 
• Alcoholics: Alcohol expands the blood vessels of the body, allowing the heat to easily dissipate, which makes the person prone to hypothermia.
• People with underlying medical conditions: Medical conditions such as hypothyroidism (underactive thyroid gland), hypoglycemia (low blood sugar), hypopituitarism (underactive pituitary gland), anorexia nervosa (a type of eating disorder), Parkinson’s disease (a degenerative disease that affects the brain), peripheral neuropathy (a condition that affects the nerves in your extremities) and dementia, increase cold intolerance in people, making them prone to hypothermia. 
• People taking certain medications: There are certain medicines that impair a person’s response to cold, such as sedatives, anaesthetics, opioids and antipsychotics.

Hypothermia occurs when the body is exposed to cold, wet or windy conditions. When we feel cold, our body utilises stored energy to keep our body warm. Eventually, as the body is continuously exposed to the cold environment, the body uses up all its stored energy and then the body temperature starts falling. 

A person can get hypothermia if they do not have adequate clothing in the cold weather or their clothes get wet or if they live in a cold and damp house. In this situation, the person spends more energy than the body is generating.

The sole reason for hypothermia is exposure to an extremely cold environment. So in order to prevent hypothermia, you need to take care of the following things: 

• Prepare for cold climate beforehand. Start wearing layers as the weather starts changing and then steadily move on to warm clothes. 
• If your woollen clothes get wet for any reason, change them immediately or else get indoors, to someplace warm.
• Always carry an extra set of clothes if you are going out and are expecting rain or snowfall.
• Avoid iced drinks or alcoholic beverages as they can reduce your body temperature.

Apart from judging the condition by appearance, doctors would diagnose hypothermia by taking body temperature with a thermometer. The rest of the symptoms would require different tests. For instance, ECG would be done to test the condition of the heart.

Hypothermia is a medical emergency. Until medical help arrives, these are the primary things you can do help someone with hypothermia:

• Take the person to a warmer and drier place
• Remove all their wet clothes and
• Drape them up in warm clothing or blankets  

It is possible that a person with severe hypothermia would be unconscious, with no pulse and no visible breathing. At this point, the hypothermic patient would require cardiopulmonary resuscitation (CPR) to get back to consciousness. CPR involves giving mouth to mouth breath to the unconscious person followed by continuous chest compressions until medical help arrives. Only a person certified for CPR should perform it or else one can end up causing more harm than good. 

When the victim reaches the medical facility, the doctors would:

• Pump warm fluids inside the body of the victim through an intravenous (IV) route (read more: what is fluid therapy?)
• Give a warm oxygen mask or breathing tube to the victim (read more: what is oxygen therapy?)
• Use an extracorporeal membrane oxygenation (ECMO) machine which can take out the cold blood from the body of the victim, warm it up and then send it back in the body of the victim.  

Further treatment would be done on the basis of the damage caused to the organs due to hypothermia.

If you notice a person with signs of hypothermia, the first thing you need to do is to call for medical help. If possible, check the person’s temperature and if it turns out to be less than 95°F (35°C), then the person needs to get medical attention immediately. Till medical help arrives, you can do the following things:

• Bring the person to a warmer place.
• If the person is wearing any wet clothes, take them off and drape them in dry and warm clothes or blankets.
• Rub the chest, neck, head, groin and other body parts of the person.
• Provide them with an electric heating blanket. If you do not have it, you can give them skin-to-skin contact while keeping a loose dry layer of blanket, clothing or even towel in-between.
• If the person is unconscious and not breathing, you can perform CPR to resuscitate them. Do not perform CPR if you have not got any training in it
• If the person is conscious, give them hot beverages to raise the temperature of their body. Do not give them alcoholic beverages. Do not try to give beverages to an unconscious person.
• Even after the body temperature has increased, keep them wrapped up in a warm blanket and wait for medical help to arrive.