The human body has to main the internal temperature at a relatively constant rate to sustain life. This ideal temperature for the body is approximately 37ºC (100.4ºF) but can be as low as 36ºC (97ºF) for adults. Any temperature from 38ºC (100.5ºF) and higher is considered to be a temperature. On the other extreme is hypothermia.
How low body temperature is hypothermia?
When you body temperature falls below 35ºC (95ºF) then this is considered to be hypothermia. It can be classified as mild or severe. Mild hypothermia is a temperature between 35ºC (95ºF) and 32ºC (89.6ºF). Severe hypothermia is a body temperature below 32ºC (89.6ºF).However, the first signs and symptoms of hypothermia becomes evident once the body temperature drops below 36.5ºC (97.7ºF).
The body temperature is maintained by several factors that are regulated by a part of the brain known as the hypothalamus. If the body temperature rises too high, then the hypothalamus initiates cooling mechisms. Blood vessels on the skin surface widen so that heat can be passed out from the blood into the environment. Sweat is released on the skin surface to help cool down the body.
When the body temperature drops too low then the hypothalamus has to find ways too warm the body. This is done by increasing metabolic activity so that more heat is generated by the body. For example, shivering is an event where muscles contract repeatedly and rapidly to increase heat generation. The superficial blood vessels narrow to minimize heat loss from the body into the environment.
It is therefore important to understand that the temperature of the skin surface is not the same as the temperature within the body (core temperature). Hypothermia is where the core temperature drops to lower than normal levels. This may be reflected by the skin temperature which feels cold. However, the surface temperature can record low despite the core temperature being normal.
Read more on hypothermia.
How To Spot Hypothermia
Hypothermia can affect every organ and system in the body. The signs and symptoms are more prominent when certain organs and systems are affected, like the skin surface, muscle activity, heart and brain function. These signs and symptoms develop gradually depending on the rate at which the core temperature decreases. It is important to know the different signs and symptoms that arise with the different stages of hypothermia.
The color of human skin varies based on several factors. One factor, apart from the natural skin pigment known as melanin, is the blood flow under the skin surface. When the body temperature drops, the blood vessels under the skin surface narrow. This reduces blood flow through it.
As a result the skin has a less pink or red appearance which is caused by the underlying blood flow. A person therefore appears pale. This may worsen when the blood flow is severely restricted and the blood becomes low in color. It results in a bluish tinge of the skin known as cyanosis.
Abnormal Heart Rate
The cardiovascular system is profoundly affected by the decrease in body temperature. Initially this may be observed as a rapid heart rate over 100 beats per minute. This is known as tachycardia and is seen in the first stage of hypothermia.
However, as the body temperature drops further towards severe hypothermia then heart activity decreases. As a result the heart rate drops to below 60 beats per minute. This is known as bradycardia. At this point, blood circulation and oxygen distribution is significantly impaired.
A host of muscle disturbances occur with hypothermia. The most prominent is shivering. This is the rapid activity of the muscles which causes trembling. The increased muscle activity is intended to increase heat generation. It is prominent in stage 1 and stage 2 of hypothermia.
Muscle coordination is also impaired by stage 2 hypothermia. This affects speech, coordination and balance. However, shivering stops as stage 3 hypothermia sets in. Muscle stiffness occurs and even the respiratory muscles may be affected.
Initially there may be rapid breathing (tachypnea) in the early stages of hypothermia. As with heart activity, the rate and depth of respiration gradually decreases. This means that breathing becomes slower (reduced rate) and shallower (reduced depth). Oxygen intake and circulation throughout the body is drastically reduced.
With prolonged hypothermia and especially in severe stages, mental activity is negatively affected. A person may become confused. Along with dizziness, slurred speech and poor coordination, these signs and symptoms appear similar to intoxication.
If the hypothermia progresses, there may even be loss of consciousness. These signs and symptoms are an indication of severe neurological disturbances and nervous system shutdown. Death is a possible shortly thereafter without prompt medical intervention.
Read more on cold injury.
What to do in hypothermia?
Hypothermia needs to be treated and managed by a medical professional. However, first aid should be administered immediately even if there are no medical personnel available. Any person can administer some of the basic first aid measures which may help to keep a person alive until professional medical attention is forthcoming.
- Remove a hypothermic person from the source of the cold source, be it oudoors in cold weather or water. Care must be taken when moving an unconscious person, especially if ne or she has sustained injuries.
- Take out all wet clothing immediately. Although a person should be covered, wet clothing will further cool down the body. Once these wet garments are removed, a person should be covered with any dry blanket or textiles.
- Warm a person up gradually. Do not immediately place a hypothermic person very close to an intense heat source. Sudden rewarming can have an adverse effects and even haste death. Start gradually with a warm compress or body heat, Never immerse in a hot water bath.
- Warm drinks can also be helpful with rewarming in hypothermic patients who are conscious. It is important that they sip slowly on these drinks and only ingest what they can swallow. Never try to feed an unconscious person.
- Cardiopulmonary resuscitation (CPR) should be commenced immediately on any person who is not breathing, does not have a pulse and is unconscious.