Hypothermia

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Hypothermia is a condition in which an organism’s temperature drops below that required for normal metabolism and bodily functions. In warm-blooded animals, core body temperature is maintained near a constant level through biologic homeostasis. But when the body is exposed to cold its internal mechanisms may be unable to replenish the heat that is being lost to the organism’s surroundings.

Hypothermia is the opposite of hyperthermia. Because the words sound alike, they are easily confused.

Profound hypothermia can be an indication to be placed on extracorporeal circulation (bypass pump).

Template:WikiDoc Sources

Please help WikiDoc by adding content here. It’s easy! Click here to learn about editing.

Template:WikiDoc Sources

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Please help WikiDoc by adding more content here. It’s easy! Click here to learn about editing.

• Normal body temperature in humans is 37°C (98.6°F). Hypothermia can be divided into three stages of severity.

• In stage 1, body temperature drops by 1-2°C below normal temperature (1.8-3.6°F). Mild to strong shivering occurs. Blood vessels in the outer extremities constrict, lessening heat loss to the outside air. Breathing becomes quick and shallow. Goose bumps form, raising body hair on end in an attempt to create an insulating layer of air around the body (this is of limited use in humans due to lack of sufficient hair, but it can be useful in other species). Often, a person will experience a warm sensation, as if they have recovered, but they are in fact heading into Stage 2. Another test to see if the person is entering stage 2 is if they are unable to touch their thumb with their little finger; this is the first stage of poor muscle coordinaton.

• In stage 2, body temperature drops by 2-4°C (3.6-7.2°F). Shivering becomes more violent. Muscle mis-coordination becomes apparent. Movements are slow and labored, accompanied by a stumbling pace and mild confusion, although the victim may appear alert. Surface blood vessels contract further as the body focuses its remaining resources on keeping the vital organs warm.

• In stage 3, body temperature drops below approximately 32°C (90°F). Shivering usually stops. Cellular metabolic processes shut down. Major organs fail. Clinical death occurs. Because of decreased cellular activity in stage 3 hypothermia, the body will actually take longer to undergo brain death.

Template:WikiDoc Sources

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

• End-stage liver disease
• Exposure
• Hypothyroidism
• Hypovolemic stroke
• Massive blood transfusion
• Sepsis
• Stroke

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Please help WikiDoc by adding content here. It’s easy! Click here to learn about editing.

Hypothermia is the opposite of hyperthermia. Because the words sound alike, they are easily confused.

Template:WikiDoc Sources

Please help WikiDoc by adding content here. It’s easy! Click here to learn about editing.

Template:WikiDoc Sources

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Please help WikiDoc by adding more content here. It’s easy! Click here to learn about editing.

Persons most likely to experience hypothermia include those who are:

• Very old or very young
• Chronically ill, especially who have heart or blood flow problems
• Malnourished
• Overly tired
• Under the influence of alcohol or drugs

Template:WikiDoc Sources

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Please help WikiDoc by adding more content here. It’s easy! Click here to learn about editing.

20% to 50% of hypothermal deaths are associated with, or even caused by, a phenomenon known as paradoxical undressing. When this occurs, the hypothermic victim becomes seriously confused and starts discarding clothing they have been wearing, a counter-productive action which increases the rate of temperature loss. There have been several published case studies of victims throwing off their clothes before help reached them.

Rescuers who are trained in mountain survival techniques have been taught to expect this effect. However, the phenomenon still regularly leads police to incorrectly assume that urban victims of hypothermia have been subjected to a sexual assault.

One explanation for the effect is a cold-inducted malfunction of the hypothalamus, the part of the brain that regulates body temperature. Another explanation is that the muscles contracting peripheral blood vessels become exhausted and relax, leading to a sudden surge of blood (and heat) to the extremities, fooling the victim into feeling warm.

Template:WikiDoc Sources