Hypothermia Information

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Understanding the Cold Facts About Hypothermia


The Cold Facts

You should be aware that cold water, under 70 degrees Fahrenheit, can lower your body's core temperature. This condition is referred to as HYPOTHERMIA. When your body's natural temperature goes too low, you will probably pass out and then drown. Even while wearing a PFD, your body may still cool down as much as 25 times faster in cold water than in air.

Amount of body fat, body size, movement and water temperature are significant factors in cold water survival. Small people cool faster than larger people. Children and the elderly tend to lose body heat more rapidly than healthy adults.

Besides impairing your vision and ability to think, alcohol works to lower your body temperature much faster when you are in the water. Therefore, you significant reduce your chance for survival.

PFDs can assist you to stay alive longer in cold water because they allow you to float without expending energy. The expediture of energy usually causes the body to quickly lose much needed warmth. A snug-fitting PFD can slow down the process of body heat loss more effectively than a loose-fitting PFD. A flotation coat or deck-style PFD is more effective in cold water since it covers more surface area of your body.

How Hypothermia Affects Most Adults
Water Temperature
(Degrees Fahrenheit) 		Exhaustion or Unconsciousness Expected Time of Survival
 
  • 32.5
  • 32.5 - 40.0
  • 40.0 0 50.0
  • 50.0 - 60.0
  • 60.0 - 70.0
  • 70.0 - 80.0
  • Over 80.0
  
 
  • Under 15 Mins
  • 15 - 30 Mins
  • 30 - 60 Mins
  • 1 - 2 Hrs
  • 2 - 7 Hrs
  • 2 - 12 Hrs
  • Indefinite
  
 
  • Under 15 - 45 Mins
  • 30 - 90 Mins
  • 1 - 3 Hrs
  • 1 - 6 Hrs
  • 2 to 40 Hrs
  • 3 Hrs - Indefinite
  • Indefinite
  



Surviving in Cold Water

When you find yourself in cold water, don't swim unless you can reach a nearby boat, fellow survivor or floating object. Even good swimmers have been known to drown while swimming in cold water. Swimming lowers your body temperature (since you are exerting energy).

If a closeby, floating object is large enough, pull yourself up on it. With more body surface area exposed to the air, this reduces your rate of heat loss. Do not use drownproofing methods that call for placing your face into the water. Keep as much of your body out of the water to maximize your survival time.

Use of the HELP (Heat Escape Lessening Posture) position (see drawing below) will lessen loss of body temperature. However, if you are wearing a Type III PFD or find that the HELP position turns you face down in the water, then use the SURVIVAL position (as shown in the drawing below). If there are multiple people in the water, then HUDDLE together for warmth.

Keep a positive outlook. This will improve your chances of survival. Never remove your PFD while you are stranded in the water; even if you become helpless from the affects of hypothermia, it will keep you afloat.

Drawing courtesy of United States Coast Guard



Stages of Hypothermia
BODY TEMP SEVERITY SYMPTOMS
95° - 98°F Mild Shivering begins; a sense of chillness sets in. Skin becomes numb, muscular performance begins to degrade, poor movement coordination, hands are immobile or fumbling.
95° - 93°F Mild Shivering is more violent; skin is pale and cold to the touch, mild confusion or apathy sets in, have difficulty in speaking, deeper feeling of cold and numbness, lack of coordination is obvious. At this stage, you are on the verge of hypothermia.
93° - 90°F Mild Mental sluggishness; unable to use hands, retrograde amenesia setting in, gross muscular incoordination, slow thought, slurred speech.
90° - 86°F Moderate Shivering ceases; mental confusion continues, coupled with incoherence and irrationality, severe lack of coordination accompanied by stiffness, have inability to walk or stand.
86° - 82°F Severe Severe muscular rigidity; sleepiness setting, extreme lethargy, slower respiration and heartbeat, dilation of eye pupils, skin is ice cold to the touch.
82° - 78°F Severe Unconsciousness; typically followed by death resulting from heart or respiratory failure.


How Body Heat is Lost
Conduction Contact between your skin and another surface results inconduction of your body heat to that surface. Sitting on the snow or ground, being rainedupon or being in the water are all examples of conduction.
Convection Convection is the process to heat air from a source. The primary function of clothing is to keep a layer of warm air (or dead air space) next to your skin, while allowing water vapors (perspiration) to escape.
Evaporation Perspiration of water vapor from the skin and moisture from the lungs. Adjust your clothing to control heat loss (when applicable).
Radiation Direct heat loss from bare, uncovered skin. Greatest heat loss is from the head, feet, groin, neck and sides of the chest.
Respiration Heat escapes during air exhalation. Breathe normally and peaceably to avoid possible panic attacks. Covering the mouth and nose with an article of clothing can help slow down heat loss.



The Rules of 50

  • An "average" adult has a 50/50 chance of surviving a 50 yard swim
    in water with a temperature of 50°F.

  • A 50 year-old adult has a 50/50 chance of surviving for 50 minutes
    in water with a temperature of 50°F.


How to Survive in Cold Water

  • DO NOT remove any clothing.
  • Where possible, button up, buckle up, zip up and tightenup collars, cuffs, hoods and shoes.
  • Devote your efforts to removing yourself from the water. Act quickly before losing use of your hands andfeet.
  • The object is to get as much of yourself (as possible)out of the water. Climb onto any floating object, including your capsized vessel.
  • DO NOT attempt to swim UNLESS you can reach anearby boat, floating object or person.
  • If you are unable to leave the water, employ one of the three survival positions - HELP, HUDDLE or SURVIVAL.
  • Remain as still as possible.
  • Keep your head out of the water.
  • Maintain a positive mental attitude towards yoursituation.


Cold Water Drowning

Some apparent drowning victims may appear deceased, but in reality are still alive. The phenomenon is known as "Mammalian Diving Reflex", which can be triggered by cold water. This conditional reflex is more commonly associated with porpoises, seals and whales. This cold water reaction shuts off blood flow to non-critical areas of the body while slowing down the metabolic rate. The remaining oxygen is circulated where it is need most: the brain, heart and lungs.

Do not ASSUME that a person is dead, when the victim - has stopped breathing, has no pulse or has bluish-purple colored skin. (A cyanotic state occurs from a depletion of oxygen from the victim's blood.) QUICKLY administer CPR and get the person transported to a medical facility immediately for specialized rewarming and revival techniques.

NEVER GIVE UP on a drowning victim!. There are documented instances where people have been successfully & completely revived after being submerged for extended periods of time. Some cases involve submersion in excess of 45 minutes.



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Hypothermia Information