Hypothermia
What You Need to Know to Survive
What You Need to Know About Hypothermia
Education is the first step to preventing injury or death from hypothermia. Use this document to learn about the effects of hypothermia, and the steps you can take to protect against it. Mustang products also play a key role in the battle against hypothermia.
WHAT IS HYPOTHERMIA?
Hypothermia is the lowering of the body core temperature as a result of exposure to a cold environment. The threat of hypothermia exists when a person is immersed in water that is colder than their normal body core temperature of 37° C (98.6° F). Many people do not realize that this threat exists even on warm sunny days.
Examples of average water temperatures are:
Pacific NorthWest 11.6° C (53° F)
Central Atlantic Coast 12.2° C (54° F)
Coastal Miami Beach 25.6° C (78° F)
Great Lakes 12.8° C (55° F)
Mustang Survival has done extensive research to understand cold-water survival. We know that many factors will effect how long you can survive.
The length of time a person can survive in cold water primarily depends on both the water's temperature and the thermal insulation of the victim's protective clothing. Although models and charts can predict approximate survival times there are many variables that ultimately effect survivability.
The Following Factors will decrease survival times :
Cold waters;
Lack of thermal insulation
Turbulent waters (waves, water flushing)
Body Movement (spent heat energy from swimming or treading)
Active winds
Physiological factors (eg: lean body composition)
Direct contact with the water
Consumption of alcohol and/or drugs
Injury
Fatigue
THE 4 CRITICAL PHASES OF COLD-WATER IMMERSION
I. First 5 minutes - Immediate Shock
The subject experiences the gasp reflex the sudden gasp of air as result of the shock, the inability to hold breath, hypertension and increased cardiac output. Most casualties in this phase succumb to drowning or heart attack before hypothermia can even begin to set to in.
II. Next 15 minutes Inhalation of Water
The subject fails to keep afloat or swim and has little ability to grasp or climb into things such as overturned vessels or life rafts. Typically, these individuals drown due to excessive inhalation of water.
III. 30 minutes - Onset of hypothermia
Stages of Hypothermia:
37° C is considered normal body core temperature. When core temperature drops to 36.1° C, muscle tone becomes affected. Most people have experienced this feeling of tension in their back and neck when they've become chilled. At a core temperature of 35° C, one is considered mildly hypothermic. Most immersion experiments with human test subjects are terminated at this point for ethical reasons. At a core temperature of 33.9° C, subjects experience amnesia, but of course don't remember it! Another 1.1° C drop down to 32.8° C; apathy that is a lack of sensation or feeling can be experienced.
At 32.2° C one is considered profoundly hypothermic and starts to lose the ability to shiver. At 31.1° C, shivering ceases. Shivering is a human's only method of increasing their internal heat generation, thus once it stops, and core temperature starts falling rapidly. At 30° C, heart arrhythmias occur. Death follows at 25° C; however the majority of people would have drowned before ever getting to this point.
IV. > 30 minutes Risk of Re-warming Shock after Rescue
Upon removal from the water, there is a continued drop in a subject's core temperature and a collapse of arterial pressure due to hydrostatic squeeze. Extreme care and proper re-warming procedures must be followed to effectively attend to the subject.
HOW CAN HYPOTHERMIA BE PREVENTED ?
In-water Tactics
When you're in cold water, don't swim unless you can reach a nearby boat, fellow survivor or floating object. Even good swimmers drown while swimming in cold water. Swimming lowers your body temperature.
If a nearby floating object is large, pull yourself up onto it. The more of your body that is out of the water, the warmer you'll be. Don't use drownproofing methods that call for putting your face into the water. Keep your head out of the water to lessen heat loss and increase survival time.
Use of the HELP position will lessen heat loss. If there are others in the water, HUDDLE together for warmth. Keep a positive outlook; it will improve your chances of survival.
Always wear your PFD. Even if you become helpless from hypothermia, your PFD will keep you afloat.
DIFFERENT LEVELS OF PROTECTIVE CLOTHING
It is advisable for everyone involved in activities on the water to wear a thermally protecting buoyancy aid. Buoyant suits, coats and bomber jackets protect from drowning by keeping people afloat. They also provide thermal insulation and protection against hypothermia by conserving body heat. The following clothing types contribute to the wearer's thermal protection by different methods.
PFD
At the very least, wear a PFD! The flotation is necessary to keep a person at the water's surface without expending what little energy they may have left. Some PFDs, by raising the body, provide less exposure to the water and its hypothermic effects.
FLOTATION COATS & SUITS
Ideally boaters should equip themselves with a flotation suit or jacket and pant combination. These products are considered 'wet' suits as water will enter the suit but the thermal properties of the suit will warm the water and help maintain the wearer's core temperature, while at the same time, keeping them afloat.
Each of our suits, coats, and jackets is designed to protect you from the cold. They provide flotation as well as hypothermia protection. Protection is achieved through the construction of each garment. This cross-section illustrates the three-layer construction.
Tight-weave high tenacity nylon outer shell is abrasion and UV resistant Closed-cell foam traps air pockets providing both buoyancy and insulation.
IMMERSION SUITS
Boaters who are out for long periods of time should carry an immersion suit, which can be donned quickly in an emergency situation. These suits are considered 'dry' suits and provide the highest level of thermal insulation as well as flotation. They are designed to keep a person alive for an extended period of time until help arrives.
BUOYANCY
Mustang Survival garments are lined with our innovative AirSoft polyvinylchloride (PVC) closed-cell foam. By trapping air pockets, this foam provides our products with both buoyancy and insulation. In fact, all Mustang garments exceed the minimum buoyancy requirements for Coast Guard approval.
THERMAL PROTECTION
Thermal protection is evaluated by using a measurement called Clo or Clothing Insulation Value. Clo is the thermal insulation value a product offers in the water. The greater the Clo value, the greater the level of thermal protection. To create the most effective protection attainable, Mustang Survival begins by evaluating the clothing's Immersed Clo values. Simply, we determine the rate at which heat is lost from the body, as well as the difference in temperature between the skin and the water. From the Immersed Clo values, predictions can be made of the rate at which a person's body temperature will drop in cold water.
Wearing a Mustang Survival Suit, with thermal protection, will increase
cold-water survival time exponentially. Flotation garments also improve
hypothermia survivability. You should now better understand how to safeguard
against the dangers of hypothermia with the proper clothing and in-water
behavior. For more information, visit mustangsurvival.com.