Hypothermia: A Cold And Warm Water Hazard August 27, 2015 13:06
In this post, we will explain the definition of Hypothermia and how to stop it from ruining your watery experience. If you just want to get right to the point, go get yourself a Surf-fur Waterparka and make sure you wear it before and after immersion in water (any water below 75 degrees can cause Hypothermia) and even in between swims or dives to rewarm.
Hypothermia is a medical emergency that occurs when your body loses heat faster than it can produce heat, causing a dangerously low body temperature. When your body temperature drops, your heart, nervous system and other organs can’t work normally. Left untreated, hypothermia can eventually lead to complete failure of your heart and respiratory system and to death. Hypothermia is most often caused by exposure to cold weather or immersion in a cold body of water. Primary treatments for hypothermia are methods to warm the body back to a normal temperature. (Mayo Clinic)
Normal human core body temperature is 37°C (98.6°F), clinically hypothermia occurs when the core temperature falls below 35°C (95°F) – that’s not much of a drop. Cold water (less than 75° F) can lower your body temperature, causing hypothermia. The human body cools 25 times faster in cold water than it does in air. Since heat is lost much more quickly in water than in air, water temperatures that would be quite reasonable as outdoor air temperatures can lead to hypothermia. A water temperature of 10 °C (50 °F) can lead to death in as little as one hour, and water temperatures near freezing can cause death in as little as 15 minutes. A notable example of this occurred during the sinking of the Titanic, when most people who entered the −2 °C (28 °F) water died within 15–30 minutes.
Hypothermia continues to be a major limitation to swimming or diving in cold water.The reduction in finger dexterity due to pain or numbness decreases general safety and work capacity, which consequently increases the risk of other injuries. Hypothermia is the cause of at least 1500 deaths a year in the United States. It is more common in older people and males. Other factors predisposing to immersion hypothermia include dehydration, inadequate rewarming between repetitive dives, starting a dive while wearing cold, wet dry suit undergarments, sweating with work, inadequate thermal insulation (for example, thin dry suit undergarment), and poor physical insulation.
The actual cause of death in cold water is usually the bodily reactions to heat loss and to freezing water, rather than hypothermia itself. For example, plunged into freezing seas, around 20% of victims die within 2 minutes from cold shock, (uncontrolled rapid breathing, and gasping, causing water inhalation, massive increase in blood pressure and cardiac strain leading to cardiac arrest, and panic); another 50% die within 15–30 minutes from cold incapacitation (inability to use or control limbs and hands for swimming or gripping, as the body “protectively” shuts down the peripheral muscles of the limbs to protect its core), and exhaustion and unconsciousness cause drowning, claiming the rest within a similar time.
Signs and symptoms vary depending on the degree of hypothermia, and may be divided by the three stages of severity;
Symptoms of mild hypothermia may include shivering, increase in blood pressure, rapid heart rate, rapid breathing, and a pale skin. These are all physiological responses to preserve heat. Mental confusion, and liver failure may also be present.
Low body temperature results in shivering becoming more violent. Muscle mis-coordination becomes apparent. Movements are slow and labored, accompanied by a stumbling pace and mild confusion, although the person may appear alert. Surface blood vessels contract further as the body focuses its remaining resources on keeping the vital organs warm. The subject becomes pale. Lips, ears, fingers, and toes may become blue.
As the temperature decreases, further physiological systems falter and heart rate, respitory rate, and blood pressure all decrease. This results in an expected heart rate in the 30s at a temperature of 28 °C (82 °F).
Difficulty speaking, sluggish thinking, and amnesia start to appear; inability to use hands and stumbling are also usually present. Cellular metabolic processes shut down. Below 30 °C (86 °F), the exposed skin becomes blue and puffy, muscle coordination very poor, and walking almost impossible, and the person exhibits incoherent/irrational behavior, or even stupor. Pulse and respiration rates decrease significantly, but fast heart rates can also occur. Major organs fail and death occurs.
- Appropriate clothing helps to prevent hypothermia. Synthetic and wool fabrics are superior to cotton as they provide better insulation when wet and dry (think Surf-fur). Some synthetic fabrics, such as polypropylene and polyester, are used in clothing designed to wick perspiration and water away from the body (think Surf-fur again). Clothing should be loose fitting, as tight clothing reduces the circulation of warm blood.
- Covering the head is effective, but no more effective than covering any other part of the body. While common folklore says that people lose most of their heat through their heads, heat loss from the head is no more significant than that from other uncovered parts of the body. Children have a larger surface area per unit mass, and other things being equal should have one more layer of clothing than adults in similar conditions, and the time they spend in cold environments should be limited.
- Applying warming devices externally, such as a heating blanket, can be good if an outlet is available.
- Placing a hot water bottle in both armpits and groin are recommended for moderate hypothermia.
- Active core rewarming involves the use of intravenous warmed fluids, irrigation of body cavities with warmed fluids use of warm humidified inhaled air, and wearing a windproof warm parka or blanket that is made with synthetic materials.
- Warm sweetened liquids can be given provided the person is alert and can swallow. Many recommend that alcohol and drinks with lots of caffeine be avoided. As most people are moderately dehydrated, warmed intravenous fluids to a temperature of 38–45 °C (100–113 °F) are often recommended.
- Maintain your core body heat and warm up in between dives as much as you can. Even if you are diving or swimming in tropical waters, you still need to rewarm your core whenever possible. It’s always colder down below.
|Water Temperature (Fahrenheit)||Exhaustion or Unconsciousness||Expected Time of Survival|
|32.5 degrees||Under 15 minutes||Under 15 to 45 minutes|
|32.5 to 40 degrees||15 to 30 minutes||30 to 90 minutes|
|40 to 50 degrees||30 to 60 minutes||1 to 3 hours|
|50 to 60 degrees||1 to 2 hours||1 to 6 hours|
|60 to 70 degrees||2 to 7 hours||2 to 4 hours|
|70 to 80 degrees||2 to 12 hours||3 hours to indefinite|
|Over 80 degrees||Indefinite||Indefinite|