Safety Tips

Cold Water Immersion & Hypothermia

Immersion in cold water kills in several ways. The colder the water temperature, the greater the threat. In Ohio, our water temperature is colder than 70 degrees F the majority of the year. Understanding your body’s reaction to cold water and the four stages of immersion will increase your ability to respond appropriately.

STAGE 1: Cold Shock/Sudden Disappearance
This response begins immediately upon immersion and will peak within the first 30 seconds to 5 minutes. The response varies among individuals and is most acute in those sensitive to cold. It will even occur in water at 77 degrees F.

The body systems affected are your breathing and circulation. Breathing changes are immediate with involuntary gasping, rapid breathing, dizziness and confusion –- resulting in water inhalation and possible drowning. Circulatory changes are a sudden rise in heart rate and blood pressure –- possibly resulting in stroke or heart attack.

STAGE 2: Swim Failure
Having survived Stage 1, a person must attempt to self-rescue, stay afloat if without a lifejacket or swim to safety within the next 30 minutes. The nerves and muscles in the arms and legs cool quickly because of the constriction in blood flow. Manual dexterity, strength of handgrip and movement speed will drop 60 percent to 80 percent. This limits a person’s ability to swim or assist in his own rescue by catching a rope or climbing a ladder.

STAGE 3: Hypothermia
Immersion in water with a temperature below body temperature presents a significant thermal threat to the human body. Heat transfer from the body to the water is fast, with skin temperatures quickly cooling to water temperatures. When the cooling goes beyond the skin and limbs and reaches the inner organs of the body core, it is called hypothermia. Hypothermia develops after 30 minutes if cooling is not stopped. A variety of symptoms affect the body by rendering the person unable to survive by staying afloat, clinging to a boat, swimming or treading water.

The symptoms follow a predictable progression:

• Shivering is the first sign and becomes vigorous with continued exposure.
• Skin color becomes flushed initially, but later may turn blue.
• Slurred speech.
• Clumsiness and poor coordination.
• Withdrawn and apathetic.
• Heart rate and blood flow slow down.
• Limbs become stiff as muscles get rigid.
• Mental confusion.
• Shivering ceases as body is no longer able to rewarm itself.
• Unconsciousness eventually occurs.
• Heart failure may occur but drowning usually occurs first.

STAGE 4: Rescue and Post Immersion Responses
Survivors being removed or rescued from the water face significant physiological changes in blood volume and distribution (this affects the heart and circulation). Rescue technique and proper treatment of immersion victims is very important. The victim will need care from a knowledgeable medical team and hospital. Handle victims gently and minimize movement. Wrap the person in blankets to prevent further heat loss and transport him/her to the nearest medical facility in a warm vehicle.

SURVIVING COLD WATER IMMERSION: A lifejacket is critical to survival. Wear it at all times. Try to avoid entering the water. If you must enter the water, do it slowly. If experiencing cold shock, hold onto something until breathing settles down. Keep your head, neck and face out of the water. Get out of the water as soon as possible. Climb aboard a boat or on top of an overturned boat if you are unable to right it. Do not attempt to swim for shore as this will cause greater exposure to the water unless you are in a stream or river current. Assume the heat escape lessening position (H.E.L.P. or Huddle) to protect the body core organs: While floating in a lifejacket, draw your knees together toward your chest and hold your upper arms tightly to your sides. Remain as still as possible. Excessive movement in cold water cools the body 35 times faster. Thrashing flushes the warmer water away from the body. Clothing provides some protection against heat loss in water, especially a waterproof outer layer. Do not attempt to remove clothing, which traps water that is warmed by the body’s heat. Carry a blanket, hat and extra dry clothing on board. Survivors should stay well hydrated and replenish their energy needs.

PREVENTION OF HYPOTHERMIA

• Always dress for the water temperature and prepare for cold water immersion.
• Particularly protect the head, neck, sides and groin, which are high heat-loss areas.
• Wear a wetsuit or drysuit if your water activity involves exposure to cold water.
• When wetsuits or drysuits are impractical due to warm air temperature, dress in several layers of clothing under your lifejacket.

SPLASH FACT Nearly 90% of boating fatalities are due to drowning and nearly half of those are attributed to the effects of immersion in cold water. Water less than the normal body temperature of 98.6 degrees F can cause heat loss. Cold water will cool a body 25 times faster than cold air of the same temperature. The colder the water, the greater the risk to the unprepared person. If the water is under 50 degrees F, the window of opportunity for rescue is only a few minutes.