Cold-Water Immersion (CWI) and Hypothermia
Cold-water immersion (CWI) kills. Knowing how the body reacts
to CWI can prepare boaters to correctly respond to this
life-threatening situation and improve the chances of survival.
THE FOUR PHASES OF COLD-WATER
IMMERSION
|
| Phase |
Time Period |
Reaction |
| Cold Shock |
First few minutes of immersion |
The shock of CWI can cause sudden water
inhalation and drowning due to involuntary gasping,
hyperventilation , panic, and vertigo. Sudden changes in
blood pressure, heart rate, and heart rhythm can also
result in death. |
| Swim Failure |
Three to 30 minutes following immersion
|
The muscles and nerves of the arms and
legs cool quickly. Motor control (manual dexterity, grip
strength, and speed of movement) can all drop
drastically. Even physically fit boaters can lose the
motor control necessary to pull themselves out of the
water or even to keep their head above the surface.
Death occurs by drowning.
|
| Immersion Hypothermia |
After 30 minutes (depending on water
temperature, clothing, body type, and behavior in the
water). |
Hypothermia occurs when your core body
temperature drops below its normal range, eventually
leading to unconsciousness, and death, with or without
drowning. |
| Post-Immersion Collapse |
Occurs during or after rescue. |
Once rescued, there is still danger
from collapse of arterial blood pressure leading to
cardiac arrest. Inhaled water can damage the lungs, and
heart problems can develop as cold blood from arms and
legs is released into the body core. |
Prepare for cold-water conditions by always dressing for the
water temperature and wearing appropriate floatation. Wear a
float coat, survival suit, or wet suit (long or short) during
cold weather. Always prepare for CWI when the combined water and
air temperature is less than 110 degrees Fahrenheit.
A boater’s chances of surviving a CWI depends on sufficient
flotation for keeping an airway, controlling breathing, heat
retention and timely rescue by self or others. If multiple
persons end up in the water, attempt to stay together, and
"huddle" to limit heat loss. Treat victims of cold water
immersion by replacing wet clothing with dry materials
(blankets, coats, clothing, etc.), talk to them, and immediately
seek medical attention.
SURVIVING A COLD-WATER IMMERSION
|
| Don’t Panic |
Protect your airway, and get to the
surface as quickly as possible. |
Control breathing. Hold onto something
or stay still. Focus on floating with your head above
water until the cold shock response lessens. |
| Get Out of the Water
|
Try to reboard the boat, even if it is
swamped or capsized. Get as much of yourself out of the
water as possible. The rate of heat loss will be slower
out of the water than if immersed in water. |
If you cannot reenter the boat, put on
a life jacket. If no life jacket is available, grab
anything that will help you float . |
| Slow Heat Loss |
Keep head and neck out of water. In as
little as 10 minutes, you may become unable to
self-rescue. Minimize movement. Don’t take your clothes
off unless absolutely necessary. |
Staying with the boat is often a better
choice than swimming. If you must swim, swim on back,
arms tight to sides of torso, thighs together, knees
bent, flutter kick with lower legs |
| Signal Rescuers |
Use a portable air horn, whistle or
visual distress signals if available. |
Continue signaling by all available
means. |
|