|Reprinted with permission from
See also his
Cold Water Brochure
|Here is a short version:
Death due to cold water immersion is currently separated into 4 phases. These
are Cold shock, swimming failure, hypothermia and post-rescue collapse.
Cold shock refers to those physiological responses that occur immediately upon
immersion in cold water.
Swimming failure refers to the relatively rapid loss of control of the hands,
arms and legs as cold water causes loss of blood flow to the limbs and loss of
nerve conduction to the limbs. Soon after entry into cold water, say 5-15
minutes, one losses the ability to swim and hold on to safety lines, capsized
boats, floating debris, etc. Drowning ensues because victims are not wearing
either wetsuits of PFDs. and they sink.
Hypothermia occurs over a longer time course and this refers to the gradual
decline in core body temperature. When a person can "remain conscious for an
hour at some temperature" it does not mean that the victim is fully functional
for an hour and then the lights suddenly go out. The victim is only functional
over the time course that corresponds to swimming failure. After that, the
victim is praying for outside assistance.
Post-rescue collapse occurs after hypothermia has resulted in low core
temperature, profoundly reduced cardiac activity, greatly reduced blood volume
due to diuresis. If the victim is not kept horizontal upon removal from the
water, blood rushes to the lower
part of the body and heart failure occurs.
Back to cold shock:
On my website, you will find a picture of a "Polar Bear Guy" standing
chest deep in ice cold water. Icicles are hanging from the ladder and dock
immediately behind him. Water is streaming off his elbows implying that he just
ducked under water and stood up. His face shows a profound gasp response. If he
had remained under water, he would have drowned.
It has been shown in tank tests that immersion in cold water profoundly reduces
ones breath holding capability-down to only seconds in some cases. This is
saying that one's ability to resist inhaling, while relatively long in air or
warm water, is seriously reduced, even nearly eliminated in some individuals,
upon immersion in cold water. The gasp follows!
If above the water's surface, hyperventilation follows for several minutes,
which can also result in loss of consciousness.
Cold water immersion results in constriction of the blood vessels on the body's
surface. One minute in 60 o F water will result in the skin turning black on
infrared viewing--meaning the skin is cold and surface circulation has been
eliminated. As a result, blood pressure spikes, catecholamines are released and
heart rate spikes. This results in a heart attack in some individuals-- like the
flat water racer in the canal in Germany. She was a trained athlete. You can not
say-- no problem, she was just predisposed. The water temp was under 40 o F.
Cold water in the ears also causes vertigo- resulting in failure of our
ability to orient relative to the surface of the water. Thus, your roll fails!
Cold water inhaled into the respiratory tract can paralyze the respiratory
tract-- no more breathing! victim is seen struggling at the surface for a minute
or less, observers say "the is making it, will be able to hold on, etc". Victim
them disappears from view.
Drowning can also occur over a few minutes after inhaling water as the
lungs gradually fail.
The message to paddlers is:
Rolling or doing rescues in cold water is no problem, providing we have dressed
to prevent direct exposure to the cold water. That is hoods, gloves, boots,
Air temperature doesn't count when you are in the water.
The ability to swim like a hot tuna in warm water has no impact on these
responses to cold water immersion.
The press and boating public in general is near totally ignorant regarding
these issues. Many agencies that are regarded as responsible for informing the
public tell the public to add air and water temp, dress in layers of synthetics
or wool, eat lots of STUFF etc. Hold real still in the water (and wait for a
magical rescue). Such suicidal advice doesn't seem to bother them! Why is that?
reprinted with permission from Chuck Sutherland
For more information please see
Off Season Boating, Cold
Shock and Hypothermia