COLD INJURIES - Medicine for Mountaineering and Other Wilderness Activities - page 404

(Heat Escape Lessening Posture) and huddling, should be initiated. Clothing should be
tightened to decrease the flow of cold water within clothing layers.
Hypothermia
The individual who survives the immediate and short-term phases of cold water im-
mersion faces the possible onset of hypothermia because continuous heat loss eventually
decreases core temperature. However, hypothermia only becomes a significant contributor
to death if immersion lasts more than thirty minutes in ice-cold water, and this period
lengthens as water temperature increases.
Even in ice-cold water, an hour or more may be required for a person to become uncon-
scious due to hypothermia, which occurs at a core temperature at or below 86°F (30°C),
if a PFD, flotation snowmobile suit, or some other device eliminates the need for vigorous
exercise to keep from drowning. Once a person is unconscious, another hour or more may
be required for the heart to stop if the head is kept above water (if a PFD is worn and water
is calm enough for waves not to wash over the mouth or if the arms are frozen to the ice).
One Minute—Ten Minutes—One Hour
The slogan “one minute—ten minutes—one hour” helps increase the chances of surviv-
ing cold water immersion by providing a simple way to remember the first three stages of
cold water immersion and what to do during each of them.
After falling into very cold water people have:
◆ One minute to get breathing under control (Panic must be avoided!)
◆ Ten minutes of useful movement (Time is available for getting out of the water or
creating a stable situation.)
◆ One hour until unconsciousness from hypothermia (A person wearing a PFD may
have another hour until the heart is stopped by hypothermia.)
Withoutflotation,remainingafloatlongenoughtodiefromhypothermiaisvirtuallyim-
possible,anddeathoccursfromdrowningastheresultofcoldshockorcoldincapacitation.
Wearing a PFD accomplishes two objectives: survival time is increased tremendously, and
the contributions of cold shock and cold incapacitation are decreased substantially.
Circumrescue Collapse
An estimated 20 percent of individuals recovered alive from cold water die as a result
of circumrescue complications, either before, during, or within hours after rescue. Prior to
imminent rescue, mental relaxation and decreased output of stress hormones may cause a
drop of blood pressure, resulting in fainting and drowning.
The act of rescue may cause sudden collapse. Pulling a person out of the water in a
vertical position removes the hydrostatic squeeze on the person's body and lower limbs,
allowing blood to pool in the extremities and causing decreased blood pressure. The extra