[Editor’s
note: Doug Cameron is a Wilderness EMT and teaches for Wilderness
Medical Associates.]

Understanding
hypothermia is critical to safety for southeastern white water
paddlers because we paddle year-round. The keys to this
understanding are prevention, preparation and recognition.

Hypothermia
is a lowering of core body temperature due to the inability of the
body’s heat production and heat retention to meet the cold challenge.
This is like a see-saw. Given time, a minimal challenge, such as a
cold apartment, can overwhelm the ability of a person with few
resources, such as a thin, elderly person who eats little and
exercises little.

What
we see in white water situations in the winter is usually a moderate
to strong challenge with all the elements of efficient heat transfer:
wind and water. As long as our bodies have sufficient energy
resources and adequate heat retention we can meet the challenge,
maintain core temperature and remain happy campers on blustery winter
white water trips.

The
problem comes when our resources are overcome by the cold challenge.
We may overturn and our dry fleece or wool clothes become wet and
less efficient at retaining heat. By 1 PM we may use up that fine
breakfast we had at Shoney’s and not have enough fuel in our
waterproof bag to keep our furnace burning brightly. Whatever the
reason, this is the time to recognize that there is a problem, stop
the trip, and balance the resources once again. This is a medical
emergency that can become life-threatening, but it can be easily
treated in the field by a properly prepared group.

The
most obvious symptom of mild hypothermia is shivering. This is the
body’s attempt to warm itself through the rapid burning of available
fuel. In addition, the body closes down the peripheral blood vessels
to improve heat retention for the critical body core systems (heart,
lungs and brain), making our hands and feet cool, clumsy and pale due
to lack of adequate circulation. As the patient gets worse he gets
the “umbles” — he stumbles, mumbles, and generally begins
to lose the ability to make the quick decisions and precise movements
required by white water travel.

Finally,
the extra fluid in our body core causes the kidneys to get rid of the
excess, and we feel the need to pee.

When
we first recognize these early symptoms (shivering, cool, clumsy pale
extremities, the “umbles,” the need to pee), we should act
right away. In the middle of the Piney River gorge, there is little
way to reduce the heat challenge. We must, instead, overbalance the
seesaw to favor our body’s ability to meet the challenge.

The
patient needs fuel (think of it as building a fire, with sugar as
tinder, carbohydrates as sticks, and proteins and [a few] fats as
logs). The patient needs plenty to drink to replace the water dumped
during cold dieresis (the 50 cent word for the need to pee when
you’re cold). The patient should continue to work (paddle or hike)
to burn that fuel and produce needed heat.

And
the patient needs an improvement in heat retention (Did you remember
that extra set of warm fuzzies?) — remembering especially the neck
and head where more than 30% of our heat loss occurs. If we do this
soon enough and aggressively enough, we can continue the trip with no
other complications.

The
keys, again, are adequate preparation and quick recognition. We
should stay well fed and well hydrated: eat and drink early and
often. We should dress for the weather, including wet or dry suits,
and remember to keep our necks and heads warm. We should carry plenty
of food, water and extra warm clothes.

When
we recognize the early symptoms (shivering, cold, clumsy extremities,
the “umbles” and the need to pee), we need to act
aggressively to reverse the condition.

Severe
hypothermia is another matter. It is a true medical emergency and is
difficult to treat successfully in the field. Body chemistry is
altered by the cold (below 90 degrees), normal heart resuscitation
techniques no longer work as well, the heart becomes fragile, and the
extremities become reservoirs for toxins and cold that can dump their
deadly contents into the core if the patient is re-warmed
improperly.

In
severe hypothermia, shivering stops and the patient begins to lose
consciousness, behaving unreasonably and eventually becoming
unresponsive. Care for the severely hypothermic patient continues to
evolve, but the current thinking is this: we should treat the patient
very gently (because of the irritable heart), prevent any further
heat loss (remove cold, wet layers and wrap warmly), and get her to
advanced medical care quickly.

Heat
packs to the head, groin, and arm pits can warm the core, but we
should avoid warming the extremities (as opposed to preventing
further heat loss). We can help core re-warming by rescue breathing
if the patient’s respiration rate is less than 8 per minute, but we
should not initiate heart compressions unless we felt a pulse and
then lost it. These patients often have a slow heart rate that is
difficult to feel in the field, and pressing on the chest will delay
transport to definitive care and may cause ventricular fibrillation.

Severe
hypothermia is a big deal and often a killer — we don’t want to go
there. Again, the lessons are two:

1)
Be prepared so that we don’t get hypothermia in the first place
(good nutrition and hydration and adequate heat retention).

2)
Early recognition and intervention when mild hypothermia occurs.


by
Doug Cameron

From
“The Watershed”, newsletter of the Tennessee Scenic Rivers
Association.