Lying on
the gravel bar you cough and sputter. It was a long cold swim thru the
rapids but you managed to get the boat and yourself to shore, no easy
task through the waves and holes. Thank God you have a lifejacket on.
Light clothing and a paddle jacket seemed warm enough in the boat with
the exercise of paddling but now, sitting next your swamped boat, you
shiver so hard you struggle just to undo the drybag to get to warm
clothes. You’re tempted to get back in the boat and keep paddling to get
warm, and to save face. The rest of the group behind you won’t even know
of your mishap. The plan was to get farther down the river to that
crystalline side creek with great fishing and picturesque campsite.
You imagine bailing the boat out and getting back in. The whitewater
continues, splashing over the deck, making sure your arms and torso
remain wet. The light rain falling all day has settled in and is steady
now. If only you had a hood for your paddle jacket. You didn’t
anticipate it could be this cold. If you had packed a hat you could put
it on now slowing radiation heat loss by as much a 50%. A cold breeze
blowing evaporates the moisture from your wet face, hands and clothing,
refrigerating you further. More heat is robbed kneeling; the bottom of
the boat and the river conduct heat away from your lower body. You shake
violently as your muscles contract involuntarily in an effort to produce
heat through the exercise of shivering. Your temperature, normally
around 98.6 has begun a slippery slide and is now about 95 degrees. You
are hypothermic.
 The bodies’ thermostat is the
hypothalamus located in the brain and sensitive to as little as 1 degree
change. It gathers information about temperature conditions throughout
the body and can control blood flow and therefore temperature. A
protective mechanism called the shell core effect keeps warm blood near
the internal organs: brain, heart and lungs and shunts precious heat
from the expendable muscles, appendages and skin of the shell. As the
brain cools chemical reactions slow, decision-making becomes difficult,
awareness of surroundings are limited. The heart cools as hypothermia
progresses, chemical balances are altered, abnormal and irregular
cardiac rhythms follow. Your extremities can handle much colder
temperatures than the core. However, cold muscles are slow to respond,
making accidents more likely. Another capsize would be disastrous.
The big rapid around the blind corner doesn’t really surprise you. A
chilly cerebrum sends only slowed signals to apathetic appendages; the
hydraulic hole in front of you is inevitable. You feel an uncontrollable
urge to urinate; intense vasoconstriction in the limbs has created an
increased volume pressure and the kidneys sense this. Your core
temperature has slid to 92 degrees. The water is cold, about 55 degrees,
matching the air temperature now as the day wears on. Water, with its
excellent conduction properties, will remove heat 25 times faster than
air. You wouldn’t be able to hold on to the boat much less swim to
shore. Drowning would be likely.
As core temperature drops below 90. Your body, sensing the futility of
shivering, will slow, then stop, in an effort to conserve glucose. Or
maybe you’ve just plain run out of fuel; you haven’t eaten since
breakfast -the rest of the crew, with lunch has been well behind all
day. Delirium sets in. You may imagine yourself swimming in warm emerald
water in some tropical setting; so warm in fact you feel a need to
remove clothing. Not an unusual response of severely hypothermic victims
who may be found in various states of undress. Perhaps, in a last ditch
effort to warm, there is a profound relaxing of formerly constricted
vessels creating a sensation of intense heat.
At around 86 degrees the cold, now chemically imbalanced blood becomes
irritating to the heart. The heartbeat becomes irregular and pumps only
the normal volume. You would not respond to your friends if they found
you now. It would be hard for a rescuer to feel a pulse or detect
respirations: critical systems slow, heartbeat may be only 20 or 30 a
minute. Eventually even this heart rhythm will deteriorate to the
cardiac equivalent of a muscle spasm and nothing short of a
defibrillator will bring it back. At about 80 degrees death is likely.
Rewarming is difficult even in a hospital at this point. As the blood
vessels and capillaries near the skin begin to dilate blood pressure
drops dramatically. Core temperature may actually drop further during
initial rewarming as cold stagnant blood in the appendages returns to
the core. Large volumes of pre-warmed IV fluid are necessary to keep you
from shock.
PREVENTION
Like blisters and sunburn, hypothermia is better prevented than endured.
- Hypothermia has been called the killer of the unprepared. Of course it
happens in the winter, but typical conditions are 30 - 50 degrees, wet
and light wind: classic spring, summer and fall weather. There are many
more travelers in the backcountry and not all may be prepared for
unexpected weather conditions. The typical hypothermia victim has been
just a little too cold for a little too long.
- Carry emergency food, and repair items. Extra energy bars, gels and
candy bars are easy to carry and quick to digest. Specific repair items
like ski binding and bike parts can make the difference between epic
struggle and inconvenience. Fire starters and emergency reflective
blankets can ease an unintended night out or help warm a hypothermia
victim.
- Dress well. Synthetic insulation layers are light compact and work
even if they do get wet. Lightweight coated nylon raingear is compact
and keeps insulation layers dry. A hat and warm gloves weigh little and
don’t take up much space.
- Stay dry. Dry clothing insulates better than wet. Avoid sweating which
not only cools you faster thru evaporation but also wastes precious
energy and fluid. - Beware of the wind. Wind refrigerates wet clothing.
Cold wind accelerates heat loss thru evaporation.
- Be ready to adjust goals to meet changing conditions. Give up the peak
and come back another day. Camp early while there’s still light and
energy left.
- Avoid exhaustion. Stay hydrated and fueled. Just like the heating
system in your home, your body needs fuel for the fire. Eat before you
feel hungry, drink before you’re thirsty. Simple carbohydrates require
less energy and oxygen to metabolize. Foods higher in fats and protein
supply fuel for recovery and replenishment. Moisture is lost via
sweating, increased respiration of exercise and other mechanisms,
depleting the overall circulating volume and making you more susceptible
to hypothermia and frostbite.
- Do not ignore shivering. Persistent or violent shivering is a sign
that you are on the verge of hypothermia. Constantly monitor your
warmth, feeding and hydrations status and that of your companions.
- Any injury or illness compromises the ability to stay warm. Anticipate
and add insulation and protect from cold early as part of your
treatments.
RECOGNIZING HYPOTHERMIA
- Heat production and retention are overwhelmed by the wind, wet and
temper ature. Body core temperature drops below 95 degrees.
Core temperature is measured rectally. A special low reading thermometer
is required. Obtaining core temperature is impractical and contributes
to making the victim colder. Look for someone who is obviously cold or
has been com- plaining of cold, shivering or not eating and drinking
regularly. Feeding, hydrating and warming anyone at risk for hypothermia
are good strategies. - Shivering. Controllable in early stages
uncontrollable as hypothermia progresses.
- Mental status changes. Beware of the UMBLES: stumbles, mumbles,
fumbles and grumbles; as the brain cools reasoning ability becomes
impaired, Victims will be awake but lethargic, confused or slow to
respond. Decision-making may be poor.
- Loss of fine motor coordination. Cold muscles can’t perform fine motor
skills, like zipping parkas, or tying boots. Stumbles and fumbles may
contribute to falling or other accidents.
TREATMENT
- Prevent further heat loss. Modify environment. Seek protection from
the wind in trees, lee side of ridges, or behind windbreaks. Remove wet
clothing. Set up a tent if available. Utilize any emergency shelter
available; I spent a night in an outhouse during blizzard in Rocky
Mountain National Park and one in an emergency blanket on a ledge in
Yosemite. Consider improvising shelter from tree limbs, dry leaves -
Insulation from seats of downed planes has saved lives.
- Increase body heat production. Exercise increases the bodies heat
production at 10 times that at rest.
- Eat. Easily digested foods are the kindling to restart the fire.
- Drink. Warm liquids are best.
- External rewarming. Place victim in a sleeping bag with padding
beneath. Place chemical heat packs or hot water bottles near the neck,
abdomen and groin area. Hot bottles can be insulated with socks.
- Body to body rewarming is fun to talk about and may work with large
sleeping bags or ones that zip together. Just placing warm bodies in the
same tent with the victims will warm it significantly.
SEVERE HYPOTHERMIA
The colder the victim, the more difficult to rewarm successfully in the
field. Hospital treatment is necessary due to rewarming complications
like shock and cardiac arrhythmias.
- Core Temp below 90 degrees. Difficult and impractical to measure. Look
for victims who have mental status changes in a setting where
hypothermia is possible.
- Serious mental status changes. Cannot cooperate, cannot eat or drink.
May be unconscious or exhibit irrational behavior, unable walk due to
very low peripheral blood flow and very cold muscles.
- May not be shivering. Either no fuel left or body realizes temperature
is continuing to drop despite the exercise of shivering.
- Slowed RR and HR. May be difficult to detect. Victims may appear dead.
TREATMENT - Evacuate. Prompt safe evacuation is the primary goal.
- Protect from the environment. Patient should ideally be packaged in a
sleeping bag with insulating pads underneath then placed in either in a
warm tent or wrapped in a tarp or tent fly for evacuation.
- Victims should be handled gently as possible to avoid irritating the
cold fragile heart.
- Add Heat to core areas like neck, chest and abdomen and groin to slow
heat loss. Take care not to burn patients.
- CPR is controversial and a difficult decision in hypothermia.
Assessment of slowed pulse and respirations are difficult under adverse
conditions, especially for cold and perhaps inexperienced rescuers. Any
spontaneous cardiac activity will always be better than CPR. Chest
compressions of CPR will cause cardiac-arrest in a victim with any
cardiac activity. Artificial respirations are less risky as they do not
constitute rough handling and add heated, humidified air to the victim.
Certainly CPR should be done only if there are no signs of life. A 30-
45 second pulse and respiration check may be necessary. CPR should not
be done if it delays evacuation, or there is a risk of hypothermia or
other danger to rescuers.
 COLD WATER
Cold lakes and rivers present a unique challenge. Water conducts heat
away 25 times faster than air. Hypothermia develops much more quickly.
Emphasis is placed on dressing appropriately and getting out of the
water quickly. Treatment for cold water hypothermia is the same. Victims
have been resuscitated after as long as 60 minutes in cold water, even
with no respiration or evident circulation. Rapid cooling of body
temperature decreases oxygen demand. Victims of possible drowning or 1
hour or less in cold water should receive vigorous CPR for at least 30
minutes for the best chance for survival.
- Water below 60 degrees is dangerously cold, at 40 you become to numb
to help yourself in just a few minutes and may become unconscious in as
little as 12 minutes. Any immersion over 6 minutes is considered long.
This may not be much of a problem in a shallow stream where you can get
out quickly but is a problem in a deep fast river, in rapids or in the
middle of a lake. Lake Powell water temperature in March is 52 degrees.
An average adult has 50/50 chance of surviving a 50-yard swim in
50-degree water.
- Loss of body heat is a major cause of death in boating accidents where
the victim becomes too cold to get out of the water and drowns.
- Cold shock can occur. Sudden immersion may trigger an involuntary gasp
followed by several minutes of hyperventilation, which may induce
cardiac arrest. Dressing appropriately can minimize this response.
- Proper clothing. Dress for the swim. Life jackets are necessary,
helping to prevent drowning, keep you up out of the water more, and keep
you warm. Wear a wet suit or dry suit with pile or fleece undergarments,
neoprene gloves, pogies, and a hat. Your clothing should be warm enough
to protect you while you re-enter your boat or get to shore.
- Have a rescue plan. On lakes know how to get back into your boat. On
rivers with short easier rapids you may be able to stay with your boat
and get to shore. On continuous class 3 or harder rivers, swimming to
shore may be the safest strategy even if it means abandoning your boat.
Back on the gravel bar, still fumbling with the drybag, someone is
shaking your shoulder. You hear talking. Looking around you recognize
friends around you. An hour later camp is set up. Trees divert the wind
and absorb the rain. You are hurried inside your tent and stripped of
wet clothing and assisted into warm dry long underwear and a sleeping
bag. Hot water bottles are placed inside the sleeping bag with you and
warmth slowly returns. In an hour you can eat and drink a little.
Another hour and you are able to join friends drying out river cloths
around the small fire. There will be more days, warmer days to make up
miles.
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