Cold, wet, rain, hypothermia weather. Taken in Snohomish County, Washington”, by pfly, from Wikimedia, HERE.
If
you are like most people, you probably consider hypothermia as something to only
worry about in the depths of winter, when it is freezing cold outside. But you would be wrong!
Hypothermia
means “low heat” and it can happen anytime you lose your core body heat
faster than you can replace it. It can
strike anytime, anywhere, indoors, or out, even in relatively warm 50oF
(10oC) temperatures! And
while hypothermia is common in the winter, according to Princeton University it
actually occurs most often during the spring and fall1 and can occur
also in the summer. Unfortunately, prominent
Seattle hiking expert Karen Sykes, who was 70 years old, died of hypothermia on
June 18, 2014, while hiking the Owyhigh Lakes Trail in Mount Rainier National
Park which has a maximum elevation of 5,272 feet (1,607 m)2.
Hypothermia
is defined as a cooling of the body’s core temperature to below 95oF
(35oC) and is often caused by a combination of three factors, cold
or quickly changing temperatures, strong winds, or being wet, either from rain,
sweat or being immersed in cold water. Four
other factors that contribute to hypothermia are high elevations, which can
experience quickly changing wind and weather; age, because the very young and
the old have a harder time regulating and maintaining their body heat;
dehydration, which decreases your body’s ability to regulate its thermostat;
and fatigue or exhaustion, because low energy means you have less to burn to
keep you warm.
How you
lose heat...
“Illustration of the basic methods heat loss”, by Baedr-9439, February 25, 2020, modified by the Author with material from A Pocket Guide to Cold Water Survival, by the Coast Guard . Original from Wikimedia, HERE.
Your
body loses heat through four processes, convection, conduction, radiation, and
evaporation.
Convection
or wind chill can cool you very quickly. Alan E. Course, in The Best About
Backpacking, wrote “a two-mile-an-hour breeze can drag down body
temperature as effectively as a twenty-mile gale if the victim’s clothes are wet”. Your body will lose between 10% to 15% of its
heat through convection.
You
lose body heat by conduction to the ground, if you are sitting or sleeping on snow
or the ground, to the air around you, or to water if you are swimming or
immersed in it. Body heat is lost to the
air at temperatures lower than 68°F (20°C), and your body will lose about 2% of
its heat by air conduction. However, you
lose body heat to water about 25 times faster than to the air, so you can lose
body heat very quickly if you are in cold water or wearing wet clothing.
Radiation
is the process of heat moving away from your body, like heat leaving a hot
stove, and usually occurs in air temperatures lower than 68°F (20°C). The body loses 65% of its heat through
radiation.
You
will lose body heat by evaporation of water from your skin if you are sweating,
or from your clothing if it is wet. During
heavy exercise, your body will shed 85% of its heat by sweating. Also, you lose some body heat through
respiration (breathing). Heat loss by
evaporation and respiration will increase in dry or windy conditions.
What is
Hypothermia...
From A Pocket Guide to Cold Water Survival, by the Coast Guard, page 7.
Hypothermia
is the lowering of your body’s core temperature to 95oF (35oC)
or below and has three stages, mild, moderate, and severe.
Mild
Hypothermia is when your core body temperature falls from 98.6o (37oC)
to between 95o and 90oF (35o to 32oC). The symptoms of mild hypothermia are intense,
but controllable shivering and cold numb hands or the “fumbles”3.
Moderate
Hypothermia is when your core body temperature falls from 90o to 86oF
(32o to 30oC). The
symptoms of moderate hypothermia are uncontrollable shivering, confusion and
movements that become slow and labored, and slurred speech -- look for the “stumbles”,
the “mumbles”, and the “grumbles”.
Severe
Hypothermia is when your core body temperature drops to between 86o
and 78oF (30o to 25oC). The symptoms are extremely cold skin,
sleepiness or unconsciousness and a pulse that is irregular or difficult to
find.
Stay at
98.6o...
Stay at 98.6o, an excerpt from A Pocket Guide to Cold Water Survival, by the Coast Guard, page 2.
There
are five things that you need to do to keep yourself at 98.6oF (37oC),
and to avoid hypothermia: dress in layers, stay dry and keep “comfortably
cold”, stay hydrated, eat often, and be prepared.
Stay
warm. Always dress in layers, because
the layers will help trap your body heat close to your skin and will prevent
the wind and the wet from stealing it away. Wear an inner layer of synthetic weave to wick
away the sweat, a middle layer of synthetic, down or wool to provide insulation
and an outer waterproof/windproof layer to break the wind. And always take a knit hat, a knit hat is
essential because heat loss from your bare head can be 50% at 40oF
(4oC) and 75% at 5oF (-15oC). Bringing extra dry clothes in case you get
wet or an extra insulative layer in case the temperature drops is also, always
a good idea.
From A Pocket Guide to Cold Water Survival, by the Coast Guard, page 6.
Stay
dry! If it is wet out, put on your
waterproof layers or take shelter. And
stay “comfortably cold” by taking off your insulative layers or your knit hat
as you become too warm, because as Les Stroud, The Survivorman says, “You Sweat
You Die”!
From A Pocket Guide to Cold Water Survival, by the Coast Guard, page 12.
Stay
hydrated and stay fed. Even low levels
of dehydration of less than a 2% loss of body weight4, can lower
your blood volume and affect your circulation and your
body’s ability to regulate its thermostat, this can result in
hypothermia. Also, your body uses food
as energy and it takes energy to make heat, so, when it is cold, you must eat
more often. But remember you need to
have water to digest your food, so if you don’t have water, don’t eat.
Be
prepared. Always dress for the worst
weather you might experience, your first line of defense against the cold and
the wet, are the clothes you are wearing and the extra clothes that you have
with you. Especially during the spring,
summer and fall, travelers in the wilderness often do not bring enough, or bring
the right kinds of clothes. And always,
bring a tent, a tarp, or some way of making an emergency shelter with you, when
you go out in the wilderness. If a storm
blows up make camp right away, because setting up camp takes time and energy,
and if you are cold, you might not have much of either. Personally, I always carry two heavy grade,
55-60 Gallon, 3.0 Mil, 38"W x 58"H, contractor trash bags, in case I
have to make an emergency trash bag shelter (for more see “Using your poncho or
a trash bag as an Emergency Shelter ©”, HERE,
or for a video, go HERE).
So,
be safe, keep warm and dry and stay at 98.6oF, spring, summer, fall,
or winter!
Don’t forget to come back next week and read “Mayapples...They Aren’t Really Apples ©”, where we will talk about a common woodland flowering plant
that really isn’t a what it is called, and which appears during the spring and
disappears by mid-summer.
I
hope that you continue to enjoy The Woodsman’s Journal Online and look for me
on YouTube at BandanaMan Productions for other related videos, HERE. Don’t forget to follow me on both The
Woodsman’s Journal Online, HERE,
and subscribe to BandanaMan Productions on YouTube. If you have questions, as always, feel free
to leave a comment on either site. I announce
new articles on Facebook at Eric Reynolds, on Instagram at
bandanamanaproductions, and on VK at Eric Reynolds, so watch for me.
That
is all for now, and as always, until next time, Happy Trails!
Notes
1 “Cold Stress Facts”, Environmental
Health and Safety, Princeton University
2 From
Eric M. Johnson, “Seattle hiking expert Sykes died of hypothermia: official”
and Pro Trails, “Owyhigh Lakes - 7.0 miles”.
3
Watch out for the “umbles”: the fumbles, a sign of cold numb hands and
mild hypothermia, and the mumbles, stumbles, and grumbles, a sign of confusion
and slowed thinking and movement, all of which are symptoms of moderate
hypothermia.
The
best field test for early or mild hypothermia, is to ask the person to walk in
a straight line, if they are unable to walk 20 to 30 feet (6 to 9 m) in a
straight line, they might be hypothermic.
From
“Warning
Signs of Hypothermia: Know Your ‘Umbles’”, by Matt Heid.
4
From “Dehydration, Hyperthermia, and Athletes: Science and Practice”, by Robert
Murray, PhD.
Sources
Coast Guard, Department
of Transportation, A Pocket Guide to Cold Water
Survival, CG 473, September 1975, https://books.googleusercontent.com/books/content?req=AKW5QafxNJBmiIml6O4jiudRpr2rz8pLfodQOiq-4gZNh4xa5uIN_rq05C2yAes1AYw67Ziq189QaQaFDHBHE0SJivfCxjMW1DReANLjFqw1qX6jEl2mz1HPKXj4BRQJv8zAOcO6oDE70Dcv__VE2uPh4tEqLSzMxDRiWOv3p6ssyQjE2bevJMX7-Ol2KDtIPQVcVuaJudJMLaOOuSUVs8qYS1Nlaxnm47GVOCXLR79KzL6nV3R0zZG4DxRt9hoYrIRGugXm6RVfbU2gxeix7JLKbxpvQsNB9w,
accessed May 1, 2022
Environmental Health and Safety,
“Cold Stress Facts”,
[© 2022 The Trustees of Princeton University], https://ehs.princeton.edu/workplace-construction/occupational-health/heat-cold-stress/cold-stress-facts, accessed June 14, 2022
Heid, Matt; “Warning Signs of Hypothermia:
Know Your ‘Umbles’”, February 11, 2014, [©
2022 Appalachian Mtn Club], https://www.outdoors.org/resources/amc-outdoors/health-and-safety/warning-signs-of-hypothermia-know-your/,
accessed June 18, 2022
Johnson, Eric M.; “Seattle hiking
expert Sykes died of hypothermia: official”, June 24, 2014, [© 2022 Reuters], https://www.reuters.com/article/us-usa-hiker-washington/seattle-hiking-expert-sykes-died-of-hypothermia-official-idUSKBN0EZ0OQ20140624,
accessed June 14, 2022
Murray, Robert, PhD.; “Dehydration,
Hyperthermia, and Athletes: Science and Practice”, Journal of Athletic
Training, July-September 1996, 31(3), pages 248–252, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1318513/,
accessed June 18, 2022
MyHealth.Alberta.ca, “Cold Exposure:
Ways the Body Loses Heat”, [© 2022 Government of Alberta], https://myhealth.alberta.ca/Health/pages/conditions.aspx?hwid=tw9037#:~:text=Convection%20(similar%20to%20sitting%20in,of%20its%20heat%20through%20convection.,
accessed June 18, 2022
Pro Trails, “Owyhigh Lakes - 7.0
miles”,[ © 2021 ProTrails], https://www.protrails.com/trail/851/mount-rainier-national-park-owyhigh-lakes,
accessed June 18, 2022
Van Lear, Denise; The Best About
Backpacking, [Sierra Club, San Francisco, 1974], page 355
Wikimedia;
“Cold,
wet, rain. Taken in Snohomish County,
Washington”, by pfly, November
12, 2007, https://commons.wikimedia.org/wiki/File:Rain_shower_after_cold_front_3.JPG, accessed June 10,
2022
Wikimedia;
“Illustration of the basic methods heat loss”, by Baedr-9439, February 25,
2020, https://commons.wikimedia.org/wiki/File:Mechanisms-of-heat-loss.png,
accessed June 17, 2022
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