Survival Medicine - Requirements for Maintenance of Health
To survive, you need water and food. You must also have and apply high
personal hygiene standards.
Your body loses water through normal body processes (sweating, urinating,
and defecating). During average daily exertion when the atmospheric
temperature is 20 degrees Celsius (C) (68 degrees Fahrenheit),
the average adult loses and therefore requires 2 to 3 liters of water
daily. Other factors, such as heat exposure, cold exposure, intense
activity, high altitude, burns, or illness, can cause your body to lose
more water. You must replace this water.
Dehydration results from inadequate replacement of lost body fluids. It
decreases your efficiency and, if injured, increases your susceptibility to severe shock. Consider the following results of body fluid loss:
A 5 percent loss of body fluids results in thirst, irritability, nausea, and weakness.
A 10 percent loss results in dizziness, headache, inability to walk, and
a tingling sensation in the limbs.
A 15 percent loss results in dim vision, painful urination, swollen
tongue, deafness, and a numb feeling in the skin.
A loss greater than 15 percent of body fluids may result in death.
The most common signs and symptoms of dehydration are—
- Dark urine with a very strong odor.
- Low urine output.
- Dark, sunken eyes.
- Emotional instability.
- Loss of skin elasticity.
- Delayed capillary refill in fingernail beds.
- Trench line down center of tongue.
- Thirst. Last on the list because you are already 2 percent dehydrated
by the time you crave fluids.
You replace the water as you lose it. Trying to make up a deficit is
difficult in a survival situation, and thirst is not a sign of how much
water you need.
Most people cannot comfortably drink more than 1 liter of water at a
time. So, even when not thirsty, drink small amounts of water at regular
intervals each hour to prevent dehydration.
If you are under physical and mental stress or subject to severe conditions,
increase your water intake. Drink enough liquids to maintain a
urine output of at least 0.5 liter every 24 hours.
In any situation where food intake is low, drink 6 to 8 liters of water per
day. In an extreme climate, especially an arid one, the average person
can lose 2.5 to 3.5 liters of water per hour. In this type of climate, you
should drink 14 to 30 liters of water per day.
With the loss of water there is also a loss of electrolytes (body salts).
The average diet can usually keep up with these losses but in an
extreme situation or illness, additional sources need to be provided.
A mixture of 0.25 teaspoon of salt to 1 liter of water will provide a
concentration that the body tissues can readily absorb.
Of all the physical problems encountered in a survival situation, the loss of water is the most preventable. The following are basic guidelines for the prevention of dehydration:
- Always drink water when eating. Water is used and consumed as a part
of the digestion process and can lead to dehydration.
- Acclimatize. The body performs more efficiently in extreme conditions
- Conserve sweat not water. Limit sweat-producing activities but drink
- Ration water. Until you find a suitable source, ration your water
sensibly. A daily intake of 500 cubic centimeter (0.5 liter) of a
sugar-water mixture (2 teaspoons per liter) will suffice to prevent
severe dehydration for at least a week, provided you keep water
losses to a minimum by limiting activity and heat gain or loss.
You can estimate fluid loss by several means. A standard field dressing
holds about 0.25 liter (one-fourth canteen) of blood. A soaked T-shirt
holds 0.5 to 0.75 liter.
You can also use the pulse and breathing rate to estimate fluid loss. Use the following as a guide:
- With a 0.75 liter loss the wrist pulse rate will be under 100 beats per
minute and the breathing rate 12 to 20 breaths per minute.
- With a 0.75 to 1.5 liter loss the pulse rate will be 100 to 120 beats per
minute and 20 to 30 breaths per minute.
- With a 1.5 to 2 liter loss the pulse rate will be 120 to 140 beats per
minute and 30 to 40 breaths per minute. Vital signs above these rates
require more advanced care.
Although you can live several weeks without food, you need an adequate
amount to stay healthy. Without food your mental and physical capabilities
will deteriorate rapidly, and you will become weak. Food replenishes
the substances that your body burns and provides energy. It provides
vitamins, minerals, salts, and other elements essential to good health.
Possibly more important, it helps morale.
The two basic sources of food are plants and animals (including fish).
In varying degrees both provide the calories, carbohydrates, fats, and
proteins needed for normal daily body functions.
Calories are a measure of heat and potential energy. The average person
needs 2,000 calories per day to function at a minimum level. An
adequate amount of carbohydrates, fats, and proteins without an adequate
caloric intake will lead to starvation and cannibalism of the body’s
own tissue for energy.
These foods provide carbohydrates—the main source of energy. Many
plants provide enough protein to keep the body at normal efficiency.
Although plants may not provide a balanced diet, they will sustain you
even in the arctic, where meat’s heat-producing qualities are normally
essential. Many plant foods such as nuts and seeds will give you enough
protein and oils for normal efficiency. Roots, green vegetables, and plant
food containing natural sugar will provide calories and carbohydrates
that give the body natural energy.
The food value of plants becomes more and more important if you are
eluding the enemy or if you are in an area where wildlife is scarce. For
- You can dry plants by wind, air, sun, or fire. This retards spoilage
so that you can store or carry the plant food with you to use when
- You can obtain plants more easily and more quietly than meat. This
is extremely important when the enemy is near.
Meat is more nourishing than plant food. In fact, it may even be more
readily available in some places. However, to get meat, you need to
know the habits of, and how to capture, the various wildlife.
To satisfy your immediate food needs, first seek the more abundant and
more easily obtained wildlife, such as insects, crustaceans, mollusks, fish,
and reptiles. These can satisfy your immediate hunger while you are preparing
traps and snares for larger game.
In any situation, cleanliness is an important factor in preventing infection
and disease. It becomes even more important in a survival situation.
Poor hygiene can reduce your chances of survival.
A daily shower with hot water and soap is ideal, but you can stay clean
without this luxury. Use a cloth and soapy water to wash yourself. Pay
special attention to the feet, armpits, crotch, hands, and hair as these
are prime areas for infestation and infection. If water is scarce, take an
“air” bath. Remove as much of your clothing as practical and expose
your body to the sun and air for at least 1 hour. Be careful not to
If you don’t have soap, use ashes or sand, or make soap from animal fat
and wood ashes, if your situation allows. To make soap—
- Extract grease from animal fat by cutting the fat into small pieces
and cooking them in a pot.
- Add enough water to the pot to keep the fat from sticking as it
- Cook the fat slowly, stirring frequently.
- After the fat is rendered, pour the grease into a container to harden.
- Place ashes in a container with a spout near the bottom.
- Pour water over the ashes and collect the liquid that drips out of
the spout in a separate container. This liquid is the potash or lye.
Another way to get the lye is to pour the slurry (the mixture of
ashes and water) through a straining cloth.
- In a cooking pot, mix two parts grease to one part potash.
- Place this mixture over a fire and boil it until it thickens.
After the mixture—the soap—cools, you can use it in the semiliquid
state directly from the pot. You can also pour it into a pan, allow it to
harden, and cut it into bars for later use.
Keep Your Hands Clean
Germs on your hands can infect food and wounds. Wash your hands
after handling any material that is likely to carry germs, after visiting the latrine, after caring for the sick, and before handling any food, food
utensils, or drinking water. Keep your fingernails closely trimmed and
clean, and keep your fingers out of your mouth.
Keep Your Hair Clean
Your hair can become a haven for bacteria or fleas, lice, and other parasites.
Keeping your hair clean, combed, and trimmed helps you avoid this danger.
Keep Your Clothing Clean
Keep your clothing and bedding as clean as possible to reduce the
chance of skin infection as well as to decrease the danger of parasitic
infestation. Clean your outer clothing whenever it becomes soiled. Wear
clean underclothing and socks each day. If water is scarce, “air” clean
your clothing by shaking, airing, and sunning it for 2 hours. If you are
using a sleeping bag, turn it inside out after each use, fluff it, and air it.
Keep Your Teeth Clean
Thoroughly clean your mouth and teeth with a toothbrush at least once
each day. If you don’t have a toothbrush, make a chewing stick. Find a
twig about 20 centimeters long and 1 centimeter wide. Chew one end of
the stick to separate the fibers. Now brush your teeth thoroughly. Another
way is to wrap a clean strip of cloth around your fingers and rub
your teeth with it to wipe away food particles. You can also brush your
teeth with small amounts of sand, baking soda, salt, or soap. Then rinse
your mouth with water, salt water, or willow bark tea. Also, flossing your
teeth with string or fiber helps oral hygiene.
If you have cavities, you can make temporary fillings by placing candle
wax, tobacco, aspirin, hot pepper, tooth paste or powder, or portions of
a ginger root into the cavity. Make sure you clean the cavity by rinsing
or picking the particles out of the cavity before placing a filling in the
Take Care of Your Feet
To prevent serious foot problems, break in your shoes before wearing
them on any mission. Wash and massage your feet daily. Trim your toenails
straight across. Wear an insole and the proper size of dry socks.
Powder and check your feet daily for blisters.
If you get a small blister, do not open it. An intact blister is safe from
infection. Apply a padding material around the blister to relieve pressure
and reduce friction. If the blister bursts, treat it as an open wound.
Clean and dress it daily and pad around it. Leave large blisters intact. To
avoid having the blister burst or tear under pressure and cause a painful
and open sore, do the following:
-Obtain a sewing-type needle and a clean or sterilized thread.
Run the needle and thread through the blister after cleaning the
- Detach the needle and leave both ends of the thread hanging out of
the blister. The thread will absorb the liquid inside. This reduces the
size of the hole and ensures that the hole does not close up.
- Pad around the blister.
Get Sufficient Rest
You need a certain amount of rest to keep going. Plan for regular
rest periods of at least 10 minutes per hour during your daily activities.
Learn to make yourself comfortable under less than ideal conditions. A
change from mental to physical activity or vice versa can be refreshing
when time or situation does not permit total relaxation.
Keep Camp Site Clean
Do not soil the ground in the camp site area with urine or feces. Use
latrines, if available. When latrines are not available, dig “cat holes” and
cover the waste. Collect drinking water upstream from the camp site.
Purify all water.