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HypothermiaHypothermia


Introduction

Dropping temperatures, wind chill, rain, sleet and snow… Cold weather conditions such as these can leave you feeling chilled to the bone. If your job

requires you to work in cold conditions, you need to be able to recognize the conditions that can lead to

hypothermia.


Introduction

Hypothermia is a temperature related disorder that occurs when exposure to cold causes a decrease in

your internal temperature so that your normal muscular and brain functions become impaired.


Introduction

Your best defense against hypothermia is to be prepared. Wear the appropriate clothing. Get adequate

food and rest. Avoid smoking, alcohol and caffeine during exposure to cold. Be able to recognize the

early warning signs of hypothermia, and know what to do if an emergency occurs.


What is Hypothermia?

While the average normal human temperature is about 98.6 degrees Fahrenheit, that temperature can vary

slightly from person to person. Your body is capable of maintaining an internal core temperature between 98.6 and 102.2 degrees Fahrenheit. When the body begins

to lose heat faster than it can produce it, your temperature begins to fall and hypothermia can occur.



Hypothermia is a cold temperature related disorder that occurs when exposure to cold causes a decrease in the core (heart, lungs, and other organs) temperature to a

level that leads to impairment of your normal muscular and brain functions.



Generally, hypothermia occurs at a core temperature of about 95 degrees Fahrenheit or below. In extreme cases, hypothermia can lead to loss of consciousness,

tissue damage, and even death.



This disorder is particularly dangerous because it affects your brain’s ability to function properly. You

lose your capacity for good judgement, reasoning, and mental clarity. You may not even be able to recognize

that you have symptoms!



There are many different variables that can lead to hypothermia. The primary factors include cold, wind,

and wetness. There are two main types of hypothermia: cold exposure and water immersion.

Causes of Hypothermia



Cold Exposure - Exposure to cold temperatures is an important factor in hypothermia, but it is not the only

factor. In fact, most hypothermia cases occur at temperatures between 30-50 degrees Fahrenheit.

Windchill is also an important factor.



For example, if the wind is calm but the temperature is -30 degrees Fahrenheit, exposed skin may freeze within one minute. But this may also happen if the wind speed is 10 MPH and temperature is -10 degrees Fahrenheit. When wetness is factored in, the effects of cold and

wind are even more chilling.



Water Immersion - Hypothermia due to water immersion, such as falling into a cold lake, is an even greater danger. The body cools up to 25 times faster

in water than in air. This rapid heat loss speeds up the hypothermia process and can result in death within

minutes.



Other factors that can contribute to hypothermia include:

Contributing Factors

•Age•Body Size•Physical Condition•Length of Exposure•Exhaustion•Hunger

•Dehydration•Certain illnesses•Some medications•Alcohol intake•Smoking•Improper clothing and equipment



It is difficult to identify a specific time frame for the onset and progression of hypothermia. One person may develop symptoms faster than another; that

same person may also progress through the stages of hypothermia much more quickly. There are a few

reasons for this:

Time Frame for Hypothermia


What is Hypothermia?Time Frame for Hypothermia

•Physical condition and mental attitude can affect the rate of core temperature drop. A person who is fit, doesn’t panic, and believes he will survive may experience a

slower drop in core temperature than someone who is not as physically and psychologically prepared.


What is Hypothermia?Time Frame for Hypothermia

•Environmental circumstances vary from one situation to another. For example, a water temperature of 70 degrees

Fahrenheit drains body heat faster than water at 80 degrees Fahrenheit. An air temperature of 50 degrees

Fahrenheit may be endurable, but with a 25 MPH wind and humidity it can be chilling.


How the Body Loses Heat

To better understand how hypothermia occurs, it is important to know how the body loses heat. There are

five different ways your body can lose heat to its surroundings:



When you breathe cold air into your lungs, it is warmed to body temperature. You lose heat to the

environment when you exhale the warm air outside of your lungs. You can reduce the heat loss

by covering your mouth and nose with a scarf or face mask.

Respiration


How the Body Loses HeatEvaporation

This type of heat loss occurs as the body becomes hot and you begin to sweat. As the perspiration

reaches the surface and evaporates from the skin, the body is cooled.


How the Body Loses HeatConduction

Heat loss can also occur when you touch a colder object. Heat from your body is transferred to that

object. An example would be touching cold equipment or sitting on the ground.



Radiation occurs when heat is radiated outward from your body to the environment. This can

happen when skin is left uncovered, especially the head, neck, and hands. Always wear the proper

clothing to prevent excess heat loss from radiation.

Radiation



Convection occurs when cool air or water move across the body. Body heat is transferred to the air or water, warming it. When the warm air or water

moves away from the body, the body then becomes cold.

Convection


How the Body Produces Heat

The human body can easily adjust to minor changes in temperature for short periods by activating its

thermoregulatory system. The thermoregulatory system is controlled by the brain, spinal cord, and a network of

nerves throughout the body that sense temperature.



The brain monitors the difference between the core(internal) temperature and the peripheral (skin and muscles) temperature. Messages are sent to the body’s two nervous systems: the somatic (voluntary) nervous

system and the autonomic (involuntary) nervous system.



The somatic, or voluntary, nervous system receives thought patterns that give you specific messages to

prevent heat loss. Examples of these messages might be to build a fire or put on more clothing. You then

decide if you will carry out those directions.

Voluntary Response to Cold



The automatic, or involuntary, nervous system controls the body’s internal organs and blood vessels

without our conscious knowledge. For example, if you fall into an icy pond the heart speeds up and

blood pressure increases. Two examples of how the body maintains or generates heat include:

Involuntary Response to Cold



This is the body’s involuntary contraction and expansion of muscles to increase heat production through friction.

Shivering

Reducing Blood Flow

The body reduces blood flow to the skin and limbs by constricting blood vessels. The purpose is to

reduce heat loss to the core - the brain, heart, lungs, and other body organs.


Before Hypothermia Begins

Mild shivering and cold hands and feet do not necessarily mean you are hypothermic. These are, however, early warning signs that you are losing more heat than you are producing. If you ignore

these signs, you will begin to experience the early stages of hypothermia.



You may start to feel tired. Your body’s metabolism increases to produce heat. This is noticed as heavier breathing and an increased pulse rate. Goose bumps appear. Goose bumps form to hold the hair follicles upright. This increases their ability to insulate and

protect the body from cold.

Early Warning Signs



Shivering begins, on and off, as your body temperature falls below 97 degrees Fahrenheit. At this point,

shivering can be overcome with an increase in physical activity.

Early Warning Signs



The body begins to reduce blood flow to the skin and limbs to reduce heat loss to the body’s core. Cold, white hands and feet are the first signs that this is

happening.

Early Warning Signs


Symptoms of Hypothermia

Hypothermia is generally believed to occur when the core temperature falls to 95 degrees Fahrenheit or

below. However, it is important to remember that not all victims experience symptoms at exactly the same

temperatures.



The response to cold varies depending on health, age, type of exposure, and physical fitness. Once

hypothermia begins, the symptoms progress steadily, from mild to severe unless treatment is received.



By identifying the symptoms, you can prevent the progression and decrease the severity of hypothermia.

Remember, a hypothermia victim may not realize what is happening.



Ignore any pleas to “leave me alone, I’m okay.” Because hypothermia affects the capacity for good judgement and mental clarity, you cannot rely on

what a victim tells you. Pay attention to the symptoms!



At this stage, the victim may appear alert and able to help himself or herself, but he or she is experiencing some mild confusion. Restricted blood flow to the

limbs causes a loss of dexterity in the fingers. Symptoms include:

Mild Hypothermia


Symptoms of Hypothermia•Uncontrolled, violent shivering

•Pain and discomfort in exposed parts•Muscles become tense

•Skin may be pale, numb, and waxy•Unable to perform complex tasks with hands (such as

buttoning your coat)•Poor muscle coordination

•Tendency to stumble•Movements become slower and less coordinated

•Difficulty in speech•Mild confusion; victim may appear dazed

•Tendency to become uncooperative or irritable



Severe hypothermia is generally believed to begin when the core temperature falls to about 91.4 degrees Fahrenheit. This stage includes conscious victims who

experience slurred speech, mental confusion and drowsiness to victims who may appear dead but are

still alive. Symptoms can include:

Severe Hypothermia


Symptoms of Hypothermia•Mental confusion

•May show signs of apathy or depression•Speech is slow, slurred, or vague

•Drowsiness or an overpowering desire to sleep•Sluggish thinking

•Signs of strange irrational behavior, such as undressing•Shivering slows and stops at about 90 degrees Fahrenheit

•Muscles become rigid•Fixed and dilated pupils

•Pulse rate slows significantly•Breathing slows, is shallow and erratic


Symptoms of Hypothermia•Cold, blue skin

•Eventually victim is unable to walk and may curl up in the fetal position to conserve heat.

•Between 89.6 and 87.8 degrees Fahrenheit the victim can become semi-comatose.

•Risk of ventricular fibrillation (irregular heartbeat) increases.

•At about 86 degrees Fahrenheit the victim can sink into a “metabolic icebox” state. You may not be able to

determine a pulse, and the victim may appear to be dead. •Eventually, cardiac arrest can occur.


Treatment

The treatment for hypothermia depends on the patient’s condition. Mildly hypothermic victims

who are conscious usually re-warm without complications once they are removed from the cold.

However, victims of severe hypothermia who are unconscious often give no indications of being

alive, but still may have vital signs.


Treatment

Never assume that an unconscious victim is dead; the vital signs may be so weak that you will not be

able to detect them, but the person can still be alive.


Treatment

•Encourage light physical activity to generate heat, such as moving the arms and legs or walking.

•Get the victim out of the elements to a dry, sheltered area.

•Remove any wet clothing and replace with dry layers.

•Wrap the person in a blanket. Make sure the head and neck are also covered.

Mild Hypothermia


Treatment

•Apply warm (NOT hot) hot pads, hot water bottles, or other objects behind the patients neck and under the

armpits.

•Provide a warm (about 110 degrees Fahrenheit) non-alcoholic, caffeine-free drink and some high energy food.

Mild Hypothermia


TreatmentSevere Hypothermia

It is always best to let the hospital re-warm a severely hypothermic person. But in some cases you may not have immediate access to a medical facility. In these

situations, there are some steps you can take to prevent further heat loss before medical treatment can

be received.



•If the victim is semi-conscious, try to keep him or her awake.

•Unconscious victims should be taken to the hospital for treatment as soon as possible. Hospitals have specialized

equipment that can detect vital signs, properly monitor the person, and control the re-warming process.



•Handle the victim as gently as possible. Rough handling, in extreme cases, can cause cardiac arrest. Keep the patient in

a horizontal position.

•Remove any wet clothing.

•Apply warm (NOT hot) heat packs or towels to the neck, armpits, sides, chest, and groin.



•Do not try to re-warm the patient in a hurry.

•Place the victim in blankets (or a sleeping bag, if available), making sure the blankets are under as well as

over the victim. Keep the head and neck covered.

•Exhale warm air near the person’s nose or mouth.



•Do NOT warm or rub the victim’s arms or legs. This may bring cold blood from the body’s surface to the core (heart

and lungs) and can cause a cardiac arrest.

•Do not give a victim of severe hypothermia who is semiconscious any liquids.

•Do NOT begin CPR unless you are absolutely sure the victim is in a state of cardiac arrest.


PreventionThe best prevention against hypothermia is to be

prepared. Your main goal is to prevent fatigue while remaining warm and dry.

Clothing

To dress properly for cold conditions, you need to understand that the higher the wind speed and the

lower the temperatures, the greater danger to exposed skin. For example, if the temperature is

-30 degrees Fahrenheit with no wind, exposed skin may freeze within one minute.


Prevention

This could also happen if the temperature is -10 degrees Fahrenheit with a wind speed of 10 MPH.

Clothing


Prevention•Wear several layers of clothing, rather than one bulky layer, so you can remove a layer when you become to

warm. The layer closest to your skin should be made of material that allows sweat to escape while keeping out

environmental moisture.

•Synthetic materials such as polypropylene and Gortex are good for this (cotton traps moisture). Wool is a good choice for the second layer because it can absorb much moisture

before it loses its ability to insulate. Wear waterproof, wind resistant clothing for the outer layer if you will be in wet

conditions.


Prevention•Do not wear clothing that is tight or constricts your

movements.

•Hands and feet are affected most during cold conditions. Wear well insulated gloves, mittens and boots. Wear two

layers of socks: a synthetic material under wool.

•Always keep your head and neck covered. Up to 50 percent of heat loss occurs through the head and neck! A

wool knit cap or a liner under a hard hat can greatly reduce heat loss.


Prevention

•Wet clothing increases heat loss. Replace wet layers as soon as possible. In very cold temperatures, changing

clothes can increase heat loss, so be careful. If you can’t change clothes indoors, the it may be better to just put on

more clothes on top of those you are already wearing.

•If possible, always bring an extra set of clothing with you in case your clothes become wet.

Keep Dry


Prevention

•Eat balanced meals with plenty of carbohydrates and drink plenty of fluids (non-alcoholic and caffeine-free) to

prevent dehydration.

•Avoid caffeine in cold weather. Caffeine is a diuretic; it causes increased urine production, which leads to increased

heat loss. It also causes dehydration.

•Avoid alcohol in cold weather. A common mistaken belief is that alcohol will keep you warm in cold weather. That is

NOT true. Alcohol dilates the blood vessels and causes blood to move away from the body’s core.

Food, Fluids & Fitness


Prevention

•Avoid nicotine and tobacco. They cause the blood vessels to constrict, increasing the risk of frostbite.

•Physical fitness and regular exercise can improve your tolerance to cold conditions.

Food, Fluids & Fitness


PreventionFrequent Breaks

•If you will be working in a cold environment, take frequent breaks to provide relief from the cold, and when

you experience uncontrolled shivering, increased perspiration, or feel numbness or pain in the extremities.

Know your physical limits.

Buddy System•Always try to work in pairs and rely on the “buddy

system” in cold environment. Be aware of any possible warning signs of hypothermia in your co-worker. If you notice any, get him or her indoors as soon as possible to

warm up.


PreventionCold Water Survival

•Always wear a personal floatation device (PFD) when you will be on the water. If you fall into cold water, the PFD

will help keep you afloat, allowing you to conserve some of your energy.

•Water safety experts recommend that persons in dangerously cold water should not swim or move around any more than necessary. Swimming and treading water consumes more energy, causes fatigue, and increases heat

loss.


PreventionCold Water Survival

•One position to use when in cold water is to draw your knees up, keeping your thighs together, and crossing your ankles. Keep your arms crossed close to your chest. This

position reduces heat loss.

•Try to keep your head out of the water as much as possible to prevent further heat loss.


Summit Training Source, Inc.

Contact us at:

1-800-842-0466

or at

[email protected]

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