UNITED STATES MARINE CORPS
Field Medical Training Battalion
Camp Lejeune
FMST 1404
Manage
Environmental Cold Injuries
TERMINAL LEARNING
OBJECTIVES
1. Given
a casualty in a combat environment and standard field medical equipment and
supplies, manage environmental cold injuries, to prevent further injury
or death. (FMST-HSS-1404)
ENABLING LEARNING
OBJECTIVES
1. Without
the aid of references, given a description or list, identify the
predisposing factors associated with cold injuries, per the student handout.
(FMST-HSS-1404a)
2. Without the aid of references, given a list of
symptoms, identify the types of cold injury, per the student handout.
(FMST-HSS-1404b)
3. Without the aid of references, given a list of
symptoms, identify the stages of hypothermia, related to decreasing core
temperature, per the student handout. (FMST-HSS-1404c)
4. Without the aid of references, given a
description or list, identify the proper treatment for cold injuries, per the
student handout. (FMST-HSS-1404d)
5. Without the aid of references, given a list,
identify preventive measures for cold injuries, per the student handout.
(FMST-HSS-1404e)
6. Without the aid of references, given a
simulated cold casualty and standard field medical equipment and supplies,
manage environmental cold casualties, per the student handout. (FMST-HSS-1404f)
1.
OVERVIEW
Throughout history the most celebrated and extreme reports of cold related
injuries have been in the field of military endeavors. From Hannibal losing
half of his 46,000-man army crossing the Pyrenean Alps to frostbite and
hypothermia, and the tens of thousands of cases of trench foot during World War
I, we have learned much. Mild to severe cold weather conditions caused 13,970
unintentional hypothermia related deaths in the US between 1978 and 1998, with
6,857 of these deaths occurring in persons 65 years of age or older. When
adjusted for age, death from hypothermia occurred approximately 2.5 times more
often in men than women. Cold injury is defined as tissue injury produced by
exposure to cold. Cold itself is not the only factor in determining whether
injury will occur. Duration of exposure, humidity, wind, altitude, clothing,
medical conditions, behavior, and individual variability all contribute to the
injury. Cold injuries can occur at nonfreezing and freezing temperatures.
Pathologically, all cold injuries are similar. Trench foot, frostbite, and
hypothermia are the cold injuries of greatest military significance.
2. DEHYDRATION
Dehydration occurs very easily
in the cold, particularly with increased physical activity. As with exposure to
heat, adherence to proper fluid hydration while working in cold environments is
necessary to minimize dehydration and the associated physical fatigue and
cognitive changes. Refer to the lesson on dehydration for more information.
3. PREDISPOSING
FACTORS
Host
Factors
Previous Cold Injury
Persons with previous cold
injury, especially recent injuries, are at higher risk for subsequent cold
injury. Individuals more sensitive to the cold should take actions to
protect themselves.
Fatigue
Slow metabolic rate and inability to increase physical activity puts poorly
conditioned personnel at increased risk. Mental and physical fatigue may
cause apathy, leading to neglect of cold weather protection principles.
Age/Rank
Most cold injuries are suffered by military personnel from 17-25 years of age.
The exact reason is unknown although these troops are generally “front line”
troops who experience more exposure and are generally less experienced dealing
with the cold. Decreased incidence of cold injury among higher ranks is a
reflection of a combination of experience, less exposure, and receptivity to
training.
Discipline, Training,
Experience
Well-trained and disciplined personnel are better able to care for themselves
through personal hygiene, care of the feet, changing clothing, and other simple,
effective preventive measures.
Psychological Factors
Personality and motivation are
significant in determining adaptability. In intense cold, such as -25° F,
the mind, as well as the body, is adversely affected. An individual becomes
numb and indifferent to nonessential tasks. Essential tasks require more
time to complete and are more difficult to accomplish. Combat anxiety,
which produces immobility, disorganization, and carelessness, coupled with
sweating and vasoconstriction in the extremities can predispose a Marine to
cold injury.
Try to develop a positive attitude
toward the cold and the situation in general. Also, develop a degree of mental
discipline to ensure unquestioning ability to follow orders.
Race/Geograph ic
Origin
Military studies suggest that
dark-skinned soldiers and those from warmer regions are more susceptible to
cold injuries. This relationship in race and cold is related to the greater
susceptibility of pigmented cells to freeze compared with non-pigmented
cells. However, with proper training and experience, a Sailor or Marine can
compensate or overcome this predisposition.
Nutrition
Poor nutrition or incomplete
meals contribute to cold injury. During cold weather operations, encourage
personnel to eat well-balanced meals (MRE’s or cold weather rations).
Other Injuries
Injuries resulting in
significant blood loss or shock reduce effective circulation to extremities
and predispose a patient to a cold injury. Injuries that make patients
immobile also lead to cold injuries.
Drugs
and Medications
Medications that cause
vasoconstriction, increase urinary output, or produce sweating should be
avoided. Tobacco and caffeine products (tea/coffee) cause vasoconstriction
and poor circulation. Alcohol is a vasodilator, and because of its
anesthetic effects, intoxicated subjects neither feel the cold nor respond
to it appropriately.
4. CONTRIBUTING
FACTORS
Environmental Factors
- weather and temperature are predominant factors and will modify the rate of
body heat loss.
Temperature - freezing temperatures are not necessary for cold injury.
Of the 428 cases of hypothermia in one year, 69 were in Florida.
Humidity - effects rate of freezing and nonfreezing injuries
Precipitation
- increases rate of body heat loss
Wind
- greatly accelerates body heat loss
Activity
Too much or too
little activity may cause or contribute to cold injuries. Over activity
creates large amounts of heat loss through rapid and deep breathing, and
perspiration trapped in clothing reduces its insulating value. Conversely,
immobility causes decreased heat production with resultant cooling in the
extremities.
5. TYPES OF COLD
INJURIES
Chilblains (Pernio) - small skin lesions that are mild but
uncomfortable inflammatory lesions on skin that is exposed to damp,
nonfreezing ambient temperatures. The hands, ears, lower legs, and feet are
involved most commonly. They are more likely to develop in those with poor
peripheral circulation. Historically, it is not of major clinical
significance to military operations.
Cause
Exposure to air temperatures just above freezing
(more likely to occur in dry, cold areas with high humidity)
Symptoms
Usually occur several hours after exposure to cold
Appear as nodular plaques (patches on the skin)
Intense pruritus (itching)
Burning paresthesia (numbness)
Treatment
Supportive in nature
Gradually re-warm the exposed area at room
temperature
Wash and dry the affected area
Apply a dry, soft sterile bandage
Symptoms usually subside with elimination of cold
Snow Blindness
- the burning of the conjunctiva and superficial cells of the cornea by
ultraviolet light from exposure to bright reflections from snow.
Cause
Ultraviolet light - e xposure
to the sun's ultraviolet rays in conjunction with gray cloudy conditions,
whiteout snow conditions, or bright sunny conditions in a snow covered
environment.
Signs and Symptoms
Gritty sensation in the eyes
Pain
Increased lacrimation (tearing)
Photophobia
Blurred vision
Headache
Treatment
Prevent further ultraviolet
exposure (sunglasses). If no sunglasses are available, patch affected eye.
Oral analgesics (NSAIDS, but do
not put local analgesics into the eyes)
Do NOT put steroid medications
into the eye
CASEVAC as the operational
environment permits
Hypothermia
- condition in which the core body temperature is below 95°F. Hypothermia
renders a casualty unable to generate sufficient heat production to return to
homeostasis or normal bodily functions. Hypothermia can occur in environments
with temperatures well above freezing. Inadequate clothing and physical
exhaustion contribute to the loss of body heat and the development of
hypothermia.
Causes
Prolonged exposure to cold
and/or wet conditions
Inadequate clothing/protection
Dehydration and/or inadequate
nutrition
Poor physical condition - slow
metabolic rate and inability to increase physical activity puts the poorly
conditioned at increased risk.
Traumatic injuries -
resuscitation with cold fluids or blood can lead to hypothermia.
Alcohol and drugs - alcohol is a vasodilator, and because of its anesthetic
effects intoxicated subjects neither feel the cold nor respond to it
appropriately.
Signs and Symptoms (Stages of Hypothermia)
Shivering
- body’s main mechanism to generate heat. Shivering increases the metabolic
rate by increasing muscle tension, which leads to repeated bouts of muscular
contraction and relaxation. There is a wide range of individual differences at
which shivering starts and stops, but typically, shivering starts when the core
temperature is 94° to 97°
F (34.4°- 36°
C) and continues until the core temperature is 84°
to 88° F (29°-
31° C).
Mild Hypothermia - individual response to cold varies. In
general, body temperatures from 93° to
97° F constitute mild hypothermia. In
this temperature range, the casualty is in an excitation (responsive) stage.
The casualty will usually remain conscious, however, they may start to exercise
poor judgment or have irrational behavior. The body’s natural defense
mechanism, shivering, will eventually diminish. The body will attempt to retain
and generate heat by increasing heart rate, blood pressure, and cardiac output.
The respiratory rate will increase, which, in the long run, only cools the body
more by breathing in cold air and losing moisture through respirations.
Moderate Hypothermia - moderate hypothermia occurs when the core
temperature is between 86° and 92.9°
F. Cognitive abilities become more difficult and the patient becomes stuporous
and does not respond to painful stimuli. Shivering is replaced by progressive
muscular rigidity. In the initial excitation phase, heart rate, blood pressure,
and cardiac output all rise. With decreasing temperatures, these all decline.
The patient in this stage is at risk for lethal cardiac dysrhythmias.
Severe Hypothermia - when the core temperature is below 86°
F, the patient is in severe hypothermia. The casualty will be unconscious with
no response to pain. Vital signs will be barely detectable or non-detectable.
Without immediate and intensive treatment, this patient will die!
Treatment
“A patient is not dead until they are warm and dead.” This phrase was created
after many patients survived prolonged hypothermic events and received CPR in
the field. No matter what your initial impression of the casualty in the field,
do NOT withhold basic or advanced life support until core temperature has
returned to normal.
Maintain
ABC’s. If CPR is initiated, maintain extensive re-warming efforts to ensure
circulation of warm blood to the body’s core.
Move casualty to a warm shelter
to prevent further heat loss
Remove wet clothing if situation
allows
Loosen or remove constrictive
clothing
Warm,
moist air via boiling water or hot shower (inhalation is the fastest way to warm
the core)
Sleeping bag re-warming (place
patient in bag with 1 or 2 buddies)
Apply heating pads or packs
(groin/armpits/neck)
Warm water bath (water
temperature between 100 °F
and 108°F)
Hot, sweet drinks (if conscious)
Monitor vital signs. Observe
for cardiac abnormalities
Monitor core temperature
rectally
Warm IV solutions (Pre-warm solution in warm water or between MRE heaters)
|
Frostbite with blebs
Frostbite with edema and cyanosis
Early frostbite with ulcerations
Frostbite at 6 weeks with demarcation
Figure 1. Frostbite |
Frostbite
- actual freezing of tissue fluids in the skin and subcutaneous tissues. Ice
crystals form between and inside the cells with resulting tissue destruction
(see figure 1). The most susceptible body parts are those areas farthest from
the body’s core, such as the hands, fingers, feet, toes, and male genitalia.
Cause
Tissue does not freeze at 32°F because
cells contain electrolytes that prevent tissue from freezing until skin
temperature reaches approximately 28°F.
When the tissue does freeze, ice crystals form, they expand and cause damage to
surrounding tissue.
Depending upon wind velocity and air temperature, the exposure time necessary to
produce frostbite varies from a few minutes to several hours.
Classification and Signs and Symptoms of Frostbite - frostbite is
classified by depth of injury and clinical presentation. The degree of cold
injury, just like burn injuries, in many cases will not be known for at least 24
to 72 hours. The classification of frostbite injury is identical to burn
injuries. There are four degrees on injury based on physical findings.
Signs and Symptoms
First-Degree Frostbite
- a superficial injury limited to skin that has brief contact with cold air or
metal.
Skin appears red progressing to
white or yellowish plaque at site of injury
No blister
or tissue loss
Skin has
stinging and/or aching sensation progressing to numbness
Healing occurs in 7 – 10 days
Second-Degree Frostbite
- involves all the epidermis and superficial dermis.
Initially
appears similar to first-degree
Thawing is
rapid, which results in superficial skin blister that has clear or milky fluid
after several hours
Tissue
surrounding injury is red and edematous
No permanent
loss of tissue
Healing occurs in 3 to 4 weeks
Third-Degree Frostbite
- involves the epidermis and dermis layers and frozen skin is stiff with
restricted movement.
After
tissue thaws, skin swells leaving blood-filled blister, indicating vascular
trauma to deep tissue.
Skin loss
occurs slowly leading to mummification and sloughing of tissue
Healing is slow
Fourth-Degree Frostbite
- frozen tissue involves full thickness completely through dermis with muscle
and bone involvement.
No mobility to frozen tissue
and only passive movement when thawed
Poor skin perfusion
Blisters and edema do NOT
develop, will see early signs of necrotic tissue
Slow
mummification process will occur along with sloughing of tissue and
auto-amputation of nonviable tissue.
Treatment
Casualties with first and second-degree frostbite should be placed with the
affected area against a warm body surface, such as covering the casualty’s ears
with warm hands or placing affected fingers into armpits or groin region.
Treatment of casualties with deeper frostbite includes:
Move to
warm shelter and provide supportive care
Rapid
immersion of affected area into warm water
Cover with
loose, dry sterile dressing that is non-compressive and non-adherent
Do NOT
allow casualty to walk on affected feet
Fingers
and toes should be separated and protected with sterile cotton gauze
Do NOT
drain blisters in the field
Provide
pain meds as needed
Start IV
and give 250 mL bolus of warm saline to treat dehydration and reduce blood
viscosity
Do NOT
give alcohol or cigarettes because of their vasoconstrictive properties
Do NOT use
direct heat source greater than 102°F on the affected area
Do NOT
allow the thawed part to refreeze (when the injured site freezes, thaws, and
then refreezes, the second freezing causes a greater amount of severe
thrombosis, vascular damage, and tissue loss)
CASEVAC
ASAP
6. PREVENTION MEASURES
Education of
troops and leaders is number one preventive measure.
Activity Levels
Activity should be maintained at a steady,
constant rate.
Quick bursts of activity should be avoided.
Buddy System
Train personnel to observe each
other for symptoms.
Train personnel to re-warm extremities (fingers/toes) by holding (not rubbing)
their buddy’s hands/feet.
Personal Measures
- The Marine Corps uses the acronym “COLD” to describe the cold weather
protection principles and preventive measure:
C
- Keep clothing CLEAN and free of oil and dirt.
Oily and dirty clothing quickly looses its insulating effectiveness.
O
- Avoid OVERHEATING. There are more heat exhaustion
cases in a cold environment because of overdressing for the type of work
performed. Overdressing and over-exertion cause an increase in body heat
production and decrease heat dissipation. As the body temperature increases,
there is a corresponding increase in perspiration, which causes saturation of
clothes with sweat. Both conditions lead to cold injuries.
L
- LAYER correctly. Clothes should be loose to
trap air between the layers, which produces the insulating effect necessary for
survival in the cold. Tight and constricting clothing produces cold injuries.
There can be as many as seven layers of clothing used to protect personnel in a
cold environment.
D
-
Keep clothing DRY. If clothing becomes wet so
does the skin, which will promote cooling and frostbite. Change wet clothing at
the first opportunity.
REFERENCES
Wilderness Medicine 5th Ed., 2007, Chapter 5
Naval Preventive Medicine
Manual, P5010, Chapter 3
Pre-hospital Trauma Life Support, Military Edition 6th
Ed, Chapter 16
REV: July 2008
Cold Injuries Review
1. Explain the effect age and rank have on an
individual’s chance for developing hypothermia.
2.
Describe the symptoms for Chilblains.
3.
List three signs or symptoms of Moderate
Hypothermia.
4. Define the acronym C.O.L.D. |
