Cold Injury and Hypothermia

To prevent hyperthermia the body must disperse >90% of the body heat produced daily as the result of metabolism and muscular activity; hypothermia occurs when the body loses more heat than it produces.


Evaporation (through sweating) accounts for 20-25% of heat loss depending on temperature, air motion, and relative humidity. Conduction normally accounts for 2% of heat loss, but can increase by a factor of five when in wet clothing. Conductive heat loss can increase 25 times when in cold water. Convection, refers to the loss of heat by the movement of air or water; cold running water convects heat 200 times faster than air. Heat loss through radiation depends on the temperature difference between the body and the environment and on exposed body surface area. Heat loss through radiation can account for as much as 70% of total heat loss under normal conditions.


Injury due to exposure to cold temperatures may be generalized, as in HYPOTHERMIA, or localized, as in FROSTBITE. Both of these problems will be discussed in this section. Cold injury can occur at temperatures above and below freezing.


This refers to a local cold injury caused by exposure to temperatures below freezing. FROSTNIP (what most children from the northern states endure several times a winter) is a condition in which the skin becomes blanched and numb. The LOSS OF COLD SENSATION is a sign of impending FROSTBITE which implies some permanent damage. Frostbite may be superficial or deep. In SUPERFICIAL frostbite, large clear blisters (blebs) will form over 24 to 48 hours. After the skin hardens, the fluid is "reabsorbed" by the body and the skin blackens to a tough layer. Over several weeks, this area of black tissue will eventually disappear, revealing "new" skin underneath that is quite tender and sensitive to hot or cold. It will eventually appear as normal skin but will always be MORE susceptible to frostbite. DEEP frostbite can involve underlying tissue, muscle, tendon, and bone. In cases of deeper injury, the skin blebs will often contain bloody fluid and tissue loss can be more extensive (see below).


1. Inadequate or poorly fitting clothing
2. Exposure to wind
3. Dampness
4. Contact with cold objects (e.g. fuel, metal)
5. Dehydration
6. Shock (prolonged low blood pressure)
7. Trauma
8. Atherosclerosis
9. Smoking
10. History of frostbite
11. Alcohol and other drugs of abuse
12. Fatigue
13. Acute mountain sickness
14. History of Raynaud's Disease

Treatment of FROSTNIP, unlike frostbite, may be done at the scene. The affected part may be warmed by hand (no rubbing) and breathing onto the injured site (into cupped hands). An alternate method is placement of the frostnipped hand under the armpit. Any question of frostbite injury should involve IMMEDIATE transport to a medical facility.

The rewarming of frostbitten tissue in the field should be avoided if the victim is within 2 hours of medical care. Great care must be taken if rewarming is instituted to avoid refreezing an injured area. Frostbitten areas should be rewarmed rapidly--optimally in water heated to a temperature of 104 to 108 degrees Fahrenheit. The use of water temperatures greater than 108 degrees Fahrenheit can be damaging. As the involved site rewarms, it will tingle and "burn," indicating the return of adequate circulation. The warm water bath should be continued for 15-30 minutes until thawing is complete and a maximal flushing (red) of the skin is seen. Pain medications are often necessary at this point. Deep frostbite injury will eventually lead to some shedding of dead tissue over the following weeks to months. Surgical removal of dead (mummified) tissue may be necessary and antibiotic therapy may be indicated for secondary bacterial infection of the frostbitten tissue. Injury to bone can often be assessed through the use of bone scanning. Nonviable bone will often require surgical amputation.


FROSTBITE should NEVER be treated by the victim at the scene. Use of a campfire (dry heat) is dangerous, as numbed tissue may become burned, adding to the injury. Also any refreezing of thawed frostbitten tissue will lead to an even greater injury.


Hypothermia refers to a generalized cold injury. It is defined as a core temperature (rectal temp) less than 35 degrees Celsius or 95 degrees Fahrenheit. The elderly, immobile, and those with altered sensorium (psychiatric patients) are at particular risk for this problem. It is interesting that the majority of cases of hypothermia occur at close to room temperature. Patients who are taking certain medications (sedatives and phenothiazines) are at particular risk for this problem.Hypothermia is a multisystem injury requiring EMERGENCY medical care. Patients are at risk for [life threatening] cardiac arrhythmia at body temps below 30 degrees Celsius (86 degrees Fahrenheit). Treatment is directed toward "active rewarming of the patient." Prognosis is generally good for uncomplicated hypothermia in the absence of cardiac arrest or associated illness. Recovery has been recorded in cases of core temperatures as low as 16 degrees Celsius (61 degrees Fahrenheit). Prolonged [cardiac arrest] resuscitations have been reported in patients with hypothermia after submersion in cold water for 3 hours.

12 Hip Dislocation
12 Hip Fracture
12 Insect Stings and Spider Bites
12 Human and Animal Bites
12 Shoulder Injury Fracture
12 Toxic Inhalations and Carbon Monoxide Poisoning
12 Facial Injury Jaw Fracture and Dislocation
12 Kidney Injury
12 Knee Injury General Considerations
12 Knee Injury Contusion
12 Knee Injury Fracture
12 Knee Injury Sprain
12 Stab Wounds
12 Leg Injury Fractures and Contusions
12 Leg Injury Shin Splints
12 Lightning Injury
12 Oral and Tongue Injuries
12 Nasal Fracture or Contusion
12 Neck Injury General Considerations
12 Neck Injury Fracture
12 Neck Injury Spinal Cord Injury
12 Pelvic Bone Fracture
12 Puncture Wounds
12 Chest Injury Rib Fracture
12 Back Injury Sacrococcygeal Injury
12 Scorpion Bites
12 Abrasion Injuries
12 Shoulder Injury Clavicle Fracture
12 Shoulder Injury Strains and Sprains
12 Snakebite
12 Neck Injury Spinal Cord Injury
12 Abdominal Injury Ruptured Spleen
12 Foot Injury Toe Fracture and Sprain
12 Vaginal or Vulvar Injury
12 Drowning and Near Drowning


Abdominal Injury
Abdominal Injury: Contusion
Animal Bites
Ankle Fracture
Ankle Injury
Ankle Injury: Contusion
Ankle Sprain
Back Injury
Back Injury : Sacrococcygeal Injury
Back Strain
Carbon Monoxide Poisoning
Chemical Burns
Chest Injuries
Chest Injury: Aortic Rupture
Chest Injury: Hemothorax
Chest Injury: Myocardial Contusion
Chest Injury : Pneumothorax
Chest Injury: Pulmonary Contusion
Chronic Back Pain
Clavicle Fracture
Compression Fractures
Decompression Sickness
Disc Disease
Gunshot Wounds
Hand Injury: Fingertip Amputations
Head Injury
Liver Injury
Marine Stings
Muscle Strains
Rib Fracture
Ruptured Spleen
Shoulder Injury: A-C Separation
Spider Bites
Spinal Cord Injury
Sternum Fracture
Testicular Injury
Wrist Injury
hi Scuba Related Injuries
i Hand Injury Finger Amputaion
de Lecerations
de Cold Injury and Hypothermia
dd Dental Injury
xs Facial Injury
sdf Neck Injury
e Shoulder Injury Dislocation
e Ear Injury
ed Elbow Injury
de Elbow Injury Fracture
dfe Elbow Injury Nursemaids
ee Electrical Injury
de Eye Injury
ed Facial Injury General Considerations
fr Facial Injury Contusion
ed Hand Injury Finger Sprains
ded Fingernail and Toenail Injuries
dd Hand Injury Fractures
23 Head Injury Skull Fracture and Concussion
44 Chest Injury Myocardial Contusion
fde Heat Illness
ed Hest Injury Hemothorax
y Back Injury Disc Disease
;l High Altitude Illness

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