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Cold Injury and HypothermiaTo 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. HEAT LOSSEvaporation (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. COLD INJURYInjury 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. FROSTBITE and FROSTNIPThis 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). FACTORS PREDISPOSING TO FROSTBITE1. Inadequate or poorly fitting clothing 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. NOTEFROSTBITE 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. HYPOTHERMIAHypothermia 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.
|  Hip Dislocation Hip Fracture Insect Stings and Spider Bites Human and Animal Bites Shoulder Injury Fracture Toxic Inhalations and Carbon Monoxide Poisoning Facial Injury Jaw Fracture and Dislocation Kidney Injury Knee Injury General Considerations Knee Injury Contusion Knee Injury Fracture Knee Injury Sprain Stab Wounds Leg Injury Fractures and Contusions Leg Injury Shin Splints Lightning Injury Oral and Tongue Injuries Nasal Fracture or Contusion Neck Injury General Considerations Neck Injury Fracture Neck Injury Spinal Cord Injury Pelvic Bone Fracture Puncture Wounds Chest Injury Rib Fracture Back Injury Sacrococcygeal Injury Scorpion Bites Abrasion Injuries Shoulder Injury Clavicle Fracture Shoulder Injury Strains and Sprains Snakebite Neck Injury Spinal Cord Injury Abdominal Injury Ruptured Spleen Foot Injury Toe Fracture and Sprain Vaginal or Vulvar Injury Drowning and Near Drowning |
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