Skiers, ice-skaters, joggers, mountain climbers and outdoor enthusiasts are all prone to cold-related skin injuries. Local cold injuries occur when the core (consisting of internal structures such as the brain, heart, lungs and abdominal organs) temperature is maintained but the shell (skin, muscles and extremities) temperature dramatically decreases. The feet are among the most commonly affected body parts with these local cold injuries. Duration of the exposure, the temperature to which the skin has been exposed and the wind velocity are the three most important factors to consider when determining the severity of a local cold injury. The most common types of local cold injuries include frostnip, chilblains, trench (or immersion) foot and frostbite. Frostnip, the most common cold-induced skin disorder in athletes, is a slow-developing condition that results in blanching or whiteness of the skin. It is usually associated with the reversible formation of ice crystals on the skin’s surface. Frostnip usually develops painlessly and affects the tips of the ears, nose, cheeks, chin, fingertips and toes. It often occurs in conditions of high wind, extreme cold or both. The affected athlete often does not notice it and frequently a companion first perceives it. There is usually no permanent tissue damage and it can be treated effectively by the firm, steady pressure of a warm hand. The skin should not be rubbed with snow. This old folklore treatment can actually result in more damage to the tissue. As the tissue gradually warms and thaws out, the color returns and the athlete may experience tingling in that body part. The skin may continue to be red for several days after the tissue is warmed. There may also be some flaking and peeling of the skin. Recognizing And Treating Chilblains And Trench Foot Chilblains and trench (or immersion) foot are commonly grouped together. Trench foot usually refers to the lower extremity, while chilblains can affect either the hands or feet. The etiology of this condition is either the repeated exposure of skin to cold water or the presence of wet extremities for prolonged periods at a temperature near freezing. Initially, this condition damages the capillaries of the skin. With further progression of the injury, necrosis or gangrene of the skin, underlying muscles, nerves and other associated tissues occurs. This can lead to swollen, cold, pale, numb skin and progresses to mottled skin with a pale or grayish blue tint. The initial symptom is tingling or burning. The extremity may also feel cold and numb. Upon rewarming of the affected body part, there is a typical sequence of events. The skin first becomes red, swollen and hot. Areas of increased burning and itchy sensations develop. The skin may then blister or develop localized gangrene or both. Recurrence of this injury tends to happen in the same area of the body and there may be permanent hypersensitivity to cold and paresthesias in the affected skin. These sequelae are probably the result of permanent injury to the peripheral vascular and nervous system. The treatment for this condition is to remove the wet, cold clothing and footgear and gently re-warm the extremity, maintaining good local hygiene and applying a warm, dry covering. The re-warming should take place in an appropriate environment where there will not be re-exposure to the cold. There is no effective treatment once permanent skin injury has occurred. Therefore, all treatment should be geared to prevent initial occurrence and to protect the area once re-warming has occurred. How To Identify The Varying Degrees Of Frostbite Frostbite represents the worst of the local cold-related injuries and usually involves the hands and feet. It is caused by the actual freezing of the soft tissue. The danger of frostbite must be considered very strongly whenever there is exposure to extreme cold. Frostbite can be classified into four stages based on the degree of injury. First-degree frostbite produces white patches on the skin surface. It is often painless and there is numbness of the affected area. There is no tissue loss, but sometimes edema occurs if it is not treated immediately. Second-degree frostbite occurs when the white patch is not caught in time. Persistent cold, pale skin that does not blanch with pressure is a common sign. You may see vesiculation or blistering with surrounding edema and erythema. The blisters are usually clear. If the patient has minor tissue loss, then recovery from these blisters is the same (over the next few weeks with reepithelialization) as if they occurred from friction or burning. Caution the patient that these same tissues may be more vulnerable to re-frosting for the next few months. If any numbness occurs that does not clear in a few hours, then deeper tissue damage may have resulted, and these tissues might be more vulnerable to cold injury for the next several years. In cases of third-degree frostbite, the blisters are larger, deeper and purplish with blood. The swelling and redness of the surrounding tissues can be quite dramatic. There is a high probability of deep tissue injury and some permanent loss. If there is little tissue loss, there will still be prolonged numbness of the area and vulnerability to cold injury for years to life. In some cases, the swelling and blistering can appear severe, yet there is no tissue loss and full recovery. Early appearances can sometimes be deceiving. Fourth-degree frostbite involves the deep soft tissues including bone and can result in mummification of the tissues and the need for amputation. Clarifying Appropriate Treatment For Frostbite The treatment of frostbite is divided into pre-hospital care, immediate care (thawing) and post-thaw care. You should direct your treatment toward preventing further injury to the tissue and deterring the necrosis of any damaged tissue. The rubbing or massaging of frostbitten tissues is strongly contraindicated because it may lead to further damage. (It is strongly recommended not to thaw the frostbitten parts while still in the field unless there is a mechanism available to keep them thawed. If the frostbitten part is thawed and then allowed to refreeze, there is a greater risk of more extensive damage.) The accepted therapy for frostbite is rapid re-warming. In this situation, a whirlpool is ideal. The temperature of the water should be between 104 to 108ºF (40 to 42ºC) with thermometer control, making sure it does not become too hot. The temperature must be checked continually since immersing the cold extremity causes loss of heat. The container should be large enough so that neither the extremity nor the athlete touches the sides. Continue to emphasize re-warming until the frozen area is deep red or bluish in color. The athlete’s body temperature can be maintained with warm drinks. Depending on the extent of the frostbite and the penetration into deeper tissues, thawing can take from 30 to 45 minutes. Upon re-warming of the frostbitten body part, the athlete will experience pain proportional to the degree of frostbite injury. An analgesic may be required to help deal with the pain. Once the body part has been re-warmed and blood flow returns, the injured tissue may appear mottled, blue or purple. There may also be swelling, resulting in large blisters or gangrenous areas several days after treatment. These blisters eventually form blackened, necrotic areas of tissue that are easily separated from the normal skin. The new skin is usually of poorer quality than the original and is very sensitive to cold. What About Post-Thaw Therapy? Management of frostbite injuries after thawing should be of a protective nature. Protect the skin with soft, sterile bandages and emphasize judicious use of topical or systemic antibiotics. Blisters should be left intact when possible, but be aware that debridement may be required after the patient has arrived at your facility. The inflammatory cascade can be inhibited by ibuprofen and aloe vera cream. You should administer tetanus toxoid to all frostbite patients. Emphasize to patients that they should protect the involved skin from prolonged contact by either elevating the limb or employing a protective cradle around the limb to prevent any pressure. Implore them to perform range of motion exercises in order to prevent stiffness of the involved joints and loss of function. For More Severe Cases Of Frostbite … Patients who have frostbite injuries that are greater than first degree should be observed in a hospital. It is difficult to assess viability accurately from the initial gross appearance of the damaged part. You should observe such injuries over time, especially when you’re considering the possibility of amputation. You should delay amputation as long as possible — sometimes weeks to months — in order to determine which tissues are truly necrotic and which are salvageable. Triple-phase bone scanning has been used to define the extent of fatally damaged tissues in an attempt to allow for early debridement and wound closure. It is recommended that you perform the bone scan close to day two for all patients who present with lesions extending proximally to include the entirety of one or more phalanges. In the case of severe sepsis, the results of the first bone scan can serve as an indication for emergency amputation. You should perform a second bone scan close to day eight if there is an area of low or absent uptake on the first bone scan. This can provide valuable information on the efficacy of treatment. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) can also provide valuable information for early intervention in cases of severe frostbite. The use of pentoxifylline to minimize tissue damage in the treatment of frostbite has also been recommended. The suggested dosage of pentoxifylline in controlled release tablet form is one 400 mg tablet three times a day with meals. The duration of treatment should be from two to six weeks. Final Thoughts Ultimately, the best way to treat frostbite is prevention. This requires awareness of not only the actual temperature but also the windchill factor (see chart above). Athletes should dress in layers, which allows sweat to evaporate and protects against the cold. Wool, Gore-Tex and lycra are excellent materials to wear. Cotton is the worst. It will actually retain lots of moisture and facilitate heat loss due to convection. It is also important to keep clothing and the inner surface of shoe gear dry in order to avert subsequent chilling from moisture next to the body. If an athlete feels that his or her body part is getting cold, he or she should move it continually, being careful not to keep it in one position for a long time. Jumping up and down and jogging in place are good sideline exercises. Adequate nutrition and hydration status are also essential. Dr. Caselli (pictured) is Vice-President of the greater New York Regional Chapter of the American College of Sports Medicine and is a Professor in the Dept. of Orthopedic Sciences at New York College of Podiatric Medicine.
References 1. Allen ME. Environmental concerns: hypothermia and frostbite. In Sallis RE, Massimino F (eds). ACSM’s Essentials of Sports Medicine. St. Louis, Mosby, 1997. pp. 134-140. 2. Athletic Training and Sports Medicine. Rosemont, IL, American Academy of Orthopedic Surgeons, 1991. pp. 849-867. 3. Barker JR, Haws MJ, Brown RI, Kucan JO, Moore WD. Magnetic resonance imaging of severe frostbite injuries. Ann Plast Surg, 1997 Mar; 38(3): 275-9. 4. Barker TA, Motz HA, Gersoff WK. Environmental factors in athletic performance. In Fu FH, Stone DA (eds). Sports Injuries. Philadelphia, Lippincott Williams & Wilkins, 2001. pp. 66-76. 5. Cauchy E, Chetaille E, Lefevre M, Kerelou E, Marsigny B. The role of bone scanning in severe frostbite of the extremeties: a retrospective study of 88 cases. Eur J Nucl Med, 2000 May; 27(5): 497-502. 6. Cauchy E, Marsigny B, Allamel G, Verhellen R, Chetaille E. The value of technetium 99 scintigraphy in the prognosis of amputation in severe frostbite injuries of the extremities: a retrospective study of 92 severe frostbite injuries. J Hand Surg (Am) 2000 Sep; 25(5): 969-78. 7. Flegel M. Sport First Aid. Champaign, IL, Human Kinetics Publishers, Inc., 1992. pp. 105-113. 8. Greenwald D, Cooper B, Gottlieb L. An algorithm for early aggressive treatment of frostbite with limb salvage directed by triple-phase scanning. Plast Reconstr Surg 1998 Sep; 102(4): 1069-74. 9. Hayes DW, Mandracchia VJ, Considine C, Webb GE. Pentoxifylline. Adjunctive therapy in the treatment of pedal frostbite. Clin Podiatr Med Surg 2000 Oct; 17(4): 715-22. 10. Purkayastha SS, Roy A, Chauhan SK, Verma SS, Selvamurthy W. Efficacy of pentoxifylline with aspirin in the treatment of frostbite in rats. Indian J Med Res 1998 May; 107: 239-45. 11. Rintamaki H. Predisposing factors and prevention of frostbite. Int J Circumpolar Health 2000 Apr; 59(2): 114-21.