Preventable frostbite due to cold pack.

Dear Editors, It is convenient to use a commercial cooling device for treatment of acute athletic injuries. However, secondary injuries may develop with improper application (1). We present a patient with unusual frostbite due to cold pack. An 18-year-old woman had right quadriceps femoris muscle strain while practicing long jump. She directly applied and fixed a commercial cold pack manufactured by Subaru Industry (Tokyo, Japan) for about 20 minutes. The following day, she noticed a painful bulla at the site of application and visited the Department of Dermatology. At the initial physical examination, a bulla with ulceration on her right thigh was noted (Figure 1). Topical application of Alprostadil Alfadex (Ono Pharmaceutical Co., Ltd., Osaka, Japan) ointment resulted in epithelialisation after a week. Ice application is a widely accepted treatment of acute athletic injuries. In addition, repeated cold applications for 24 to 48 hours with each application lasting from 10 to 30 minutes are generally recommended (2). A cold pack, which comprises ammonium nitrate and water, produces rapid cooling. According to the company, the surface on the cooling pack reaches about −5◦C to −10◦C approximately for 5 minutes and gradually warms up to 10◦C after 60 to 90 minutes at room temperature. Therefore, the temperature of this cooling pack is too cold and can cause frostbite if it is applied directly to the skin. In cold weather, protecting extremities by clothing is useful to prevent frostbite (3). Similarly, it should be recommended to use this cooling pack wrapped in a towel. A cold pack is useful, but it can cause secondary injuries such as frostbite if used improperly. Because primary care of acute athletic injuries is self-provided, such as in this patient, or by another athlete nearby rather than by medical specialists, it is important to provide appropriate instructions for cold application treatment to prevent frostbite. Figure 1 Frostbite on right thigh.