Sprained ankles, strained ("pulled") muscles, broken bones and bruised muscles are accompanied by swelling. Swelling interferes with healing, so anything that will prevent or reduce swelling should help the victim recover from an injury more quickly.
The sooner you attend to swelling after an injury the better. The best approach is to apply cold to the injured area right away. Cold shrinks the blood vessels, which reduces bleeding in the area and helps to prevent swelling. It also helps prevent the muscles from going into spasm and relieves pain.
The use of cold as a treatment goes back centuries. Today, methods of applying cold are more advanced, but the principles and the need for precautions are the same. When you apply cold, the skin will initially feel cold, often followed by relief of pain from the injury. As icing progresses, the victim will feel a burning sensation, then pain in the skin and finally numbness.
To avoid skin damage, stop when the skin begins to feel numb. Applying too much cold for too long can cause frostbite or even nerve damage.
Cold treatment is not for everyone. Those who are very sensitive to cold will not be able to tolerate icing long enough to do any good. People with problems in the blood vessels near the skin should avoid cold applications, especially those with Raynaud's phenomenon (a condition in which the blood vessels in the fingers, toes, ears and nose constrict dramatically when exposed to cold).
The length of time you apply cold will vary depending on the method and location of the injury. Areas with little body fat (like the knee, ankle and elbow) do not tolerate cold as well as fatty areas (like the thigh and buttocks). For the bonier areas, keep to the low end of the recommended application ranges listed below. For best results, apply cold at regular intervals throughout the waking hours of the day, allowing a few hours between treatments. Time off will keep cooling effects from accumulating and will allow the skin to return to normal temperature. An ice bag is the best method for most people, but there are several alternatives.
Ice bags
Ice bags are the old standby for applying deep, penetrating cold. Fill a bag made of thick plastic, rubber or waterproof fabric with ice. If you use a regular plastic food bag, place a wet, thin towel (like a dish towel) between the bag and the skin.
The bag will mold better around the injury site if the bag is not filled completely with ice or if crushed ice is used. An interesting alternative is using a bag of frozen peas or corn. Apply cold for 10 to 30 minutes, depending upon the amount of fat in the area.
Chemical cold bags
Chemical cold bags stay at air temperature until squeezing the bag and mixing the chemicals produces cold. They work well in the wilderness where ice is usually unavailable except from snow.
The chemical action does not produce a great amount of cold. Nevertheless, the bags provide a good first aid approach. Because the temperature is not very low, a 30-minute application should not be a problem, and the bag can be applied directly to the skin.
Immersion
Immersion means placing the foot, hand or elbow in icy water filled with crushed ice or ice cubes. However, some injured parts do not lend themselves to immersion because too much of the uninjured area is exposed to cold or the area cannot be immersed well. Ten to 20 minutes is the suggested immersion time.
Ice massage
Ice massage involves rubbing ice on the bare skin with a circular motion. It is easy to apply and focuses the cold on the injured area. A useful approach is to fill a paper or foam cup with water and freeze it until needed. Then peel away the top to reveal the ice and hold the bottom of the cup to apply. Ice cubes or cups can also be used.
The cold tends not to penetrate as deeply nor last as long as the methods described above. When applying to bony areas such as the ankle, apply for only seven to 10 minutes. Double the time when applying to fatty areas such as the thigh.
Whichever method is used, remember to ice early and ice often. Avoid harmful effects like frostbite by letting the skin recover between cold applications.