FRICTION BLISTERS - PATHOPHYSIOLOGY, PREVENTION AND TREATMENT

Blisters occur frequently, especially in vigorously active populations . Studies using repetitive rubbing techniques show that blisters resul t from frictional forces that mechanically separate epidermal cells at the level of the stratum spinosum. Hydrostatic pressure causes the ar ea of the separation to fill with a fluid that is similar in compositi on to plasma but has a lower protein level. About 6 hours after format ion of the blister, cells in the blister base begin to take up amino a cids and nucleosides; at 24 hours, there is high mitotic activity in t he basal cells; at 48 and 120 hours, new stratum granulosum and stratu m corneum, respectively, can be seen. The magnitude of frictional forc es (F-f) and the number of times that an object cycles across the skin determine the probability of blister development - the higher the F-f , the fewer the cycles necessary to produce a blister. Moist skin incr eases F-f, but very dry or very wet skin decreases F-f. Blisters are m ore likely in skin areas that have a thick horny layer held tightly to underlying structures (e.g. palms of the hands or soles of the feet). More vigorous activity and the carrying of heavy loads during locomot ion both appear to increase the likelihood of foot blisters. Antipersp irants with emollients and drying powders applied to the foot do not a ppear to decrease the probability of friction blisters. There is some evidence that foot blister incidence can be reduced by closed cell neo prene insoles. Wearing foot socks composed of acrylic results in fewer foot blisters in runners. A thin polyester sock, combined with a thic k wool or polypropylene sock that maintains its bulk when exposed to s weat and compression, reduces blister incidence in Marine recruits. Re cent exposure of the skin to repeated low intensity F-f results in a n umber of adaptations including cellular proliferation and epidermal th ickening, which may reduce the likelihood of blisters. More well-desig ned studies are necessary to determine which prevention strategies act ually decrease blister probability. Clinical experience suggests drain ing intact blisters and maintaining the blister roof results in the le ast patient discomfort and may reduce the possibility of secondary inf ection. Treating deroofed blisters with hydrocolloid dressings provide s pain relief and may allow patients to continue physical activity if necessary. There is no evidence that antibiotics influence blister hea ling. Clinical trials are needed to determine the efficacy of various blister treatment methods. Considering the pervasive nature of frictio n blisters, there is a substantial amount of basic and applied researc h that remains to be performed, especially in the areas of prevention and treatment.