FRICTION BLISTERS - PATHOPHYSIOLOGY, PREVENTION AND TREATMENT

Blisters occur frequently, especially in vigorously active populations. Studies using repetitive rubbing techniques show that blisters result from frictional forces that mechanically separate epidermal cells at the level of the stratum spinosum. Hydrostatic pressure causes the area of the separation to fill with a fluid that is similar in composition to plasma but has a lower protein level. About 6 hours after formation of the blister, cells in the blister base begin to take up amino acids and nucleosides; at 24 hours, there is high mitotic activity in the basal cells; at 48 and 120 hours, new stratum granulosum and stratum corneum, respectively, can be seen. The magnitude of frictional forces (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 increases F-f, but very dry or very wet skin decreases F-f. Blisters are more 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 locomotion both appear to increase the likelihood of foot blisters. Antiperspirants with emollients and drying powders applied to the foot do not appear to decrease the probability of friction blisters. There is some evidence that foot blister incidence can be reduced by closed cell neoprene insoles. Wearing foot socks composed of acrylic results in fewer foot blisters in runners. A thin polyester sock, combined with a thick wool or polypropylene sock that maintains its bulk when exposed to sweat and compression, reduces blister incidence in Marine recruits. Recent exposure of the skin to repeated low intensity F-f results in a number of adaptations including cellular proliferation and epidermal thickening, which may reduce the likelihood of blisters. More well-designed studies are necessary to determine which prevention strategies actually decrease blister probability. Clinical experience suggests draining intact blisters and maintaining the blister roof results in the least patient discomfort and may reduce the possibility of secondary infection. Treating deroofed blisters with hydrocolloid dressings provides pain relief and may allow patients to continue physical activity if necessary. There is no evidence that antibiotics influence blister healing. Clinical trials are needed to determine the efficacy of various blister treatment methods. Considering the pervasive nature of friction blisters, there is a substantial amount of basic and applied research that remains to be performed, especially in the areas of prevention and treatment.