A study of uniaxial tension on the superficial dermal microvasculature.

A spring-loaded apparatus was designed to apply uniaxial tension to forearm skin in 17 human subjects--10 normals, 6 psoriatics, and 1 patient with scleroderma. Simultaneously, the effects of stretching on the upper dermal vasculature were observed stereomicroscopically. Progressive changes (collapse) in the superficial microvasculature--vertical capillary loops and horizontal subpapillary plexus--with increasing tension were photographed. Force and strains were recorded at the points of disappearance of virtually all vessels. An average force of 11.9 newtons (N), accompanied by a mean strain of 10.3%, resulted in occlusion of all vessels. A much higher force (18.5 N) was necessary to occlude blood flow in the 1 patient with scleroderma. In summary, we have described a new technique for the study of mechanical forces on the blood supply of the epidermis. The data have shown that uniaxial tension has important effects on the superficial dermal microvasculature, resulting in impedance and obliteration of blood flow at relatively low magnitudes.