Microangiopathy of the skin has been recognized as an important factor in the development of skin diseases connected with chronic venous insufficiency (CVI). Here the relationship between postcapillary transmural pressure and precapillary vaso-constriction - we call it the postural feedback system - was examined in venous ulcers (n = 12) and compared to blood flow regulation in the inner ankle area of healthy controls (n = 12). Blood flow changes were measured by laser Doppler fluxmetry. Changes in the laser Doppler flux (LDF) minus the biological zero value were measured after 3 min of arterial occlusion, during 3 min of venous occlusion, while the leg was elevated and while it was lowered and expressed relative to the pretest resting value. In venous ulcers the LDF remained nearly unchanged after arterial occlusion (3 vs. 190%, p < 0.001), leg elevation caused an LDF decrease contrary to what was seen in the controls (-17 vs. +80%, p < 0.001), in the lowered leg an LDF decrease was found (-51 vs. -65%) and venous occlusion led to a profound reduction of flux (-78 vs. -84%). In severe CVI the precapillary arterioles seem to be dilated even with the leg at heart level. This finding means that the postural feedback system under resting conditions is upregulated, and 'luxus' hyperperfusion results. The upregulated postural feedback system contributes to the cutaneous microangiopathy due to chronic venous congestion.

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A new apparatus for non-invasive positioning of laser Doppler flux (LDF) probes in skin areas where local attachment is impossible.

BACKGROUND/AIMS: Laser Doppler flux (LDF) measurements are used in various medical fields, e.g. in the evaluation of microangiopathy. LDF measurements can be performed on unaltered skin as well as in wounds or skin flaps to measure blood flow properties under different conditions. In day-to-day practice, it is often difficult to carry out LDF measurements in the mentioned areas because a probe cannot be fixed accurately on a sterile wound or in an ulcer. The inadequacy of the peripheral equipment presently available for such potentially significant areas of application contrasts with the high technological standard of laser Doppler fluxmetry touted by the manufacturers. CONCLUSION: We have developed a completely new tripod probe holder (Pat. pending) for both standard and special probes. This new probe holder allows measurements without touching the surface by fixing the holder in remote distance to the area measured. Even in wounds or other critical areas as skin flaps LDF measurements can be performed. The construction and possible applications of this novel peripheral device will be discussed.

Blood Flow Velocity↗