Title: Dynamics of Skin Microcirculation in Humans
Abstract: The human cutaneous microcirculation has so ar been studied by rather crude methods, such as plethsmography and l33Xn clearance. New sophisticated and noninvasive techniques are now available, with which the microcirculation of the skin can be continuously studied and measured for hours. With two such methods, i.e.,Laser-Doppler flowmetry and dynamic capillaroscopy, fast dynamic fluctuations of the microcirculation can be allowed. Under resting conditions, the total skin flow of small area (1–2 mm2) varies consistently with time, These variations are caused by the arterial pulse, but also by active vasomotion with a frequency of about 4–8 cy-les/min. These fluctuations can also be seen in single kin capillaries, but with a somewhat faster frequency: −10 cycles/min. The reaction of the cutaneous micro-circulation to provocation tests, such as postocclusive reactive hyperemia response and venous occlusion (50 mm Hg), can also be studied. The time to peak during postocclusive reactive hyperemia is very consistent. In response to venous congestion, capillary flow rate falls drastically, whereas Laser-Doppler flow is much less dramatically reduced. These discrepancies suggest that the Laser-Doppler flowmeter records blood flow in skin vessels in addition to the superficial, nutritional capillaries. The dynamic pattern of the skin microcirculation is altered in patients with hypertension, diabetes, and obstructive arterial disease.