Insight in Human Skin Microcirculation Using In Vivo Reflectance-Mode Confocal Laser Scanning Microscopy

Reflectance-mode confocal laser scanning microscopy allows in vivo imaging of the human skin. We hypothesized that this high-resolution technique enables observation of dynamic changes of the cutaneous microcirculation. Twenty-two volunteers were randomly divided in two groups. Group 1 was exposed to local heating and group 2 to local cold stress. Confocal microscopy was performed prior t0 (control), directly t1 and 5 min t2 after local temperature changes to evaluate quantitative blood cell flow, capillary loop diameter, and density of dermal capillaries. In group 1, blood flow increased at t1 (75.82 ± 2.86/min) and further at t2 (84.09 ± 3.39/min) compared to the control (61.09 ± 3.21/min). The control capillary size was 9.59 ± 0.25 μm, increased to 11.16 ± 0.21 μm (t1) and 11.57 ± 0.24 μm (t2). The dermal capillary density increased in t1 (7.26 ± 0.76/mm2) and t2 (8.16 ± 0.52/mm2), compared to the control (7.04 ± 0.62/mm2). In group 2, blood flow decreased at t1 (41.73 ± 2.61/min) and increased at t2 (83.27 ± 3.29/min) compared to the control (60.73 ± 2.90/min). The control capillary size was 9.55 ± 0.25 μm, decreased at t1 (7.78 ± 0.26 μm) and increased at t2 (11.38 ± 0.26 μm). Capillary density decreased at t1 (5.01 ± 0.49/mm2) and increased at t2 (7.28 ± 0.53/mm2) compared to the control (7.01 ± 0.52/mm2). Confocal microscopy is a sensitive and noninvasive imaging tool for characterizing and quantifying dynamic changes of cutaneous microcirculation on a histomorphological level.