Skin trauma rapidly induces thermoregulatory plexus hyperemia, while an increased nutritive papillary capillary function can be detected after 24h.

Abstract

Clinical assessments and laser Doppler perfusion measurements (LDPM) of skin microcirculation have limited value, as they fail to capture events regulated by local metabolic needs at a papillary capillary level. This study aimed to examine the ability of computer-assisted video microscopy (CAVM) and diffuse reflectance spectroscopy (DRS) to assess skin nutritive perfusion-compared to LDPM. Healthy volunteers (n=10) were examined after (≈1 and ≈24h) an incision (5×1mm) on the forearm, at 0.1mm (only with CAVM), 2-3mm, and 30mm from the trauma. No changes were detected by CAVM after ≈1h. After ≈24h, 0-1mm from the trauma, both CAVM parameters were increased: functional capillary density (capillary crossings/mm, 11.8±1.4 vs. 7.3±1.2, p<.01) and capillary flow velocities (CFV, %capillaries with brisk flow, 10±6.8 vs. 1±1, p<.01). At a distance of 2-3mm, only CFV was increased (6.2±6.1 vs. 1±1, p<.05). DRS and LDPM measurements increased 2-3mm from the trauma line in relation to baseline after both ≈1 and ≈24h, that is, with DRS (%microvascular oxygen saturation): 45.8±7.4% (baseline), 70.0±12.5% (≈1h), and 73.1±10.4% (≈24h), p<.01 and with LDPM (a.u.): 7.2±2.5 (baseline), 28.3±18.7 (≈1h), and 45.9±16.3 (≈24h), p<.01. ≈24h after skin trauma, an increased function of the nutritive papillary capillaries can be detected by CAVM.