Microvascular remodeling following skin injury.

OBJECTIVE: The aim of this study was to describe possible remodeling (i.e., dilatation and elongation) of papillary capillaries induced by increased oxygen demand for the repair process following a skin wound. METHODS: Computer-assisted video microscopy was used to examine 10 healthy volunteers before (baseline) and after (≈1 h and ≈24 h) an incision (5 mm long and 1 mm deep) on the forearm, 0-1 mm and 30 mm (control site) from the incision. We defined categories from 0 (low) to 3 (high) to grade dilatation and elongation of the nutritive papillary capillaries, as well as the visibility of the superficial vascular plexus. Approximately 10 000 capillaries from 200 films were scored. RESULTS: The nutritive papillary capillaries were dilated and elongated (p < 0.01) after ≈24 h; that is, elongation (score 1.9 ± 0.9) vs baseline (score 0.9 ± 0.6), p < 0.01 and dilatation (score 2.2 ± 0.7) vs baseline (score 0.3 ± 0.3), p < 0.01. Superficial plexus visibility increased (p < 0.01) after ≈1 h (score 2.0 ± 0.7) and ≈24 h (score 2.7 ± 0.3) vs baseline (score 0.8 ± 0.4). CONCLUSION: The superficial vascular skin plexus showed enhanced visibility already ≈1 h after the skin trauma. Morphological remodeling in the nutritive papillary capillaries-dilatation and elongation after ≈24 h-facilitate increased O2  supply.

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

OBJECTIVE: 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. METHODS: Healthy volunteers (n = 10) were examined after (≈1 and ≈24 h) an incision (5 × 1 mm) on the forearm, at 0.1 mm (only with CAVM), 2-3 mm, and 30 mm from the trauma. RESULTS: No changes were detected by CAVM after ≈1 h. After ≈24 h, 0-1 mm 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 2-3 mm, only CFV was increased (6.2 ± 6.1 vs. 1 ± 1, p < .05). DRS and LDPM measurements increased 2-3 mm from the trauma line in relation to baseline after both ≈1 and ≈24 h, that is, with DRS (%microvascular oxygen saturation): 45.8 ± 7.4% (baseline), 70.0 ± 12.5% (≈1 h), and 73.1 ± 10.4% (≈24 h), p < .01 and with LDPM (a.u.): 7.2 ± 2.5 (baseline), 28.3 ± 18.7 (≈1 h), and 45.9 ± 16.3 (≈24 h), p < .01. CONCLUSIONS: ≈24 h after skin trauma, an increased function of the nutritive papillary capillaries can be detected by CAVM.