Regional differences of vasodilatation and vasomotion response to local heating in human cutaneous microcirculation.

BACKGROUND: The aim of this study was to evaluate the vasodilatation and vasomotion response to local heating in the cutaneous microcirculation of the ankle, dorsum of foot and forearm. Recently, it has been suggested that this response differs between the forearm and the leg. PROBANDS AND METHODS: Twenty-nine young healthy adults were recruited. They underwent measurement by laser Doppler flowmetry (LDF) in three sites of the body (ankle, dorsum of foot, forearm). Percentage change of the median flow of the skin before and after provocation and normalised perfusion flow to maximal dilation (cutaneous vascular conductance--CVC % Max) during short provocation test were monitored. Spectral analysis of laser Doppler flowmetry signals was performed using the fast Fourier transform algorithm. RESULTS: Significant differences were found in CVC % Max between ankle/dorsum (45.18±6.38% Max vs. 51.24±6.87% Max, respectively; p<0.05) and between ankle/forearm (45.18±6.38% Max vs. 54.49±5.37% Max, respectively; p<0.05). Percentage change of flux after provocation has revealed significant differences between ankle/dorsum (394.1±204.5% vs. 577.4±273.5%, respectively; p<0.05) and ankle/forearm (394.1±204.5% vs. 637.1±324.7%, respectively; p<0.05). Total spectral activity of vasomotion has differed between ankle/dorsum and ankle/forearm: 69.59 [49.58-96.04] vs. 93.01 [73.15-121.8] (p<0.05) and 69.59 [49.58-96.04] vs. 107.5 [80.55-155.8] (p<0.05), respectively. CONCLUSIONS: Cutaneous microcirculation exhibits regional differences. Significant variability of function between ankle and dorsum of foot suggests that leg microcirculation is not uniform.

Healing process of venous ulcers: the role of microcirculation.

In order to describe adequately the process of healing in the intermediate degrees, we investigated microcirculatory changes in the venous ulcers at well-defined stages of wound repair. We investigated dynamic changes in microcirculation during the healing process of venous ulcers. Ten venous ulcers were investigated in three consecutive clinical stages of wound healing: non granulation tissue (NGTA), GTA and scar. Subpapillary microcirculation was measured by laser Doppler perfusion (LDP) imaging and expressed using LDP values in arbitrary units. Nutritive perfusion by capillary microscopy and expressed as capillary density (CD) - the number of capillaries per square millimetre. Before the development of GTA the LDP was low (median 1·35; lower-upper quartiles 0·71-1·83) accompanied with zero CD in all but one patient who had a density of 1. With the first appearance of GTA in the same area, the LDP was improved (2·22; 1·12-2·33; P = 0·0024) when compared with NGTA, in combination with a significant increase in CD (1·75; 0-3; P = 0·0054). In scar, the LDP was similar to that in the NGTA (1·03; 0·77-1·83; P = 0·278), combined with the highest CD (5·75; 4·5-8) in comparison with the previous stages of the area (for both pairs, P < 0·0001). Venous ulcers are caused by poor nutritive and subpapillary perfusion. Subpapillary perfusion plays a major role in the formation of GTA. In a scar, the increased nutritive perfusion is sufficient to cover the blood supply and keep skin viable while subpapillary perfusion is low.

Microcirculation in mixed arterial/venous ulcers and the surrounding skin: clinical study using a laser Doppler perfusion imager and capillary microscopy.

To treat mixed skin ulcers effectively, it is important to investigate skin microcirculation in greater detail. Therefore, we used laser Doppler perfusion imaging and capillary microscopy for assessing both subpapillary and nutritive microcirculation in four defined regions of the skin in 17 patients with mixed ulcers caused by a combination of peripheral arterial occlusive disease and chronic venous insufficiency. Laser Doppler area flux was significantly higher in the ulcer areas than in the areas without granulation tissue and those in intact skin. The flux in the scars was higher than that in the intact skin or in the ulcer areas without granulation tissue. Capillary density in the intact skin was higher than the densities in nongranulation tissue areas, granulation areas, and scar areas (p<0.001 for all comparisons). To conclude, the ulcer areas without granulation tissue did not show a healing tendency due to poor subpapillary and nutritive perfusion; the granulation tissue exhibited high subpapillary perfusion as a sign of healing. In the scars, sufficient blood supply could be detected in both layers as a sign of an almost complete healing process. Blood supply in the intact skin is, however, already affected by distorted microcirculation in the ulcers.