Non-linear analysis of skin blood flow in patients suffering from chronic venous leg ulcers

SummaryThe elevated ambulatory pressure in the peripheral venous system in patients suffering from chronic venous insufficiency manifests itself not only in the form of disturbed macrocirculation but also and particularly in microangiopathic changes. Laser Doppler fluxmetry is a well established method to measure cutaneous blood flow. Aim of the study was to investigate the cutaneous vasomotion at the inner ankle in patients suffering from chronic venous insufficiency in the clinical stadium C6 compared to healthy subjects. Patients, methods: In 38 patients suffering from venous ulcer and in 33 healthy subjects continous time series of Laser Doppler fluxmetry (LDF) data were recorded with a sampling frequency of 50 Hz over a period of 15 min. The patients were supine and LDF was measured at the inner ankle. Time series were analyzed using newly developed methods (wavelet analysis and biorthogenal decomposition). Results: There was a statistically significant difference in mean LDF between patients and healthy controls (94 SD 65 AU [C6] vs. 28 SD 13 AU (C0), p < 0.001). There also were statistically significant differences in the scaling levels using wavelet analysis corresponding to sympathetic activity, corresponding to myogenic activity in the vessel wall and corresponding to the heart beat. Conclusion: There are changes in vasomotion between patients with venous ulcers and healthy controls. We found a vasale neuropathy and a high degree in dysregulating skin perfusion. The new innovative strategies are suited for describing microcirculation and controlling therapies.