Fingertip Model for Blood Flow and Temperature

It has been shown that chronic illnesses such as systemic sclerosis and diabetes mellitus are related to some disorders at the capillary level, such as increased vessel permeability, the presence of avascular areas, enlarged loops, poor circulation, and increased tortuosity (Daly and Leahy 2013). There has been an increasing interest in using microcirculation as a marker for cardiovascular health and metabolic functions, as it may be related to the development of instruments for detecting a variety of pathological processes in the circulatory system. Since the skin is readily accessible, it provides an appropriate site to assess peripheral microvascular reactivity. Vascular reactivity is a primary feature of the circulatory system that enables the vasculature to respond to physiological and physical stimuli that require adjustments in blood flow, vessel tone, and vessel diameter. For more than two decades, methods that focus on the noninvasive exploration of cutaneous microcirculation have been mainly based on optical microscopy and laser Doppler techniques (Roustit and Cracowski 2012). In recent years, laser Doppler flowmetry (LDF), in combination with wavelet analysis of blood flow oscillations, has been increasingly used to detect alterations in vessel tone. Blood flow modulations in microvessels form five non-overlapping frequency bands within the wave range 0.0095–3 Hz (Stefanovska et al. 1999) and the lowest frequency range (0.0095–0.021 Hz) is related to the functional activity of the microvessel endothelium. Fedorovich (2012) investigated the correlation ContentS