Estimation of the nutrient skin blood flow using a segmented thermal clearance probe

Abstract

Summary A segmented thermal clearance probe modified from similar heated thermocouple devices adapted for non‐invasive application, is described. This instrument responds rapidly to changes in the nutrient skin bloodflow in the papillary dermis to a depth of 1·5 mm. It differentiates nutrient from total skin bloodflow. The dimensions of its components can be modified in order to assess bloodflow changes at different depths depending on different experimental or clinical requirements.

Non-invasive blood perfusion measurements using a combined temperature and heat flux surface probe

“…Castellana et al [17] placed a thin-film resistor on the skin surface to provide heat and measure the temperature. Holti and Mitchell [18] placed a thermopile between a heated copper cylinder and a surrounding annulus of copper on the surface of the skin. They attempted to relate blood perfusion to the measured radial temperature difference established after several minutes of heating.…”

<title>Tissue perfusion monitoring and imaging by coherent light scattering</title>

“…The infinitesimal photocurrent i(t,r) produced by the total field ET(t,r) at position r on the photosensitive area of the detector is, if noise is neglected, proportional to the instantaneous intensity23'24 . * i(t,r) = C0 (ET(t,r) ET (t,r)) (6) where C0 is an instrumentation constanL…”

Microvascular investigations in diabetes mellitus

“…The temperature difference between these is measured using thermocouples and decreases as the blood flow beneath the probe increases. 65 Although, in muscle, the measurement depends greatly on the proximity of the probe to a blood vessel,66 in the skin, thermal clearance probes measure total skin blood flow (including flow through arterio-venous anastomoses in the microcirculation) and not nutritive flow only.67 The technique can give important information about flow distribution, especially if used in conjunction with a measure of total flow, such as laser Doppler flowmetry.66 An alternative method is to measure the power consumption of a thermostatically controlled heating element.68 The higher the blood flow, the more rapidly heat will be removed from the skin under the heating element and the more power will have to be supplied to maintain a fixed temperature. This approach is particularly attractive when the heating element used is that of a tcPo2 electrode or thermostatically controlled laser Doppler probe holder.…”