Thermo-Electrical Analogy of Skin Properties and Low-Pass Filter, Correlation between Skin Temperature and Blood Flow Oscillations in Extremities

The possibility of simplifying of the Shitzer’s model relating changes in skin temperature and skin blood flow in extremities has been determined. Analogy between the equation of simplified model and the equation describing the analog low-pass filter has been demonstrated. The established electro-thermal analogy allows us to calculate the waveform of cutaneous blood flow in extremities using values of time derivative of the temperature. The proposed model was verified using simultaneous measurements of the temperature by infrared thermography of hands and assessment of blood flow oscillations by photoplethysmography.