An electrical model of biological tissues undergoing hyperaemia

Tissue hyperaemia is a physiological consequence of the temperature increase that follows, for example, the absorption of electromagnetic or ultrasound power in clinical diathermy. Diathermy, as well as other physical therapies (for example massotherapy), affects the local blood content of tissues through various mechanisms (vasoconstriction/dilatation, opening/closing of precapillary sphincters). A method for evaluating hyperaemia in superficial and medium-depth tissues has been recently proposed, which is based on four-electrode impedance measurements. A microcirculation model has also been developed to describe the hyperaemic effects of local diathermic therapy. This paper describes an electrical model of the tissues in hyperaemic conditions which allows us to correlate electrical impedance measurements to microcirculation modifications.