On assessment of skin reactivity using electrical impedance.

Pathophysiological events in biological tissue are characterized by a shift in electrical impedance spectra of the tissue under study. In this paper, techniques based on electrical impedance are reviewed with emphasis on their possible role in evaluating the skin reactivity of an individual, including results from impedance measurement studies on patients with allergic contact reactions, wheals, tuberculin tests, and irritant contact reactions and on an appropriate number of controls. The results show that, compared to relevant controls, at different types of experimental cutaneous reactions, both of allergic and irritant type, statistically significant changes of the impedance parameters have been detected. Each reaction type had a specific impedance index pattern. Data up to now indicate that the improved impedance technique offers not only a noninvasive alternative for characterization and perhaps differentiation between the skin responses induced by either an allergen or an irritant, but also a capability to distinguish responses induced by chemically different irritants.