Improved technique for testing autonomic dysfunction: evaluation of transient behaviour of the autonomic response.

The transient behaviour of the autonomic response has been studied by means of a reactometer incorporating self-balancing of the electrodermal impedance. This instrument has been used for the indirect measurement of certain parameters associated with the autonomic response detected as skin electrical resistance relative variation (SERV) and capacitance (SECV). Transient signals of the electrodermal impedance response were obtained online by differentiating the analogue output of the impedance reactometer: d(SERV)/dt and d(SECV)/dt. We describe here how the use of the transient signals of the electrodermal impedance response can improve the accuracy and reduce variability and dispersion of the results and how autonomic conduction velocities (ACV) can be indirectly measured.