Assessment of sympathetic nerve activity for pulse current stimuli based on log-linearized peripheral arterial viscoelastic model

This study proposes a novel method to assess the sympathetic activity based on the log-linearized peripheral arterial viscoelastic model. The arterial stiffness included in the model was calculated from the measured electrocardiogram, continuous left radial arterial pressure, and left second finger photo-plethysmogram while applying the triangular pulse current to the right forearm. Additionally, the self-reported numeric rating scale (NRS) was compared with the estimated stiffness. As results of four subjects, the relation between the stiffness and the NRS was approximated by the sigmoid function. The result thus showed the proposed method has a potential to assess a pain objectively.