Harutoyo HIRANO

This paper proposes an estimation algorithm of the arterial viscosity using cuff pressures and cuff pulse waves measured from an automatic oscillometric sphygmomanometer. A change in the arterial viscosity %η during the enclosed zone flow-mediated dilation (ezFMD) test is calculated as an index for vascular endothelial function.The index %η was measured and the receiver operating characteristic (ROC) analysis for the arterial viscosity change %η was performed in the experiment. The mean arterial viscosity change for the healthy subjects and that for the subjects at high-risk of arteriosclerosis were 13.4 ± 55.1 ％ and -32.7 ± 34.0 ％ (mean ± S.D., p < 0.05), respectively, and the area under the curve calculated from the ROC analysis was 0.77. It was thus concluded that the proposed method may evaluate vascular endothelial function.

This paper examines a relationship between an arterial stiffness parameter β and nociceptive mechanical stimuli. The stiffness parameter β which reacts according to peripheral sympathetic nerve activity is calculated from continuous arterial pressures and photoplethysmograms based on the log-linearized peripheral arterial viscoelastic model, while mechanical stimuli were applied to the subjects in the experiments. The results showed a significant correlation between the stimulus velocity and the stiffness parameter β when stimulus amplitude was constant (r = 0.63 (p < 0.05)) and that between the stimulus amplitude and the normalized stiffness parameter β_n when stimulus velocity was constant (r = 0.54 (p < 0.01)). It was therefore concluded that the arterial stiffness parameter β may react to amplitude and velocity of mechanical stimuli.

This study proposes a novel system that evaluates human higher brain functions with a tablet device based on cognitive information processing models. The system consists of three parts. The first part is to measure touch events on the tablet associated with visual cognition, reaching motion control, rhythmic motion control, and working memory retrieval; the second part to calculate indices from the measured touch events based on the cognitive information processing models; and the third part to assess a risk score calculated from the indices normalized to a control group, hi this paper, the validity of the proposed system was discussed with the calculated indices from adult healthy subjects. The results showed that the risk score increased linearly by age (r = 0.64, p < 0.01). This suggests that the proposed system has the potential to evaluate higher brain functions objectively and quantitatively.

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.

This study proposes a novel noninvasive arterial stiffness estimation technique based on the oscillometric method and applies it to assess the vascular endothelial function. Change of the arterial stiffness during the enclosed zone flow-mediated dilation test was calculated from the measured blood pressure, the cuff oscillation, and the applied pressure to the cuff. As results, the arterial stiffness change for the four healthy subjects was -42±17% and that for the four patients with high-risk of arteriosclerosis was -2.9±11%. The mean changes had significantly different between the two groups (p<0.01). The result thus indicated proposed method could assess the vascular endothelial function.