Preliminary Study for Hemodynamics Monitoring using a Wearable Device Network

Blood flow, posture and phenotype (such as age, sex, smoking habit or physical activity) are closely related to vascular health. Episodic monitoring of the vascular system in clinical setting can lead to late diagnose. Inexpensive wearable devices for continuous monitoring of vascular parameters have been widely used, however, they often have limitations in data interpretation: changes in the environment setting can significantly affect the meaning of the results. This paper proposes a low cost networked body worn sensors for realtime analysis of hemodynamics and reports preliminary results on the relation between blood flow (measured through pulse arrival time (PAT)), the effect of postures and age ranges based on experiments with 13 volunteers of different age ranges (< 25 years old and > 50 years old). Standing, supine and sitting postures were investigated while photoplethysmograph (PPG) sensors were placed at different locations (ear, wrist and ankle). Results show the PAT changes according to the investigated locations and postures for both age group. Also, the average PAT values of the older group are generally higher than those of the younger group. In the older group, the average PAT value is higher for the supine posture than that of the sitting posture which is itself higher than that of the standing posture. In the younger group, the average PAT is higher in supine than that of the sitting and standing postures which have similar average PAT values. This indicates that hemodynamics vary with posture and age.