Unobtrusive In-Home Respiration Monitoring Using a Toilet Seat

Abstract

Non-invasive monitoring of pulmonary health could revolutionize the care of health conditions ranging from COVID-19 to asthma to heart failure, but current technologies face challenges that limit their feasibility and adoption. Here, we introduce a novel approach to monitor respiration by measuring changes in impedance from the back of the thigh. The integration of electrodes into a toilet seat ensures patient compliance with unobtrusive daily respiration monitoring benefitting from repeatable electrode placement on the skin. In this work, the feasibility of the thigh and the sensitivity of impedance to respiration have been investigated empirically by comparing thorax and thigh-thigh bioimpedance measurements to spirometer measurements, and computationally, using finite element modeling. Empirical results show a measurable peak-peak impedance (0.022 ohm to 0.290 ohm for normal breathing across 8 subjects) with respiration across thigh-thigh and a high correlation (0.85) between lung tidal volume and impedance change due to respiration. Thigh-thigh bioimpedance measurements were found to be able to distinguish between shallow, normal, and deep breathing. Further, day-to-day variability in the relationship between impedance and tidal volume was investigated. The results suggest that the novel approach can be used to detect respiration rate and tidal volume and could provide valuable insight into disease state for conditions ranging from COVID-19 to heart failure.