The Potential of Wearable Limb Ballistocardiogram in Blood Pressure Monitoring via Pulse Transit Time

Peyman Yousefian,Ui Kun Kwon,Jongwook Lee,Dae-Geun Jang,Ramakrishna Mukkamala,Sungtae Shin,Jin-Oh Hahn,Azin Mousavi,Youn Ho Kim,Byung-Hoon Ko,Chang-Sei Kim

doi:10.1038/s41598-019-46936-9

Abstract

The goal of this study was to investigate the potential of wearable limb ballistocardiography (BCG) to enable cuff-less blood pressure (BP) monitoring, by investigating the association between wearable limb BCG-based pulse transit time (PTT) and BP. A wearable BCG-based PTT was calculated using the BCG and photoplethysmogram (PPG) signals acquired by a wristband as proximal and distal timing reference (called the wrist PTT). Its efficacy as surrogate of BP was examined in comparison with PTT calculated using the whole-body BCG acquired by a customized weighing scale (scale PTT) as well as pulse arrival time (PAT) using the experimental data collected from 22 young healthy participants under multiple BP-perturbing interventions. The wrist PTT exhibited close association with both diastolic (group average r = 0.79; mean absolute error (MAE) = 5.1 mmHg) and systolic (group average r = 0.81; MAE = 7.6 mmHg) BP. The efficacy of the wrist PTT was superior to scale PTT and PAT for both diastolic and systolic BP. The association was consistent and robust against diverse BP-perturbing interventions. The wrist PTT showed superior association with BP when calculated with green PPG rather than infrared PPG. In sum, wearable limb BCG has the potential to realize convenient cuff-less BP monitoring via PTT.

Highlights

Which pulse transit time (PTT) and pre-ejection period (PEP) vary in the opposite directions, due to the mutual cancellation of their respective changes in response to BP5,6
Our prior work suggests that characteristic features extracted from the BCG acquired with a scale-like platform have the potential for convenient cuff-less blood pressure (BP) monitoring[5,6]
We elucidated the physical implications of the whole-body BCG due to the force exerted by the blood ejected by the heart: that it originates from the BP gradients in the ascending and descending aorta[16]

Summary

Introduction

Which PTT and PEP vary in the opposite directions, due to the mutual cancellation of their respective changes in response to BP5,6. Inspired by our prior success with the whole-body BCG and the ultra-convenience of wearable limb BCG, the goal of this study was to investigate the potential of wearable limb BCG to enable cuff-less BP monitoring via PTT, by investigating the association between wearable limb BCG-based PTT and BP in comparison with whole-body BCG-based PTT and PAT To this aim, a wearable BCG-based PTT was calculated using the BCG and photoplethysmogram (PPG) signals acquired by a wristband as proximal and distal timing reference (called the wrist PTT). The primary novelty of the present work distinct to our prior work is that it shows the potential of limb BCG for wearable BP monitoring It elucidated the typical shape of the wrist BCG waveform, and it demonstrated the wrist BCG features relevant to PTT calculation with physical justification. The secondary novelty of the present work is that it illustrated the feasibility of using commercial low-cost weighing scale for acquisition of the BCG for PTT-based BP monitoring

Objectives

Methods

Results

Discussion

Conclusion