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

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.

Wearable Sensing and Telehealth Technology with Potential Applications in the Coronavirus Pandemic

“…The advantage of this method is that the R-peak of the ECG signal is easy to detect, especially during resting conditions. Several studies use alternative cardiac signals for ECG, such as impedance plethysmography (IPG) [99,100], phonocardiogram (PCG) [101,102], or ballistocardiogram (BCG) [103,104]. To improve the user comfort, a peripheral PTT-based multi-wavelength method has been proposed using two or multiple PPG sensors [105][106][107].…”

Pulse Transit Time-Pulse Wave Analysis Fusion Based on Wearable Wrist Ballistocardiogram for Cuff-Less Blood Pressure Trend Tracking

“…We used the experimental data collected in our prior work 7,13 . In brief, we studied 23 young healthy volunteers (age 23+/-5 years; 17 males and 6 females; height 174+/-9cm; weight 74+/-16kg) under the approval and guidance of the University of Maryland Institutional Review Board (IRB).…”

“…Fourth, we extracted the PPG feet using the intersecting tangent method 23,24 (Figure 1). Fifth, we performed PWA on the wrist BCG beats and extracted the fiducial points including the G, H, I, J, K, and L waves (Figure 1), as described in detail in our prior work 7,13 . Sixth, we extracted the reference DP and SP from the reference BP pulse beats as the minimum (DP) and maximum (SP) values in individual beats.…”

“…On an individual basis, we arranged the reference BP as well as BCG PTT and PWA features as follows similarly to our prior work 7,13 . First, we segmented the ranges of reference DP and SP across all resting periods and BP-perturbing interventions into 1mmHg bins.…”

“…PTT is the time required for an arterial pulse wave to travel between two different sites in the arterial tree, e.g., between a central artery (e.g., ascending aorta or carotid artery) and a peripheral artery (e.g., radial artery, digital artery, or tibial artery). Vast majority of prior work has investigated the use of pulse arrival time (PAT: the time interval between the R wave in the electrocardiogram (ECG) and a fiducial point in the photoplethysmogram (PPG); see 2 and the references therein), while other work has explored the use of PTT derived using other physiological signals, such as impedance plethysmography (IPG)-PPG pair 3 , PPG pair (see 4 and the references therein), ballistocardiogram (BCG)-PPG pair [5][6][7] , and seismocardiogram (SCG)-PPG pair 8 to list a few. Second, PWA approach exploits fiducial points in an arterial pulse wave to construct predictors of BP, often in conjunction with the state-of-the-art data mining and machine learning techniques.…”