Enabling Wearable Pulse Transit Time-Based Blood Pressure Estimation for Medically Underserved Areas and Health Equity: Comprehensive Evaluation Study (Preprint)
Executive Summary
This study evaluates a wrist-worn device leveraging pulse transit time (PTT) for cuffless blood pressure (BP) estimation in a diverse population. Using seismocardiography (SCG) and photoplethysmography (PPG) sensors, the device achieved mean absolute differences of 2.90 mm Hg for diastolic BP (DBP) and 3.39 mm Hg for mean arterial pressure (MAP), meeting IEEE standards for wearable BP devices. The study highlights demographic differences in arterial stiffness and demonstrates the feasibility of remote BP monitoring for underserved populations.
Answer Machine Insights
Q: How accurate is the device for diastolic blood pressure estimation?
The device achieved a mean absolute difference of 2.90 mm Hg for diastolic blood pressure estimation.
Our PTT-based wrist-worn device accurately monitored diastolic blood pressure (DBP) and mean arterial pressure (MAP) in a diverse population (N=44 participants) with a mean absolute difference of 2.90 mm Hg and 3.39 mm Hg for DBP and MAP, respectively, after calibration.
Q: What demographic differences were observed in arterial stiffness?
Significant differences in arterial stiffness were observed based on obesity, sex, race, and age, with calibration coefficients reflecting these variations.
We observed that the participant-specific calibration coefficients used in the standard linear PTT-BP estimation model for DBP, shown in equation 1 (ie, K1 and K2), are significantly different between subpopulations with large variations in demographic factors known to affect arterial stiffness.
Key Results
Mean absolute difference for DBP estimation: 2.90 mm Hg.
Mean absolute difference for MAP estimation: 3.39 mm Hg.
Visual Evidence
Figure 1. Concept overview and study design. Sensor information and placement locations for wearable system (blue) and reference system (purple). Noninvasive pulse transit time (PTT) measurement concept overview using seismocardiogram (SCG) and photoplethysmogram (PPG) sensors. Study protocol tasks in chronological order with duration and mean (SD) of mean arterial pressure (MAP) values for each task. Sample filtered signals from the participant with the lowest signal-to-noise ratio (SNR) signals (n=37): a hypertensive, high BMI, older Black female. In order from top to bottom: electrocardiogram (ECG), SCG, infrared PPG, red PPG, green PPG signals measured from the wearable system (blue) and the synchronized ECG, and arterial blood pressure (ABP) signals measured by the reference system (purple). Systolic blood pressure (SBP; top) and diastolic blood pressure (DBP; bottom) plotted across the full protocol for participant 37, with rest periods (green) and perturbations used to modulate BP (red) highlighted in chronological order, and the location where the reference finger-cuff continuous blood pressure (BP) system was paused during the exercise indicated. ABP: arterial blood pressure; BP: blood pressure; DBP: diastolic blood pressure; ECG: electrocardiogram; LED: light-emitting diode; PD: photodiode; PPG: photoplethysmogram; PTT: pulse transit time; SBP: systolic blood pressure; SCG: seismocardiogram.
Clinical Snapshot
Evidence Rating
Relevance
high Priority