Wrist-worn device allows remote BP monitoring in underserved areas

A cuffless, wrist-worn, pulse transit time (PTT)-based device can be used to accurately monitor diastolic blood pressure (DBP) and mean arterial pressure (MAP), while also providing acceptable measurements for systolic BP (SBP), according to a recent study.

“Using a convenient wearable device can empower users and facilitate remote BP monitoring in medically underserved areas, thus providing widespread hypertension screening and management for health equity,” the researchers said.

“To the best of our knowledge, this is the first study to accurately estimate DBP and MAP using noninvasive PTT measurements acquired from a holistic population, with considerable differences in body fat percentage, melanin levels, and vascular stiffness associated with age and hypertension,” they added.

The study included 44 participants, which were separated into two different analytical populations: a homogenous sample of young and healthy participants (n=26) and a sample of older, Black participants from a medically underserved community and with higher body mass index (n=18). Hypertensive status and medications used were self-reported for both groups.

All participants were given the wearable SeismoWatch, while a finger-cuff BP sensor was used as the reference standard. Measurements were collected during 2-minute baseline periods while sitting and standing, followed by a series of perturbations artificially triggered through a mental arithmetic test, a cold pressor test, and a physical exercise session. Rest periods were allowed in between scenarios to modulate BP.

In the overall cohort (n=44), the wrist-worn device showed high agreement with the finger BP sensor in terms of DBP and MAP, with mean absolute differences (MAD) of 3.39 and 2.90 mm Hg, respectively. The deviation in measurements was higher for SPB, with a MAD of 5.36 mm Hg. Looking at the root mean square error showed similar patterns. [JMIR Mhealth Uhealth 2021;9:e27466]

These findings remained consistent when stratifying by cohort. In the subgroup of healthy participants, the MAD values between the SeismoWatch and finger sensor were 2.69, 3.21, 5.17 mm Hg for DBP, MAP, and SBP estimation, respectively. Deviations tended to be slightly higher for the cohort from the underserved community: 3.20, 3.64, and 5.63 mm Hg, respectively.

Findings were also mostly unchanged when restricting the analysis to the 10 obese participants. MADs for DBP, MAP, and SBP were 2.69, 3.17, and 5.02 mm Hg, respectively.

“Noninvasive and cuffless approaches to monitor BP, in light of their convenience and accuracy, have paved the way toward remote screening and management of hypertension,” though there is a lack of robust assessment of these technologies, particularly in diverse populations, the researchers said.

“The knowledge gained from this study—especially when combined with the advent of low-profile, flexible electronics capable of robustly detecting physiological biosignals—represents a significant step toward the unobtrusive monitoring of BP in ambulatory settings and health equity for persons in medically underserved areas,” they added.