Feasibility of Remote Blood Pressure Estimation via Narrow-band Multi-wavelength Pulse Transit Time

• Published in: ACM transactions on sensor networks Vol. 20; no. 4; pp. 1 - 21
• Main Authors: Slapničar, Gašper, Wang, Wenjin, Luštrek, Mitja
• Format: Journal Article
• Language: English
• Published: New York, NY ACM 11.05.2024
• Subjects: Applied computing; Computing methodologies; Emerging tools and methodologies; Hardware; Health informatics; Model verification and validation; multi-wavelength; blood pressure; photoplethysmography; pulse transit time; Remote sensing
• ISSN: 1550-4859; 1550-4867
• DOI: 10.1145/3597302

Contact-free sensing gained much traction in the past decade. While remote monitoring of some parameters (heart rate) is approaching clinical levels of precision, others remain challenging (blood pressure). We investigated the feasibility of estimating blood pressure (BP) via pulse transit time (PTT) in a novel remote single-site manner, using a modified RGB camera. A narrow-band triple band-pass filter allowed us to measure the PTT between different skin layers, harvesting information from green and near-infrared wavelengths. The filter minimizes the inter-channel influence and band overlap, however, some overlap remains within the filter bands. We further resolve this using a color-channel model and a novel channel-separation method. Using the proposed setup and algorithm, we obtained multi-wavelength (MW) PTTs in an experiment inducing BP changes to 9 subjects. The results showed good absolute Pearson’s correlation coefficient between both MW PTT and systolic BP (R = 0.61, p = 0.08) as well as diastolic BP (R = 0.54, p = 0.05), pointing to feasibility of the proposed novel remote MW BP estimation via PTT. This was further confirmed in a leave-one-subject-out experiment, where a simple Random Forest regression model achieved mean absolute errors of 3.59 and 2.63 mmHg for systolic and diastolic BP respectively.