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Proceedings Paper

Novel method for non-invasive blood pressure measurement from the finger using an optical system based on dynamic light scattering
Author(s): Adi Schejter Bar-Noam; Alexander Kaminsky; Albert Bravo; Louis Shenkman; Naomi Nacasch; Ilya Fine
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Paper Abstract

Self-measurement of blood pressure (BP) is important for monitoring treatment of hypertension, but current instruments are cumbersome and at times also impractical, especially for the older population. Current optical solutions, such as PPG-based technologies that were developed for improving convenience, provide derived measurements that are often inaccurate, particularly for diastolic values. Alternatively, by using dynamic light scattering (DLS) we are able to measure the direct hemodynamic response. We propose a simple physical model that explains the relation between arterial pressure values and the hemodynamic response which is measured from the finger root following changes in externally applied pressure. Based on this model we have developed a small-scaled, optical, mobile device that measures BP at the finger using dynamic light scattering. The apparatus is positioned at the base of the index finger and contains a ring with an inflatable cuff with two miniaturized dynamic light scattering (mDLS) sensors situated distal to the cuff. The cuff is inflated to above systolic pressure, and changes in blood flow (hemodynamics) are measured during cuff deflation. BP measurement is carried out using specially designed algorithms based on hemodynamic indexes and waveform analysis which capture systolic and diastolic points in real-time. Using this apparatus, we measured BP from 69 patients visiting a hypertension outpatient clinic, and a control group of 15 healthy subjects. BP readings were compared with measurements recorded at the arm location with an Omron device used in the clinic. The mean absolute error (MAE) for systolic and diastolic blood pressure was 7.8 and 9 mmHg, respectively at all ranges of BP measured. In conclusion, using Elfi-Tech's innovative technology, it is possible to measure BP accurately at the finger location using a compact, convenient mDLS-based device with high accuracy.

Paper Details

Date Published: 22 July 2019
PDF: 9 pages
Proc. SPIE 11075, Novel Biophotonics Techniques and Applications V, 110750P (22 July 2019); doi: 10.1117/12.2525685
Show Author Affiliations
Adi Schejter Bar-Noam, Elfi-Tech Ltd. (Israel)
Alexander Kaminsky, Elfi-Tech Ltd. (Israel)
Albert Bravo, Elfi-Tech Ltd. (Israel)
Louis Shenkman, Tel Aviv Univ. (Israel)
Naomi Nacasch, Meir Medical Ctr. (Israel)
Ilya Fine, Elfi-Tech Ltd. (Israel)

Published in SPIE Proceedings Vol. 11075:
Novel Biophotonics Techniques and Applications V
Arjen Amelink; Seemantini K. Nadkarni, Editor(s)

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