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Wearable Non-invasive Continuous Cuff-
less Blood Pressure Measurement
Ghalib Janjua
ESR 8
Supervised by Jim McLaughlin
This project has received funding from the European Union's Horizon 2020 research and innovation programme under the
Marie Sklodowska-Curie grant agreement No 676201
Hypertension Hypertension is biggest challenge worldwide in public health [1].
Hypertension Mortality: according to WHO, death toll due to
hypertension is 9.4 million every year [2], which is 55.3% of total
death due to cardiovascular disease (CVD). CVD causes one third of
total deaths around the globe. Hypertension Morbidity: there is
dramatic increase of 600 Million to 1 Billion patients suffering from
hypertension since 1980 to 2008; almost 40% of adults of age 25 and
above had been diagnosed with hypertension worldwide, in 2008.
The Joint National Committee 7th report (JNC 7) [3] stated that
unawareness of hypertension is over 30% in hypertensive patients,
which more complicate the public-Health system worldwide [2].
Cancer 21%
Diabetic 6%
Cardiovascular Dieases
51%
Respiratory Dieases
22%
Chart Title
In Practice System Blood pressure (BP) measurement is performed either invasively by
an intra-arterial catheter (continuous and accurate but has increased
risk), noninvasively by cuff sphygmomanometer (safe but less
reliable and very infrequent), on finger by pressurized cuff
(continuous monitoring system but non wearable and very expansive)
and arterial tonometry requires skill operator to measure it.
State of the Art Over the past decade, pulse transit time methodology have
shown promising result to calculate BP. Evolution of BP &
PTT measurement devices are shown in Fig 3 below, but to
date, there is no standard independent wearable cuff-less
non-invasive continuous BP measurement device in the
market.
Research Methodology Pulse Transit Time (PTT) and Pulse Wave Velocity (PWV)
have been shown to co-relate with arterial BP and have
been reported to be suitable for indirect BP measurement
[5]. Arterial PTT can be estimated from ECG and PPG
waveforms. A method for continuous BP monitoring not
requiring a cuff and only requires ECG electrodes and a
PPG Sensor is the non-invasive protocol involving PTT. To
date, r-squared correlations are low, much work is required
on improving signal quality, signal processing, and optimum
capture of the key signal parameters which will be the
focus for this research. Currently, we are comparing PTT
measurement using three methods: by measuring time
difference (Delta T) between: Firstly, ECG R and PPG 1st
derivative, Secondly, Inline PVD signal peaks and thirdly,
Inline PPG signals peaks on Brachial Artery, as shown below.
[1] Patricia M Kearney, Megan Whelton, Kristi Reynolds, Paul Muntner, Paul K Whelton, and J. He, “Global burden of hypertension-analysis of worldwide data” Lancet, vol. 365, pp. 217–223, 2005.
[2] W. H. Day, “World Health Day 2013, A Global Hypertension”, p. 9, 2013.
[3] A. V Chobanian, “The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. The JNC 7 Report,” JAMA, vol. 289, no. 19, p. 2560, 2003.
[4] Based on the Global Economic Burden of Non-communicable Diseases, Prepared by the World Economic Forum and the Harvard School of Public Health, 2011.
[5] G. Jeong, K. Yu, and N. Kim, “Continuous Blood Pressure Monitoring using Pulse Wave Transit Time,” Measurement, pp. 2–5, 2005.
Fig 1. Cost of Care by Diseases [4]
Fig 2. Cuff BP(Top left), CNAP System(top Right), Arterial line(lower left) & Tonometry(lower right)
Fig 3. VisiMobile(Top left), Scanadu (Top right) & ST+D by Intelesense (bottom )
Fig 4. PTT calculation using ECG & PPG signal (on left), inline PVD Sensor on Brachial artery (in middle)
& Inline PPG Sensor at wrist and index finger (on Right)