Calibration-free blood pressure monitoring using biometric earbuds

Calibration-free blood
pressure monitoring using
biometric earbuds
March 26th, 2020
© 2020 Valencell Inc.
www.valencell.com/patents

© 2020 Valencell, Incwww.valencell.com/patents
Agenda
• The blood pressure challenge and background on
Valencell’s efforts in BP technology development
• Why the ear?
• Clinical study overview and results
• Continuous BP monitoring
• Use cases for the technology
• Where we’re going from here
• Evaluating the technology for your next device

Hypertension management is a significant public health issue
[1] CDC: https://www.cdc.gov/bloodpressure/index.htm
[2] WHO: https://www.who.int/gho/ncd/risk_factors/blood_pressure_prevalence_text/en/
[3] Your Guide to Lowering Blood Pressure. U.S. Department of Health & Human Services, NIH Publication No. 03-5232 May 2003. https://www.nhlbi.nih.gov/files/docs/public/heart/hbp_low.pdf
[4] Tolonen H, Koponen P, Naka A, et al. Challenges in standardization of blood pressure measurement at the population level. BMC Med Res Methodol. 2015; 15:33.
[5] Wagner S, Toftegaard TS, Bertelsen OW. Challenges in Blood Pressure Self-Measurement. Int J Telemed Appl. 2012; 2012: 437350.
[6] de Greeff A, Lorde I, Wilton A, et al. Calibration accuracy of hospital-based non-invasive blood pressure measuring devices. Journal of Human Hypertension volume. 2010; 24: 58–63.
[7] Home Blood Pressure Monitors Inaccurate? Up to a Third May Give Imprecise Blood Pressure. https://www.webmd.com/hypertension-high-blood-pressure/news/20030516/home-blood-pressure-monitors-inaccurate#1
[8] How can I get my OMRON blood pressure monitor re-calibrated? https://www.omron-healthcare.com/eu/category/blood-pressure-monitors
[9] Chung E, Chen G, et al. Front Med. 2013 Mar;7(1):91-101. doi: 10.1007/s11684-013-0239-5..
CDC: Hypertension
was a primary or
contributing cause of
death for > 410,000
Americans in 2014 [1]
CDC: 1/3rd of American
adults have
hypertension, and only
½ know they have the
disease [1]
WHO: The “silent killer”
is estimated to cause
~7.5M deaths/year
worldwide (roughly
12.8% of all deaths) [2]
HHS: Combining
prevention with
regular BP monitoring
can improve health
and reduce risk of
heart attack or
stroke [3]
Few households
own a BP monitor
and comply with
regular monitoring
due to difficulties with
properly using
a BP cuff [4-8]

History of Valencell BP development
2009 2011 2014 2016 2017 2018 2019
Valencell
begins
studying BP
monitoring via
PPG in parallel
with HRM
Valencell
completes
preliminary
feasibility study;
R&D put on
hold for funding
Fundraising;
foundational
patent on BP
monitoring
method is filed
Funding acquired;
Early-stage PPG
BP demo unit is
developed with
data from <100
subjects
>500 datasets
collected;1st
calibration-free
generalizable
algorithm
demonstrated
1st patent
granted;
Valencell
begins
massive data
collection effort
>15,000 datasets
collected; cuff-
like BP tracking
demonstrated;
internal ISO
Dec 2019
R&D Feasibility Prototype Dev Productization
2020
Product launch
as a general
wellness device
& pursuing
medical device
partnerships

The ear is one of the best locations on the body
for accurately measuring blood pressure via PPG
Ear Region
Wrist
Finger
The ear region comprises a high density
of arterioles, which have the highest
blood pressure content when compared
with capillaries, venules, and veins [1]
The ear region has the highest blood
perfusion when compared with the wrists
and other distal body locations [3]
[1] https://courses.lumenlearning.com/ap2/
[2] 9. Netea RT, Lenders JW, Smits P, Thien T. Arm position is important for blood pressure measurement. J Hum Hypertens. 1999;13(2):105–109.
[3] Tur et al, Basal Perfusion of the Cutaneous Microcirculation: Measurements as a Function of Anatomical Position, The Journal of Investigate Dermatology, 81:442-466, 1983.
1) Optimal vascular structure 2) Fixed distance from heart 3) Highest blood perfusion
Having a fixed distance from the
heart, the ear location is free of the
arm positioning errors inherent to
brachial cuffs [2]
Fixed Distance
Variable Distance
Accurate heart rate, blood pressure, core body
temperature, breathing rate, body sounds, etc. can
be monitored at the ear (as opposed to the wrist)
4) The most metrics in one spot

Hearables are the biggest segment of the wearables market
10%
CAGR
2020 2024
Hearables
Source: IDC “Worldwide Wearables Market
Braces for Short-Term Impact Before
Recovery in 2020, According to IDC”
Hearables
6.5%
CAGR
204M units 301M units
Wearables
160M units
Wearables
220M units

A biometric audio earbud
can accurately monitor
BP during free-living
conditions without the
need for a cuff
Presenting Author: Dr. Steven F. LeBoeuf
Additional authors: Dr. Chris Eschbach, Tushar Tank, Dr. Ryan
Hodges, Seth Long, and Dr. Daniel Moore
Valencell, Inc., Raleigh, NC
BACKGROUND
RESULTS
A training dataset (Fig. 2) was collected from BP measurements on
>3000 subjects in 3 sequential readings: a manual auscultatory
reading, an automated oscillometric cuff reading, and a PPG reading
from a commercial PPG sensor embedded within a wireless audio
earbud. With the manual readings serving as “ground truth”, a machine
learning model for ear-PPG BP (EPBP) was trained to predict both
systolic and diastolic BP based solely on ear-PPG sensor data and
subject meta data (age, height, weight, and gender).This machine
learning model was then integrated into Valencell’s PerformTek®
biometric software to provide an EPBP solution comprising 2 key
software components: 1) an automated data qualifier and 2) a BP
estimator. The data qualifier was configured to automatically determine
whether the PPG measurement was likely to yield cuff-like accuracy,
and the BP estimator was configured to estimate BP based on the
qualified data.
An unbiased accuracy assessment of the EPBP solution was
generated by statistical analysis of the model’s BP predictions for a
qualified test dataset of >100 total participants (Fig. 3). This test
dataset was collected following the ISO 81060-2(2018) standard for
noninvasive sphygmomanometers and was never used to train the
EPBP model.
Daily self-monitoring of blood pressure (BP) is widely recognized as a
cost-effective method to identify and manage hypertension in
conjunction with physician-prescribed interventions. However, few
American households own a BP monitor and even less comply with
daily monitoring, in part due to annoyances associated with porting and
properly donning a BP cuff. The purpose of this study was to
demonstrate the accuracy of a cuff-less, calibration-free BP monitoring
technology, based upon photoplethysmography (PPG), embedded
within a popular consumer audio earbud form-factor (Fig. 1).
The resulting qualified test dataset comprised 654 measurements from
147 subjects (Fig. 3). For the qualified test dataset, the accuracy and
tracking characteristics of the EPBP model predictions were found to be
comparable to that of the automated cuff , having a mean ±
estimation error within 5 ± 8 mmHg, with respect to the manual reading
(Fig. 5).
DISCUSSION
For more information, scan the
QR code, go to
www.valencell.com, or email
info@valencell.com
METHODS
Fig. 1: Valencell developed and validated a novel machine learning model, based on
PPG datasets collected from thousands of unique participants, to estimate BP from PPG.
FIG 1 - METHODS
FIG 3 – QUALIFIED TEST DATASET
BIOMETRIC AUDIO
EARBUDS PRODUCE CUFF-
LIKE ACCURACY IN
MONITORING BLOOD
PRESSURE
The ultimate purpose of this R&D program was to develop and validate the
world’s first commercially viable cuff-less, calibration-free, all-PPG BP monitoring
solution that could ultimately: 1) provide demonstrable public health value,
2) provide cuff-like accuracy in a general population, and 3) be integrated with
existing popular consumer form-factors. Both objectives were achieved. Moreover,
for the qualified test dataset, it was found that the biometric earbud solution was
able to categorize hypertension status with cuff-like accuracy (Fig. 4).
CONCLUSION
A PPG-enabled audio earbud can accurately monitor BP during free-
living conditions without the need for a cuff.
DISCLOSURE INFORMATION
*All authors are employed by Valencell, Inc.: valencell.com/patents
FIG 5 – RESULTS
PPG Auto-cuff
Accuracy 89% 88%
Precision 73% 69%
Sensitivity 77% 75%
Specificity 93% 92%
FIG 2 – TRAINING DATASET
FIG 4 – HYPERTENSION STATUS
Fig. 4: The PPG-based BP model was
shown to identify hypertension status as
effectively as an auto-cuff.

Valencell’s approach comprises machine learning
applied to >15,000 datasets from ~5000 subjects
1) Massive data collection
Thousands of training datasets collected in
the US, Vietnam, & Philippines
2) BP model development
PPG-based model development
utilizing machine learning tools
3) Proving generalization
Model applied to a test dataset
collected via ISO 81060-2:2018 protocol
4) Embedded solution
Integrating model into Valencell’s
PerformTek® biometric operating system

Valencell’s embedded software qualifies input data
and outputs accurate BP estimates
Inputs Processing Outputs
PPG Data
Inertial Data
Static Biometrics
BP Measurement
Qualifier
BP
Estimator

Truly unbiased assessment: the training dataset and qualified test
dataset did not overlap (no test datasets were used in training)
Training Dataset Qualified Test Dataset
(ISO 81060-2:2018)

Valencell’s BP monitoring technology shows cuff-like accuracy
in the qualified test dataset never used to build the BP algorithm
(654 measurements from 147 subjects)
Ear PPG Error 1.7 ± 7.7 mmHg
Auto Cuff Error 0.9 ± 8.0 mmHg
Ear PPG Error -1.1 ± 8.0 mmHg
Auto Cuff Error -2.3 ± 6.8 mmHg
Systolic Diastolic
*Note: In the ISO testing
protocol, manual auscultatory
readings are considered to
be “ground truth”

Valencell’s ear PPG solution can categorize
hypertension status equivalently to an automated BP cuff
PPG Auto-cuff
Accuracy 89% 88%
Precision 73% 69%
Sensitivity 77% 75%
Specificity 93% 92%
*Note: All SBP measurements ≥ 130 mmHg were classified as hypertensive

Both “qualified” and “unqualified” datasets can yield accurate BP
• Valencell’s automated qualifier determined that
~85% of subjects would produce accurate BP
measurements with respect to the manual cuff
• Thus, ~15% of subjects would be likely to have
an unsatisfactory level of accuracy
• However, reviewing 4-week longitudinal
datasets, it was found that a one-time
calibration corrected errors for “unqualified”
subject measurements
±8 mmHg
60%
±10 mmHg
25%
±14 mmHg
15%

The marketable use case available today:
calibration-free for 85% & one-time calibration for 15%
(BP  ±  errors within ~5 ± 10 mmHg)
~85% of subjects
will see accurate BP
without a calibration
~15% of subjects will
see accurate BP with
a one-time calibration
Valencell is continually improving the BP software,
targeting ≥ 95% of subjects seeing calibration-free high accuracy

Feasibility has been demonstrated for “continuous” BP monitoring
Data collected from controlled breathing studies shows the expected 180º out-of-phase
relationship between systolic blood pressure and heart rate, with a resolution better than 5 mmHg

Feasibility has been demonstrated for “continuous” tracking
via stress-induced BP modulation
Preliminary testing of isostatic exercise protocols, designed to raise and lower BP by 20 mmHg,
has shown that Valencell’s BP monitoring solution is capable of continuous tracking

“Your numbers look great. I’ve updated your
diet and exercise plan. Don’t forget you have
an 8AM meeting today.”
“I’ve recommended the route that keeps
your BP lowest for your commute today.”
“I noticed you’re
having an after-
lunch food coma
- you might want
to take a quick
walk and get a
cup of coffee.”
“I’ve customized this
exercise session based
on your activity today to
get you in Heart Rate
Zone 2 which helps lower
blood pressure.
Enjoy!”
“Would you like me to play
your relaxing track for your
commute today?”
“Your BP is elevated, and you appear to
be stressed. Would you like me to start a
relaxation session?”
“It seems like you had a stressful day. Would
you like to do a quick meditation to relax?
Overall your weekly BP trend look good –
keep up the exercise plan.”
“I’ve prepared a
summary of how
well you did on
your exercise
goals on your
phone. I’ll play
your relaxation
music.”
General Wellness:
Monitoring BP using a
biometric audio earbud

Medical Device:
Monitoring BP via a
biometric earpiece
Earbud measures:
• Heart rate
• Heart rate variability
• Blood oxygenation
• Blood pressure
• Body temperature
Sends data to electronic
health record periodically
Healthcare provider
and patient discuss
vital signs, trends in
numbers, and any
changes suggested for
exercise and diet plan.

Where we’re going from here
Expanding Data Collection
Continual Model
Improvement
Other Body Locations &
Form Factors

Valencell BP Evaluation Kit
Valencell’s Evaluation Kit for the calibration-free, cuff-less blood pressure technology includes the following:
Hardware
• Wired earbud with embedded PPG-
sensor
• USB development board
• Low-power MCU board
• PC (provided by evaluating team)
Software
• Blood pressure firmware embedded
in MCU board
• All of Valencell’s biometrics are
delivered on the same MCU
• PC data collection app
Documentation
• Evaluation Kit user guide
• Guidance on hardware & software
set-up and use; data collection
videos
• Test procedures and validation
white papers

Summary
• Valencell’s calibration-free PPG BP monitoring solution demonstrates cuff-like performance
without the cuff
• Following the data collection guidelines of the ISO 81060-2:2018 protocol, the ear PPG BP
solution demonstrated an accuracy within the required error limit of 5 ± 8 mmHg for the
qualified test dataset
• The current solution is ready for commercialization in the consumer market as a general
wellness product, and regulatory efforts are underway to enable medical-grade solutions
• Though not designed for continuous monitoring, successful continuous monitoring has been
demonstrated
• Evaluation Kits with Valencell’s BP technology are available now – reach out at
info@Valencell.com if you are interested in collaborating on a device together!

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