Blood Pressure Measurement in
Low-Resource Settings
Group 38
Members: Satish Chandrasekhar, Karthik Krishnan, Matt Everett
Client: Dr. Donald Elbert
September 22, 2014
Background and Need for
Blood Pressure Measurement
Blood Pressure
Classification
Systolic BP (mmHg)
Diastolic BP
(mmHg)
Need Both/Either?
Hypotension
<90
<60
Either
Normal
(Normotension)
90-120
60-80
Both
Prehypertension
120-139
80-89
Either
Stage 1 Hypertension
140-159
90-99
Either
Stage 2 Hypertension
>159
>99
Either
Table 1. NIH Guidelines for Hypotension and Hypertension Diagnosis
Problems with Hypertension/Hypotension
• Hypertension is a precursor to cardiac disease
• Myocardial Infarction
• Stroke
• Chronic Heart Failure
• Hypotension
•Dizziness
• Fainting
Demographics of Hypertension
Country
Adults w/
hypertension (%)
USA
33
India (urban, 30% of
population)
40.6
India (rural, 70% of
population)
17
India (total)
25
• 2009 – Contributed to 348,000
deaths
• 170 million cases in India
• 77.9 million cases in the United
States
Need for Blood Pressure Measurement
• Approximately 20% of adults with hypertension in US unaware that
they have disorder
• 16% of all adults in India undiagnosed
• Limitations:
• Cost
• Training
Measurement Techniques
and Existing Technologies
Auscultatory Method
• Widely used in clinic by doctors
• Inflate and deflate cuff while
listening to sounds in
sphygmomanometer
Use of Korotkoff sounds in BP measurement. Shaded region of curve represents region in which
sounds can be distinguished [14] .
Aneroid Sphygmomanometer
• Used in conjunction with stethoscope
• Uses auscultatory method
• Cost: $10 - $60
• Accuracy within 0.4kPa (3 mm Hg)
•Measured by trained clinicians
• Medical training required to
distinguish sounds
Aneroid sphygmomanometer
[15]
Oscillometric Method
• Measures pressure waves
• Can measure mean arterial
pressure accurately
• Not as good of estimates
for systolic and diastolic
pressure
http://tensoval.com/oscillometric-measurement-devices.php
Wrist Monitors
• Uses oscillometric method
• Requires little to no training to
use
• Cost: $30 - $90
• Susceptible to changes in body
position
Omron Wrist Monitor [34]
LionsGate Mobile BP Monitor
• Also uses oscillometric method
• Outputs results to mobile
smartphone
• Currently not on market for sale
Pulse Wave Velocity
• Measure pulse at two points on body, and
amount of time needed for pulse to reach
each point
• Velocity = Distance/Time
• Not as accurate
• Susceptible to motion artifacts and
variations due to body position
• Needs to be calibrated with other BP
measurement technique
http://content.onlinejacc.org/article.aspx?articleid=1144323
SOMNOtouch by SOMNOmedics
• Uses Pulse Wave Velocity
Method
• Outputs data to wrist monitor
• Also not available for sale in US,
pending FDA approval
Invasive Cannulation
• Insert cannula into artery to measure
blood pressure changes
• Most accurate method
• Drawbacks:
• Invasive/inconvenient
• Training required to perform procedure
Cannulation of Radial Artery [33]
Patents
• Patch Sensor
• Optical Methods
•Emission, reflection, sensing
•Calibrate using BP measurements
Patch Sensor
Project Scope and
Design Specifications
Design Specifications
Parameter
Specification
Cost
Less than $25 (Rs. 1500)
Training Required to Operate
Literate individuals with no medical training
Rapid
Results within 30 seconds of set-up
Accurate
Within 0.67kPa (5 mmHg) of current methods
Reusable
All components must be reusable
Safe
Must not cause harm to user
Measurement
Non-continuous, as a screening tool
Non-invasive
Must not require surgical procedure to measure
Preliminary Design Schedule
and Team Responsibilities
Tentative Design Schedule
Team Responsibilities
• All 3 members have input in all parts of design process
• Would also collaborate to learn unfamiliar material
• Strengths/Focus:
• Matt – Software
• Satish & Karthik – Electronics/Circuits
• All 3 members will work to schedule meetings with client (Dr. Elbert)
and mentors
Questions?
References
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References
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30.
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31.
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32.
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