Transcript Hypertension Detector for Developing Countries

Hypertension Detector for
Developing Countries
Matthew Trachtenberg
Leading Causes of Deaths, by Country Income Level
Matthew Trachtenberg 2010
"Global Health Risks: Selected Figures and Tables." (2004).
http://www.who.int/entity/healthinfo/global_burden_disease/global_health_risks_report_figures.ppt.
What are the biggest contributors to global mortality
– Risk Factors
13.5% of Deaths
Worldwide
Matthew Trachtenberg 2010
Lopez, AD, CD Mathers, and M Ezzati. Global Burden of Disease and
Risk Factors. Oxford University Press, USA, 2006. Print.
Costs of Hypertension
• Suboptimal blood
pressure costs
$370 Billion
globally
– Treatment may cost
up to $1 Trillion in
health spending
– Indirect costs could be
as high as $3.6 Trillion
Gaziano, T. , Bitton, A. , Anand, S. , Weinstein, M. , , . (2009). The Global Cost of
annually
Nonoptimal Blood Pressure. Journal of Hypertension, 27(7), 1472-1477.
http://www.rd.com/living-healthy/high-blood-pressure-causes/article118951.html
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Need 1: Detect Hypertension
• Reliably detect hypertension (systolic BP >
140mmHg, diastolic BP > 90mmHg)
– False Positives versus False Negatives
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Births Attended by Skilled Health Personnel
Africa
North and South America
Southeast Asia Region
8%
54%
Attended
46%
Europe
4%
Attended
92%
Eastern Mediterranean
Region
Attended
48%
52%
Western Pacific Region
8%
41%
Attended
96%
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Attended
59%
Attended
92%
"World Health Statistics." (2009). <http://www.who.int/whosis/whostat/en/>.
Need 2: User-Friendly
• Easy to use – user may not be able to read or
understand numbers
• Minimal training required
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Preeclampsia
• Preeclampsia/eclampsia is a severe
complication of pregnancy classically diagnosed
by severe hypertension and protein in urine
•Preeclampsia/eclampsia is currently the 2nd
leading cause of maternal mortality in
developing countries; partly due to low
detection rates
•Of the small fraction of women who receive
prenatal care, only half of them are estimated to
have had their blood pressures monitored
•Treatment (injectable magnesium sulfate) is
cheap and effective but relies on accurate and
early diagnosis
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http://www.jhpiego.org/quarterly/winter09/Nepal.htm
Preeclampsia
(A) Size of territory
drawn according to its
land area.
(B) Size of territory
drawn according to its
population.
(C) Size of territory
drawn according to the
proportion of maternal
deaths that occur there
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Duley, Lelia. "The Global Impact of Pre-Eclampsia and Eclampsia." Seminars in Perinatology 33 3 (2009):
130-37. Print.
Need 3: Respect the Culture
• Women in deeply conservative societies will
not expose their upper arm to a volunteer for
a typical blood pressure cuff.
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Public Spending on Health
Per Person:
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Dorling, Newman, et. al. World Mapper (2005).
<http://www.worldmapper.org/textindex/text_health.html>.
Need 4: Usable in Developing Countries
• Inexpensive to manufacture (<$10)
• Devices that can be recharged/powered by
alternative power sources.
• Robust in wide temperature ranges and in
extreme dry and wet areas. Survive water and
drops
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Hypertension Detector - Preeclampsia
•
Purpose: Detect all preeclampsia conditions by testing in a community done
by semi-literate volunteers who will visit house to house to check the blood
pressure of pregnant women on a regular basis.
Specifications:
• Reliably detect hypertension (systolic BP > 140mmHg, diastolic BP > 90mmHg)
• Easy to use– user may not be able to read or understand numbers
• Minimal training needed.
• Easy to accurately calibrate in the field
• Culturally compatible e.g. women in deeply conservative societies will not
expose their upper arm for a typical blood pressure cuff.
• Inexpensive to manufacture (<$10)
• Power that can be recharged/generated by alternative power sources.
• Robust in wide temperature ranges and in extreme dry and wet areas.
As Requested by JHPIEGO
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Technologies Available for Preeclampsia Diagnosis
Intra-arterial Measurement
• Highly Accurate
• Highly Invasive
• Extensive Training
Required
• Expensive Recording
Equipment Necessary
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http://www.medtek.ki.se/medicaldevices/album/Ch%206%20Mea
surement%20methods%20&%20values/slides/F%20611b%20Intra-arterial%20blood%20pressure%20measurent.html
Key technologies needed for Preeclampsia Diagnosis
Korotkoff Sounds
• No power source
• Extensive Training Required
– Sphygmomanometer
– Cuff inflated above arterial
pressure (obliteration of pulse)
– Cuff is gradually deflated
– Korotkoff sounds appear and
disappear at the systolic and
diastolic pressure respectively
• Necessary to interpret
numbers/results correctly
Perloff, D, et al. "Human Blood Pressure Determination by
Sphygmomanometry." Circulation 88 5 (1993): 2460. Print.
http://www.topnews.in/usa/files/Blood%20Pressure.jpg
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Key technologies needed for Preeclampsia Diagnosis
Complete Care Blood Pressure
System - $129
• Two cuff sizes
• Reports systolic and diastolic
blood pressure, pulse, time, and
date
• Has hypertension indicator
• Has irregular heartbeat
detector
• Stores and averages readings
• Runs on 4 AAA batteries
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http://www.seventhavenue.com/catalog/product.jsp?productId=45496
Key technologies needed for Preeclampsia Diagnosis
Gitway Inc Blood Pressure
Monitor - $20
• Worn on the wrist
• Shows your pulse and
systolic/diastolic pressures
• Memory recall stores 60
previous readings
• Requires two AA batteries
(not included)
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http://www.amazon.com/Get-Organized-JB5237-PRESSURE-MONITOR/dp/B0013J9LYS
Key technologies needed for Preeclampsia Diagnosis
Microlife 3AS1-2 ~$30
• Semi-automated
upper arm device
• Memory of 60
readings with averaging
ability
• Blood pressure and
pulse measurement
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de Greeff, A., et al., Development of an accurate oscillometric blood pressure device for
low resource settings. Blood Pressure Monitoring, 2008. 13(6): p. 342.
Key technologies needed for Preeclampsia Diagnosis
Clinitek 100 Ames - $700
• Configured to read
MULTISTIX 10 SG Reagent
Strips ( ~ $0.35 each)
• A reflectance photometer
that analyzes the color and
intensity of the light
reflected from the reagent
area and displays the
results in clinically
meaningful units.
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http://www.dotmed.com/listing/512737
Key technologies needed for Preeclampsia Diagnosis
Dipsticks for Proteinuria
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• In the absence of
protein, the dipstick
panel is yellow.
• Proteins in solution
interfere with the dyebuffer combination,
causing the panel to
turn green.
• Indicate early renal
damage.
Carroll, MF, and JL Temte. "Proteinuria in Adults: A Diagnostic Approach."
American family physician 62 6 (2000): 1333-42. Print.
How the Devices Add Up
Device
New Design
Intra-Arterial
Korotkoff
Sounds
Complete Care
BP System
Detect
Hypertension
yes
User-Friendly
Respect
Culture
yes - gives binary result and
yes - used
user only needs to inflate
on the wrist
cuff
yes
yes
yes
no - requires extensive
training
no - requires extensive
training
yes - has hypertension
indicator
no
no
Developing
Countries
Price
yes - crank power
less than $10
no - requires sterility
due to invasiveness
and an outlet for the
measurement device
yes - no power
required
no - battery-powered
over $100
no
yes - solar power
charger is being
developed
$30
Microlife
yes
Gitway Inc BP
Monitor
yes
no - user has to interpret yes - used
no - battery-powered
results
on the wrist
Preeclampsia
Dipsticks
yes
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$15 for a kit
no
no - user has to interpret
results
yes - color coded
expensive
yes
yes - no power
required
$20
Around $1
each
My First Prototype < $20
Photoplethysmography
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Modular and Alternative Power
Sources
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Honors Instrumentation Project
Fall 2009 – Trachtenberg, Stark
Design – Gowri Jayaram and Shin Rong Lee
• Automatic pump to inflate
• Solenoid valve to deflate
• Used parts and packaging from a disassembled wrist BP cuff
on the market
• Battery Powered (9v)
Honors Instrumentation Project
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Fall 2009
Oscillometric Method
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http://www.blood-pressure-hypertension.com/how-to-measure/measureblood-pressure-8.shtml
New Design/Project Proposal
• Cost < $10
• Interchangeable with any standard cuff
• Has hypertension indicator (initially measures
just diastolic pressure but eventually both)
– Visual LED (red/green) feedback means there is no
need for an LCD screen
• Crank-powered. ~20 seconds of cranking per
use
• Manual pump to inflate and a leaky valve to
deflate
• Worn on the wrist
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New Design/Project Proposal
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Is this just a cheap version of other
devices?
No.
• A crank utilized to charge a super-capacitor will eliminate costs
from batteries and their replacements. A super-capacitor can
withstand the charging and discharging over the entire life of the
device without a replacement needed.
• Instead of an LCD screen outputting specific numbers, the
microcontroller will interpret what they mean and diagnose the
person as hypertensive or healthy. This will save LCD screen costs
and make the device more user-friendly.
• The device is designed to be modular so that donated cuffs can
be used with the device and replaced by new ones as needed.
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Acknowledgements
•JHPIEGO
•Dr. Acharya and Dr. Thakor for their guidance and assistance
•Mr. Christopher Browne and Mr. Martin Pearson for his
advice, and materials
•Heather Benz, Nasir Bhanpuri , Mehdi Rahman, Bejan
Darbandi, Natan Davidovics for their advice, and input
Questions/Feedback
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Blood Pressure Detection Algorithm
>90
mm
Hg
Ye
s
Ye
s
Light
Green
LED
Crank
device for
power
N
o
Pump to
180mmHg
N
o
Light
Red
LED
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Light
Yellow
LED
Deflate Cuff
~(2mmHg/s)
Detect Max
Pulse
Amplitude
and 2/3
Pulse
Amplitude
Light
Red
LED
Read
Pressure
<90m
mHg
Light
Green
LED
Circuit Diagram
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Cost Analysis
-Wrist Cuff with Air Bladder, Bulb, Tubing
$ 0.50
-Pressure Sensor
$ 6.89
-Circuit components
$ 6.00
-Hand Crank Power Generator
$ 2.00
TOTAL COST
$15.39
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System Circuit
Matthew Trachtenberg 2010