Hypertension Detector for Developing Countries Matthew Trachtenberg.
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Transcript of Hypertension Detector for Developing Countries Matthew Trachtenberg.
Hypertension Detector for Developing Countries
Matthew Trachtenberg
Leading Causes of Deaths, by Country Income Level
"Global Health Risks: Selected Figures and Tables." (2004). http://www.who.int/entity/healthinfo/global_burden_disease/global_health_risks_report_figures.ppt.
Matthew Trachtenberg 2010
What are the biggest contributors to global mortality– Risk Factors
Lopez, AD, CD Mathers, and M Ezzati. Global Burden of Disease and Risk Factors. Oxford University Press, USA, 2006. Print.Matthew Trachtenberg 2010
13.5% of Deaths Worldwide
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 annually Gaziano, T. , Bitton, A. , Anand, S. , Weinstein, M. , , . (2009). The Global Cost of
Nonoptimal Blood Pressure. Journal of Hypertension, 27(7), 1472-1477.
http://www.rd.com/living-healthy/high-blood-pressure-causes/article118951.html
Matthew Trachtenberg 2010
Need 1: Detect Hypertension
• Reliably detect hypertension (systolic BP > 140mmHg, diastolic BP > 90mmHg)– False Positives versus False Negatives
Matthew Trachtenberg 2010
Births Attended by Skilled Health Personnel
At-tende
d46%
54%
Africa
Attended92%
8%
North and South America
At-tended
48%52%
Southeast Asia Region
Attended96%
4%
Europe
Attended59%
41%
Eastern Mediterranean Region
Attended92%
8%
Western Pacific Region
"World Health Statistics." (2009). <http://www.who.int/whosis/whostat/en/>.Matthew Trachtenberg 2010
Need 2: User-Friendly
• Easy to use – user may not be able to read or understand numbers
• Minimal training required
Matthew Trachtenberg 2010
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
http://www.jhpiego.org/quarterly/winter09/Nepal.htmMatthew Trachtenberg 2010
Preeclampsia
Duley, Lelia. "The Global Impact of Pre-Eclampsia and Eclampsia." Seminars in Perinatology 33 3 (2009): 130-37. Print.
(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
Matthew Trachtenberg 2010
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.
Matthew Trachtenberg 2010
Public Spending on Health
Dorling, Newman, et. al. World Mapper (2005). <http://www.worldmapper.org/textindex/text_health.html>.Matthew Trachtenberg 2010
Per Person:
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
Matthew Trachtenberg 2010
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.
Matthew Trachtenberg 2010As Requested by JHPIEGO
Intra-arterial Measurement• Highly Accurate• Highly Invasive• Extensive Training
Required• Expensive Recording
Equipment Necessary
Technologies Available for Preeclampsia Diagnosis
http://www.medtek.ki.se/medicaldevices/album/Ch%206%20Measurement%20methods%20&%20values/slides/F%206-11b%20Intra-arterial%20blood%20pressure%20measurent.html
Matthew Trachtenberg 2010
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
Key technologies needed for Preeclampsia Diagnosis
http://www.topnews.in/usa/files/Blood%20Pressure.jpg
Matthew Trachtenberg 2010
Perloff, D, et al. "Human Blood Pressure Determination by Sphygmomanometry." Circulation 88 5 (1993): 2460. Print.
Key technologies needed for Preeclampsia Diagnosis
http://www.seventhavenue.com/catalog/product.jsp?productId=45496
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
Matthew Trachtenberg 2010
Key technologies needed for Preeclampsia Diagnosis
http://www.amazon.com/Get-Organized-JB5237-PRESSURE-MONITOR/dp/B0013J9LYS
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)
Matthew Trachtenberg 2010
Key technologies needed for Preeclampsia Diagnosis
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.
Microlife 3AS1-2 ~$30
• Semi-automated upper arm device• Memory of 60 readings with averaging ability• Blood pressure and pulse measurement
Matthew Trachtenberg 2010
Key technologies needed for Preeclampsia Diagnosis
Matthew Trachtenberg 2010
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.
http://www.dotmed.com/listing/512737
Dipsticks for Proteinuria • In the absence of protein, the dipstick panel is yellow.
• Proteins in solution interfere with the dye-buffer 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.Matthew Trachtenberg 2010
Key technologies needed for Preeclampsia Diagnosis
How the Devices Add UpDevice Detect
Hypertension User-Friendly Respect Culture
Developing Countries Price
New Design yesyes - gives binary result and
user only needs to inflate cuff
yes - used on the wrist yes - crank power less than $10
Intra-Arterial yes no - requires extensive training no
no - requires sterility due to invasiveness
and an outlet for the measurement device
expensive
Korotkoff Sounds yes no - requires extensive
training no yes - no power required $15 for a kit
Complete Care BP System yes yes - has hypertension
indicator no no - battery-powered over $100
Microlife yes no - user has to interpret results no
yes - solar power charger is being
developed$30
Gitway Inc BP Monitor yes no - user has to interpret
resultsyes - used
on the wrist no - battery-powered $20
Preeclampsia Dipsticks yes yes - color coded yes yes - no power
requiredAround $1
each
Matthew Trachtenberg 2010
My First Prototype < $20
Matthew Trachtenberg 2010
Photoplethysmography
Modular and Alternative Power Sources
Matthew Trachtenberg 2010Honors 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)
Matthew Trachtenberg 2010Honors Instrumentation Project Fall 2009
Oscillometric Method
Matthew Trachtenberg 2010http://www.blood-pressure-hypertension.com/how-to-measure/measure-blood-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
Matthew Trachtenberg 2010
New Design/Project Proposal
Matthew Trachtenberg 2010
Is this just a cheap version of other devices?
Matthew Trachtenberg 2010
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.
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
Matthew Trachtenberg 2010
Blood Pressure Detection Algorithm
Matthew Trachtenberg 2010
Pump to 180mmHg
Light Green
LED
Deflate Cuff ~(2mmHg/s)
Detect Max Pulse
Amplitude and 2/3
Pulse Amplitude
Yes
No
Read Pressure
>90mmHg
<90mmHg
Light Yellow
LED
Crank device for
power
Yes
No
Light RedLED
Light RedLED
Light Green
LED
Circuit Diagram
Matthew Trachtenberg 2010
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
Matthew Trachtenberg 2010
System Circuit
Matthew Trachtenberg 2010