The document summarizes the design and evaluation of a blood pressure measurement device for use in low-resource settings. It describes: 1) Requirements defined through stakeholder interviews to address the need for periodic blood pressure monitoring in busy hospital wards. 2) The design process including prototyping, usability testing, and validation studies with nursing students and healthcare providers in Ghana. 3) Evaluation results showing the prototype met most requirements, with further changes needed to reduce size and cost and add multiple cuff sizes.

1. The final design is an auscultatory blood pressure measurement device along with the evaluation of how this prototype
meets the engineering specifications.
First functional prototype was evaluated on how it met the user
requirements engineering specifications.
Requirements were defined and translated into specifications through
interviews, observations, research, and benchmarking. A subset of the
requirements are shown below
The second leading cause of maternal mortality worldwide and the third
leading cause of maternal mortality in Ghana is hypertensive disorders
during pregnancy, mainly preeclampsia and eclampsia. [1,2]
The team observed that due to the business of the wards, it was difficult
for healthcare providers to periodically measure blood pressure.
Blood Pressure Measurement Device
for use in Low-Resource Settings
PROBLEM
ACKNOWLEDGMENTS
User Requirements Specification
Safe
< 10 seconds to disengage
ISO hazard numbers for health, flammability, and
reactivity should be 0.
Adheres to standards of medical devices
Accurate
Mean difference ≤5 mmHg and standard deviation
of 8 mmHg for measurements compared to
mercury sphygmomanometer measurements
Easy to Maintain
All parts and maintenance tools accessible in
Ghana
All parts independently replaced
Allows for calibration in intended use setting
Easy to Operate
< 3 minute to use
>80 uses per charge cycle
No more than 1 additional piece of equipment in
order to operate
Portable
>80% of users carry with one hand
<320mm (L) x134mm(W)x 84mm(H)
<2.8 kg
Low-Cost ≤ $75
REQUIREMENTS AND SPECIFICATIONS
FINAL DESIGN & EVALUATION
Prof. C.A.Turpin, Prof. K. A. Danso, Prof. A. T. Odoi, Prof. H. S. Opare-Addo, and Dr. Thomas Okpoti
Konney, Staff from Obstetrics and Gynecology Department at Komfo Anokye Teaching Hospital, Amy
Hortop, Toby Donajkowski, ME 450 staff, Maria Young and Insitu consultants from University of Michigan
College of Engineering, and Michelle Aebersold, Ben Oliver, and nursing students from UM Nursing School
Table 1 Design driving requirements and specifications [1] Say L … (2014) Global Causes of Maternal Death: A WHO Systematic Analysis, Lancet.
[2] Der, E. M., Moyer, C., Gyasi, R. K., Akosa, A. B., Tettey, Y., Akakpo, P. K., … Anim, J. T. (2013). Pregnancy Related Causes of Deaths in Ghana: A 5-Year Retrospective
Study. Ghana Medical Journal, 47(4), 158–163.
[3] Reinders, A., Cuckson, A.C., Lee, J.T.M., Shennan, A.H., 2005, "An Accurate Automated Blood Pressure Device for Use in Pregnancy and Pre-eclampsia: the Microlife
3BTO-A", an International Journal of Obstetrics and Gynaecology, DOI: 10.1111/j.1471-0528.2005.00617.x
Gauge for checking
accuracy
Headphones
Buttons to mark
systolic (left) and
diastolic (right)
pressure values
Stethoscope
Cuff
Deflation button
LCD Screen
Table 4 Main design critiques and resulting changes to design
Device casing
with storage
DESIGN PROCESS
Advantages (+) Disadvantages (-)
• Accurate – gold standard • “Cumbersome”
• Mercury used
• Stethoscope required
• Easy to use
• Quick
• No additional equipment
• Expensive
• Difficult to maintain
• Inaccuracies in
hypertension [3]
EVALUATION
Figure 1 Comparison of commonly used devices
Figure 3 Device design and its components
• Creating a rechargeable power supply circuit
• Lowering cost of device
• Continuing accuracy and usability testing with n > 30 UM nursing students
• Obtaining feedback from physicians, biomedical technicians, and other
stakeholders in Ghana
Performed
validation studies
KATH : July-August, 2015
U of M : Present
Requirement Evaluations Performed Resulting Change
Accurate •Measurement range test
•Deflation Rate test
•Accuracy comparison to aneroid gauge
device
• Deflation method sound and
air fluctuation reduction
• Microphone stethoscope
noise reduction
Easy to Operate •Timed procedure length (n=3)
•Simulations with nursing students (n=3)
• Button placement location in
closer proximity to user
Portable •Portability testing (n=20)
•Device measured & weighed
• Device size reduction
Second functional prototype was evaluated on its design and functions
by KATH and Korle Bu Teaching Hospital healthcare providers (n=45).
Table 3 Excerpt of evaluations performed and design changes made based on the results
Figure 2 Design process, prototype generation, and evaluation process flow chart
Current prototype was evaluated and the design was critiqued.Specification Protocol Validation
< 10 seconds to disengage
Pressure disengage time
measurement
No hazardous material Cross-checking
Adheres to standards of
medical devices
Standards testing and
cross-check
Mean difference ≤5±8
mmHg
Simulation Testing
All parts and maintenance
tools accessible in Ghana
Consult with KATH
biomedical technicians
All parts independently
replaced
Research
Allows for calibration in
intended use setting
Consult with KATH
biomedical technicians
< 3 minute to use
Procedure time
measurement
>80 uses per charge cycle Energy Analysis
No more than 1 additional
piece of equipment needed
Observed required for
cross-check
>80% users carry with 1
hand
Usability Testing
<320(L)x134(W)x84(H)mm3 Direct Measurements
<2.8 kg Direct Measurements
≤ $75 Bulk Price Cost Analysis
Table 2 Results for preliminary device evaluations performed
Hand pump
Requirement Feedback Resulting
Change
Accurate + Measurement comparisons (LCD & aneroid gauge)
− Different cuff sizes needed
− Button response time slow-
•Addition of cuff
connector
•New button delay
time
Easy to Operate + Microphone stethoscope–
+ Automatic deflation
+ Measurement values on screen
− Need different systolic and diastolic button placement
•New button design
placement
Portable − Device’s large size •Size reduction
The team conducted design ethnography in the Department of Obstetrics
and Gynecology at the Komfo Anokye Teaching Hospital (KATH) in Ghana.
• Performed eight weeks of clinical observations to conduct interviews,
focus groups, and observations with over 60 KATH stakeholders
• Informed down selection with input from domestic and Ghanaian
stakeholders
BENCHMARKING
Problem Definition & Concept Generation Prototyping
Usability Testing Validation
FUTURE WORK
Preliminary Validation Completed
Further Validation Needed
Specification Not Met
Performed needs
assessment
Developed requirements
& specifications
Generated >100 concepts
& nonfunctional prototypes
Selected final concept
and built 1st prototype
U of M: Sept-Dec, 2015
Returned to KATH for
design evaluation
KATH : March, 2016
Evaluation and Redesign
Iterated design &
built 2nd prototype
U of M: Dec-Feb, 2016
3rd prototype validation
studies with nursing
students
Requirement Outcome
Ease of Use 13 out of 17 prefer prototype over
mercury sphygmomanometer
Ease to Transportability 12 out of 18 prefer the prototype over
the mercury sphygmomanometer
Safe 13 out of 17 viewed the prototype to
be safer than the mercury
sphygmomanometer
Table 5 Results of surveys from Ghanaian healthcare providers
A need was identified for a maintainable device to assist healthcare
providers in periodically measuring the blood pressures of
obstetrics patients in low-resource tertiary referral hospitals.
Mercury sphyg
Automatic bp
device
Figure 4 Nonfunctional
prototype used to get design
feedback
+
The device allows for
measurements
without graduated
markings
-
Device requires
additional step with
buttons
+
Device can be
calibrated using a y-
tube
-
Device’s
manufacturing cost
estimate is high
+ Device is portable -
Device needs
different cuff sizes for
various patients
+
Device is modularly
design with
accessible parts
- Device is big
Table 6 Design critique of the current prototype
Current evaluations
performed include:
• 19 out of 20 students
carried device with one
hand
• Estimated manufacturing
price is $76.50
• Current prototype is
308mm x 153mm x 100
mm
Jungsoo Chang, Lauren Kennedy, Si Long Tou, Caroline Soyars, Dr. Thomas Konney, Prof. Cornelius Turpin, Prof. Kathleen Sienko