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

AccurateMean 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 disengagePressure 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

replacedResearch

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

handUsability 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

assessmentDeveloped requirements

& specifications

Generated >100 concepts

& nonfunctional prototypesSelected 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