Peak Inspiratory and Peak Inspiratory and Expiratory Flow Meter Expiratory Flow Meter

Team:Team:

Andrew Eley, Sarah Offutt, Darshan Patel,Andrew Eley, Sarah Offutt, Darshan Patel,

Eric BaderEric Bader

BME 200/300BME 200/300

December 2, 2005December 2, 2005

Client:Client:Christopher G. Green, MDChristopher G. Green, MD

Pediatric Pulmonology Pediatric Pulmonology UW HospitalUW Hospital

Advisor:Advisor:John Webster, Ph.D.John Webster, Ph.D.

Dept. of Biomedical EngineeringDept. of Biomedical EngineeringUniversity of WisconsinUniversity of Wisconsin

AbstractAbstract A device for measuring both peak inspiratory A device for measuring both peak inspiratory

and expiratory air flow in a single device is and expiratory air flow in a single device is desired. It will help prevent the misdiagnosis desired. It will help prevent the misdiagnosis of vocal chord dysfunction as asthma. A of vocal chord dysfunction as asthma. A prototype was built to measure these air prototype was built to measure these air flows. The design is a clear plastic tube that flows. The design is a clear plastic tube that contains a plunger which pushes the indicator contains a plunger which pushes the indicator arrows depending on the air flow. The device arrows depending on the air flow. The device was calibrated and tested with a rotameter. was calibrated and tested with a rotameter. Future work includes manufacturing of better Future work includes manufacturing of better parts, obtaining a patent, and marketing for parts, obtaining a patent, and marketing for use. use.

Problem StatementProblem Statement The goal of this project was to create a The goal of this project was to create a

peak inspiratory and expiratory flow meter peak inspiratory and expiratory flow meter in a single device. Peak expiratory flow in a single device. Peak expiratory flow meters are used to monitor asthma and meters are used to monitor asthma and measure flows of about 700 liters per measure flows of about 700 liters per minute. Vocal chord dysfunction, which minute. Vocal chord dysfunction, which causes stenosis of air passages during causes stenosis of air passages during inspiration, is often misdiagnosed as inspiration, is often misdiagnosed as asthma. Having a peak inspiratory and asthma. Having a peak inspiratory and expiratory flow meter in one device can expiratory flow meter in one device can help prevent a misdiagnosis of a patient’s help prevent a misdiagnosis of a patient’s condition. condition.

BackgroundBackground

Asthma Asthma – Exhaling, air restrictions in Exhaling, air restrictions in

the lower airwaysthe lower airways– Caused by external triggersCaused by external triggers– Treated with medicationsTreated with medications

Vocal Chord DysfunctionVocal Chord Dysfunction– Inhaling, air restrictions Inhaling, air restrictions

caused by vocal chordscaused by vocal chords– Possible causes, exercise, Possible causes, exercise,

nervousnessnervousness– Treated with speech Treated with speech

therapytherapy

Background/Current MethodsBackground/Current Methods

Expiratory Flow Meters, Expiratory Flow Meters, use to monitor asthmause to monitor asthma– Exhaling force moves Exhaling force moves

plungerplunger– PortablePortable– Measured in Measured in

Liters/MinuteLiters/Minute– Breathing ZonesBreathing Zones

Inspiratory Flow MeterInspiratory Flow Meter– Inhaling force moves Inhaling force moves

plungerplunger– PortablePortable

Proposed DesignProposed Design

Design CriteriaDesign Criteria– Combination Combination

expiratory-inspiratory expiratory-inspiratory flow meterflow meter

– Measure peak flow rates, 700 L/min expiratory, 400L/min inspiratory

– Simple device using Simple device using springs and diskssprings and disks

– No use of electricityNo use of electricity– Safe – clear plasticSafe – clear plastic

Altered DesignAltered Design

Prototype DesignPrototype Design

How it worksHow it works– Dual ActionDual Action

Inhaling/ExhalingInhaling/Exhaling

– Plunger pushes Plunger pushes Indicator ArrowsIndicator Arrows

– Springs balance the Springs balance the force on the plunger force on the plunger caused by the caused by the pressure differencepressure difference

– Scale on the side for Scale on the side for reading reading measurementmeasurement

Testing and CalibrationTesting and Calibration

Used a rotameter Used a rotameter to calibrate and to calibrate and test the inspiratory test the inspiratory and expiratory and expiratory flows.flows.

ResultsResults

Peak Inspiratory Flow Calibration Curve

y = 0.1708e0.009x

R2 = 0.996

0

1

2

3

4

5

6

7

0 100 200 300 400 500

Flow (L/min)

Dis

tan

ce T

rave

rsed

(cm

)

Results Cont.Results Cont.Peak Expiratory Flow Calibration Curve

y = 0.5213e0.0093x

R2 = 0.9782

0

1

2

3

4

5

6

7

0 50 100 150 200 250 300

Flow (L/min)

Dis

tan

ce

Tra

ve

rse

d (

cm

)

Project ExpensesProject Expenses

Our Device --- Our Device --- MaterialsMaterials– Clear plastic tube Clear plastic tube

$1.97$1.97– End caps - plunger End caps - plunger

$1.96$1.96– Solid metal rod Solid metal rod $0.82$0.82– Connecting rodConnecting rod $0.30$0.30– Springs Springs $0.00$0.00

$5.05

Estimated Cost with

Manufactured parts

$4.50

Future WorkFuture Work Device made from machined parts with Device made from machined parts with

higher quality materialshigher quality materials– Indicators, plastic covering, Indicators, plastic covering,

removable mouthpieceremovable mouthpiece

Replacement with a new set of springs Replacement with a new set of springs to obtain a sufficient range with a linear to obtain a sufficient range with a linear relationship.relationship.

Add breathing zone indicators to show Add breathing zone indicators to show acceptable values for peak inspiratory acceptable values for peak inspiratory and expiratory flow.and expiratory flow.

Future Work Cont.Future Work Cont.

Calibrate device with a more accurate Calibrate device with a more accurate method and with multiple trials.method and with multiple trials.– Rotameter proved to be insufficient.Rotameter proved to be insufficient.

Possibly apply for a patent and find a Possibly apply for a patent and find a company to manufacture this device company to manufacture this device for commercial use.for commercial use.

ReferencesReferences Allen, James MD. (2002). Allen, James MD. (2002). Vocal Cord DysfunctionVocal Cord Dysfunction. Retrieved . Retrieved

October October 2, 2005, from2, 2005, fromhttp://home.columbus.rr.com/allen/http://home.columbus.rr.com/allen/

vocal_cord_dysfunction.vocal_cord_dysfunction.htm.htm.

American Lung Association. (2005, July). American Lung Association. (2005, July). Asthma in Adults Asthma in Adults Fact Fact SheetSheet. Retrieved October 2, 2005, from. Retrieved October 2, 2005, from

http://www.lungusa.org/site/pp.asp?http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=22596.c=dvLUK9O0E&b=22596.

Framingham School. (2005, June). Framingham School. (2005, June). Framingham School Health Framingham School Health Services: Asthma. Services: Asthma. Retrieved October 2, 2005. fromRetrieved October 2, 2005. fromhttp://www.framingham.k12.ma.us/schoolhealth/http://www.framingham.k12.ma.us/schoolhealth/

health_info/health_info/Asthma.htm.Asthma.htm.