Peak Inspiratory and Expiratory Flow MeterClient: Christopher G. Green, MD Pediatric Pulmonology UW Hospital Advisor: John Webster, Ph.D. Dept. of Biomedical Engineering University of WisconsinAbstractProblem StatementBackgroundBackground/Current MethodsProposed DesignAltered DesignPrototype DesignTesting and CalibrationResultsResults Cont.Project ExpensesFuture WorkFuture Work Cont.ReferencesPeak 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 BaderBME 200/300BME 200/300December 2, 2005December 2, 2005Client:Client:Christopher G. Green, MDChristopher G. Green, MDPediatric Pulmonology Pediatric Pulmonology UW HospitalUW HospitalAdvisor:Advisor:John Webster, Ph.D.John Webster, Ph.D.Dept. of Biomedical EngineeringDept. of Biomedical EngineeringUniversity of WisconsinUniversity of WisconsinAbstractAbstractA 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 StatementThe goal of this project was to create a peak The goal of this project was to create a peak inspiratory and expiratory flow meter in a inspiratory and expiratory flow meter in a single device. Peak expiratory flow meters single device. Peak expiratory flow meters are used to monitor asthma and measure are used to monitor asthma and measure flows of about 700 liters per minute. Vocal flows of about 700 liters per minute. Vocal chord dysfunction, which causes stenosis of chord dysfunction, which causes stenosis of air passages during inspiration, is often air passages during inspiration, is often misdiagnosed as asthma. Having a peak misdiagnosed as asthma. Having a peak inspiratory and expiratory flow meter in one inspiratory and expiratory flow meter in one device can help prevent a misdiagnosis of a device can help prevent a misdiagnosis of a patient’s condition. patient’s condition.BackgroundBackgroundAsthma 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 medicationsVocal 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 therapyTreated with speech therapyBackground/Current MethodsBackground/Current MethodsExpiratory Flow Meters, Expiratory Flow Meters, use to monitor asthmause to monitor asthma–Exhaling force moves Exhaling force moves plungerplunger–PortablePortable–Measured in Liters/MinuteMeasured in Liters/Minute–Breathing ZonesBreathing ZonesInspiratory Flow MeterInspiratory Flow Meter–Inhaling force moves Inhaling force moves plungerplunger–PortablePortableProposed DesignProposed DesignDesign 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 plasticAltered DesignAltered DesignPrototype DesignPrototype DesignHow it worksHow it works–Dual ActionDual ActionInhaling/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 measurementreading measurementTesting and CalibrationTesting and CalibrationUsed a rotameter Used a rotameter to calibrate and to calibrate and test the inspiratory test the inspiratory and expiratory and expiratory flows.flows.ResultsResultsResults Cont.Results Cont.Project ExpensesProject ExpensesOur 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$5.05Estimated Cost with Manufactured parts$4.50Future WorkFuture WorkDevice 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 Calibrate device with a more accurate method and with multiple accurate method and with multiple trials.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.ReferencesReferencesAllen, James MD. (2002). Allen, James MD. (2002). Vocal Cord DysfunctionVocal Cord Dysfunction. Retrieved
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