Continuous Wave Continuous Wave Doppler DeviceDoppler Device

Group 16:Group 16:Abbas BandukwalaAbbas BandukwalaPadma ChunduruPadma Chunduru

Chris HarveyChris HarveyAdvisor: Dr. Raul GuzmanAdvisor: Dr. Raul Guzman

Project ObjectiveProject Objective

Design, build and test a system to Design, build and test a system to measure Doppler velocity waveforms measure Doppler velocity waveforms in ankle blood vesselsin ankle blood vessels

Improve current technologyImprove current technology Better signal qualityBetter signal quality Easier measurementEasier measurement

Peripheral Vascular Peripheral Vascular Disease (PVD)Disease (PVD)

Definition: restriction of blood flow to limbs Definition: restriction of blood flow to limbs due to narrowing or clogging of arteriesdue to narrowing or clogging of arteries

CausesCauses Common vascular diseasesCommon vascular diseases Artherosclerosis, aneurysms, venous thrombosisArtherosclerosis, aneurysms, venous thrombosis Distort normal blood pressure and flowDistort normal blood pressure and flow

At risk populationsAt risk populations >50 years old>50 years old SmokersSmokers DiabeticsDiabetics High blood pressure or high cholesterolHigh blood pressure or high cholesterol

Peripheral Vascular Peripheral Vascular Disease (PVD)Disease (PVD)

Incidence of PVDIncidence of PVD 1 in 20 people >50 years old = ~10 1 in 20 people >50 years old = ~10

million peoplemillion people 75% of cases go undiagnosed75% of cases go undiagnosed

Importance of DiagnosisImportance of Diagnosis PVD is a strong predictor of heart PVD is a strong predictor of heart

diseasedisease PVD patients are at a higher risk of PVD patients are at a higher risk of

stroke and heart diseasestroke and heart disease

Noninvasive Vascular Noninvasive Vascular Disease DiagnosisDisease Diagnosis

Disease diagnosis using noninvasive Disease diagnosis using noninvasive techniquestechniques Check for presence, location, severity of Check for presence, location, severity of

diseasedisease External diagnosis is quick, noninvasiveExternal diagnosis is quick, noninvasive Screen high-risk patient populationsScreen high-risk patient populations Goal: reduce the number of Goal: reduce the number of

undiagnosed cases of PVDundiagnosed cases of PVD ~50 screenings/month or ~600 ~50 screenings/month or ~600

screenings/year at the Vanderbilt screenings/year at the Vanderbilt University Vascular LabUniversity Vascular Lab

Noninvasive Noninvasive MeasurementMeasurement

Blood pressure Blood pressure cuff occlusion cuff occlusion techniquetechnique

Doppler velocity Doppler velocity waveforms are waveforms are measured at DP measured at DP and PT arteries and PT arteries in anklein ankle

medicine.ucsd.edu/clinicalmed/ extremities.htm

www.curtin.edu.au/.../podiatry/ encyclopedia/vasdisease/

For the DP, the pulse felt on the top of the For the DP, the pulse felt on the top of the foot,  between the first and second metatarsal foot,  between the first and second metatarsal bones. In 8 to 10 per cent of the population this bones. In 8 to 10 per cent of the population this pulse cannot be detected. (www.WebMD.com)pulse cannot be detected. (www.WebMD.com)

Noninvasive Noninvasive Measurement for DPMeasurement for DP

http://www.csuchico.edu/phed/atc/Foot/PostTibArtery.jpg

Noninvasive Noninvasive Measurement for PTMeasurement for PT

Doppler Velocity Doppler Velocity WaveformsWaveforms

Triphasic, Normal

Biphasic, Abnormal

Monophasic, Abnormal

Doppler TheoryDoppler Theory

Measures velocityMeasures velocity 2 piezoelectric 2 piezoelectric

crystalscrystals Transmitting, Transmitting,

receivingreceiving Change in Change in

frequency due to frequency due to movement of red movement of red blood cellsblood cells

Crystals

RBCBlood Flow

Current Non - Invasive Current Non - Invasive Methods UsedMethods Used

Continuous Wave Continuous Wave Doppler PenDoppler Pen

PlethysmographyPlethysmography

Duplex Duplex UltrasonographyUltrasonography

Advantages/Advantages/DisadvantagesDisadvantages

Hard to locate proper vein Hard to locate proper vein or artery if blood velocity or artery if blood velocity is low.is low.

Must train person to use Must train person to use device.device.

User hand tied down with User hand tied down with devicedevice

Duplex ultrasound device Duplex ultrasound device is very large and expensiveis very large and expensive

Device is compatible with Device is compatible with all persons. all persons.

How we are going to go How we are going to go about solving the problem?about solving the problem?

Ace Bandage

Piezoelectric Crystals

Data Acquisit

ion & Analysis

High Pass & Amplifier circuit

Power Supply

A/D Converter

Advantages of Doppler Advantages of Doppler Array and LabView ProgramArray and LabView Program Cheap because it does not require Cheap because it does not require

trained crewtrained crew Easier to find signalEasier to find signal Better analysis of patient vascular system Better analysis of patient vascular system

in lower extremities in lower extremities Works on a high percentage of the Works on a high percentage of the

populationpopulation Universality of deviceUniversality of device User is able to perform multiple functionsUser is able to perform multiple functions

PartsParts

Doppler crystal Doppler crystal array ($45/crystal)array ($45/crystal)

Doppler pens Doppler pens ($100/pen)($100/pen)

ComputerComputer Connectors Connectors

(~$25/crystal)(~$25/crystal) A/D ConverterA/D Converter LabViewLabView

An Ace bandageAn Ace bandage Doppler GelDoppler Gel Doppler Audio Doppler Audio

Amplifier Amplifier Power supplyPower supply Op-amps, resistors, Op-amps, resistors,

capacitorscapacitors BreadboardBreadboard

Past WorkPast Work Investigation into the use of Doppler as a Investigation into the use of Doppler as a

means of vascular disease diagnosismeans of vascular disease diagnosis Research on the equipment necessary for Research on the equipment necessary for

data acquisitiondata acquisition Acquisition of equipmentAcquisition of equipment Multiple signals (waveform) can be Multiple signals (waveform) can be

displayed on LabView programdisplayed on LabView program LabView program can pick the signal with LabView program can pick the signal with

higher amplitudehigher amplitude

Current StatusCurrent Status

Development of LabView programDevelopment of LabView program Input of audio Doppler outputInput of audio Doppler output Display of signal on an oscilloscope in LabViewDisplay of signal on an oscilloscope in LabView Recording of data for analysis (of signal Recording of data for analysis (of signal

quality) quality) Highest Signal to Noise Ratio (SNR) Highest Signal to Noise Ratio (SNR)

Current StatusCurrent Status

Audio Doppler Box

LabView Program

A/D Converter

Doppler Pencil

Audio Doppler Box

FutureFuture

LabView changes to pick the higher LabView changes to pick the higher SNR as opposed to higher SNR as opposed to higher amplitudeamplitude

Working on crystals that can give Working on crystals that can give signal and can eventually be signal and can eventually be incorporated into an arrayincorporated into an array Increase sensitivity so the input signal Increase sensitivity so the input signal

can be perceivedcan be perceived