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Continuous Wave Doppler Device

Continuous Wave Doppler Device. Group 16: Abbas Bandukwala Padma Chunduru Chris Harvey Advisor: Dr. Raul Guzman. Project Objective. Design, build and test a system to measure Doppler velocity waveforms in ankle blood vessels Improve current technology Better signal quality

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Continuous Wave Doppler Device

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  1. Continuous Wave Doppler Device Group 16: Abbas Bandukwala Padma Chunduru Chris Harvey Advisor: Dr. Raul Guzman

  2. Project Objective • Design, build and test a system to measure Doppler velocity waveforms in ankle blood vessels • Improve current technology • Better signal quality • Easier measurement

  3. Peripheral Vascular Disease (PVD) • Definition: restriction of blood flow to limbs due to narrowing or clogging of arteries • Causes • Common vascular diseases • Artherosclerosis, aneurysms, venous thrombosis • Distort normal blood pressure and flow • At risk populations • >50 years old • Smokers • Diabetics • High blood pressure or high cholesterol

  4. Peripheral Vascular Disease (PVD) • Incidence of PVD • 1 in 20 people >50 years old = ~10 million people • 75% of cases go undiagnosed • Importance of Diagnosis • PVD is a strong predictor of heart disease • PVD patients are at a higher risk of stroke and heart disease

  5. Noninvasive Vascular Disease Diagnosis • Disease diagnosis using noninvasive techniques • Check for presence, location, severity of disease • External diagnosis is quick, noninvasive • Screen high-risk patient populations • Goal: reduce the number of undiagnosed cases of PVD • ~50 screenings/month or ~600 screenings/year at the Vanderbilt University Vascular Lab

  6. Noninvasive Measurement • Blood pressure cuff occlusion technique • Doppler velocity waveforms are measured at DP and PT arteries in ankle

  7. Noninvasive Measurement for DP • For the DP, the pulse felt on the top of the foot,  between the first and second metatarsal bones. In 8 to 10 per cent of the population this pulse cannot be detected. (www.WebMD.com) www.curtin.edu.au/.../podiatry/ encyclopedia/vasdisease/ medicine.ucsd.edu/clinicalmed/ extremities.htm

  8. Noninvasive Measurement for PT http://www.csuchico.edu/phed/atc/Foot/PostTibArtery.jpg

  9. Doppler Velocity Waveforms Triphasic, Normal Biphasic, Abnormal Monophasic, Abnormal

  10. Doppler Theory • Measures velocity • 2 piezoelectric crystals • Transmitting, receiving • Change in frequency due to movement of red blood cells Crystals Blood Flow RBC

  11. Current Non - Invasive Methods Used • Continuous Wave Doppler Pen • Plethysmography • Duplex Ultrasonography

  12. Advantages/Disadvantages • Hard to locate proper vein or artery if blood velocity is low. • Must train person to use device. • User hand tied down with device • Duplex ultrasound device is very large and expensive • Device is compatible with all persons.

  13. How we are going to go about solving the problem? Ace Bandage Data Acquisition & Analysis Piezoelectric Crystals Power Supply A/D Converter High Pass & Amplifier circuit

  14. Advantages of Doppler Array and LabView Program • Cheap because it does not require trained crew • Easier to find signal • Better analysis of patient vascular system in lower extremities • Works on a high percentage of the population • Universality of device • User is able to perform multiple functions

  15. Doppler crystal array ($45/crystal) Doppler pens ($100/pen) Computer Connectors (~$25/crystal) A/D Converter LabView An Ace bandage Doppler Gel Doppler Audio Amplifier Power supply Op-amps, resistors, capacitors Breadboard Parts

  16. Past Work • Investigation into the use of Doppler as a means of vascular disease diagnosis • Research on the equipment necessary for data acquisition • Acquisition of equipment • Multiple signals (waveform) can be displayed on LabView program • LabView program can pick the signal with higher amplitude

  17. Current Status • Development of LabView program • Input of audio Doppler output • Display of signal on an oscilloscope in LabView • Recording of data for analysis (of signal quality) • Highest Signal to Noise Ratio (SNR)

  18. Current Status Audio Doppler Box LabView Program Audio Doppler Box Doppler Pencil A/D Converter

  19. Future • LabView changes to pick the higher SNR as opposed to higher amplitude • Working on crystals that can give signal and can eventually be incorporated into an array • Increase sensitivity so the input signal can be perceived

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