Peripheral Edema Sensor
Jovan Popovich
Mike Moeller
Biomedical Engineering
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Project Goal
To develop a diagnostic method for testing peripheral
edema using impedance analysis methods
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Presentation Overview
• Background on Edema
• Current Assessment Technique
• Proposal of Impedance Analysis
• Background of Technique
• Related Products/methods
• Overview of Current Project
• Testing Methods and Considerations
• Challenges
• Future Work
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Edema
Edema: excess fluid build-up
in the interstitial tissue from
homeostatic imbalance
Affects 4.4 Million People in the
United States
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Causes of Edema
• Congestive Heart Failure
• Right Side
• Kidney disease/damage
• Loss of protein
• High salt concentration
• Liver disease
• Drop in albumin level
• Blood Clots and Tumors
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Effects of Edema
• Poor blood circulation
• Increased local pressure
• Loss of vessel elasticity
• Painful Swelling
• Problems with Constricting Clothes/Shoes
• Difficulty in Walking
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Current Medical Assessment of Edema
• With no diagnostic device for tracking edema levels
• Currently it is viewed only as an all-or-nothing symptom
Level
Pitting Edema – Measurement
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Barely detectable indentation
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Noticeable Indentation
3
4
Deep Indentation
Very Deep Indentation
Rebound Time
skin rebounds immediately
15 seconds for skin to rebound
30 seconds for skin to rebound
Greater than 30 seconds
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Project Goal: Continuous Physiological Monitor
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Provides Physician with a better insight
as to when and why a patient’s symptoms
are occurring
• Need for a Chronic Edema Sensor
• Indication of type of disorder
• Reveal severity of problem
• Reveal triggers and possible causes
• Show what effects medication has
http://www.data-input.de/media/elektroden-anleitung-fuss.jpg
Impedance Analysis
• Cell/Tissue have unique Dielectric properties
• Frequency dependent response
• Technique has been used for Biosensing
Applications
• Potential for miniaturization and portable
devices
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Body Composition Monitor
• Determines:
•
•
•
•
Total body fat
Skeletal muscle
Resting metabolism
Body mass index
• Uses full body analysis instead of localized tests
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Measurement Setup
• Two Electrode Technique
• LCR Meter: integrates both characteristics
• Four Electrode Technique
• Requires advanced measurement tool
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Impedance Analysis Equipment
• LCR Meter for preliminary testing
• Measurements: 100Hz, 120Hz, 1kHz, 10kHz, 100kHz
• Yields resistance values (ohms), and phase angle
• Impedance Analyzer
• Measurement signals: up to MHz range
• Yields tabulated impedance and phase values
• Also can show temperature (ohmic heating)
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Electrodes
• Skin Impedance
• Precise impedance characteristics: Zskin-electrode = Zelectr. + Zcont. + Zskin
• Location
• Good Contact
• Electrode Material
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Overall Testing Considerations
• Electrode Characteristics
• Tissue Analogue Testing
• Efficacy/Reproducibility of data
• Trial Testing
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Anticipated Challenges
• Correct Estimation of skin contact impedance
• Interpreting and correlating data to Edema symptoms
• Sensitivity
• Finding participants for clinical trials
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Material Costs
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Material
Handheld LCR Meter
Price
$575
ECG Monitor Electrodes
$40
Wire
$50
Connectors/clips
$10
Gallium 99.99% Pure (40[g])
$100
Weight Scale (BMI capable)
$50
Total Cost
$825
Research Schedule
October
Further research on Bioelectrical Impedance Analysis methods
November
Contact/lead Interface preliminary design
December
Mechanical design and reinforcement of sensors
January
February
March
Determination of sensor placement for best results
Data Acquisition and Interpretation of BIA
Modifications to test and beginning of patient trials
April
Compilation of results and conclusions about overall design
May
Finish research report and present results
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Project Summary
• Bioimpedance analysis to measure peripheral edema
• Develop reliable, repeatable testing method
• Electrode Design
• Signal
• Time Course
• Eventually Consideration: portable sensor
• Data used for feedback on patient symptom severity and patient/drug
response
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Research Personnel
Advisors/Contacts
Prof. Mansoor Nasir
• Research Advisor
Prof. Kenneth Cook
• Tech. consultant
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Researchers
Michael Moeller
• Research mech. design & placement
• Data Collection
• Report: background writing
Jovan Popovich
• Research further in BIA
• Data Interpretation
• Report: data plotting, discussion
References
• http://www-rohan.sdsu.edu/~ens304l/electrodes.jpg
• http://www.medicalnewstoday.com/articles/159111.php
• http://www.med724.com/product-p/mmm-2231pack.htm?site=google_base
• http://www.medicinenet.com/edema/page5.htm
• http://www.skintact.com/46.0.html
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Questions
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Questions
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Questions
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Questions
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Questions
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Consideration: Sensor Device
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Measurement Setup
Impedance
Meter/Analyzer
Source Signal
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Contact
Electrodes
Human
Subject