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Pressure-Sensing Catheter Calibration. March 9, 2007. Team Members: Danielle Ebben Anita Zarebi Anthony Wampole Erik Yusko Marty Grasse. Client: Nancy Sweitzer, M.D. Colette Wagner. Advisor: William Murphy, Ph.D. Outline. Problem Statement Background Design Constraints - PowerPoint PPT Presentation
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Pressure-Sensing Catheter Calibration
Team Members:Danielle Ebben
Anita ZarebiAnthony Wampole
Erik YuskoMarty Grasse
Client:Nancy Sweitzer, M.D.Colette Wagner
Advisor:William Murphy, Ph.D.
March 9, 2007
Outline Problem Statement Background Design Constraints Status Update Acrylic Pressure Chamber Measurement and Control Systems Future Direction
Problem StatementIn order to accurately measure internal blood pressures, a properly calibrated pressure sensitive cardiovascular catheter may be used. The current techniques for calibrating the catheter are unreliable, which causes concern about the validity of the test results. The goal of the project is to devise a testing system which more reliably calibrates and verifies the accuracy of the catheter in both atmospheric tests and tests which simulate internal bodily conditions.
Project Background Catheters used to measure
blood pressure inside the heart Clinical trials in progress Catheter pressure readings
inconsistent Calibration method of
manufacturer unknown Need an effective way to
calibrate the pressure transducers on the catheter www.healthsystem.virginia.edu
Design Constraints Both atmospheric and saline environments Accuracy to +/- 2 mmHg Able to achieve 200 mmHg; damage-
resistant to 300 mmHg Temperature control Cost < $300
Design Solution Air/water tight container Partially filled with saline Pressure sensor mounted in wall Air pump compresses air in the top
of the container Pressure is transferred to
saline Operator enters desired pressure
Pressure maintained by feedback from sensor to pump
Compare catheter pressure readings to container pressure
Status at End of Semester Machined container out of
acrylic Attempted to seal with O-
ring and cork gasket Seal around top edge
leaky Donated pump did not
generate enough pressure Feedback loop and
temperature control not yet incorporated
Box Alterations Reduced height
2 x 4 x 18 vs. 4 x 4 x 18 Reduces amount of force
Added stability Screws Horizontal and Vertical Struts
Completely seal container
Use of sheath system to thread catheter
Filling port
Over-Pressure valve
Additions Due To Sealing
Swagelok
SheathCatheter
Measurement & Control Systems
PCVisual Basic
Air Pump
NichromeElement
Pressure Transducer
DAQ
SSRSSR
Thermocouple
DifferentialAmplifier
Two-StageAmplifier
VoltageSupply
HighCurrentSource
Pressure Control Block Temperature Control Block
PCVisual Basic
Air Pump
NichromeElement
Pressure Transducer
DAQ
SSRSSR
Thermocouple
DifferentialAmplifier
Two-StageAmplifier
VoltageSupply
HighCurrentSource
Pressure Control Block Pressure sensor DAQ Computer Program
Voltage converted to pressure
Decide appropriate course of action
PC Visual Basic
Air Pump
Pressure Transducer
DAQ
SSRDifferentialAmplifier
VoltageSupply
PCVisual Basic
Air Pump
NichromeElement
Pressure Transducer
DAQ
SSRSSR
Thermocouple
DifferentialAmplifier
Two-StageAmplifier
VoltageSupply
HighCurrentSource
Pressure Control Block Pressure sensor DAQ Computer Program
Voltage converted to pressure
Decide appropriate course of action
PC Visual Basic
Air Pump
Pressure Transducer
DAQ
SSRDifferentialAmplifier
VoltageSupply
PCVisual Basic
Air Pump
NichromeElement
Pressure Transducer
DAQ
SSRSSR
Thermocouple
DifferentialAmplifier
Two-StageAmplifier
VoltageSupply
HighCurrentSource
Temperature Control BlockPC
Visual Basic
DAQ
SSR
Thermocouple
Two-StageAmplifier
HighCurrentSource
NichromeElement
Heating Element: nickel chromium wire
Two Stage amplifier: Differential amp with cold
junction compensation Pure gain amp
PC in turn reads/controls a current flow
Future Direction Acrylic Pressure Chamber
Complete structural stabilization Machine nichrome wire path
Measuring and Control Systems Implement amplifier circuits and power supplies
Calibration Protocol Write a calibration/validation protocol for use
Questions?
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