Abstract Blood pressures within the heart and surrounding vessels are typically measured with pressure transducer equipped catheters The accuracy of blood pressure measurements has been called into question as calibration data is not provided to the client A product is needed to calibrate and verify the catheter pressure transducer measurements while simulating in vivo conditions Abstract This product was developed to encase the catheter in saline solution while achieving pressures up to 200mmHg An air pump increases pressure in the chamber through manual or computer control Pressure in the chamber is monitored with an additional pressure transducer imbedded in the tank In a second generation prototype a feedback loop will pressurize the chamber to a user specified value via pressure sensor micro controller and air pump Background z Heart Disease 1 Killer of Americans z Potential for new blood pressure monitoring technology to have high impact z Proper catheter calibration key to validate new technology Source National Center for Health Statistics of the Centers for Disease Control and Prevention Problem Motivation z Developing Technology z Catheter z z Catheter www sjm com globals popups ablate htm z New method for BP measurements in clinical trials Catheter BP measurements must be valid and accurate Catheter validates new technology Catheter s accuracy is questionable z Calibration procedure is lacking and or unknown Existing Calibration Design z Description z z z Tubular enclosure holds saline solution and catheter Monometer pressurizes enclosure Catheter Shortcomings z z z Leaks Unstable pressure Not repeatable Valves Design Criteria z Test at range of pressures in saline z z Stable constant calibration values z z z z z 50 mmHg increments 2 allowable error Inexpensive Minimal setup Sterile Complimentary calibration protocol Final Design z z z z Air water tight container Partially filled with saline Pressure sensor mounted in wall Air pump compresses air in the top of the container z z Operator enters desired pressure z z Pressure is transferred to saline Pressure maintained by feedback from sensor to pump Compare catheter pressure readings to container pressure Design Specifics z Rectangular z z z Acrylic z z Easy accurate machining Easy adjustments via removable top Chemically bond acrylic with ethylene dichloride All edges were sealed with z z Silicon caulk Silicone o ring Testing z Air Tight Seal z z z z Manually tested container for air tight seal using manometer Corners of container catheter insertion and pressure sensor entry point are leak free O ring failed to seal in some areas Air Pump z z Donated pump was intended for liquid applications Insufficient for generating adequate air flow rate Future Work z z z z z Evaluate methods in creating entirely sealed container Custom air pumps Design and implement temperature control Evaluate and improve calibration methods Integrate feedback control z Programming Future Work Monometer Pressure Desired Pressure INA118 Amplifier MS232 PC out MICROCONTROLLER Pressure Transducer SSR Air Pump 5V DC Voltage Supply Regulator SSR Relief Valve Acknowledgements z z z z z Kurt Saupe Assistant Professor SMPH Dan Yee SMPH Dave Markovitch SMPH Michael Graham Professor CBE COE Student Shop Personnel
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