AbstractBlood 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.AbstractThis 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.Backgroundz Heart Disease #1 Killer of Americansz Potential for new blood pressure monitoring technology to have high impactz Proper catheter calibration key to validate new technologySource: National Center for Health Statistics of the Centers for Disease Control and PreventionProblem Motivationz Developing Technologyz New method for BP measurements in clinical trials z Catheter BP measurements must be valid and accurate z Catheter validates new technologyz Catheter’s accuracy is questionablez Calibration procedure is lacking and/or unknownCatheterwww.sjm.com/globals/popups/ablate.htmCatheterExisting Calibration Designz Descriptionz Tubular enclosure holds saline solution and catheterz Monometer pressurizes enclosurez Shortcomingsz Leaksz Unstable pressurez Not repeatableValvesCatheterDesign Criteriaz Test at range of pressures in salinez 50 mmHg incrementsz Stable/constant calibration valuesz 2% allowable errorz Inexpensivez Minimal setupz Sterilez Complimentary calibration protocolFinal Designz Air/water tight containerz Partially filled with salinez Pressure sensor mounted in wallz Air pump compresses air in the top of the containerz Pressure is transferred to salinez Operator enters desired pressurez Pressure maintained by feedback from sensor to pumpz Compare catheter pressure readings to container pressureDesign Specificsz Rectangularz Easy & accurate machiningz Easy adjustments via removable topz Acrylicz Chemically bond acrylic with ethylene dichloridez All edges were sealed withz Silicon caulkz Silicone o-ringTestingz Air Tight Sealz Manually tested container for air tight seal using manometerz Corners of container, catheter insertion, and pressure sensor entry point are leak-freez O-ring failed to seal in some areasz Air Pumpz Donated pump was intended for liquid applicationsz Insufficient for generating adequate air flow rateFuture Workz Evaluate methods in creating entirely sealed containerz Custom air pumpsz Design and implement temperature control z Evaluate and improve calibration methodsz Integrate feedback controlz ProgrammingFuture WorkMICRO-CONTROLLER5V DC Voltage Supply/RegulatorPressure TransducerMS232 PC-out SSR – Air PumpMonometer PressureINA118 AmplifierDesired PressureSSR –Relief ValveAcknowledgementsz Kurt Saupe, Assistant Professor, SMPHz Dan Yee, SMPHz Dave Markovitch, SMPHz Michael Graham, Professor, CBEz COE Student Shop
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