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Redesign of ECMO Circuit Pressure Alarm System

University of Pittsburgh Senior Design - BioE1161. Redesign of ECMO Circuit Pressure Alarm System. Desiree Bonadonna Apryle Craig Laura Gilmour. Summary. Market review Problems Regulations Solutions Implementing the design Testing Future work. Need for Pressure Monitor Redesign.

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Redesign of ECMO Circuit Pressure Alarm System

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  1. University of Pittsburgh Senior Design - BioE1161 Redesign of ECMO Circuit Pressure Alarm System Desiree Bonadonna Apryle Craig Laura Gilmour

  2. Summary • Market review • Problems • Regulations • Solutions • Implementing the design • Testing • Future work

  3. Need for Pressure Monitor Redesign • >120 Neonatal/Pediatric ECMO Centers in United States, increasing at a rate of ~2-5/year • Growing number of private perfusion groups • Sold through distributors and consultants • Clots in the circuit are the most common mechanical complication (19%)

  4. Need for Pressure Monitor Redesign • Expenditure may be between $80,000 and $100,000 per life saved • Insurance reimbursement rate 60-70%

  5. Users: Healthcare Workers • Perfusionists • ECMO Technicians • Nurses • Physicians • Current system with roller pump is analog • Current system with centrifugal is digital • Redesign of the ECMO pressure system includes: • Digital system for roller pump • Additional pressure monitor • Audible and visual alarm

  6. User Requirements • Accurate to within +/- 15mmHg • Refresh rate should not exceed 15 seconds • Cost effective • Safe and reliable • Meets medical device regulations

  7. Imprecise/inaccurate readings Convert to digital display Unknown post-heat exchanger pressure Add a third pressure gauge Requires constant monitoring Add audible and visual alarms Cluttered Design the device to hang on an IV pole Current ECMO Circuit Pressure Problems and Proposed Solutions:

  8. Regulations Classification: • Class II, CFR 870.2100 • Cardiovascular blood flowmeter Predicate device: • Digibio Digital Blood Pressure Monitor Electronic Regulations: • IEC 61000-4-2 • IEC 60601-1-2

  9. JCAHO 2004 National Patient Safety Goals Goal #6: Improve the effectiveness of clinical alarm systems. a)    Implement regular preventive maintenance and testing of alarm systems. b)    Assure that alarms are activated with appropriate settings and are sufficiently audible with respect to distances and competing noise within the unit.

  10. Project Objectives and Features: Programmable Alarm Range “Assure that alarms are activated with appropriate settings…” Adjustable range for anthropometric differences and varying pathologies

  11. Project Objectives and Features: Audible Alarm “…are sufficiently audible with respect to distances and competing noise within the unit.” • Immediate notification of deviation • Alarm=120dB • Mean unit noise level = 80-89dB • Startle response occurs at 30dB > mean noise • Max Impulses = 1016-P/10 = 8,913

  12. Project Objectives and Features:Visual Alarm Indicates which pressure is deviant from set range

  13. Project Objectives and Features: Digital Display  Human Factors Decrease Human Error Ease of Use

  14. Project Objectives and Features: Additional Pressure Indicator Pressure drop across heat exchanger can be determined and differentiated from patient

  15. Design Alternatives Based on human factors

  16. Design Alternatives

  17. Engineering Technologies/Methodologies Technologies • SolidWorks • PSpice • Rapid Prototyping • Excel Methodologies • Circuitry analysis • Digital logic

  18. Schematic of One Display Unit ADC & Display Op-Amp Audible Alarm Visual Alarm

  19. 2 Stages of A/D Converter Choice: • 1st type produced larger error and required more circuitry • 2nd type (ICL7107) included built-in display driver

  20. 3 Stages of Op-Amp Design: • Scaled down 0-10V to 0-.2V and included another inverting op-amp • Scaled down 0-1V to 0-.2V • Eliminated 2nd inverting op-amp since input was determined to be negative

  21. Visual Alarm Highlights: • Programmable range • Comparators for high and low • Switches to view range while adjusting it • LED lights when out of range

  22. Audible Alarm Highlights: • Inverters needed between comparator and OR-gate • OR-gate will be 6:1 in final design

  23. Experimental Design A/DTP-001 • Tests linearity of input voltage to output reading PCTP-001 • Tests deviation of first-generation prototype from known pressure VACTP-001 • Tests accuracy and independence of visual alarms AACTP-001 • Tests accuracy and independence of audible alarm

  24. A/DTP-001 Results

  25. PCTP-001 Results

  26. PCTP-001 Results

  27. Statistical Analysis Within the physiological range, the percent error of our device is lower than that of the currently used technology at CHP.

  28. Statistical Analysis

  29. Competitive Analysis • Analog Pressure Gauges • Custom Made Digital Monitors • COBE Cardiovascular • SIII Pump Modules • Console mounted control unit • Strengths • Smaller • Not part of a kit • Less expensive • Hangs on IV pole • Weaknesses • Does not monitor all • circuit information such • as temperature, etc.

  30. Team Roles

  31. Project Management

  32. Future Work • Further Testing • Visual Alarm VACTP-001 • Audible Alarm AACTP-001 • Electrical Prototyping • Second Generation Prototype

  33. Acknowledgements University of Pittsburgh Department of Bioengineering Department of Electrical Engineering Michael Shaver, CCP Steven Jacobs, PhD Vikram Sundararaman

  34. Questions?

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