Liver Excision-Cauterization

1. University of Pittsburgh Senior Design - BioE1160/1161 Liver Excision-Cauterization Amine Hallab Kevin Mihelc Jen Bacior Hiroki Meguro April 18th, 2005 Mentors: Kelly Dympna MD, John Patzer PhD

2. Outline • Background • Problem Statement and Design Proposal • Quality System Considerations • Design Description and Progression • Heat and Materials Analysis • Experimental Design • Testing Results • Future Considerations

3. Background • 1 in 10 Americans are or have been afflicted with liver disease • Treatments – Liver transplant • The causes of liver diseases are poorly characterized • Liver biopsy • Common procedure for afflicted liver diagnosis • Essential tool for metabolic processes research • American Liver Foundation 2003 • Maddrey, W C, “Atlas of the Liver,” 2004, Current Medicine Inc

4. Background Cont’d • Liver biopsy results in major bleeding • The current excision procedure is inconvenient • The cauterization post excision is complicated and time consuming • Requires immediate freezing upon excisionfor metabolite testing • The metabolites are affected by the time from excision to freezing • Askin et al. 2002

5. How do surgeons take a liver biopsy ? 1cm -Fully excised pig liver - Picture taken by Amine Hallab - BioScience Tower

6. Problem Statement • For transplant surgery and research purposes • There currently is no device that will excise a biopsy and cauterize the host tissue simultaneously • For research purposes • There is no mechanism to ensure biopsy temperature control for metabolic processes measurements

7. Design Proposal • Liver Excision-Cauterization (LEC) • LEC Functions • To excise a biopsy wedge and cauterize at the same time • To provide temperature control • Thermal and electrical insulation/conduction Design & Customer Requirements • Sharp blade • Small and easy to use • Easy to sterilize • Outer conduction • Inner insulation • Affordable price

8. Features & Benefits • Combines 3 functions: tissue excision, wound cauterization, biopsy insulation • Researchers can assure accuracy in metabolic measurements • Prevent blood loss with easier and faster technique • Market size is estimated by • 6,000 liver Transplants per year • In 2002 alone, $262 million was spent on liver research • LEC would be sold by surgical instrument companies • Comparable surgical instrument only sells for $100.00 • www.ustransplant.org • American Liver Foundation (2002 annual report)

9. Quality System Considerations • Safety • Stainless steel • Support stresses of cutting technique • Surgical latex gloves • User thermal and electrical protection • Sharpness of the blades • Avoid liver tissue deformation • Blades can be re-sharpened • Human factors • Ease of use • User hand comfort • Protection from heat and current • Regulatory • Class II device

10. Project Management

11. Design Progression 25cm 25cm Initial LEC Design LEC Version 2.0 LEC Version 3.1 LEC Version 3.0

12. Design Progression Cont’d 15cm Physical Features: • Sharp blade • Bent shaft • Small • Prototype • Nickel-plated ABS • Final Tool • Stainless steel and Ceramic LEC Version 4.0

13. Design Description t1 α t2 Conductive Material Insulation Material L= 2 cm t1 = 0.5 mm t2 = 1.5 mm α = 60˚ L

14. Structural Design and Materials • The volumetric triangular shape provides: • Uniform conduction and efficient insulation • Materials selection for proposed product • Stainless steel as the conductive surface • High thermal conductivity (14.6 W/m-K @ 100˚C) • Low electrical resistivity (0.5 Ω-cm) • Ceramic as the insulation material • High electrical resistivity ( >106 Ω-cm) • Low thermal conductivity (1.46 W/m-K @ 25˚C) • www.accuratus.com

15. Heat Transfer Model • Differential thermal energy balance • Eq (1) used to verify selected materials • Heat transfer and thermal diffusivitychosen to .provide • Uniform conduction through stainless steel • Insignificant biopsy temperature increase • Conclusion • Proposed LEC materials will sufficiently meet the .required temperature control needs of the product

16. COSMOSWorks Analysis FEA Thermal Study: • – 60°C applied to porcine liver piece • 110°C applied to back face of basket

17. COSMOSWorks Analysis Thermal Analysis on Nickel-plated Somos 14120 (Prototype Materials) Thermal Analysis on Cast Stainless Steel and Ceramic Porcelain (Proposed Final Materials)

18. COSMOSWorks Analysis • Conclusions: • Theoretical analysis shows that both the prototype and final LEC product will adequately promote hemostasis while protecting the biopsy tissue

19. Experimental Methods for Testing • Porcine Liver • Cutting capability • Cauterization efficiency • Insulation efficiency • Biopsy tissue protection • Cutting and cauterizing simultaneously

21. 1cm

22. Testing Results • Excision ability – Failure • Cauterization – Success • Quick cauterization – Failure • Biopsy protection – Success • Overall • Positive user feedback

23. Constraints Limiting Phase I • Economic • Labor costs to produce a single .stainless steel and ceramic prototype • Regulatory • Scheduling between our device testing .and available animal research

24. Future Considerations • Current generator with bipolar technique • Modification in cutting mechanism • Sharper blades • Cut as product of shearing • Outer surface modification • Quicker cauterization • Human factors modification • Handle protection and reduction in size

25. Acknowledgments • Thank you to Drs. Hal Wrigley and Linda Baker whose generous gift made this project possible • Thank you to department of BioEngineering for the generous support • John Patzer, PhD • Kelly Dympna, MD • Professor Gartner • Bob Barry

26. THANK YOU

28. Time = 1 sec T (C) Position cm

30. Time = 50 sec T (C) Position cm

31. Time = 100 sec T (C) Position cm