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

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

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

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 excision for metabolite testing The metabolites are affected by the time from excision to freezing – Askin et al. 2002

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

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

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 Outer conduction Inner insulation Affordable price Sharp blade Small and easy to use Easy to sterilize

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 $ – – American Liver Foundation (2002 annual report)

Quality System Considerations Human factors – Ease of use – User hand comfort – Protection from heat and current Regulatory – Class II device 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

Project Management BioE 1160 Goals Initial Design Concept Liver & Biopsy Research Solid Model Safety & Regulation Market & Task communication Design History File J. Bacior H. Meguro A. Hallab K. Mihelc BioE 1161 Goals Materials & Structural Analysis SolidWorks Testing Heat Transfer Analysis Prototype & Fabrication Animal Testing J. Bacior H. Meguro A. Hallab K. Mihelc

Design Progression Initial LEC DesignLEC Version 2.0 LEC Version 3.0 LEC Version cm

Design Progression Cont’d Physical Features: – Sharp blade – Bent shaft – Small – Prototype »Nickel-plated ABS – Final Tool »Stainless steel and Ceramic LEC Version cm

Design Description t2t2 t1t1 L α Conductive Material Insulation Material L = 2 cm t 1 = 0.5 mm t 2 = 1.5 mm α = 60˚

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 ( ˚C) »Low electrical resistivity (0.5 Ω-cm) – Ceramic as the insulation material »High electrical resistivity ( >10 6 Ω-cm) »Low thermal conductivity ( ˚C) –

Heat Transfer Model Differential thermal energy balance – Eq (1) used to verify selected materials – Heat transfer and thermal diffusivity chosen 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

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

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

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

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

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

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

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

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

Time = 1 sec Position cm T (C)

Time = 50 sec Position cm T (C)

Time = 100 sec Position cm T (C)