• Login
    View Item 
    •   DSpace@RPI Home
    • Rensselaer Libraries
    • RPI Theses Online (Complete)
    • View Item
    •   DSpace@RPI Home
    • Rensselaer Libraries
    • RPI Theses Online (Complete)
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Thermomechanics of electrosurgical procedures

    Author
    Karaki, Wafaa
    View/Open
    179498_Karaki_rpi_0185E_11404.pdf (8.825Mb)
    Other Contributors
    Borca-Tasçiuc, Diana-Andra; De, Suvranu; Borca-Tasçiuc, Theodorian; Wang, Ge, 1957-;
    Date Issued
    2018-12
    Subject
    Mechanical engineering
    Degree
    PhD;
    Terms of Use
    This electronic version is a licensed copy owned by Rensselaer Polytechnic Institute, Troy, NY. Copyright of original work retained by author.;
    Metadata
    Show full item record
    URI
    https://hdl.handle.net/20.500.13015/2348
    Abstract
    Starting with Pennes’ bioheat transfer equation to model the temperature profiles observed during ex vivo experiments, we show that the apparent specific heat of the tissue increases significantly at 100°C, highlighting the important role latent heat loss plays in energy dissipation. A proposed two-scale model that couples evaporation at the microscale with energy conservation at the macroscale is able to capture evaporation losses at 100°C and prevent further temperature increase. However, to account for the coupled effects of phase change of water in the intra- and extracellular spaces to vapor, vapor transport, and mechanical deformation, a more comprehensive thermo-mechanical model based on continuum mixture theory is proposed to accurately predict temperature in in vivo and ex vivo experiments on porcine liver tissue. We highlight the effect of applied power on tissue cutting and coagulation damage by coupling this model to an Arrhenius damage model to capture dynamic tissue heating during in situ electrosurgical cutting. The mixture model is coupled to a multi-frequency model to quantify the effect of frequency-dependent electrical properties on the rate of energy generation during ex vivo and in vivo electrosurgical tissue heating with multi-frequency power modes.; The goal of this thesis is to establish the thermomechanical foundations of the response of soft hydrated tissues subjected to excitation by radiofrequency alternating current during electrosurgical procedures. Such procedures are finding increasing application in both surgery and therapeutic endoscopy to conduct various procedures including cutting, ablation, coagulation, and desiccation. However, with rapid heating that results in maximum temperatures exceeding 100°C within seconds, electrosurgery has the potential to cause thermal injuries. Existing models do not provide insight into the different modes of energy dissipation during electrosurgical procedures and often neglect important phenomena such as phase change and vapor transport. These limitations are reflected in large prediction errors when compared to experiment. They also do not offer a quantitative understanding of the effects of electrode motion and neglect the multi-frequency nature of the waveforms used in cutting and coagulation. To overcome these limitations, we have performed ex vivo and in vivo experiments on porcine liver tissue and developed a hierarchy of models of increasing sophistication to systematically capture and quantify the effects of phase change, mass transport, deformation, and damage for both stationary and moving electrodes operating with a variety of waveforms.;
    Description
    December 2018; School of Engineering
    Department
    Dept. of Mechanical, Aerospace, and Nuclear Engineering;
    Publisher
    Rensselaer Polytechnic Institute, Troy, NY
    Relationships
    Rensselaer Theses and Dissertations Online Collection;
    Access
    Restricted to current Rensselaer faculty, staff and students. Access inquiries may be directed to the Rensselaer Libraries.;
    Collections
    • RPI Theses Online (Complete)

    Browse

    All of DSpace@RPICommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    Login

    DSpace software copyright © 2002-2022  DuraSpace
    Contact Us | Send Feedback
    DSpace Express is a service operated by 
    Atmire NV