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ULTRASONIC SURGICAL INSTRUMENTS: A MULTI-VARIATE STUDY FOR CUTTING-RATE EFFECTS

VAITEKUNAS, JEFFREY J.
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1052935131

Abstract Details

2003, PhD, University of Cincinnati, Engineering : Engineering Mechanics.
In spite of the proven efficacy and safety of ultrasonic surgical systems, the mechanisms for cutting and coagulation are not well understood. Preferred operating parameters and ranges should be used if clinical benefit can be shown. Therefore this research was designed to determine whether frequency, normal force, velocity and blade shape affect the cut-rate of an ultrasonic surgical instrument. Test velocities covered the range available from current ultrasonic surgical systems. Three values for normal force were selected based on previous testing. A low value corresponded to a "light" touch typically applied in fine dissection between tissue planes, and a heavy value typically used in skin incisions such as a laparotomy. Two specimens were chosen for evaluation: wax and liver. The basic behaviors of the observed cut-rates obtained at 55.5 kHz with a 2.1 mm diameter round blade were similar for wax and liver. Using analysis of variance (ANOVA), normal force, ultrasonic velocity and their first order interaction are shown to significantly affect cut-rate up to 5 N in wax and 2.5 N in liver. In wax, cut-rate is shown to be independent of frequency, and in liver the data indicate that cut-rate is independent of frequency, but are not sufficient to draw a statistical conclusion. In liver above a threshold, cut-rate increases significantly and depends on blade shape. A model for wax cutting was developed based on melting and removal of wax. Several assumptions were made and two parameters were determined by a regression. Still, the model predictions were accurate for the data on which the regression was performed. The model also predicts with reasonable accuracy the behavior observed at other frequencies for other blade shapes. The model can certainly be improved by more rigorous development; nonetheless, it does demonstrate the basic mechanisms involved in wax cutting. The results from the liver experiments and data analysis suggest that much more work is needed to accurately determine the underlying mechanisms of complex behavior of cutting tissue. The outcome of this research on liver cutting is the identification of promising directions for future research.
DR. EDWARD GROOD (Advisor)
155 p.
ultrasound; surgery; medical device; tissue cutting; Langevin stack

Recommended Citations

Citations

  • VAITEKUNAS, J. J. (2003). ULTRASONIC SURGICAL INSTRUMENTS: A MULTI-VARIATE STUDY FOR CUTTING-RATE EFFECTS [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1052935131

    APA Style (7th edition)

  • VAITEKUNAS, JEFFREY. ULTRASONIC SURGICAL INSTRUMENTS: A MULTI-VARIATE STUDY FOR CUTTING-RATE EFFECTS. 2003. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1052935131.

    MLA Style (8th edition)

  • VAITEKUNAS, JEFFREY. "ULTRASONIC SURGICAL INSTRUMENTS: A MULTI-VARIATE STUDY FOR CUTTING-RATE EFFECTS." Doctoral dissertation, University of Cincinnati, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1052935131

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Cincinnati and OhioLINK.