Scaling Laws and Size Thresholds for Minimally Invasive Surgical Instruments

Friedman, D.C.W. (2011) Scaling Laws and Size Thresholds for Minimally Invasive Surgical Instruments. Doctoral thesis, University of Washington.

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Abstract

Minimally invasive surgery introduced significant changes to the field of surgery. New procedures became possible, and existing procedures were performed in new ways. With the increasing popularity of robotic surgery, the field is changing once again. One significant impact of robotic surgery is the ability to scale motions. The surgeon can move his hands over a distance of ten centimeters and see the tool tips move only two centimeters. As time passes, surgeons will expect the scaling to continue, with tool tips moving only a few millimeters when they move their hands over a distance of ten centimeters, and with the tool tips themselves shrinking at the same rate. As robotic surgery progresses, it will be important to know how small surgical tools can be made and still be functional. The focus of my dissertation is to identify size thresholds for key components of minimally invasive surgical instruments. <p> For my dissertation, I focused on rigid graspers and needle drivers with articulated wrists. I developed a reference geometry similar to currently available instruments, and used it to identify a set of pertinent physical properties that should be considered for minimally invasive surgical instruments. I also conducted a brief survey of published material on tissue properties and developed a model of real world constraints that need to be met, including the maximum safe force that can be applied to tissue and the force needed to grasp a suture needle. After collecting this information, I defined a series of design thresholds based on the physical principles I identified and my real world constraints model, and in the context of the reference instrument design I identified. These design thresholds indicate the useful range of instrument diameters for which the instrument can satisfy all of the real world constraints. My dissertation also includes a comprehensive survey of reported da Vinci instrument failures compiled from the FDA's MAUDE database. Surgeons and institutions can voluntarily (and anonymously) report adverse events (such as instrument failures), and the product manufacturer can provide a response. This survey identifies common types of failures, but does not provide information about relative instrument failure rates.

Item Type: Thesis (Doctoral)
Subjects: C Surgical Robots > C Surgical Robots(General)
C Surgical Robots > CC Preventing Tissue Damage
Divisions: Department of Electrical Engineering
Depositing User: Tim Brown
Date Deposited: 27 Jul 2015 22:52
Last Modified: 27 Jul 2015 22:52
URI: http://brl.ee.washington.edu/eprints/id/eprint/112

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