UBC Theses and Dissertations

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UBC Theses and Dissertations

Development and evaluation of an automated pre-robotic system and an advanced robot for surgical retraction Findlay, Judy M.


The application of advanced robotics to surgical tasks can help to improve the delivery and quality of treatment, reduce the cost of surgery, and increase safety. Despite these advantages, robots have not found their niche in the surgical setting to the extent that they have in many industries. For the health care industry and society to reap the benefits offered by advanced surgical robots, technological challenges related to the application of advanced surgical robots to surgical tasks must be met, and the barriers to clinical acceptance must be overcome. Surgical retraction is a technique employed in most surgical procedures to expose the anatomical structures of interest to the surgeon. Many problems associated with this common surgical task could be addressed by advanced surgical robots which could be easily repositioned, and could accept a variety of retractors for different applications. Using a robot could liberate surgical assistants for other tasks, and could allow the retraction pressure to be monitored and the surgeon alerted to excessive pressures. In this thesis two approaches to automated surgical retraction are developed with the overall objective of demonstrating each approach in the surgical setting to determine the feasibility of the approaches as alternatives to current retraction techniques. The first approach involves the development of an automated effector for operating from a pre-robotic platform. Gross positioning of the retractor is performed manually with the pre-robotic device, while the automated effector provides fine positioning control to adjust the surgical exposure, as well as three automated modes of operation: 1) maintaining the retractor position within a desired position window, 2) maintaining the retraction pressure within safe limits, and 3) periodically releasing the retraction pressure. The second approach involves the development of an advanced surgical robot for retraction that provides both gross and fine positioning, as well as the automated modes of operation. In contrast to the first system, this system is fully robotic. This thesis describes the development of two systems based on these approaches. As a significant part of the development, a new physiologic sensor was developed for monitoring the retraction pressure. A model of retraction pressures was established based on measurements made during hip replacement and abdominal surgeries. Using this model, an improved retraction pressure sensor with multiple sensing sites was developed, and control algorithms for automating retraction were developed. As part of the system development, requirements for an operator interface were identified and a versatile operator interface system was adapted and integrated into the robotic system to provide intuitive control. An important part of the work involved the identification of the crucial need for a safety standard for surgical robots, and the further identification of the critical issues that such a standard would have to address. From this, a set of general design requirements for surgical robots was developed, and specific approaches for addressing the safety issues in a prototype of an advanced surgical robot for retraction were developed and integrated into the systems. The feasibility of each approach was demonstrated during successful surgical trials of the automated pre-robotic system and the advanced surgical robot during abdominal surgery. A comparative evaluation of the systems, in terms of quality of treatment, costs and payback, and safety, led to an identification of advantages that each approach offered and of problems associated with the implementations. The automated pre-robotic system was found to have advantages over the fully robotic approach in terms of cost, use, and safety, for the task of bilateral retraction during abdominal surgery.

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