EVALUATION OF SURGICAL INSTRUMENTS FOR USE IN MINIMALLY INVASIVE SURGERY

Open Access
Author:
Addis, Matthew Raymond
Area of Honors:
Mechanical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Mary I Frecker, Thesis Supervisor
  • Matthew M Mench, Honors Advisor
Keywords:
  • Surgical Instrument Testing
  • NOTES
  • NOTES instruments
Abstract:
With the advancement of technology and society’s understanding of scientific principles, come new ways to improve the quality of patient’s lives, including the prevention of unnecessary morbidity and mortality. Medical advancements provide new medical treatments and technologies that are increasingly safer, less invasive and more successful. One, relatively recent, medical advancement is the creation of Minimally Invasive Surgery (MIS). This field of medicine allows for new as well as traditional procedures to be performed with less risk and greatly improved outcomes. One of the very recent sub-specialties of MIS, having only been established approximately five years ago, is Natural Orifice Translumenal Endoscopic Surgery (NOTES). These procedures are conducted through a flexible endoscope that is inserted into the body through the mouth, anus, vagina or urethra and leave no external scars, reduce length of hospital stays, and greatly reduce the patient’s chances of getting an infection. For these reasons, and others, NOTES is a quickly growing field, but is still in its early developmental stages. In fact, many obstacles exist that have widely prevented NOTES from moving from animal testing to human testing. Perhaps the greatest of these obstacles is the current lack of sufficient instrumentation. This shortage of instruments greatly reduces the number of possible surgical procedures and the number of conditions NOTES could one day cure. Another major hurdle faced by NOTES surgeons is the lack of a standardized testing procedures and task lists similar to those that already exist for laparoscopic surgery (Called “Rosser Station Tasks”). This task list is not only necessary to sufficiently evaluate new instrument designs, but also to train and certify new NOTES surgeons. The first goal of the research presented in this thesis was to use the “Rosser Station Tasks” list for laparoscopic instruments as a starting point to design a list of tasks for use in endoscopic training and evaluation. This achievement was accomplished by compiling tasks that were designed in three ways. The first three tasks were adopted from previous literature and modified for use with endoscopic instruments instead of laparoscopic procedures. The first adopted task is the Fuzzy Ball task and tests an instruments ability to complete fine grasping objectives. The second adopted task is the Cup Drop Drill originally presented in the “Rosser Station Tasks” list. This is the only of the Rosser station tasks that was adopted for endoscopic use and it tests the maneuverability and control of a forceps instrument. The last adopted task is the Ring Around task. This task, which is a modified version of the Sea Spike task presented in previous literature, evaluates the instrument’s ability to grasp and maneuver fine objects. In addition to the adopted and modified tasks, three new tasks were designed. The first new task is the Material Pull task, which evaluates a forceps’ ability to grasp and pull on a soft material that simulates tissue. The second new task is the Simulated Biopsy task and tests a forceps’ ability to grasp and remove material from a target as is done in a surgical biopsy. The last task on the list was newly designed for this research and is called the Force Gauge task. The Force Gauge task evaluates the maximum pull-off force that a forceps instrument can deliver. Combined, these six tasks form a new Standardized NOTES Instrument Task List. This task list can now be used to objectively evaluate any NOTES forceps design. However, by modifying or emitting tasks as well as designing additional tasks to test certain functions, this task list can serve as a basis to test any endoscopic instrument, not just forceps. As the field of NOTES continues to grow and is widely implemented for surgical procedures, these training and certification processes will become increasingly more important. The second goal of the research presented here was to use the new Standardized NOTES Instrument Tasks List to evaluate a new endoscopic forceps instrument currently under development at the Pennsylvania State University. This evaluation was completed by having twelve surgical residents perform the tasks on the list in an endoscopic box trainer with both a commercially available “standard” instrument and the new prototype instrument for comparison. At the completion of the testing, each participant was asked to fill out a survey which evaluated iii the various aspects of each instrument. The resulting data and feedback illuminated several important things about the new forceps design. Most importantly the new instrument performed favorably compared to the standard instrument. It was felt that the new design fills a void and provides an instrument that excels at fine grasping, where few instruments of its kind are currently available. It was also identified that the new instrument allows for superior control of intermediate positions between fully opened and fully closed. These advantages as well as other comments from the participants clearly demonstrate that the new instrument is superior to the standard instrument in several respects. However, as with any prototype, several weaknesses were pointed out as well. The most important of these weaknesses is that the prototype design does not perform well as a biopsy forceps. This is primarily due to a lack of teeth on the forceps due to manufacturing limitations, and the tendency of the prototype instrument to remove material by scraping instead of grasping. This is not ideal for biopsies, so the instrument should not be used as such. Several necessary improvements were also identified. Most prominently, it was identified that the prototype design jaw length and distal jaw opening need to be increased. In addition, an increase in the instrument’s ability to rotate easily is also desirable. These improvements would further improve the prototype design’s ability to grasp fine objects, particularly from awkward angles. In summary, two goals were set and accomplished by the research. A new Standardized NOTES Instrument Tasks List was created and then used to evaluate an endoscopic forceps instrument being developed at the Pennsylvania State University. This testing has also proved sufficiently challenging to capture and maintain participants’ concentration, which is desirable for any testing procedure. The data and feedback provided show that the new design is good and fills a void in instrumentation needs, but needs to be further refined for commercial production. These advancements will prove increasingly more important as NOTES continues to expand and becomes a practical and widely implemented solution to surgical needs.