The Design of the Endo-Tubular Friction Carrier

Abstract

Background: Minimally invasive surgery (MIS) is a surgical procedure which is characterized by inserting long and slender instruments through small porthole incisions. On many occasions tissue will have to be extracted from the operation site through one of these small portholes, therefore the sheaths of the instruments that are inserted into the body are limited in diameter. Less than optimal functioning of the transport of tissues which occurs within currently available transport mechanisms in laparoscopic instruments can be attributed to the selected method of transport, i.e.: aspiration (also commonly known as suction). The combination of modes of less-than-optimal functioning are referred to within this report as sub-optimal transport behaviour. The different modes of sub-optimal behavior limit the transport rate and the reliability with which the tissue can be extracted.
Methods: An analysis of the modes of sub-optimal behavior was used to formulate a list of qualitative and quantitative functional requirements which were used in order to produce several conceptual solutions. These conceptual solutions were subsequently divided into categories which are mutually exclusive and collectively exhaustive (the ACCREx method). The most promising conceptual solution was developed into a prototype and is based on the egg-laying needle in insects. The prototype was subsequently subjected to a test procedure in order to determine if it was able to transport tissue and to investigate several factors which may influence the transport rate. The effects of the gelatin mixture density, particle presence, motion sequence were assessed in several sub-experiments. In addition, minced meat was transported in order to accurately mimic morcellated tissue.
Results: From the results of Sub-experiment I it can be concluded that there was a statistically significant difference in inverted transport rate between the different batches of pure gelatin artificial tissue mimicking material. The highest ITR was attributed to mixture D2. From the results of Sub-experiment I it was also concluded that there was no statistically significant difference in inverted transport rate between the different batches of grainy gelatin artificial tissue mimicking material. The addition of particles was not statistically significant. Statistical analysis between the hexasected motion sequence (DH2) and trisected motion sequence (DT2) show that there was no significant difference in inverted transport rates. Sub-experiment III shows that the prototype was able to transport compacted minced meat.
Conclusion: The prototype has shown that the friction-based transport principle has the potential of becoming a viable and reliable alternative to suction as a transport method within laparoscopic instruments. Future work should be directed towards improving the speed with which transport occurs, to investigate what improvements can be made to increase the reliability and the development of the proof-of-principle prototype into a fully functional medical device.