Mechanical analysis of end-to-end silk-sutured anastomosis for robot-assisted surgery

Prevalence of haptic feedback in robot-mediated surgery: a systematic review of literature

With the successful uptake and inclusion of robotic systems in minimally invasive surgery and with the increasing application of robotic surgery (RS) in numerous surgical specialities worldwide, there is now a need to develop and enhance the technology further. One such improvement is the implementation and amalgamation of haptic feedback technology into RS which will permit the operating surgeon on the console to receive haptic information on the type of tissue being operated on. The main advantage of using this is to allow the operating surgeon to feel and control the amount of force applied to different tissues during surgery thus minimising the risk of tissue damage due to both the direct and indirect effects of excessive tissue force or tension being applied during RS. We performed a two-rater systematic review to identify the latest developments and potential avenues of improving technology in the application and implementation of haptic feedback technology to the operating surgeon on the console during RS. This review provides a summary of technological enhancements in RS, considering different stages of work, from proof of concept to cadaver tissue testing, surgery in animals, and finally real implementation in surgical practice. We identify that at the time of this review, while there is a unanimous agreement regarding need for haptic and tactile feedback, there are no solutions or products available that address this need. There is a scope and need for new developments in haptic augmentation for robot-mediated surgery with the aim of improving patient care and robotic surgical technology further.

Modeling of blood flow through sutured micro-vascular anastomoses

Microanastomosis is a surgical procedure used to reconnect two blood vessels using sutures. The optimal microanastomosis may be predicted by assessing the factors that influence this invasive procedure. Blood flow and hemodynamics following microanastomosis are important factors for the successful longevity of this operation. How is the blood flow affected by the presence of sutures? Computational Fluid Dynamics (CFD) is a powerful tool that permits the estimation of specific quantities, such as fluid stresses, that are hardly measurable in vivo. In this study, we propose a methodology which evaluates the alterations in the hemodynamic status due to microanastomosis. A CFD model of a reconstructed artery has been developed, based on anatomical information provided by intravascular ultrasound and angiography, and was used to simulate blood flow after microanastomosis. The 3D reconstructed arterial segments are modeled as non-compliant 1.24 - 1.47 mm diameter ducts, with approximately 0.1 mm arterial thickness. The blood flow is considered laminar and the no-slip condition is imposed on the boundary wall, which is assumed to be rigid. In analyzing the results, the distribution of the wall shear stress (WSS) is presented in the region of interest, near the sutures. The results indicate that high values of WSS appear in the vicinity of sutures. Such regions may promote thrombus formation and subsequently anastomotic failure, therefore their meticulous study is of high importance.

Multi-objective optimization of end-to-end sutured anastomosis for robot-assisted surgery

BACKGROUND

Due to differences in surgical operations between free-hand and robot-assisted vessel anastomosis, there exist new challenges in applying the manipulation criteria of free-hand surgery to robot-assisted surgery in order to guarantee successful completion of the surgical procedure.

METHODS

A mathematical model is established to optimize the process variables in vessel anastomosis. The distance between entry point and cross-section, suture tension and the number of individual sutures are selected as design variables. The allowable range of suture tension and the difference between longitudinal stresses of vessel tissue on transverse sections are used as the objective functions. Simulation experiments are carried out to obtain the allowable range of suture tension and tissue stress distribution, based on numerical analysis.

RESULTS

For a vessel in anastomosis with 4 mm diameter, a larger distance between the entry point and the cross-section and/or more sutures can result in less tissue deformation and a tighter joint between the two vessel ends. The allowable range of suture tension is a function of the number of individual sutures and increases with the decrease of the distance between entry point and cross-section. The optimal designs providing the suture configuration of distance between entry point and cross-section and the number of individual sutures are presented in the case that the performance of robot-assisted anastomosis can be guaranteed without strong control of suture tension.

CONCLUSIONS

The work provides meaningful results for the optimal design of the suturing procedure in robot-assisted vascular anastomosis when the robotic system does not allow tactile feedback.