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.