Measurement of inserting motion of bladeless trocar at real surgery for development of a virtual training system for initial trocar placement in laparoscopic surgery.

ABSTRACT

BACKGROUND/AIMS: The optical view method is an alternative to the open method as a laparoscopic entry technique, but it calls for a certain experience. Therefore we undertook the development of a training system for optical view method in initial trocar placement. For this purpose, kinetic data concerning insertion of a trocar were measured by means of non-invasive monitoring during actual surgery. METHODOLOGY: We slotted force and motion sensors into an adapted trocar and measured the kinetic aspects of trocar insertion in terms of force and torque. The measurement was carried out at the time of the second and third trocar insertion by a single experienced surgeon. RESULTS: The measurement was carried out at 11 sites in 6 patients. We measured position, inserting force and inserting torque of the measuring trocar continuously. Mean maximum inserting force was 71.4N (range 63.9-75.5N) at the perinavel port and 65.3N (range 31.8-83.8N) at other sites. Mean maximum torque was 0.19Nm (range 0.18-0.21Nm) at the perinavel port, and 0.23Nm (0.15-0.35Nm) at other sites. The number of rotations needed to penetrate the abdominal wall differed considerably among the patients. CONCLUSION: In the measurement by an experienced operator, inserting force and torque data were consistent and generally did not depend on the patient characteristics or the site of puncture. Difficulty in penetration according to the physical characteristics of the patients was adjusted by differences in the number of rotations applied to the trocar.