Haptic interactions during natural orifice translumenal endoscopic surgery

Natural orifice translumenal endoscopic surgery (NOTES) is viewed as an emerging surgical technique with significant potential to perform surgical interventions with minimal external scarring and reduced patient trauma. However, this technique uses an endoscope to perform surgical operations which require application of substantial forces and torques for insertion and maneuvering. We have, for the first time, developed an instrumented tool handle with a 6 axis load cell to measure the forces and torques applied during NOTES procedures and used it to make actual measurements during the performance of NOTES techniques by surgeons using an ex-vivo simulator. Data were collected for 10 subjects with varying experience levels at the annual SAGES meeting. We observed that the typical forces were about 10 N with peaks up to 25 N in the push/pull direction. A nominal torque of 50 N-mm with peaks up to 200 N-mm in the clockwise and counter-clockwise directions was observed about the push/pull axis. In comparison, the interaction forces in traditional laparoscopic surgery are in the range of 0-10 N. The data are useful not only in understanding the level of force and torque applied during actual NOTES procedures, but also in developing specifications for a custom haptic feedback system for a virtual reality-based NOTES simulator designed to train the next generation of NOTES surgeons.