Mechatronic concept of a semiautonomous instrument changing system for flexible NOTES platforms

Objective: NOTES mechatronic support systems are still needed to overcome the well-known problems of the new technique. New developments will be established only if they are adapted to the clinical workflow. Therefore it is important that tasks of the assistant and of the physicians are equally considered. Changing of flexible instruments is a task that is mostly carried out by the assistant. Because of the flexible design and the length of the manipulators the handling is quite difficult. Instruments can be contaminated by carelessness during the insertion into the working channel and changing is a time consuming task which should be facilitated. We describe a mechanical instrument changing system to standardize, and to accelerate this process and to reduce the workload of the staff.

Methods and procedures: We developed a prototype of an instrument changing system for NOTES platforms which can insert automatically one of four flexible conventional endoscopic instruments directly into the working channel. The prototype consists of two main components. The changing unit manages and changes the instruments. The handgrips are fixed in so-called actuators which operate the instruments. The instrument changer can be controlled from a console or a remote control. The whole concept is modular and can be adapted to new requirements. It was even designed that HF surgery is still possible.

Results: The first prototype was tested in the laboratory. Instruments used are the Olympus HotClaw FD-420LR, Olympus Electrosurgical Knife KD-611L and a Storz flexible Biopsy Forceps. The flexible Gastroscope 13806PKS (Karl Storz, Tuttlingen) was temporarily used as the manipulator. The entire exchange process from instrument choosing to placement at the tip takes 28 s on average. Instruments were automatically positioned with an accuracy of± 4,4 mm (n ((equals)) 20; standard deviation 2.98 mm) directly at the endoscope tip.

Conclusions: The prototype of the instrument changer has been evaluated successfully in in-vitro experiments. Actually a new manipulator is developed and the instrument changer will be an important sub-component of the whole concept. In the future the user can change the instruments by direct command via the system and is not relayed on the help of an assistant.