Instrument Exchange System (IES) for robot assisted laparoscopic surgery

Robotic systems for minimally invasive surgery often are limited in diversity of instruments. However during manual laparoscopic procedures surgeons use a large variety of instruments and change them up to 80 times. Within the Fraunhofer project "WholeO'Hand" this challenge has been addressed and an automated exchange system has been developed. Methods: Based on an analysis of the surgical situation a product development procedure has been performed. The process resulted in an overall concept for an instrument exchange system (IES). The main idea is the capsular design of the instruments and their movement inside a working tube by a hydraulic mechanism. The working tube peaks through the abdominal wall of the patient and stays there during the procedure. Outside the body a storage cylinder can keep up to five different surgical instruments in separate chambers. An exchange sequence works as follows. From the distal end of the working tube capsule "A" gets "sucked" into its storage chamber. An actuation unit turns the storage cylinder and aligns instrument "B" with the working tube. Hydraulic pressure then moves the capsule to the distal end of the tube. Results: Based on the described concept a prototype of the system has been designed and realized. The storage cylinder is made out of PEEK and shows dimensions of Ø 80 x 175 mm. The working tube is made of stainless steel and has an outer diameter of Ø 16 mm with a total length of 300 mm. The actuation unit consists of two autoclavable electric motors and has been tested successfully. In first experiments capsular instrument dummies have reliably been exchanged. Conclusion: Concept, realisation and promising experimental results of an IES have been described. In future developments the system has to be miniaturized and weight reduced to get towards a handheld IES as a medical product.