Design and feasibility of PASSIST, a passive instrument positioner.

Background And Purpose: During minimally invasive procedures, an assistant controls the camera and often a laparoscopic grasper. Ideally, the surgeon should be able to manipulate the instruments because the indirect way of control complicates the surgeon's observation and actions and disturbs eye-hand coordination. Reported replacements for the assistant are active positioners, "robots," such as the Aesop and the EndoAssist. Because positioning instruments is often a static task, the Academic Medical Center has developed a passive assistant for instrument positioning (PASSIST) to allow solo surgery.

Methods: The PASSIST was designed to be simple, fully autoclavable, slender, and stiff. The joints have adjustable friction and spring compensation for stabilizing the instrument in a fixed position, enabling intuitive single-hand repositioning.

Results: The PASSIST has been tested in three laparoscopic procedures: cholecystectomy, laparoscopically assisted vaginal hysterectomy, and spondylodesis. In all of these procedures, the assistant could be replaced satisfactorily, and the surgeon was able to manipulate all of the instruments on his own.

Conclusion: Solo surgery using the PASSIST is feasible. The positioner enables the surgeon to manipulate the viewpoint, to have a stable image, and therefore to improve observation and manipulating actions.