Scope actuation system for articulated laparoscopes

Abstract

Background: An articulated laparoscope comprises a rigid shaft with an articulated distal end to change the viewing direction. The articulation provides improved navigation of the operating field in confined spaces. Furthermore, incorporation of an actuation system tends to enhance the control of an articulated laparoscope.

Methods: A preliminary prototype of a scope actuation system to maneuver an off-the-shelf articulated laparoscope (EndoCAMaleon by Karl Storz, Germany) was developed. A user study was conducted to evaluate this prototype for the surgical paradigm of video-assisted thoracic surgery. In the study, the subjects maneuvered an articulated scope under two modes of operation: (a) actuated mode where an operating surgeon maneuvers the scope using the developed prototype and (b) manual mode where a surgical assistant directly maneuvers the scope. The actuated mode was further assessed for multiple configurations based on the orientation of the articulated scope at the incision.

Results: The data show the actuated mode scored better than the manual mode on all the measured performance parameters including (a) total duration to visualize a marked region, (a) duration for which scope focus shifts outside a predefined visualization region, and (c) number of times for which scope focus shifts outside a predefined visualization region. Among the different configurations tested using the actuated mode, no significant difference was observed.

Conclusions: The proposed articulated scope actuation system facilitates better navigation of an operative field as compared to a human assistant. Secondly, irrespective of the orientation in which an articulated scope's shaft is inserted through an incision, the proposed actuation system can navigate and visualize the operative field.

Keywords: Articulated scopes; Laparoscopic surgery; Robotic scope assistant system; Scope holders; Surgical robots.

Fig. 1

a An articulated scope (EndoCAMeleon by Karl Storz) connected to a camera head (Image1HD by Karl Storz). Rotating the knob at the rear end of the scope (shown in Panel A1) controls the scope angulation, rotating the viewing direction from 0° to 120° (shown in Panel A2). b The articulated scope and the camera head are placed on a support plate. A gear mechanism is attached to the knob (as shown in Panel B1), which is engaged by the angulation motor (shown in Panel B2). Actuating the angulation motor rotates the knob, which in turn changes the scope angulation. c A scope adapter is used to host the support plate. The support plate is inserted inside the inner cylinder (shown in Panel C1) along the groove and locked in position using the locking pins. d The scope adapter is equipped with a connector to attach the assembly to a mechanical arm. Rotation of the inner cylinder with respect to the outer cylinder rotates the articulated scope along its axis

Fig. 2

Architecture of the proposed system for actuating an articulated scope using the surgeon’s head motions. The hardware of the system includes a head tracking unit, a clutch, an interfacing workstation, and the scope adapter. The interfacing workstation acts as a computational unit to process the commands and data streams to/from different hardware units

Fig. 3

The three head motions (roll, yaw, and pitch) performed by the surgeon to interact with the system, the actuation produced by the system based on the perceived head motions, and changes in the view of the operating field based on the actuation produced by the system

Fig. 4

a Pictorial representation of a patient in left lateral decubitus position depicting right lung lobes and ribs. b A closed loop track drawn on the right lung lobes for the subject to visualize during the navigation task. c Fabricated lung phantom used in the study. d Scope adapted connected to a UR5 robotic manipulator for placing the articulated scope with respect to the lung phantom. The view acquired by the articulated scope is shown in Panel D1. e Configurations (representing the orientation of the articulated scope shaft) used in the study

Fig. 5

Boxplots presenting parameters used to assess the user-study task of navigating a track. The track was navigated using an articulated scope under manual and actuated mode of operations. The actuated mode was further categorized into six different configurations

Fig. 6

The average scores using the NASA-TXL workload assessment scale (from 1 to 10) for actuated mode and manual mode