Evaluation of Haptic Feedback on Bimanually Teleoperated Laparoscopy for Endometriosis Surgery

Abstract

Robotic minimal invasive surgery is gaining acceptance in surgical care. In contrast with the appreciated three-dimensional vision and enhanced dexterity, haptic feedback is not offered. For this reason, robotics is not considered beneficial for delicate interventions such as the endometriosis. Overall, haptic feedback remains debatable and yet unproven except for some simple scenarios such as fundamentals of laparoscopic surgery exercises.

Objective: This work investigates the benefits of haptic feedback on more complex surgical gestures, manipulating delicate tissue through coordination between multiple instruments.

Methods: A new training exercise, "endometriosis surgery exercise" (ESE) has been devised approximating the setting for monocular robotic endometriosis treatment. A bimanual bilateral teleoperation setup was designed for laparoscopic laser surgery. Haptic guidance and haptic feedback are, respectively, offered to the operator. User experiments have been conducted to assess the validity of ESE and examine possible advantages of haptic technology during execution of bimanual surgery.

Results: Content and face validity of ESE were established by participating surgeons. Surgeons suggested ESE also as a mean to train lasering skills, and interaction forces on endometriotic tissue were found to be significantly lower when a bilateral controller is used. Collisions between instruments and the environment were less frequent and so were situations marked as potentially dangerous.

Conclusion: This study provides some promising results suggesting that haptics may offer a distinct advantage in complex robotic interventions were fragile tissue is manipulated.

Significance: Patients need to know whether it should be incorporated. Improved understanding of the value of haptics is important as current commercial surgical robots are widely used but do not offer haptics.

Fig. 1.

Overview of experimental bimanual laser surgery setup. Two master joysticks are controlled by the operator. Steering commands are sent to a laser laparoscope holding slave robot and a robot controlling a grasper. The interaction force exerted by the slave is fed back via a bilateral controller and is well perceivable by the operator.

Fig. 2.

Endoscopic view of an endometriosis intervention; the different components that make up the scene are annotated.

Fig. 3.

Photograph of tomato model marked with green pen; the part of the exocarp that needs to be ‘surgically’ removed from the mesocarp.

Fig. 4.

Experiment layout; an endometriosis model is placed remotely. The grasper is used to put the tissue under tension; the CO laser is handled to remove a superficial patch while maximally keeping healthy tissue intact. The grasper is equipped with a force measurement system consisting of a pair of extra-corporeal force sensors. Both instruments access the region through a trocar. The laparoscope robot is controlled unilaterally while the grasper can be controlled either unilaterally or bilaterally.

Fig. 5.

Free body diagram to derive the static equilibrium of the instrument driver and of the instrument itself. A first force transducer connects the two bodies. The instrument driver is hingedly connected via a 2 DoF passive joint to the end effector of the LoTESS. Rotation of the instrument about its axis is accomplished through the instrument driver. The instrument passes a cannula that is hinged in a 3 DoF passive joint. A second force transducer mounted at this point measures the interaction forces exerted on the body wall. All forces measured by the first force sensor that cannot be explained as originating from the body wall are thus caused by interaction with the targeted organ; here such interaction is assumed to take place at the tip of the instrument.

Fig. 6.

Time series of through one exemplary exercise in which haptic feedback was available. Coloured bars on top indicate the activation of the CO laser and the ‘clutching’ state of the laser and the grasper. During the first stage of the exercise, contact forces are close to zero as the surgeon is only using the laser for edging and the grasper is unclutched; in the second phase the forceps is actively used to position the patch for the laser.

Fig. 7.

Zoom in on the time series of the region marked in Fig. 6. Next, tracking performance of the slave grasper and the respective master – over the same region. Note that no ‘clutching’ took place during this time window.

Fig. 8.

Sample of processed model of 3rd exercise of surgeon number 5. A single exocarp patch visible at the right. Good outcome visible as no green coloured mark, targeted tissue, remains on the surface of the tomato.

Fig. 9.

Analysis of the metric “maximum force” grouped by surgeon and classified by type of controller.

Fig. 10.

Analysis of the metric “maximum force” represented individually for every exercise in chronological order of execution and matched by surgeon.