Simulator-based assessment of haptic surgical skill: a comparative study.

The aim of this study was to examine if the forces applied by users of a haptic simulator could be used to distinguish expert surgeons from novices. Seven surgeons with significant operating room expertise and 9 novices with no surgical experience participated in this study. The experimental task comprised exploring 4 virtual materials with the haptic device and learning the precise forces required to compress the materials to various depths. The virtual materials differed in their stiffness and force-displacement profiles. The results revealed that for nonlinear virtual materials, surgeons applied significantly greater magnitudes of force than novices. Furthermore, for the softer nonlinear and linear materials, surgeons were significantly more accurate in reproducing forces than novices. The results of this study suggest that the magnitudes of force measured using haptic simulators may be used to objectively differentiate experts' haptic skill from that of novices. This knowledge can inform the design of virtual reality surgical simulators and lead to the future incorporation of haptic skills training in medical school curricula.

Assessment of Open Surgery Suturing Skill: Image-based Metrics Using Computer Vision.

OBJECTIVE: This paper presents a computer vision algorithm for extraction of image-based metrics for suturing skill assessment and the corresponding results from an experimental study of resident and attending surgeons. DESIGN: A suturing simulator that adapts the radial suturing task from the Fundamentals of Vascular Surgery (FVS) skills assessment is used to collect data. The simulator includes a camera positioned under the suturing membrane, which records needle and thread movement during the suturing task. A computer vision algorithm processes the video data and extracts objective metrics inspired by expert surgeons' recommended best practice, to "follow the curvature of the needle." PARTICIPANTS AND RESULTS: Experimental data from a study involving subjects with various levels of suturing expertise (attending surgeons and surgery residents) are presented. Analysis shows that attendings and residents had statistically different performance on 6 of 9 image-based metrics, including the four new metrics introduced in this paper: Needle Tip Path Length, Needle Swept Area, Needle Tip Area and Needle Sway Length. CONCLUSION AND SIGNIFICANCE: These image-based process metrics may be represented graphically in a manner conducive to training. The results demonstrate the potential of image-based metrics for assessment and training of suturing skill in open surgery.

Salient haptic skills trainer: initial validation of a novel simulator for training force-based laparoscopic surgical skills.

BACKGROUND: There is an increasing need for efficient training simulators to teach advanced laparoscopic skills beyond those imparted by a box trainer. In particular, force-based or haptic skills must be addressed in simulators, especially because a large percentage of surgical errors are caused by the over-application of force. In this work, the efficacy of a novel, salient haptic skills simulator is tested as a training tool for force-based laparoscopic skills. METHODS: Thirty novices with no previous laparoscopic experience trained on the simulator using a pre-test-feedback-post-test experiment model. Ten participants were randomly assigned to each of the three salient haptic skills-grasping, probing, and sweeping-on the simulator. Performance was assessed by comparing force performance metrics before and after training on the simulator. RESULTS: Data analysis indicated that absolute error decreased significantly for all three salient skills after training. Participants also generally decreased applied forces after training, especially at lower force levels. Overall, standard deviations also decreased after training, suggesting that participants improved their variability of applied forces. CONCLUSIONS: The novel, salient haptic skills simulator improved the precision and accuracy of participants when applying forces with the simulator. These results suggest that the simulator may be a viable tool for laparoscopic force skill training. However, further work must be undertaken to establish full validity. Nevertheless, this work presents important results toward addressing simulator-based force-skills training specifically and surgical skills training in general.

A haptic simulator to increase laparoscopic force application sensitivity.

Laparoscopic surgery demands perceptual-motor skills that are fundamentally different from open surgery, and laparoscopists must be adept at perceiving tissue interaction at the surgical site and then applying precise amounts of forces through instruments without damaging tissues. A haptic simulator that emulates multiple salient laparoscopic tasks and renders differing degrees of forces was created. Two of the haptic skills tasks were evaluated in two studies to determine their ability to distinguish and then train laparoscopic force application sensitivity. Results suggested that the simulator has the capability of rendering salient force feedback information to which novices become increasingly more perceptually sensitive.

Cannulation Skill Assessment Using Functional Data Analysis.

OBJECTIVE: A clinician's operative skill-the ability to safely and effectively perform a procedure-directly impacts patient outcomes and well-being. Therefore, it is necessary to accurately assess skill progression during medical training as well as develop methods to most efficiently train healthcare professionals. METHODS: In this study, we explore whether time-series needle angle data recorded during cannulation on a simulator can be analyzed using functional data analysis methods to (1) identify skilled versus unskilled performance and (2) relate angle profiles to degree of success of the procedure. RESULTS: Our methods successfully differentiated between types of needle angle profiles. In addition, the identified profile types were associated with degrees of skilled and unskilled behavior of subjects. Furthermore, the types of variability in the dataset were analyzed, providing particular insight into the overall range of needle angles used as well as the rate of change of angle as cannulation progressed in time. Finally, cannulation angle profiles also demonstrated an observable correlation with degree of cannulation success, a metric that is closely related to clinical outcome. CONCLUSION: In summary, the methods presented here enable rich assessment of clinical skill since the functional (i.e., dynamic) nature of the data is duly considered.

Assessing surgeon and novice force skill on a haptic stiffness simulator for laparoscopic surgery.

Though several simulators and training methods are available for basic laparoscopic skills, few have addressed force-based skills. In this work, we discuss a haptic simulator that renders virtual materials of different stiffness profiles to be used for haptic skills differentiation. A force-based task was designed on the simulator and the performance of surgeons and novices was analyzed. Results indicate that surgeons and novices differ in their ability to use the haptic device to reproduce target stiffness levels. This work provides an important step towards quantifying haptic skill metrics for the design of surgical skills training simulators.

Haptic tasks for physical laparoscopic ("Box") trainers to differentiate surgeon skill.

In this work, we present four tasks, primarily testing haptic laparoscopic skill that can be simulated in a conventional box trainer. Results from examining expert surgeon and novice performance is presented as evidence that these tasks can be used for training haptic skills for laparoscopy in a box trainer.

Assessment of open surgery suturing skill: Simulator platform, force-based, and motion-based metrics.

Objective: This paper focuses on simulator-based assessment of open surgery suturing skill. We introduce a new surgical simulator designed to collect synchronized force, motion, video and touch data during a radial suturing task adapted from the Fundamentals of Vascular Surgery (FVS) skill assessment. The synchronized data is analyzed to extract objective metrics for suturing skill assessment. Methods: The simulator has a camera positioned underneath the suturing membrane, enabling visual tracking of the needle during suturing. Needle tracking data enables extraction of meaningful metrics related to both the process and the product of the suturing task. To better simulate surgical conditions, the height of the system and the depth of the membrane are both adjustable. Metrics for assessment of suturing skill based on force/torque, motion, and physical contact are presented. Experimental data are presented from a study comparing attending surgeons and surgery residents. Results: Analysis shows force metrics (absolute maximum force/torque in z-direction), motion metrics (yaw, pitch, roll), physical contact metric, and image-enabled force metrics (orthogonal and tangential forces) are found to be statistically significant in differentiating suturing skill between attendings and residents. Conclusion and significance: The results suggest that this simulator and accompanying metrics could serve as a useful tool for assessing and teaching open surgery suturing skill.

Perceptual metrics: towards better methods for assessing realism in laparoscopic simulators.

This work proposes a novel class of metrics for assessing haptic realism in laparoscopic surgical simulators. Results from a proposed perceptual metric are presented and discussed.

Role of haptic feedback in a basic laparoscopic task requiring hand-eye coordination.

This work discusses the role and importance of haptic feedback and simulator training for simple laparoscopic tasks akin to the FLS peg-transfer task. Results from a study designed to examine haptics for this purpose are discussed.

Comparative study of haptic training versus visual training for kinesthetic navigation tasks.

Kinesthetic motion appears in tasks ranging from minimally invasive surgical procedures to patient rehabilitation. In this work, a comparative study is performed using two training paradigms for kinesthetic tasks. Subjects are trained to learn a complex 3D path through either the haptic method or the visual method. After the training period, subjects trace the learned 3D path without any feedback. Performance is evaluated primarily based on path deviation and time. Results indicate that haptically trained users have significantly higher performance than visually trained users. Other relevant results are also presented that can have a significant effect in the design of haptics-based interaction systems.

Surgical Suturing with Depth Constraints: Image-based Metrics to Assess Skill.

Suturing is one of the most fundamental surgical skills, requiring careful and systematic instruction for skilled performance. In this paper, we evaluate the performance of attending surgeons and surgical residents on an open surgery suturing task to examine if the introduction of different depth levels affects their performance. A vision algorithm is used to extract metrics meaningful in the assessment of suturing skill. As subjects perform a suturing task on the platform, our vision algorithm computes metrics identified to be potentially useful in assessing suturing skill: distances from optimal entry and optimal exit points, stitch length, stitch time, idle time, needle swept area, needle tip trace distance, needle tip area, and needle sway length. Preliminary experimental data from a study with 5 attending surgeons and 7 surgical residents are presented. Results demonstrate that the metrics of distance from optimal exit points, idle time, needle swept area, needle tip trace distance, needle tip area, and needle sway length are useful in quantifying the effect of depth constraints on suturing performance.

Endovascular seldinger needle placement: a simulator for examining haptic skills.

In this work, we develop an affordable haptic simulator for examining haptic skills required for endovascular Seldinger needle placement.

Objective differentiation of force-based laparoscopic skills using a novel haptic simulator.

BACKGROUND: There is a growing need for effective surgical simulators to train the novice resident with a core skill set that can be later used in advanced operating room training. The most common simulator-based laparoscopic skills curriculum, the Fundamentals of Laparoscopic Skills (FLS), has been demonstrated to effectively teach basic surgical skills; however, a key deficiency in current surgical simulators is lack of validated training for force-based or haptic skills. In this study, a novel haptic simulator was examined for construct validity by determining its ability to differentiate between the force skills of surgeons and novices. METHODS: A total of 34 participants enrolled in the study and were divided into two groups: novices, with no previous surgical experience and surgeons, with some level of surgical experience (including upper level residents and attendings). All participants performed a force-based task using grasping, probing, or sweeping motions with laparoscopic tools on the simulator. In the first session, participants were given 3 trials to learn specific forces associated with locations on a graphic; after this, they were asked to reproduce forces at each of the locations in random order. A force-based metric (score) was used to record performance. RESULTS: On probing and grasping tasks, novices applied significantly greater overall forces than surgeons. When analyzed by force levels, novices applied greater forces on the probing task at lower and mid-range forces, for grasping at low-range forces ranges and, for sweeping at high-range forces. CONCLUSIONS: The haptic simulator successfully differentiated between novice and surgeon force skill level at specific ranges for all 3 salient haptic tasks, establishing initial construct validity of the haptic simulator. Based on these results, force-based simulator metrics may be used to objectively measure haptic skill level and potentially train residents. Haptic simulator development should focus on the 3 salient haptic skills (grasping, probing, and sweeping) where precise force application is necessary for successful task outcomes.