Surgical Simulator Design and Development

With the introduction of minimally invasive surgery (MIS), it became necessary to develop training methods to learn skills outside the operating room. Several training simulators have become commercially available, but fundamental research into the requirements for effective and efficient training in MIS is still lacking. Three aspects of developing a training program are investigated here: what should be trained, how it should be trained, and how to assess the results of training. In addition, studies are presented that have investigated the role of force feedback in surgical simulators. Training should be adapted to the level of behavior: skill-based, rule-based, or knowledge-based. These levels can be used to design and structure a training program. Extra motivation for training can be created by assessment. During MIS, force feedback is reduced owing to friction in the laparoscopic instruments and within the trocar. The friction characteristics vary largely among instruments and trocars. When force feedback is incorporated into training, it should include the large variation in force feedback properties as well. Training different levels of behavior requires different training methods. Although force feedback is reduced during MIS, it is needed for tissue manipulation, and therefore force application should be trained as well

Feedback in laparoscopic skills acquisition: an observational study during a basic skills training course

This study aimed to obtain insight in the effect of expert feedback during a basic laparoscopic skills training course for residents. A questionnaire was held among participants regarding provided feedback and the self-perceived laparoscopic skills improvement. The participants (n = 24) who completed the questionnaire were in their first to fifth postgraduate year. Most feedback was directed at intracorporeal knot tying (47% reported extensive feedback), while camera navigation and body positioning received the least feedback (40% and 43%, respectively, responded to have received no feedback at all). After the course, the self-perceived competence in intracorporeal knot tying and cutting had improved significantly, while camera navigation, body positioning, pointing, and grasping tasks did not improve. In conclusion, most benefit from expert feedback can be obtained at the start of the learning curve. Therefore, the basic laparoscopic skills course should be attended early in residency. Additionally, it is crucial that training objectives are clear prior to a course for both the expert and the trainee, in order to focus the feedback on all training objectives

Visual force feedback in laparoscopic training

Background - To improve endoscopic surgical skills, an increasing number of surgical residents practice on box or virtual reality (VR) trainers. Current training is focused mainly on hand–eye coordination. Training methods that focus on applying the right amount of force are not yet available. Methods - The aim of this project is to develop a low-cost training system that measures the interaction force between tissue and instruments and displays a visual representation of the applied forces inside the camera image. This visual representation continuously informs the subject about the magnitude and the direction of applied forces. To show the potential of the developed training system, a pilot study was conducted in which six novices performed a needledriving task in a box trainer with visual feedback of the force, and six novices performed the same task without visual feedback of the force. All subjects performed the training task five times and were subsequently tested in a post-test without visual feedback. Results - The subjects who received visual feedback during training exerted on average 1.3 N (STD 0.6 N) to drive the needle through the tissue during the post-test. This value was considerably higher for the group that received no feedback (2.6 N, STD 0.9 N). The maximum interaction force during the post-test was noticeably lower for the feedback group (4.1 N, STD 1.1 N) compared with that of the control group (8.0 N, STD 3.3 N). Conclusions - The force-sensing training system provides us with the unique possibility to objectively assess tissuehandling skills in a laboratory setting. The real-time visualization of applied forces during training may facilitate acquisition of tissue-handling skills in complex laparoscopic tasks and could stimulate proficiency gain curves of trainees. However, larger randomized trials that also include other tasks are necessary to determine whether training with visual feedback about forces reduces the interaction force during laparoscopic surgery.Biomechanical EngineeringMechanical, Maritime and Materials Engineerin

Time-Action Analysis of Catheter Manipulation During Navigation Tasks in Bifurcations

Endovascular intervention is a form of minimally invasive intervention that allows catheters to be placed in practically any location of the vascular tree. However, to provide access to all these remote locations, an extensive array of catheters is needed. A specific catheter is choose based on experience, without any objective indication of its suitability during the actual procedure (Bakker, N. H., Tanase, D., Reekers, J. A., and Grimbergen, C. A., 2002, "Evaluation of Vascular and Interventional Procedures with Time-Action Analysis: A Pilot Study," J. Vasc. Intervent. Radiol., 13(5), pp. 483-488). The aim of this study is to evaluate several catheters using time-action analysis during a navigation task in bifurcations of various geometries. The relation between the geometry of bifurcations, the catheters, and the time taken to perform specific actions is investigated. Nine novices manipulated five widely used selective catheters with a 0.035" guidewire in a model. In the model, four bifurcations of various diameters and angles were selected. Each bifurcation was cannulated six times with two different yet suitable catheters. The participants had no direct vision of the model but navigated the instruments using the images that were captured by a camera and displayed on a screen. All images presented to the participant were recorded and used for detailed time-action analysis of the various actions to cannulate a branch (e.g., catheter or guidewire retracted, rotated, and advanced). On average, the participants needed 28.3 s to cannulate a branch. When the ratio between the diameter of the main and side branch was high, the average time per task increased significantly, as did the number of attempts to navigate into a branch. However, neither the choice between the two suitable catheters for each bifurcation, nor the angles of the bifurcation made a significant difference in navigation time. Time-action analysis enabled objective measurement of the time spent on various actions to cannulate a branch. The results revealed that most time was spent on retracting and rotating the catheter. This was comparable for all catheters and branches, showing that all the instruments were manipulated in a similar way and presented the same difficulties

Adaptive neuro-fuzzy inference systems (ANFIS) for supervised classification of competence in MIS based on psychomotor skills

INTRODUCTION: Objective assessment of motor skills has become an important challenge in minimally invasive surgery (MIS) training.Currently, there is no gold standard defining and determining the residents' surgical competence.To aid in the decision process, we analyze the validity of a supervised classifier to determine the degree of MIS competence based on assessment of psychomotor skills METHODOLOGY: The ANFIS is trained to classify performance in a box trainer peg transfer task performed by two groups (expert/non expert). There were 42 participants included in the study: the non-expert group consisted of 16 medical students and 8 residents ( 10 MIS procedures performed) and 4 experienced surgeons. Instrument movements were captured by means of the Endoscopic Video Analysis (EVA) tracking system. Nine motion analysis parameters (MAPs) were analyzed, including time, path length, depth, average speed, average acceleration, economy of area, economy of volume, idle time and motion smoothness. Data reduction was performed by means of principal component analysis, and then used to train the ANFIS net. Performance was measured by leave one out cross validation. RESULTS: The ANFIS presented an accuracy of 80.95%, where 13 experts and 21 non-experts were correctly classified. Total root mean square error was 0.88, while the area under the classifiers' ROC curve (AUC) was measured at 0.81. DISCUSSION: We have shown the usefulness of ANFIS for classification of MIS competence in a simple box trainer exercise. The main advantage of using ANFIS resides in its continuous output, which allows fine discrimination of surgical competence. There are, however, challenges that must be taken into account when considering use of ANFIS (e.g. training time, architecture modeling). Despite this, we have shown discriminative power of ANFIS for a low-difficulty box trainer task, regardless of the individual significances between MAPs. Future studies are required to confirm the findings, inclusion of new tasks, conditions and sample population

An Isolator System for minimally invasive surgery: the new design

Background - The risk of obtaining a postsurgical infection depends highly on the air quality surrounding the exposed tissue, surgical instruments, and materials. Many isolators for open surgery have been invented to create a contained sterile volume around the exposed tissue. With the use of an isolator, a surgical procedure can be performed outside sterile environments. The goal of this study was to design an Isolator System (IS) for standard laparoscopic instruments while instrument movements are not restricted. Methods - The developed IS consists of a sleeve to protect the instrument shaft and tip and a special balloon to protect the incision and trocar tube. A coupling mechanism connected at the sleeve allows instrument changes without contamination of the isolated parts. Smoke tests were performed to show that outside air does not enter the new IS during a simulated laparoscopic procedure. Eight test runs and one baseline run inside a contained volume filled with thick smoke were performed to investigate whether smoke particles entered the Isolator System. Filters were used to identify smoke entering the Isolator System. Results - Seven filters showed no trace of smoke particles. In one test run, a part of the IS loosened and a small brown spot was visible. The filter from the baseline run was completely covered with a thick layer of particles, proving the effectiveness of the test. During all test runs, the isolated instrument was successfully locked on and unlocked from the isolated trocar. Instrument movements gave no complications. After removal of the isolated instrument, it took three novices an average of 3.1 (standard deviation (SD), 0.7) seconds to replace it correctly on the isolated trocar. Conclusions - The designed IS for laparoscopy can increase sterility in environments where sterility cannot be guaranteed. The current design is developed for laparoscopy, but it can easily be adapted for other fields in minimally invasive surgery.Biomechanical EngineeringMechanical, Maritime and Materials Engineerin