The popularity of laparoscopic techniques has created to a new domain in surgical training, with a move away from the apprenticeship model, toward structured programs of teaching new skills outside the operating room in laparoscopic training institute. Hands-on courses enables young surgeons to practice techniques on synthetic, porcine or more recently virtual-reality models, are now commonplace with facility of animal dissection. The aim of newer laparoscopic training has been to ensure trainees are armed with basic laparoscopic skills, such as hand-eye coordination and depth perception prior to entering the operating room. The success of these initial courses led to the development of similar courses for the advanced laparoscopic skills required for gastric and colonic surgery.
Figure: Demonstration of different types of knot to keep them in memory
Compared to aviation, where virtual reality (VR) training has been standardized and simulators have proven their definite benefit in increasing skill, the objectives, needs, and means of VR training in minimal access surgery (MIS) is established.
Rasmussen distinguishes three levels of human behaviour:
- Skill based level
- Rule based level, and
- Knowledge-based behaviour.
Skill-based behaviour
This represents surgeon’s behaviors that takes place without conscious control. Task execution is highly automated at this level of behaviour and is based on fast selection of motor programs which control the appropriate muscles. The motor programs are based on an accurate internal representation of the task, the system dynamics, and the environment at hand (e.g., learned by training and experience). An example of an everyday skill is walking. Many tasks in surgery can be considered as a sequence of skilled acts. For example, an experienced surgeon performs a suture task smoothly, without conscious control over his or her movements.
Figure: Different types of simple pelvitrainers
In MIS, suturing can also be considered as skill-based behaviour. However, because of the indirect access to the tissue it is a much more complicated skill because of reduced depth perception and difficult hand–eye coordination.
Figure: Pelvitrainer exercises to improve skill
Rule-based behaviour
At the next level of human behavior, rule-based behavior is applied. During rule-based behaviour task execution is controlled by stored rules or procedures. These may have been derived empirically from previous occasions or communicated from other persons’ expertise as instructions or as a cookbook recipe. Appropriate rules are selected according to their ‘‘success’’ in previous experiences. For example, procedural steps and the recognition of anatomy and pathology in MIS require rule-based behavior. At the rule-based level, the information is typically perceived as discrete signs (Fig. 1). A sign serves to activate or to trigger a stored rule. Stopping your car in front of a red light is a good example of a sign (red light) that triggers a stored rule (stop car). In laparoscopic cholecystectomy, having fully established the critical view of safety is the sign that triggers the rule that the appropriate structures may be clipped next.
Knowledge-based behaviour
In unfamiliar situations, faced with a task for which no rules are available from previous encounters, human behavior is knowledge based. During knowledge-based behaviour the goal is explicitly formulated, based on an analysis of the overall aim. Different plans are
developed, and their effects mentally tested against the goal. Finally a plan is selected. Serious complications that occasionally occur during surgery demand a great deal of knowledge-based behaviour from the surgeon. He or she has to analyze the complication and the aim of the surgical procedure in order to develop strategies to counter the complication. Then he or she has to select the best strategy and consequently take the appropriate actions.
At the knowledge-based level, information is perceived as symbols. Symbols refer to chunks of conceptual information, which are the
basis for reasoning and planning. Pathological symptoms are a good example of symbols in medical practice.
Training in laparoscopic surgery is beginning to evolve into a stepwise, curricular approach that is not organ or procedure-specific. Instead, it is necessary to learn manipulative skills, which are then combined to achieve proficiency in tasks such as laparoscopic suturing or division of a vessel. The constituent parts can then be combined with anatomical knowledge to enable completion of a specific procedure. Basic psychomotor skills can be learnt with a simple, cheap version of a video-box trainer. Higher level skills such as dissection and use of high-energy instruments will necessitate the use of more realistic tissues, which can be achieved on porcine or human cadaveric models. Recent advances in virtual reality simulation are also beginning to produce realistic simulations of complete procedures, for example, laparoscopic cholecystectomy.
It would be rational to assume that a high-fidelity simulation model, such as anesthetized animal tissue, would be superior in terms of training outcome to a synthetic plastic model.
Figure: The simple pelvitrainer can be used for improving suturing skill
In fact, a study comparing two groups learning to perform micro-anastomotic repair of a transected spermatic cord on either the animal or synthetic model found no difference in eventual outcome of the two groups. The synthetic model is obviously cheaper and does not require specialized storage facilities. It can be assumed that as the subjects were using real sutures and instruments, the nature of the task was learnt regardless of the fidelity of the simulated tissue.
Training objectives, needs, and means
To enable the design and evaluation of an effective and efficient training method it is of utmost importance to determine the training objectives, needs, and means, since they provide an answer to the questions:
- What is the end goal of the training?
- What should be trained?
- How can we train it?
The objectives represent the level of competence that is expected of the trainee after he or she has completed the training. Training needs are the difference between the initial level of competence of the trainees and the required level of competence after successful completion of the training defined in the objectives. Ultimately, demands for effectivity and efficiency on the one hand, and the state-of-the-art in technology on the other hand, determine the tools and methods for training, i.e., the training means. Effective training ensures that all training objectives are met. Efficient training ensures that the training means are cost effective and that the required training time is minimized. Since safety and patient outcome are the most important criteria in surgery, training effectivity should be of primary importance.
Figure: The programming of virtual reality simulator will increase rule base level
The complexity and the costs of the training means are largely determined by the training objectives that have been set. Fulfilling all training needs of laparoscopic residents with only one training method will require a highly complex and probably very expensive trainer in which all three levels of behavior can be trained. Such a trainer is not yet available. The complexity and the cost of a training means are relatively low if the training objectives comprise skill-based behaviour only, since this can be trained with simple models such as Pelvitrainers. Evidently, the cost and complexity of a training means increase when the training objectives advance from the training of skillbased behavior to the training of knowledge-based behavior. Fortunately, the overall effectivity of training increases as well when higher levels of behavior, such as knowledge-based behavior, are incorporated in the training objectives.
Figure: Prototype virtual reality pelvitrainers
Present training in laparoscopy
A closer look at the training program of laparoscopic residents provides an indication of the training needs that are addressed and the training means that are available today. Much as in conventional surgery, the laparoscopic surgeon must effectively combine the three levels of behavior. Instrument handling and dissection techniques require skill-based behavior, whereas the recognition of surgical anatomy requires a great deal of rule-based behavior. Complications such as uncontrollable bleeding or unsuspected situations such as the encountering of aberrant anatomy require problem solving on a knowledge-based level.
Obviously, training of skill-based behavior in laparoscopic surgery is highly desired as laparoscopy combines unusual hand–eye coordination with the use of complex instruments. Surgical residents
are usually trained in laparoscopic surgery during a 2-day introduction course. Basic skill-based behaviour such as instrument tissue handling and minimally invasive suturing are trained. Additionally, rule-based behaviour is trained through lectures, textbooks, and video instructions. After the resident has successfully completed this course, he or she will receive training in the operating room. It is only in operating room that most knowledge- based behaviour necessary to deal with complications and emergencies is acquired. Currently, a living animal model provides the only way to effectively train rule- and knowledge-based behaviour outside the operating room. Training on living animal models is very useful in the training curriculum of resident surgeons. However, at the same time the use of laboratory animals for training is discouraged by many government policies. Technological innovations, such as virtual reality simulation, will change the way laparoscopic surgery is trained. Current accomplishments in surgical simulation envision the dawning of the next-generation surgical education. In this respect, aviation industry provides excellent examples of the effectiveness and efficiency of virtual reality simulators as a means of training.
Simulator training in aviation in contrast to surgery, the training needs in aviation has explicitly been defined by regulatory authorities like Federal Aviation Administration (FAA) and the training means are certified accordingly. The training objectives, needs, and means in pilot training have been investigated in depth, and models of pilot behaviour have been developed as a tool to design, to evaluate, and to optimise training methods. Half a century of extensive research has resulted in many training tools, from basic flight training devices to the high-tech full flight simulator (FFS).
Figure: Different types of Virtual reality systems for endoscopy
After the introduction of VR training methods in the 1990s, the training of surgeons has often been compared to the training of pilots. The training of laparoscopic residents can best be compared to type conversion training of pilots. During type conversion training, young pilots who have finished flight training at the academies and have recently joined an airline are trained to fly a particular type of aircraft. The general objective of type conversion training is to teach the trainee how to safely control, navigate, and manage a particular operational aircraft. Since the trainees have already acquired much of the skill-based behaviour required to fly a multiengine aircraft, the training needs mainly consist of acquiring additional rule- and knowledge-based behaviour. The trainees have to learn the new checklists and the specific procedures during takeoff and landing, and they have to become familiar with all the aircraft systems like electronics, hydraulics. Furthermore, they have to train all sorts of emergency scenarios that may occur during actual flight. Training of this knowledge-based behaviour is very important since it significantly improves flight safety. This training provides an excellent training tool to accomplish all the specified training needs. The high level of realism during training of a pilot have even made zero flight time training possible, during which type conversion training takes place completely outside a real aircraft.
Figure: HALS training box
Defining the training objectives, needs, and means For the sake of proper training and for the safety of our patients, the objectives, needs, and means in laparoscopy training should be defined. Along this guideline, VR simulators should be developed. An explicit formulation of the training objectives facilitates the development and certification of a simulator since it determines what the simulator should be capable of. For example, pilots spend many hours training on low-cost simulator.
Figure: Virtual reality trainer with programmable circuit
The laparoscopy simulators that have been developed during the past decade can all be considered as laparoscopy training devices. Most of these simulators specifically aim at training skill-based behavior, such as endoscopic manipulation and endoscopic camera navigation. However, performing safe laparoscopy also requires a professional level of rule- and knowledge-based behaviour from the surgeon. Ideally these should also be trained outside the operation theatre. Currently, the training of rule- and knowledgebased behavior outside the operation theatre is only possible on living animal models. However, technological innovations like increasing computing power, detailed anatomical models, soft tissue modeling, force feedback will enable the integration of all levels of behaviour in a VR training simulator for laparoscopy. In the future, this might result in a full-scale laparoscopy simulator (FLS), comparable to the FFS in pilot training. Perhaps a FLS even introduces zero operating time training as the ultimate objective.
The medical society should establish detailed objectives of training. Recently, experts have begun to investigate what level of professional behaviour is required to perform safe laparoscopy. In addition, they are establishing the training needs of laparoscopic residents by determining what should be trained to accomplish the training objective. The question of which aspects of skill, rule, and knowledge-based behaviour should be trained is addressed. Currently, there is no such standard available. Once the training objectives have been standardized and the training needs at the different levels of behaviour have been identified, the simulator society will have clear guidelines as to what their training devices should be capable of.
One of the most obvious training needs of laparoscopic residents is the training of manual skills. The manual skills required during laparoscopy are rather different from those in conventional surgery. Training of skill-based behavior is feasible with basic trainers such as a Pelvi trainer. The VR basic skill trainers that are commercially available usually simulate a generic abdomen and endoscopic instruments on a computer monitor. Basic tasks, such as pickand place tasks, are implemented to train endoscopic manipulation. The training of skill-based behavior does not require a highly realistic anatomical environment, e.g., the organs do not necessarily have to be simulated realistically. For example, the virtual reality trainer simulates basic manipulation tasks in a highly simplified environment similar to the Pelvi trainer box. Several studies have reported that training on the virtual reality facilitated the learning of skill-based behaviour.
Figure: Virtual reality trainer with software control
An advantage of virtual reality simulators over simple Pelvitrainers is the capability to easily extend the training to the rule-based level of behavior, since textbook theory, instructions, and training videos can easily be integrated in the simulator software. Much textbook material and many training videos that provide rule-based behaviour training have been made available on the Internet. Laparoscopy simulators are capable of training skill and rule-based behavior. To train knowledge-based behavior, a laparoscopy simulator should be capable of accurately imitating the surgical environment encountered during laparoscopic surgery.
Figure: Virtual reality trainer for LAVH
The perceived information from the environment should be simulated accurately to ensure effective training. The training of knowledge-based behavior on a simulator still poses a huge challenge. Two fundamental problems occur. Whereas the physics that determine the behavior of an aircraft is fairly well known and described mathematically, the physics that describes the behavior of soft-tissue organs is highly complicated and many parameters are simply still missing. Additionally, each aircraft roughly has the same flight characteristics and cockpit layout, but each new patient has a different anatomical layout than the previous one. Laparoscopy simulators have to be able to generate ‘‘random’’ patients.
Figure: Simulated models of GB and CBD to improve Choledocoscopic skill
The integration of knowledge-based behavior training in a future simulator would enhance safety levels in laparoscopy, since then every possible surgical complication could be trained beforehand. As in aviation, intensive training can reduce a situation that at first required improvising at a knowledge-based behaviour level from the trainee, to a situation that can be solved by applying trained rules.
Conclusions
In this article it has been pointed out that it is important to establish the training objectives, needs, and means, since they provide an answer to the questions What is the end goal of the training?, What should be trained?, and How can we train it? Rasmussen’s model of human behavior provides a practical framework for the definition of the training objectives, needs, and means in MAS, and the evaluation thereof.
Prof. Dr. R. K. Mishra
MRCS; M.MAS
Master in Minimal Access Surgery
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发表于 2013-2-5 21:44:26
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发表于 2013-8-9 07:57:55
