Dr. Rajesh Aggarwal, Department of Surgery & Cancer, Imperial College London, UK, describes and discusses how healthcare professionals utilize simulation for practice an assessment of technical skills and procedures to enhance competency, improve transfer of knowledge, surgical performance and patient safety.
Primum non nocere ‘above all, do no harm’ is a fundamental of medical practice. However, the Institute of Medicine’s report of 2000, To Err is Human, revealed that up to 98,000 hospital deaths occur in the USA as a result of medical error each year. Further global studies suggest that 10% of patients admitted to hospitals suffer harm. Medicine has relied upon a ‘see one, do one’ approach to learning and experience. Whilst this has been successful for hundreds of years, this also exposes patients to inexperienced healthcare practitioners, albeit supervised. The dangers and harm associated with this are ethically, politically and economically unacceptable.
The term ‘learning curve’ has been used to account for higher complication rates, increased mortality, and longer procedure times among inexperienced practitioners and teams. Ascent of the learning curve should no longer be achieved through trial and error. It is necessary to explore, define and implement models of health professional training that do not expose the patient to preventable errors. One such model is simulation-based training.
There are three broad domains in which healthcare professionals utilize simulation. Simulation techniques may be used for practice and assessment of technical procedures, which is the focus of this review. It can take a variety of forms ranging from simple bench models to sophisticated virtual reality machines. Second, simulated or standardized patients have long been used to teach clinical skills and are the foundation for performance-based assessment in numerous licensing examinations worldwide. Third, simulation technologies have been used for team training, to enhance function in tension-filled complex situations.
The Advent of Laparoscopic Surgery
The advent of laparoscopic surgery in the late 1980s has been described as ‘the biggest unaudited free for all in the history of surgery’. While the gold standard technique now for cholecystectomy, anti-reflux, colorectal and bariatric surgical procedures, its introduction was less than harmonious. Reports of increased rates of bile duct injury, bowel and aortic injury engaged credentialing societies to develop guidelines for safe acquisition of laparoscopic skills, predominantly on animal models, prior to attempting procedures on patients. Despite extensive expansion of simulation-based training on animal, synthetic, and now virtual reality simulation, there remains a paucity of integration of simulation-based practice into clinical training curricula.
Evidence for the benefits of simulation-based training in laparoscopic surgery date from the early part of this century. In 2000, Scott et al. revealed that training under the guise of a 4-week laparoscopic skills curriculum on box trainers enhanced surgical performance on a laparoscopic cholecystectomy in the operating room. Further studies by Grantcharov et al. and Seymour et al. in 2004 and 2002, respectively, confirmed the ability of training on a virtual reality simulator to enhance operative speed and economy of movement, and to decrease technical error. A more recent Cochrane review of virtual reality simulation has confirmed these findings, based on 23 trials involving 622 participants.
The benefits of simulation go beyond practice on a model; the trainee can practice in an educationally orientated and safe environment, at progressively more challenging levels that are appropriate to the learner, leading to the development of a proficiency-based approach to skills acquisition. In our department, we have led the development of proficiency-based training curricula in laparoscopic surgery, endovascular intervention, endoscopy, and microsurgery. This can provide a training standard that can be applied locally, regionally, or nationally.
Proficiency-based Training Curricula
The aim of a training curriculum is for an individual to acquire skills to a predetermined level of proficiency before progression to more challenging cases. It is thus not solely the simulator, but also the mode of training on the simulator, that determines the degree of transference of skill to the operative setting. This constitutes knowledge-based learning, a stepwise technical skills pathway, ongoing feedback and progression toward proficiency goals, enabling transfer to the real environment.
In 2009, Aggarwal et al. applied a stepwise process to the modules and metrics of the LapMentor virtual reality simulator, resulting in the development of a whole-procedure training curriculum for laparoscopic cholecystectomy (figure 1). The modules were deemed construct valid through comparison of performance across three levels of surgical experience. Furthermore, learning curve data were established to ensure that repetitive practice indeed improved performance in novices, as measured by the simulator. The technical skills taught by training on the simulator are thus relevant for laparoscopic cholecystectomy, and should lead to a reduction in the time taken to achieve proficiency in real patients.
Training within the curriculum commences at the basic skills modules, followed by training at the two most challenging skills, evidenced by the fact that they have significant learning curves. Progression to the procedural tasks necessitates achievement of the benchmark proficiency criteria, which are based on scores derived from the performance of experienced laparoscopic surgeons. The structure of the curriculum is identical for the four procedural tasks, leading to the full-procedure module, which again has proficiency criteria for the trainee to achieve before completion of the training period. It is important to note that the curriculum adheres to the concept of ‘distributed’ rather than ‘massed’ training schedules, with a maximum of two sessions performed per day, each at least one hour apart. Finally, to confirm acquisition of skill rather than attainment of a good score by chance, all benchmark levels must be achieved at two consecutive sessions.
This training programme is not intended as a substitute for skills acquisition in the operating theatre, though it allows part of the learning curve to be transferred to the skills laboratory. The curriculum does not take into account previous procedural or technical knowledge, nor objectively measure this before enlisting trainees into technical practice. A cognitive skills module is essential at the front end of any training programme, such as that available from the Royal College of Surgeons of England for laparoscopic cholecystectomy. Furthermore, completion of this curriculum is based on dexterity, rather than safety scores or clinical outcome measurements. This is an important aspect of research with respect to the use of technical skills rating scales and, furthermore, the integration of such scales into the simulator software.
Evidence for Transfer to Real World Performance
The benefits of training in an educationally orientated environment that enable review of performance and the ability to make errors without consequences are powerful incentives to employ simulators within the medical curriculum. Although there is interest in simulation-based training, especially for the high-fidelity virtual reality simulation, their presence remains within the confines of research departments, with a paucity of data to prescribe the widespread application of such tools.
Although the intention is to shorten the learning curve on real procedures, few studies have objectively investigated the degree to which simulation in medicine satisfy this demand. Within the airline industry, the method of establishing the quality of a new simulator is to assess its transfer-effectiveness ratio (TER). The difference in number of trials or time taken to achieve performance criterion (in the air) between untrained and simulator-trained pilots is divided by total training time received by the simulator-trained group. It is thus possible to calculate how cost and time-effective the addition of a simulator would be in a training program.
Aggarwal et al. investigated the ability of an evidence-based virtual reality training curriculum for acquisition of laparoscopic skills to transfer to improved performance on real laparoscopic procedures. They compared 20 novice surgeons, performing a series of cadaveric porcine laparoscopic cholecystectomy procedures, half of whom had undergone a virtual reality training curriculum, as previously described. The virtual reality trained group performed significantly better in terms of dexterity and video-based scores at the first cholecystectomy than the control group. Further, the results reported equivalence of performance between the simulation-trained and control groups at the third and fifth sessions, respectively. Although the learning curve for the VR-trained group was shorter and flatter than that for the control subjects, both groups of subjects demonstrated statistically significant learning curves over subsequent procedures. This demonstrates the fact that simulation-based training is not a substitute, but instead an adjunct to traditional modes of training.
The final aim was to define how the differences between the two learning curves related to time spent on the virtual reality simulator, i.e. the TER of a simulation-based surgical training curriculum. Similar studies in the aviation industry have described a TER of 0.5, although the results of this study defined a TER of 2.28, i.e. every minute that was spent training on the simulator was equivalent to 2.28 minutes on the cadaveric porcine cholecystectomy.
With this information, it is possible to accurately chart the effects of integrating simulation-based training programs into the medical curriculum. The 2-fold approach would seek to define initial outlay costs, and then to determine the time taken to recover those costs by projected reductions in time and expense spent learning laparoscopic skills in the operating theater. Only with such data can we warrant the use of simulator-based training as part of standard practice.
Experience and Expertise
Effective methods to reduce errors lead to the concept of expertise, which represents a very high level of skill acquisition and is the result of a gradual improvement through extended experience in a given domain. It seems that expert performance is not the result of extensive experience alone, but rather the consequence of engaging in specific training purposely designed to improve the current level of skill.
Ericsson has proposed that individual differences in attained professional performance can be explained by differences in deliberate practice (figure 2). This framework is based on the assumption that expert performance results from engagement in activities deliberately chosen for their ability to improve performance and maintain it at the highest level. Deliberate practice calls individuals to focus their training on defined effortful tasks, or drills. It involves repeated practice with immediate feedback on performance, often delivered by teachers and coaches.
The importance of deliberate practice in attainment of expert performance was first described in a study of expert musicians studying in Berlin. Those in the best groups were found to spend more time in solitary practice, concentrating upon the improvement of specific aspects of the music performance, as directed by their music teachers. The best experts spent 4 hours per day including weekends on this type of solitary practice. By the age of 20, the best expert musicians had spent over 10,000 hours of practice.
Attained level of expertise has been closely related to time devoted to deliberate practice in different domains requiring a high level of technical performance such as music, chess and sport. In a typical case of deliberate practice a coach designs a training activity to improve a specific aspect of an athlete’s performance. These kinds of practice tasks permit athletes to stretch their performance beyond their current level through focus on improvement in a given aspect. Furthermore, by receiving immediate feedback and opportunities to reflect on possible refinements, competitive athletes are able to improve with repeated exposures to similar tasks, or drills, over time.
In 2011, Crochet et al. performed a randomized controlled study to define whether deliberate practice could be successfully applied to training for laparoscopic cholecystectomy on a virtual reality simulator, with the intended outcome of improved quality of surgical skills. The second aim was to investigate the transfer of surgical skills from a VR simulator onto real tissues, after deliberate practice training. After training on the LapMentor virtual reality simulator, skills improved with regard to dexterity parameters in both groups. However, members of the control group completed the procedures in a shorter time and with fewer numbers of movements than the deliberate practice group, with a greater rate and final level of plateau. Conversely, the deliberate practice group achieved significantly higher scores on the video-based rating scales, which are a measure of quality rather than dexterity alone. For the 10th, 15th, and 20th LCs on the simulator, the DP group achieved global rating scores of 39%, 56%, and 50% greater than those of the control group, respectively, with similar results achieved for the procedural rating scale.
The delivery of healthcare is undergoing a major transition period across the globe. Drivers for change range from the introduction of new technologies such as primary angioplasty and robotic surgery, to restriction in work hours of trainee doctors. The dilemma of how to train doctors and allied health professionals in more specialized techniques, in a shorter period of time, together with maintenance of the highest levels of patient safety and in a cost-effective manner is a difficult one.
Innovation in healthcare means that traditional methods are challenged in order to achieve higher standards, but the process of innovation should not in itself be harmful to patients. It is thus necessary to challenge traditional processes of surgical achievement. The design, development and implementation of innovative training curricula, which are underpinned by objective measures of performance, has already begun. The challenge is for the surgical community to engage healthcare managers, policy makers and patients to help drive the change from a fixed-time variable-outcome model, toward a fixed-outcome variable-time model of training young surgeons. This will be more cost and time-efficient, but also has the potential to reduce unintentional and unnecessary error in the operating room.