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Ultrasound simulators in obstetrics and gynecology: state of the art

2014; Wiley; Volume: 46; Issue: 3 Linguagem: Inglês

10.1002/uog.14707

1469-0705

G. E. Chalouhi, V. Bernardi, Y. Ville,

Surgical Simulation and Training

Ultrasound is the primary method of imaging in obstetrics and gynecology1. Its use encompasses screening as well as expert examination of normal and abnormal cases2. It has become an essential part of practice in obstetrics, including maternal–fetal medicine, as well as in gynecology, often irrespective of the ability, competence and experience of the operators3, 4; the lack of standardization in training and assessment of skill has become a matter of concern worldwide. The majority of international institutions have set criteria and a minimum number of procedures that are required to perform obstetric and gynecological ultrasound in clinical settings5. These, however, vary between institutions and there is a wide range in skill level of both trainees and practitioners. For instance, the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) has suggested a minimum of 200 obstetric scans for residents in obstetrics and gynecology6. The American Institute of Ultrasound in Medicine (AIUM) has defined standards for training to be applied to sonologists. They also require specific ultrasound training for at least 3 months or the performance of at least 300 ultrasound examinations as part of an accredited residency or fellowship program. Their determination of competency for trainees is, however, based on residency review-committee standards, which do not define specific numbers of scans for trainees, but require competency assessment by program directors and faculty7. The American College of Obstetricians and Gynecologists (ACOG) requires specific ultrasound training for at least 3 months for completion of a fellowship graduate medical education of maternal–fetal medicine8. Training standards and assessment of competency are likewise not standardized across the different European countries. Performance of a minimum number of scans is required in Germany, Switzerland and Denmark, while no formal curriculum for ultrasound teaching is provided nor is any minimum number of scans required in Italy and Sweden. Attending a dedicated course and achieving a certificate of competency is mandatory in France, Germany, Switzerland and the UK9. In the UK, the Royal College of Obstetricians and Gynaecologists (RCOG)10 and in France, the National College of Obstetricians and Gynecologists (CNGOF)11 require that trainees should be assessed on their ability rather than through any given number of examinations. In both countries, candidates also sit both a theoretical and a practical examination10. To date, teaching and training have been mostly patient-centered5. Theoretical knowledge is not sufficient, and practical training can either be achieved on actual patients or on volunteers. However, this conventional patient-centered approach involves numerous difficulties and disadvantages. It puts the trainees in an uncomfortable situation, especially during the initial phase of training, when the interaction with the patient may distract them from becoming familiarized with handling and manipulation of the ultrasound probe and with interpretation of the ultrasound images12. Furthermore, developing competency in ultrasound is largely dependent upon the variety and number of cases encountered during clinical practice and there is a great diversity of opportunities among different students13. Often, the concept of trainees practicing on them is also stressful for the patient12, particularly in cases undergoing transvaginal sonography or in the presence of a fetal malformation. Even for volunteers, repeat examination by inexperienced and often stressed trainees can be uncomfortable and has the potential to cause anxiety. The limited availability of ultrasound machines dedicated to training is an additional limiting factor even for motivated trainees who are willing to train after hours, and the presence of trainees during working hours interferes significantly with the normal activity of the unit. We view as unacceptable the process of inexperienced trainees practicing on actual patients as the very first step of their learning process, which may be characterized by a significant number of errors and extensive time requirements. The increased focus on medical errors and patient safety also calls for development of alternative methods of continuous education and assessment of skills14. This has, understandably, led to insurance companies becoming involved in the development of simulation in medicine. For example, the patient safety and medical malpractice company of the Harvard medical community, 'CRICO', decided to offer premium incentives not only to anesthesiologists but also to obstetricians and gynecologists who participated in simulation-based courses, after proving that training with simulators results in reduced costs from malpractice claims12, 15-17. Moreover, patients are more likely to allow students to perform procedures on them following prior simulation training18. These changes in the context of medical education and training have paved the way for a new concept of learning, focused mainly on student's needs and the protection of patients, in which virtual reality and simulation can find important and complementary roles19. In this Editorial we review the current literature to provide an overview regarding the use of simulation in ultrasound in the field of obstetrics and gynecology. According to the Society for Simulation in Healthcare (SSH), simulation can be defined as the 'imitation or representation of one act or system by another'20. David Gaba, a pioneer in medical simulation, has defined it as a 'technique to replace or amplify real experiences with guided experiences that evoke or replicate substantial aspects of the real world in a fully interactive manner' and he has underlined that standardization, reproducibility and safety are some important aspects made possible by simulation21. Simulation and virtual reality were first introduced into the field of education by the military and the aviation and nuclear power industries. Their aim was to find an effective and safe method of training, considering that training a team and system testing in the real world were dangerous and expensive22. The introduction of simulators into medical education followed, the first being Resusci AnneTM, developed for the teaching of cardiopulmonary resuscitation in the 1950s by the Norwegian toy-maker Åsmund Laerdal, in cooperation with a group of anesthesiologists23. Then came 'Sim One'24, created in the 1960s by Abrahamson and Denson, which was followed in the 1980s by two similar high-fidelity anesthesia simulators, CASETM 25 and GASTM 26. Since then, simulation has been used in multiple medical fields and specialties, and its development has continued in various areas, including anesthesiology25, emergency care27, 28, cardiology29, obstetrics30-32 and surgery33, 34. Simulation offers the possibility of making errors without risk of negative patient outcomes, such as death, misdiagnosis, complaints and claims19. Additionally, the negative emotions generated by failure or error, which are considered to be critical to the medical learning process, are experienced more constructively in a simulation context than they are in real life12. Simulation presents, therefore, the possibility of shifting the perspective of education from the conventional patient-centered approach to a newer and more innovative learner-centered approach5. Several authors have demonstrated the importance of integrating simulation technology into medical education, not only for skills training, but also for assessment of competency12, 19, 35, particularly in the fields of internal medicine, anesthesiology36 and minimally-invasive surgery37, as well as in obstetrics with the widely used maternal birthing simulators (CAE Fidelis Maternal Fetal Simulator; Gaumard's NOELLE® Maternal Birthing Simulator). Ultrasound simulators are integrated simulators, generally composed of a human mannequin, a mock probe and a computer. Usually, the mock probe is connected directly to the computer, whose screen displays the ultrasound image depending upon the probe's position and movements. Most of these simulators use electromagnetic tracking systems to define the probe's position. The mock probe usually contains a three-dimensional (3D) sensor, capable of acquiring virtual position data instantaneously. As these data are transferred to the computer, it evaluates the location and position of the probe on the mannequin and displays the related two-dimensional (2D) images38-43. A haptic device can be used instead of a mannequin, allowing measurement of the pressure applied to the probe and providing realistic feedback on this force44, 45. This, however, is limited in that it allows a lower range of movements to the probe, while lacking a simulated environment in the absence of a mannequin or a 'patient-look-alike' structure. Furthermore, variations in the pressure applied to the probe do not show differences in the force-feedback nor in image quality (in contrast to live scanning)46. Most of these systems provide a 3D animated illustration of the anatomy surrounding the probe and its position and relations with the different organs and systems44. This option is particularly useful in the first phases of training, in order to help the trainees to become familiar with ultrasound scanning ergonomy and improve their hand–eye coordination and to locate the insonation planes within the examined structure. This animated illustration can be hidden on demand or in the subsequent steps of training. Ultrasound simulators have been applied mainly to teach the basic skills of cardiac ultrasound examination to students and residents in emergency and internal medicine (Table 1). Over the last few years, several studies have investigated the effectiveness of simulation-based echocardiography training compared with conventional methods such as theoretical lectures and hands-on training on patients. Most of these studies have been underpowered, with limited sample size, but they suggest significant improvements among simulation-trained students with regards to anxiety levels, performance, efficiency, competence and recognition of clinical scenarios, as well as a high level of compliance and satisfaction4. Findings of these studies include, for example, that the use of echocardiographic simulators gave very positive results regarding motivation and a decrease in anxiety compared with examination of real patients47, while use of transesophageal echocardiographic simulation proved not only to be realistic and helpful50, but also to be superior to conventional methods of teaching48, 49. Simulation has also been found to be helpful for introducing to surgery residents the use of ultrasound in trauma cases51. CAE Vimedix Ultrasound Simulator System (CAE Healthcare, Montreal, Quebec, Canada) 12 third- or fourth-year medical students or physicians currently in their first 3 years of residency training CAE Vimedix Ultrasound Simulator System (CAE Healthcare, Montreal, Quebec, Canada) It has been established that there is improvement in knowledge and better recognition of clinical scenarios after training sessions on the simulator52, however, the necessity of supervised training even in simulation situations is still under debate. A study by Cawthorn et al.53 underlines the importance of supervised training, stating the necessity of combining both teaching methods. Simulators in the field of obstetric ultrasound appeared at the beginning of this century38. In 2003, Newey and colleagues50 used the virtual ultrasound scanner 'VirUS' to assess inter- and intraoperator repeatability of nuchal translucency thickness measurements among expert ultrasound operators and suggested its potential in operator training (Table 2). Comparison of training in first- and second-trimester screening by only theoretical lectures vs theoretical lectures & practical sessions on simulator In 2004, Maul et al.38 evaluated the SonoTrainerTM system for training in first- and second-trimester ultrasound screening. They divided 45 certified obstetricians into two groups, the first receiving theoretical and practical training on the SonoTrainerTM, and the second receiving only theoretical teaching. The results were significantly better in the former group, suggesting the utility of practical phantom training. However, the study did not demonstrate whether the improvement was related to the simulation training specifically or, more generally, to the fact that these operators had undergone hands-on training (Table 2). Staboulidou et al.54, in 2010, aimed to evaluate the effectiveness of simulation integrated into obstetric ultrasound training courses over 100 courses held with 1266 participants over 2 years. Each participant answered a questionnaire for evaluation of knowledge before and after the course. The results suggested a significant improvement of knowledge after completion of the course (P < 0.0001), although the specific contribution of simulation to any improvement was not clear (Table 2). Nitsche and Brost5, in 2013, underlined the utility of simulation training and proposed a 'fetal pig ultrasound training model' as an alternative to the expensive and still limited commercial models. This simulator consisted of a fetal pig heat-sealed within a formalin-filled plastic bag. While offering economic benefits, this model presents various limitations, including obvious anatomical differences from the human fetus (Table 2). A recent study by Burden and colleagues52 evaluated the trend of improvement among 26 participants, including 18 trainees and eight certified experts in obstetric ultrasound using virtual-reality ultrasound simulation. Participants performed five sequential modules measuring crown–rump length and three repetitions of a late-pregnancy growth scan. Outcome measures included mean percentage deviation from target measures and time needed to complete a scan. Even with the small sample size, results showed significant improvement over subsequent scans, particularly among the trainee group (Table 2). However, only five scans may be insufficient to demonstrate any real improvement in the participants' ultrasound technique. Transvaginal ultrasonography is particularly difficult to teach within a clinical setting, requiring extensive training time, experienced tutors with plenty of available time and a wide variety of compliant patients, both with normal and with pathological findings, who are willing to undergo examination on multiple occasions55. The transvaginal probe is a dedicated one, and displays anatomical structures in a way that is unique to this approach56, with ergonomy different from that of the transabdominal probe. Clearly these are limiting factors both for training and even more so for assessment of skills13, when the patient is usually a volunteer undergoing a supplementary scan, thus necessitating a search for complementary methods to implement in ultrasound educational programs44. Heer and colleagues13, in 2004, developed a software-based training system, with cases previously recorded during a normal pelvic examination defining interpolative model-based simulation (Table 3). In the first phase of the study, they evaluated the congruence of the actual gynecological scan with the virtual one, submitting three virtual cases to 25 sonologists experienced in gynecological ultrasound. Secondly, they tested the simulator on 24 fourth-year medical students with no experience in ultrasound. Following a 6-min presentation, the students were able to perform a basic pelvic scan on the simulator, including measurements of endometrial thickness comparable to the ones measured by expert sonographers. Training with this technique suggested that standardized ultrasound teaching and learning with the model was comparable to performing a live gynecological ultrasound scan. However, it could be argued that these conclusions might not be relevant in clinical practice as the judgment criteria used for assessment (uterus position, presence or absence of pathology, endometrial thickness measurement, demonstration of ovaries and pouch of Douglas) might have been too simple. Blue Phantom (Redmond, WA) female pelvis models 16 final-year medical students (ultrasound novices) + 12 Ob/Gyn consultants (experienced US practitioners) A prospective randomized controlled trial56 conducted on 134 medical students compared the effectiveness of transvaginal ultrasound training delivered using an ultrasound simulator with that delivered using volunteers. This study found that simulators did not perform as well as did live models, concluding that they should be regarded as an adjunct to, rather than a substitute for, live models. In a recent experimental study, Madsen et al.44 explored trainees' learning curves using a high-fidelity transvaginal ultrasound simulator, and tested the validity and reliability of the different metrics used. They compared results obtained by a group of 16 novices with those obtained by 12 consultants in obstetrics and gynecology, determining 48 metrics which could discriminate the level of expertise, and established the validity and reliability of the simulator in assessment of skill. Furthermore, they observed the trend of improvement of novices, finding them to reach a level considered suitable for clinical practice after 3–4 hours of virtual training. Whenever a new training method is implemented, ideally it should create a chain of impact at several levels. The most credible and most widely used training evaluation methodology in the world is the evaluation model that emerged from the work by Donald Kirkpatrick and Jack Phillips57, 58. It measures training outcomes at five levels, starting at reaction/planned action and ending with return on investment (ROI). The five levels are summarized as follows: Level 1 – Reaction and Satisfaction: of the participants to the training, usually measured in surveys, and their Planned Action (their plans to use what they have learned); Level 2 – Learning: assesses how much participants have learned (with pre- and post-tests); Level 3 - Behavior, Application and Implementation: assesses whether the skills and knowledge gained in training are applied and practiced in the workplace or have changed learners' behavior; Level 4 - Results: measures the extent to which the institutions' measures (output, quality, costs and time) have improved after training; although this can be considered as the goal of a strategy, it is important to go beyond this level of evaluation to verify that the program's costs do not outweigh its benefits; Level 5 - Return on Investment (ROI): the ultimate level of evaluation, this compares the benefits from the program with its cost59, 60. The evaluation of simulation in obstetric and gynecological ultrasound has until now remained mainly at Levels 1 and 2 of the Kirkpatrick and Phillips model. Most studies have evaluated reaction, satisfaction54 or learning38, 52. Although several ultrasound simulators currently available include measurement of time to complete tasks and accuracy of measurement, most studies have not yet evaluated the transfer to clinical practice of knowledge acquired during simulation training61. In addition to the measurable benefits, most training programs will have intangible benefits, including stress reduction and increased commitment of trainees, improved patient satisfaction, reduction of patient complaints as well as reduction or avoidance of conflict62. According to Phillips63: 'In some programs, the intangible (non monetary) benefits can be more important than tangible (monetary) measures. Consequently, these measures should be monitored and reported as part of the overall evaluation. The challenge is to efficiently identify and report them.' These benefits should also be addressed in the future. The best or most effective method of training students in obstetric and gynecological ultrasound has yet to be defined. The importance of hands-on repeat-training until proficiency is reached is well known, and has superseded the previous, no longer acceptable principle of 'see one, do one, teach one'46. So far, standardization of the teaching of ultrasound among different institutions and countries has been achieved neither for educational purposes nor for assessment of practitioners' skills and accreditation. In particular, given the high variability between people in the time and training needed to gain proficiency, it is unlikely that a minimum set number of scans can reflect adequately candidates' skills; some trainees reach a level of competency that is suitable for clinical practice after a few scans, while others need more time to reach the same level64. Thus, assessment of skill should be based on practical tests during which the candidate demonstrates their abilities, as in the 'competency-based' method proposed by RCOG10, 54. There is broad consensus on the utility of integrating virtual reality into ultrasound education and training programs6, 10, 12-14, 19, 21, 22, 38, 44, 46, 48, 50, 52-54, 61, 64-72. It has been proposed as a valid and reliable method for assessment of skills, implying its potential for use in accreditation procedures44. However, simulation might never replace completely clinical training and there will always be a need for tutor supervision53. It could be useful as a method for introducing students to ultrasound practice, allowing them to become familiar with image optimization and probe orientation, without being confronted with a clinical setting that might be stressful and disturbing44. Whilst the number of commercially available ultrasound simulators continues to increase (Table 4), they remain expensive devices which require maintenance and adequate training for their use. These factors may limit the widespread adoption of the technology. Some distributors claim that acquisition of simulators can be economically benefical45, by allowing trainees to improve their performance without monopolising ultrasound machines required in the clinical setting. However, not only do such claims need to be verified, but evaluation studies on their efficacy need to be performed, both of which rely on constructive interaction between clinicians and engineers. Internal medicine, emergency medicine, cardiology, TTE, gynecology, obstetrics, breast sonography, vaginal sonography, urology, rectal sonography, freehand punctures for different pathologies, neonatal hip sonography