Surgical simulation technology has advanced significantly in recent years. Medical-simulation validation studies have established that surgical skills honed using a simulator significantly improved trainee performance by decreasing operating times, improving efficiency, and decreasing errors. Integration of surgical simulation technologies into the medical training and education system improves the quality of the graduating surgeon, reduces the time to proficiency, and improves overall patient safety. This article discusses the current state of medical-simulator technology research, development, and use. It points to growing support from the surgical governing and regulation agencies; and predicts that medical students and surgical residents will be able, and mandated, to develop procedural skills in a life-like and no-risk environment.
In light of current technological advances, increased scrutiny of the medical profession, and new directions in medical training, reducing patient risk is of paramount concern, particularly for surgical procedures.
Introduction to simulation
Medical-simulator technology is providing students the training media that enable them to achieve proficiency before entering the operating room. This is no surprise given the science of simulation, which is well over 50 years old in other high-risk professions (aviation, nuclear power plants, etc), and has demonstrated the following (Brandon Hall Research News, 2005):
Simulations provide a safe environment in which to make mistakes.
Some of the best learning comes from assessing your own mistakes.
Well-designed simulations often significantly reduce training time.
When training on simulators, the focus is on creating the most efficient path for solving a specific problem.
Simulations allow practice of hazardous procedures.
An example is the ability to practice shutting down a nuclear reactor.
Creating the simulation can help streamline the processes that are being taught.
Improvements in process are often made when creating simulations.
There can be significant retention of simulation procedures.
The closer the simulation resembles a learner’s actual work environment, the greater the retention.
Simulations allow training to take place without pulling expensive equipment offline.
It is prohibitively expensive to pull a $40-million aircraft out of service for training on F-15 aircraft, for example.
Simulations are the best way to transfer expert thinking.
It does this by “modeling” expert behavior in the learning process.
In the medical domain, simulation has become widely accepted over the past 15 years. The medical-simulation validation studies have established that surgical skills honed using a simulator significantly improved trainee performance by decreasing operating times, improving efficiency, and decreasing errors. In short, integration of surgical simulation technologies into the training and education system improves the quality of the graduating surgeon, reduces the time to proficiency, and improves the overall patient safety. The imperative is to develop the devices that can achieve this goal.
The medical profession, academics, authoritative organizations (training, testing, licensing, and certification bodies), and commercial companies have accepted the importance of simulation within the context of a quantitative assessment environment unique to simulators. Evidence of the impact on skills training of using high-fidelity technology that prepares the surgeon before performing the same procedure on a patient has been demonstrated. The impact on patient safety is a priority—mistakes and corrections can be made on a simulator, not on a patient.
Surgery and aviation are sufficiently similar to generate intense interest among surgical educators in the aviation paradigm of training. The obvious training parallel is simulation. Proficiency-based aircrew training has demonstrated that the most effective transfer of training occurred when the student was first proficient in the simulator. With a validated surgical simulator, proficiency criteria can be perfected before permitting the student surgeon to operate on a patient. Therefore, the most pressing need for the near future is to design and validate simulators that train to proficiency within many different specialties.
The American College of Surgeons is interested in promoting surgical simulators by identifying targets for simulation: researching, writing, and implementing the plan for medical-simulation training; and investigating sources of funding. The obstacle to success is bringing the available knowledge and technology together to create devices that are robust, validated, and fluid enough to allow for the potential envisioned. This includes not only training in basic skills but also in the most complex procedures, where performance and judgment are critical. Recreating environments that can be hazardous, again as achieved in flight training, is crucial to the training of a surgeon, with the understanding that patients cannot be placed at risk.
In addition, it is necessary to build a library covering the full range of simple to complex procedures with the many variations that occur from patient to patient. Experiencing the range of procedures from the library along with the busy surgical residency exponentially increases the surgical opportunities within the same given period. For example, just as there has been the traditional medical case of the week to challenge the residents’ knowledge and clinical acumen, it will be possible to provide a surgical case of the week on which the trainee can practice.
Surgical rehearsal is an even further development of simulation technology that is achieved because the technology exists to import patient-specific data. As this technology becomes more refined, the surgeon will import the patient-specific image and data, practice the surgical procedure in simulation, and identify critical areas of attention for presentation during the operation. The surgeon will detail the pathology to be addressed (resected, modified, or corrected) and define the areas at risk (such as critical anatomic structures).
A Broader View of Surgical Simulation
High-fidelity virtual reality (VR) simulators have long had an impact on improving the skill level of military and commercial pilots, and they hold similar promise for the medical field. Based on the lessons from aviation training over the past 3 decades, computer-assisted devices have had significant success in augmenting the education and training of surgical residents in several fields. VR simulation has already played an introductory role in the training of residents for laparoscopic, gastrointestinal, plastic, ophthalmologic, dermatologic, urologic, and some laryngological procedures. The efficacy of VR simulation as a teaching tool is clear, but whether it is superior to conventional teaching methods remains uncertain in many instances. Recently, it has been reported that VR training positively influences resident operating room performance and, potentially, safety.
Some early attempts at surgical simulation have met with failure for a number of reasons. First, adequate technology was not available when the concept began to take shape over a decade ago, and the quality of many early surgical simulators was inferior. Second, the science used to evaluate the efficacy of surgical simulators was statistically inadequate and did not measure transfer of training to operating room performance—the ultimate test of a simulator. Finally, the surgical community did not see the value of simulation in all of its variations and applications.
In recent years, as the technology and validation methods have matured and as the surgical community has become more aware of their potential uses, the need for simulators to teach, assess, and perhaps even certify surgeons has become apparent. Otolaryngology has taken a leadership role in this pursuit.
Extension to Other Surgical Specialties
While endoscopic techniques have become standard in several other surgical disciplines, neurosurgeons have only recently started to apply these methods to pituitary and other cranial base lesions. Recent studies have compared traditional approaches to the sella turcica using the operating microscope with endoscopic assistance and endoscopic surgery alone. No significant difference in outcome was demonstrated in these studies. However, patients operated on with the endoscopic approach experienced faster recovery, shorter hospital stays, and minimal postoperative discomfort. The two main characteristics of the endoscopic approach, when compared with the standard microsurgical operation, are the use of the endoscope as a unique optical device and the absence of a transsphenoidal retractor. Moreover, the use of an endoscope allows the surgeon to have a clearer picture and better visualization of all the surroundings, inside and outside the sella. There is a trend to minimally invasive neurosurgery, and the concept of training by rehearsal is likely to be generalized in the next years. Specific training is required along with the necessary validation tools to insure safety and efficacy in the treatment of pituitary and other cranial base pathologies.
Several surgical procedures in ophthalmology including dacryocystorhinostomy for tear drain obstruction, orbital decompression for thyroid-associated ophthalmopathy, and optic canal decompression for compressive optic neuropathy have, in recent years, evolved away from transcutaneous and transconjunctival approaches in favor of endoscopic transnasal and transsinus surgical techniques. These techniques use the same instrumentation and surgical principals necessary for endoscopic sinus surgery and require parallel technical and cognitive skills. Currently, clinical training in endoscopic orbital and lacrimal surgical techniques are in the curriculum of fellowship training for the ophthalmic subspecialty of oculoplastic surgery, as defined by the American Society of Ophthalmic Plastic and Reconstructive Surgeons. Traditional transcutaneous and transconjunctival approaches remain in the curriculum of general ophthalmology residency training, and graduates of general ophthalmology training programs are not expected to be proficient in endoscopic surgical techniques.
Preliminary Studies and Rationale
Surgical metrics
In 2002, the Metrics for Technical Skills Conference was convened to create objective measurements that could be assigned to the individual components of an endoscopic sinus surgery procedure. Before this conference, there had been no publication of a classification of errors in endoscopic sinus surgery or a methodology for error occurrence identification and measurement (metrics).
Experts from the fields of medicine, simulation, and education were assembled to identify each error, which were then classified into taxonomy according to the type (technical, cognitive, or combined), and assigned quantifiable measurement units. The final list, as seen in Box 1 , was approved by consensus. This approach has inculcated a culture of safety into the surgical training program, has been vetted by the American Academy of Otolaryngology-Head and Neck Surgery Foundation and by the American Rhinologic Society. In addition, it has been used as evidence by the American College of Surgeons in their decision to become engaged in surgical simulation as a training modality. For the first time, metrics assigned to an entire surgical procedure may be used as an objective basis for the scoring of surgical skills. The potential of integrating such data into the scoring algorithm of a surgical simulator is apparent.
Technical
Scope handling
Scope dirty
Tool: scope collision
Contact with wall
Repetitive scope insertion
Bleeding obscuring view
Improper insertion of scope
Wandering scope unstable
Instrument handling
Mucosal injury (tissue respect)
Dissection error
Past pointing
Instrument out of view
Controlling field of view
Lack of perspective
Image task alignment
Cognitive
Know anatomy
Misidentifying (anatomic recognition)
Incomplete examination (leaving out steps)
Know instruments
Wrong tool choice
Wrong scope choice
Know procedure sequences
Task out of sequence
Omit a step
Lack of progress
Know procedure technique
Improper exposure
Wandering scope: not recognizing target
Not recognizing an injury
Artery injury
Bleeding
Combined
Over or under dissection (improper tissue resection)
Injuries
Orbital injury
Cranial nerve injury
Lamina papyracea
Cribriform plate injury
Lacrimal system injury
Destabilization of the middle turbinate
Improper location of injection
Rotation (navigation)
From Satava RM, Fried MP. A methodology for objective assessment of errors: an example using an endoscopic sinus surgery simulator. Otolaryngol Clin North Am 35(2002):1289–301.
Validation studies
The process of achieving the goal of objective surgical training and assessment may be intuitively apparent, but it is not arbitrary and requires planned development, evaluation, and implementation.
Validation of proposed virtual simulators is essential in achieving the goal of high stakes assessment (ie, determination of whether a tested individual will advance in their surgical training). The validation studies must be above reproach so that physicians are convinced of the power of simulation as a training tool. Only then may surgery accept objective high-stakes assessment.
Numerous validation benchmarks are currently used in the testing literature and, although new to the surgical community, they have been employed in psychology research for more than a century. These benchmarks are recognized as important in creating high-stakes assessment; however, there is currently no mandated requirement for these tests. The process of validating a simulator will be briefly mentioned as it has been extensively discussed elsewhere.
The most subjective validation benchmark tests are used during the initial phases of test construction. These include face validity and content validity and they rely on the input of experts to determine whether the contents of the test are appropriate and whether the test is cohesive. In contrast, concurrent validity is used to compare existing training curriculums or other gold-standard assessment tools to that employed by the simulator. Importantly, discriminant validity focuses on whether the scores generated by the simulator accurately correlates with appropriate factors and is therefore critical in determining whether the simulator is able to stratify the subjects into appropriate skill levels. Predictive validity is commonly the final benchmark test employed. It is essential for determining whether scores on the simulator can accurately predict real skill performance and thus uniquely focuses on clinical outcomes. Predictive validity testing is the most important benchmark test because physicians are concerned with whether simulator training translates to improved skill performance, which in turn imparts improved patient safety.
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