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The healthcare industry includes millions of practitioners who participate in on-going education, training, and certification. Although the airline industry has used flight simulators for many years, difficult technical challenges have limited the use of virtual reality in medicine. HT Medical Systems embarked on a research program that has resulted in an ability to realistically interact with computer environments, based on the Visible Human Datasets (VHDs), that represent accurate behaviors of tissues and organs
The research has now led to several successful commercially available medical simulation products.
All of HT Medical System's simulation products include a software module, an interface device, and a computer. The interface devices replicate the look and feel of medical devices. These interface devices incorporate tactile feedback mechanisms that allow the computer to control levels of resistance that are appropriate for the medical procedure that is being simulated. This paper provides a status report on several VHD-based medical simulation products for endoscopic and endovascular interventional procedures.
Endoscopy Simulations
In October 1998 HT Medical Systems introduced the PreOp Endoscopy simulator (Figure 1) at the Second Visible
Human Project Conference. Since that introduction the system has been installed in numerous residency
training sites within North America, Asia and Europe. Content has now been developed covering Basics of
Bronchoscopy, Pediatric Endoscopic Intubation, Bronchoavleolar Lavage, Endobronchial Sampling
(Figure 2), Flexible
Sigmoidoscopy, and Ureteroscopy.
Several studies of educational validation are ongoing. One, which is now complete, was a multi-center prospective cohort study was performed by A. Mehta, et al and was presented at the 2000 International Conference of the American Lung Association and American Thoracic Society. This study looked at the ability of the assessment tool within the simulator to objectively measure bronchoscopy skills. The study was conducted at the Department of Pulmonary and Critical Care Medicine, Cleveland Clinic Foundation, Cleveland, OH; and North Shore University Hospital, Manhasset, NY. The three cohorts included experts who performed >500 bronchoscopies (n=9), intermediates who performed >25, but < 500 bronchoscopies (n=7), and novices who had observed but never performed a bronchoscopy (n=11). Each study participant performed two bronchoscopy cases on the simulator and objective performance measures were recorded by the simulator. The data shows that the system can differentiate between expert, intermediate, and novice bronchoscopists.
Endovascular Simulations
The Company launched an endovascular simulation product line in January of 1999. This system provides a
simulated flouroscopic view of the heart. The computer-based heart model utilizes the VHD as a base-line
and was modified to provide variation in anatomy and pathology.
We have developed many software routines specifically to allow creation of deformable models of the heart. Our current models consist of casts of the interior of the right heart, for use in pacemaker leads placement (Figure 3). We have tied the deformations of the heart to the electrical model of the heart in such a way that the electrical state of the heart ideally predicts the mechanical state and position of the heat's surface. This binding of the two systems is independent of heart rate: the rate of the electrical model is accurately depicted by deformations, such that our heart model can be seen to beat and beat effectively up to rates of 200 beats per minute.
Inherent in this model of normal cardiac electrical behavior is the ability to monitor abnormal electrical states. Our model directly supports modeling the following pathological electrical states:
In addition to the above, the electrical model directly supports such corrective measures as pacing the heart from the atria, ventricles, or both. Defibrillation of the electrical model is also supported as a means of escape.
Conclusion
Medical simulators use computer graphics and robotics technology to simulate real patients, with anatomical and
physiological features and complications. These systems provide an opportunity to assess both cognitive decision
making skills and motor skills involved in procedures including endoscopy and balloon angioplasty. The use of this
technology on an ongoing basis will help medical practitioners establish and maintain skills, effectively introduce new
procedures, and provide a basis for evaluation of quality of care.
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