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Biomedical Sciences and Visualization

Virtual Simulation of Regional Anesthesia

Epidural analgesia is one of the most frequently used techniques for the relief of pain during surgery. In most hospitals with an obstetric anesthesia service, epidural analgesia is the most prominently used anesthesia technique for vaginal childbirth and cesarean section. The procedure involves the injection of a local anesthetic or opiod into the epidural space of the spinal column. Although a single degree-of-freedom task, it is a delicate manual operation that requires the placement of a catheter into the epidural space using only haptic cues to guide the needle. By feeling the resistive forces of the needle passing through the various tissues, the anesthesiologist must maneuver the tip of the needle into the correct space without perforating and damaging the spinal cord in the process.

Limitations of physical models such as mannequins include lack of patient variance, inaccurate representation of biological tissue, and physical wear from repeated use. The use of cadaveric material offers limited opportunities and associated risks. The best method of training residents on this delicate and dangerous manual task remains the use of live patients, a scenario obviously not optimal for patients. In addition, teaching this technique requires highly intensive tutorial interaction with faculty due to the significant learning curve in understanding exact placement of the needle.

This ongoing collaborative effort between researchers at The Ohio State University Hospitals, Immersion Corporation, and OSC is to create and test a virtual simulator for training residents in the use of regional anesthesiology. Under funding from the Department of Defense, we are creating a system for teaching a specific method of regional anesthesia, the epidural technique. Our methods include the application and integration of virtual technologies. Our system components include a high-performance graphics workstation capable of stereo display, a real-time volume renderer, a voice-activated interface, and a one-dimensional haptic probe capable of simulating the resistive forces of penetrated tissues.

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The system will enable the resident to investigate various three-dimensional reconstructed data sets in a nonthreatening environment. The system can be cued through voice activation to provide additional information in text, audio, or graphical form. Furthermore, the system incorporates the necessary components to allow the resident to "feel" the technique as performed by the expert. By providing a new form of procedural training in a nonthreatening environment, the simulator will increase the proficiency level of the resident in technique delivery and improve competency required for live human trials.

Acknowledgments
This research is supported by AFOSR GRANT F49620-94-C, The Link Foundation, and from generous support from Pharmacea Deltec. We would like to acknowledge the continued support of Silicon Graphics, especially the discrete phrase recognition software. And finally, we would like to acknowledge the encouragement and support from our colleagues in the Department of Anesthesiology, Immersion Corporation, and OSC. Special thanks goes to Dr. Petra Schmalbrock, in the Department of Radiology at The Ohio State University Hospitals for the imaging protocol and support in data acquisition, and Dr. Roni Yagel, in the Department of Computer and Information Science, for support in developing the real-time volume renderer.

Further Reading
Virtual Reality Technology Applied to Anesthesiology, McDonald JS, Rosenberg LB, Stredney D, Medicine Meets Virtual Reality III: Interactive Technology & the New Paradigm for Healthcare, Satava et al, Eds., 1995 IOS Press, Amsterdamnpgs. 237-243.

A Virtual Simulation Environemnt for Learning Epidural Anesthesia, Don Stredney, Dennis Sessanna, John S. McDonald, Leslie Hiemenz, and Louis B. Rosenberg. Medicine Meets Virtual Reality IV: Healthcare in the Information Age, Weghorst et al, Eds. 1996 IOS Press, Amsterdamn. pgs. 164-175.

A Physiologically Valid Simulator for Training Residents to Perform an Epidural Block, Hiemenz L, McDonald JS, Stredney D, and D Sessanna, Proceedings of the 15th SOuthern Biomedical Engineering Conference, March 29-31, 1996