Simulations provide safe and controlled environments, immediate performance feedback, and practice for skills under unique or dangerous conditions. Virtual environments have proven to be effective in training dismounted soldiers and military checkpoint guards, for example.
In this study, 15 medical students, 6 males and 9 females, from the Eastern Virginia Medical School in Norfolk, Virginia, had to perform an emergency chest tube thoracostomy - incision and insertion of a tube in the chest to permit fluid to drain - on a mannequin in a Cave Automatic Virtual Environment (CAVE) while surrounded by visual and auditory depictions of gunfire, explosions, and a virtual sniper. They performed the surgery under both daytime and nighttime combat conditions. When tested again four months later, they demonstrated that they retained the necessary skills for the procedure.
This study was possibly the first to test performance with a standard mannequin-based medical simulator within a fully immersive virtual environment. The procedure was performed on the TraumaMan System mannequin, developed by Simulab Inc. in Seattle, Washington. It is used across the world for surgery education and approved for the Advanced Trauma Life Support (ATLS) Surgical Skills Practicum by the American College of Surgeons.
The simulation system consisted of two computers connected through a 100-mbps network switch. A 4-pipe SGI Onyx 2 computer was used for the display and to provide the sound. This computer used MultiGen-Paradigm's Vega software running on the IRIX 6.5 operating system. The second computer was an SGI O2 and served as the main console to launch the application. The images were presented with a resolution of 1024x768 on three 10x10 ft walls. In addition, a barricade of boxes was created within the CAVE. A modified Radio Shack invisible beam entry alert system was fixed to the top of the boxes about 3 ft above the ground. This sensor detects when the trainee's head is above the safe cover of the barricade and signals the virtual sniper to engage.
The study describes the combat simulation as a small town under fire with one building in flames. The combat was simulated using the VEGA special effects module to trigger visual and auditory explosion events and background gunfire at specific times. The events were timed to repeat at specific intervals and the entire scenario ran in a continuous loop until the participant finished the procedure.
Day and nighttime conditions were created using different settings of the time-of-day feature in the VEGA software. The daytime conditions produced enough ambient illumination from the CAVE walls to make the barricade, mannequin, and instruments easily visible. Under the nighttime conditions, however, very little illumination was provided by the CAVE walls forcing the students to perform the procedure in almost total darkness except for occasional explosions that provided temporary increases in illumination, according to the study.
The students' completion times demonstrated that they could perform the surgery efficiently, but the quality of their work suffered. Those who performed the procedure faster were more susceptible to "sniper" fire. Furthermore, stress created by the simulated environment may have caused some students to engage in inappropriate and dangerous behaviour that would likely result in their being killed in a real combat situation, as the authors explained.
The study was performed by Elizabeth A. Schmidt, Mark W. Scerbo, and colleagues from the Old Dominion University and from the Eastern Virginia Medical School, both in Norfolk, Virginia.
The Human Factors and Ergonomics Society, which celebrated its 50th anniversary in September 2007, is a multi-disciplinary professional association of more than 4500 persons in the United States and throughout the world. Its members include psychologists and other scientists, designers, and engineers, all of whom have a common interest in designing systems and equipment to be safe and effective for the people who operate and maintain them. More information is available at the web site of the Human Factors and Ergonomics Society.