Sem Lampotang, Walter Dobbins, Michael L Good, Nikolaus Gravenstein, Dietrich Gravenstein

Department of Anesthesiology, University of Florida, Gainesville, FL 32610-0254, USA

Summary: We implemented an interactive, Web-based simulation of the flow of oxygen, nitrous oxide, carbon dioxide and volatile anesthetics in an anesthesia machine to help our residents learn how an anesthesia machine functions. The simulation is implemented using Director 7.0, a multi-media authoring software package for producing Web-based animations. Using the Shockwave 7 Web player, the animation can be viewed at the University of Florida Department of Anesthesiology URL: http://needle.anest.ufl.edu/anest4/am

Introduction: The inner workings of an anesthesia machine, a "familiar" piece of equipment used daily by anesthesiologists, remains somewhat of a mystery for some. Specifically, how adjustment of anesthesia machine controls affects gas flow remains an area where residents can benefit from learning tools that exploit the latest Internet technology. Understanding how an anesthesia machine works internally is difficult because the gas molecules are invisible and cannot be traced through the system. The challenge, therefore, is to construct a transparent mental model of the anesthesia system that is accurate, enhances understanding and is readily accessible.

Methods: The objective was to design a simplified and accurate representation of the anesthesia machine, including the ventilator, and to animate gas flow through it during all phases of mechanical, manual and spontaneous ventilation. Specific learning objectives were to show the flow of gas in the CO2 absorber (an area where we find that residents have difficulty), the operation of safety features like the O2 failsafe and failure modes. We used Director 7.0 (Macromedia, San Francisco, CA) to perform the animation and SoundForge XP 4.0d (Sonic Foundry, Madison, WI) for sound effects to reinforce the learning experience. To view the animation, the Shockwave 7 Web player specific to the user's PC platform (Windows or Macintosh) must first be downloaded (free download) by clicking on a hot link in the URL above. Minimum system requirements for Shockwave 7 are: 12 MB RAM, 6 MB free disk space, 8-bit, 256-color monitor, Windows (Pentium, Windows 95, Navigator 3.0 or Explorer 3.0 or AOL 3.0) or Macintosh (Power Macintosh, System 7.6.1, Navigator 3.0 or Explorer 4.01).

Results: The representation of the anesthesia machine is shown below. In preliminary technical evaluations, the bellows was smoothly animated through the "tweening" feature. The ability to open and close controls like the O2 flush and the APL valve by clicking on them with the mouse provides dynamic, interactive learning.

Discussion: Others have animated gas flow in an anesthesia machine [1-3]. Issues included: speed of animation dependent on CPU speed [1], restricted RAM addressing capabilities of Smalltalk\V 286 (16 MB maximum) in 1988 [1], QuickTime (bundled with Explore!^TM [3]) conflicting with other applications, requiring a dedicated computer, Web inaccessibility [1-3], affordability [3] (Ohmeda sold the Explore!^TM CD) and platform specificity (IBM or Macintosh). Our Web-based animation is intended to be educational, interactive, affordable (read free) and viewable from any location or platform (IBM/Mac) with Internet access, including the OR.

1. Hekker JJ: Computer animated graphics as a teaching tool for the anesthesia machine simulator. Master's thesis, 1988, Technische Universiteit Eindhoven, The Netherlands

2. Goldman JM, Ward DR, Daniel LC, Squire CJ: Understanding the circle breathing circuit - An educational computer simulation. ASA scientific exhibit, page 530, 1995 ASA Annual Meeting Program

3. George J. Sheplock, Ohmeda Education Services et al: Explore!^TM The anesthesia system, Compact Disc, 1996