Mannequin-Based Simulators (Realistic, Full-Scale, High-Fidelity "Macro" Simulators)

Comprehensive Anesthesia Simulation Environment and Eagle Medsim

In 1986, Gaba and DeAnda began developing the Comprehensive Anesthesia Simulation Environment (CASE) with a primary goal of conducting research into decision making by anesthetists (the first transcript of an anesthetist responding to a simulated intraoperative crisis was obtained in spring 1986).^[33] CASE used a commercially available mannequin modified to enable occlusion of the left main stem bronchus, infusion of CO₂ , and insertion of intravenous lines. This mannequin allowed mask ventilation, intubation, and auscultation of breath sounds, but it did not have palpable pulses or spontaneous ventilation. The behavior of all of the waveform generators and actuators was coordinated through a central control computer. The control logic of CASE was provided by an operator typing commands at the IOS from a written simulation script describing the appropriate changes for a variety of anticipated actions on the part of the subject in the simulation. An experienced anesthesiologist observed the activities of the subject and directed the simulator operator by means of a private headset intercom. This control logic and IOS enabled the simulator to respond to any actions on the part of the subject, not just those that were previously anticipated.

The CASE system was evaluated by residents^[33] (and later by faculty and private practitioners) and was rated as very realistic, except for the plastic mannequin. The success of such a crude system, which lacked physiologic and pharmacologic models, lies in the exceptional variability of patients and in the ability of anesthetists to "suspend disbelief" if placed in a plausible clinical situation. The responses of the simulator only have to be plausible for the situation to appear very realistic. This is especially true for critical event training situations, in which plausible, but unusual events are presented. On the other hand, physiologic and pharmacologic models do offer substantial advantages, including greater consistency and reproducibility of situations, the ability to handle multiple physiologic changes simultaneously, and greater automation of the simulation process. In 1989, a major redesign of the system incorporated a physiologic model of the cardiovascular system.^[34] Waveforms and electronic data streams, including heart sounds, were generated directly from the cardiovascular model. CASE was used extensively in conducting the anesthesia crisis resource management (ACRM) training program described in a subsequent section of this chapter.

In 1992, a manufacturer of military aviation and space flight simulators (CAE-Link) licensed technology from Gaba's simulator group and from Schwid's group as part of its development of a commercial anesthesia simulator system. ^* The product line was later sold to MedSim Eagle Simulation.

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Figure 84-3 High-fidelity patient simulator system (MedSim Eagle Patient Simulator). The mannequin is shown in the middle and is the interface of trainees with the simulation. Upper pictures from left to right: opened simulator chest with fully functional lungs, pneumatic systems, sensors, and electronics cables; eyes with movable lids and reactive controllable pupils; and interface cart with gas analyzer and servo control boards. Lower pictures from left to right: interface cart with built-in network personal computer, umbilical cords from the interface cart to the mannequin, clinical monitoring and the main simulation workstation, and interface cart with noninvasive blood pressure simulator (NIBP) for oscillometric measurements.

Their patient simulator ( Fig. 84-3 ) is completely operated by physiologic, pharmacologic, and finite-state models with detailed models of cardiovascular, pulmonary, fluid, acid-base-electrolyte, and thermal physiology. It includes many of the available functions of the mannequin-based simulator systems mentioned in Table 84-2 .

The IOS in the Eagle Patient Simulator uses a graphic user interface ( Fig. 84-4 ) to provide a rich set of tools for the instructor to choose and implement different events (up to five events can run simultaneously), different simulated patients, and complete scenarios. The instructor can tailor each event in advance by altering features such as the onset time, severity, or manifestations of the event. Tailored events can be saved under different names to allow the creation of a library of events or situations. A drug editor allows alteration of drug kinetic and dynamic parameters. An "advanced controls" window permits the instructor to modulate the physiologic models by adding to or subtracting from the predicted instantaneous values of parameters underlying key vital signs.

Around the year 2000, for undisclosed managerial reasons, MedSim Eagle Simulation stopped producing or supporting the simulator system, but approximately 50 to 75 systems are still in use around the world.

Gainesville Anesthesia Simulator and METI Human Patient Simulator

Shortly after the CASE simulator was developed, a similar simulator was produced at the University of Florida, Gainesville, by a team headed by Good and Gravenstein.^[1] An interesting component of the Gainesville Anesthesia Simulator (GAS) was an anesthesia machine modified to incorporate a variety of mechanical faults that could be triggered electronically. GAS also featured a complex, quantitatively accurate physical simulation of multiple gas exchange. The lung concentrations of O₂ , N₂ O, N₂ , and one volatile anesthetic could be physically made to match the alveolar gas content predicted by a mathematical model of gas exchange and anesthetic uptake and distribution.

The GAS was also commercialized, first by Loral Data Systems, and further developed by Medical Education Technologies, Inc. (METI, Sarasota, FL). Now called the Human Patient Simulator (HPS) ( Fig. 84-5 ), it also uses full physiologic and pharmacologic mathematical models. Its mannequin supports numerous clinical cues and interventions as shown in Table 84-2 . The IOS of the HPS ( Fig. 84-6 ) runs on a powerful dual-processor Macintosh computer (running Unix via OSX) and allows real-time control of parameters and situations. METI also offers a child-sized mannequin (PediaSim) that has the same functionality as the adult model and can be controlled by the same base computer and IOS. Recently, METI released a more mobile and much less expensive simulator called "Emergency Care Simulator (ECS)." The ECS mannequin has fewer functionalities than the HPS does, and it uses its own "virtual" monitor screen rather than interfacing to real clinical monitors (except for the electrocardiogram). It is controlled by the same physiologic and pharmacologic models and IOS used in the METI HPS.

Laerdal SimMan

Laerdal (Stavanger, Norway) is a manufacturer of, among other products, basic life support and advanced cardiac life support training devices ranging from cardiopulmonary resuscitation mannequins to mega-code training stations. Laerdal entered the arena of true simulators with introduction of the SimMan simulator in 2000 ( Fig. 84-7 ).

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Figure 84-4 The instructor/operator's station (IOS) of the MedSim Eagle Patient Simulator. This screen provides complete control of patients, events, and physiologic parameters. The right-hand window is the "advanced control" to influence physiologic parameters of the models "on the fly." Through the IOS drugs can be entered and electromechanical actions triggered (e.g., pupils, pulse, and arms control). Abnormal events can be preset and triggered singly or in combination. Running scenarios can be "snapped" and stored, and the simulator can be later restored to that scenario's state.

Figure 84-5 The METI Human Patient Simulator. The mannequin rests on a standard ICU bed. Interface and linkage hardware is contained in a separate cart. A loudspeaker in the headrest provides the "patient's voice" to allow the mannequin to act as a "standardized patient."

Figure 84-6 The METI instructor/operator's station (IOS) allows full control over the model-based physiology and pharmacology of the "patient." The numbers over the mannequin show the status of all physiologic variables of the model (e.g., blood gases, cardiocirculatory parameters). At the IOS more than one patient can be run at a time and dynamically allocated to different mannequins. The IOS is the same for the Human Patient Simulator as for the Emergency Care Simulator.

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Figure 84-7 The SimMan mannequin (Laerdal) during trauma resuscitation training. The mobility and the advanced airway features together with some manual task training possibilities (such as chest tube placement, manual blood pressure measurements) make this type of simulator well suited for training sessions outside simulation centers. (Courtesy of A. Timmermann, University of Göttingen, Germany.)