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October 1997
Volume 61 |
Number 10
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| Using Simulators
for Education and Training in Anesthesiology |
W. Bosseau Murray, M.D.
Arthur J.L. Schneider, M.D.
Simulators have been used increasingly in medical education and
training. Anesthesiologists can claim credit for much of the initial
work with full patient simulation, and this article deals primarily
with the use of simulators for education and training in anesthesiology.
It should be noted, however, that many others, including emergency
room personnel, acute care nurses, various medical specialists,
medical students and community science students, have benefited
from exposure to these simulators, most of which are still found
in anesthesiology departments (see
accompanying article).
Simulators of the '90s
A full-patient simulator consists of a human mannequin animated
with a variety of electromechanical or pneumatic devices that
produce respiratory movement, palpable pulses, heart and lung
sounds, realistic airway anatomy, exhaled carbon dioxide, thumb
twitches and "urine." Complex interactive mathematical
models of drug function, metabolism, cardiac function, gas exchange
and fluid balance are resident in an integral system computer.
Information on administered "drugs" and dosages is sensed
with bar code readers and sensitive scales. It is important to
understand that the simulator's response to therapeutic manipulations
derives from the constant updating of the mathematical models.
The responses of these models such as changes in blood pressure
or respiratory rate control a variety of actuator-produced responses,
which are, in turn, sensed by real operating room monitors applied
to the mannequin. Realism is enhanced with all the props necessary
to replicate the patient care environment.
Full physiologically responsive patient simulators, suitable
for anesthesia training, are marketed by two commercial firms.
The Eagle Patient Simulator is available from Eagle Simulation,
Inc. of Binghamton, New York (previously CAE Link/CAE Electronics).
The METI Human Patient Simulator is available from Medical Education
Technology Inc. of Sarasota, Florida (previously Loral-Gainesville).
Part-task trainers such as intubation models and computerized
case simulations are also widely used but are not discussed here.
Simulators are expensive to purchase and to maintain. A commercial
simulator costs nearly $200,000, and operational costs may exceed
$500 an hour, largely due to personnel costs. Simulators must
be used effectively and efficiently to produce acceptable return
on investment.
Education With Simulators
All levels of cognitive learning are not equally appropriate
for full environment simulation. Lower levels of learning such
as knowledge acquisition and comprehension (e.g., knowing and
understanding the gas laws) may be better taught in classrooms.
Application and analysis of learned rules lend themselves somewhat
more readily to simulation (e.g., concepts such as low cardiac
output predicted by the Frank-Starling law can be realized as
hypotension in simulation). Clinical training involves higher
level application of the facts and principles learned primarily
in libraries and lecture halls. Higher levels of cognition, including
synthesis and analysis, are even more appropriately taught and
tested in a simulated environment.
At this level, the student must use previously learned rules
in original or unique combinations to develop solutions to newly
encountered problems and, later, to analyze this solution for
effectiveness (e.g., adjusting a ventilator with long compliant
hoses for a patient with high pulmonary resistance and then determining
whether ventilation is adequate). Simulators become most effective
when training involving motor skills such as endotracheal intubation,
airway maintenance and twitch height palpation is mixed with cognitive
analysis and synthesis in a realistic distracting environment
of alarms, monitors, chart keeping and drape arrangement. Attitudinal
learning is also enhanced since students enjoy simulator experiences,
perhaps partly because learning is separated from the stress and
responsibility of real patient management.
Real clinical cases provide only random opportunities to supply
an appropriate level of complexity for a particular student. Furthermore,
the student has but one opportunity to solve a true clinical problem.
Many of these opportunities are unpredictable, fleeting, yet dangerous;
often senior clinicians must assume control. In the simulator,
a problem can be repeated as the trainee considers a variety of
treatment options. As skills develop, the simulation scenario
can be made more complex and demanding. For example, the simulation
scenario can demonstrate variants of "shock" from simple
hypovolemia, requiring only fluid administration, to advanced
hypovolemia complicated by cardiac failure, to anaphylaxis with
or without cardiac failure.
Crew Resource Management (CRM) training was developed in the
airline industry to teach and test the ability of cockpit crews
to work together in the management of crisis situations. Anesthesia
Crisis Resource Management (ACRM) applies these same ideas to
the multidisciplinary teams present in various clinical settings.
The principles of ACRM are readily taught and practiced in simulators
around the world, including definition of the roles of leaders
and followers, good communication, obtaining help as needed, utilizing
all forms of resources and avoiding fixation by repeated reassessment
of the whole picture.
Examples of Simulator Application
Different sorts of airway skills must be taught to the different
levels of health care workers who respond to an emergency code.
A full simulator allows practice ventilation of a normal airway
with immediate tactile feedback, provides for monitoring of end-tidal
carbon dioxide and peripheral oxygen saturation and supplies the
instructor an opportunity to introduce laryngospasm and low compliance
as the trainee gains skill. Nonanesthesiologist physicians and,
in some settings, respiratory therapists must be skilled in routine
endotracheal intubation. A simulator program with graded intubation
difficulty and urgency can be developed. Anesthesiologists are
expected to demonstrate the highest level of skill in airway management,
as manifest in the ASA Difficult Airway Algorithm in "Practice
Guidelines for Management of the Difficult Airway." Practice
with transtracheal jet ventilation, retrograde intubation and
esophageal-tracheal combitube ventilation can be readily obtained
with a simulator.
The response to major critical events can be practiced in the
simulator. The total loss of operating room electrical power is
an unusual event usually remembered clearly by those to whom it
has happened. Having been through simulated loss of power teaches
one to check for a flashlight preoperatively and, through rehearsal,
makes the real event much less perplexing. Scenarios of mild,
moderate and severe anaphylaxis can be repeated until the trainee
becomes facile at recognition and treatment. Malignant hyperthermia,
contamination of gas supplies, drug overdose and operating room
fires have all lent themselves to simulator scenarios.
Economics of Clinical Instruction
Clinical management requires analysis of multiple monitoring
inputs and synthesis of a treatment plan. Although students may
have all the bits of basic knowledge necessary for patient care,
combining this information into an appropriate mental management
model is often difficult to teach in a lecture format. In simulation,
however, various treatment plans can be evaluated by the trainee
and the instructor, simply by repeating the scenario. This approach
is much more economical than actual patient treatment over many
hours in the intensive care unit.
In our institution, it has been determined that operating room
time costs approximately $1,000 per hour. If we assume that each
procedure is prolonged for 30 to 60 minutes by teaching anesthesiology,
surgery and nursing students and that about 13,500 cases are done
per year, the cost estimate becomes quite high. Recent emphasis
on cost containment makes the greater use of simulators in medical
education look more and more attractive. Simulator training outside
the operating room can possibly result in both safer anesthesia
care and reduction of the time spent in operating room training.
It must be admitted that real cost savings have yet to be determined.
Research in the Simulated Operating Room
Simulator facilities also provide opportunities for clinical
research. Several groups have looked at the way trainees respond
to critical incidents in patient management. The appropriateness
and timeliness of responses to cardiac arrest or malignant hyperthermia,
the accuracy and completeness of anesthesia records, the effects
of fatigue on performance and the detrimental effects of multiple
alarms and signals have all been investigated in simulation facilities.
Equipment questions, such as design and placement of anesthesia
machine controls, monitor display configuration and data acquisition
system design questions have also been addressed.
Considerable research attention is being placed on the potential
usefulness of simulators in testing and assessing the clinical
competence of medical practitioners. Advanced cardiac life support
training may be obtained with a simulator device.
Summary
There are, at this time, more than 50 anesthesia simulators in
operation worldwide. Listing the diverse emphases and interests
of each simulator group is beyond the scope of this report. Those
interested in individual sites are referred to the Fall 1995,
Spring 1996 and Fall 1996 issues of the APSF Newsletter
or to World Wide Web sites such as <http://web.anes.rochester.edu/simulate/simusers.html>.
While the concept of simulation is ancient, realistic computer-controlled
simulated patients are relatively new. Cost control, the need for
educational accountability, requirements for lifelong learning and
demonstration of professional skill, demands for cross training
and competence in several activities and the exploding universe
of scientific information seem, together, to present formidable
educational challenges. Simulation offers at least a partial answer.
W. Bosseau Murray, M.D., is Associate Professor
of Anesthesiology, Pennsylvania State University College of Medicine,
Hershey, Pennsylvania.
Arthur J.L. Schneider, M.D., is Professor
of Anesthesiology, Pennsylvania State University College of Medicine,
Hershey, Pennsylvania.
E-mail the author.
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