Simulation in the 21^st century has come to be known as a technique of imitating the behavior of some situation of a process by means of a suitable analogous situation or apparatus.  Modern simulators have been developed to acquire the skills necessary to control movement such as aircraft, automobiles, and ships.  Additionally modern simulators have been developed to acquire the skills necessary to control processes such as air traffic control, atomic power, and anesthesia.

The first anesthesia simulator was developed at the University of Southern California in the late 1960s.  It featured spontaneous ventilation, a heart beat, temporal and carotid pulses, blood pressure, a mouth that opened and closed, blinking eyes, muscle fasciculation, and a coughed.  It responded to 4 intravenous drugs: thiopental, succinylcholine, epinephrine, and atropine.  Additionally it responded to oxygen and nitrous oxide.  The first anesthesia simulator was based upon scripting.  A script prescribes the consequences of an action.  Thus if 400 mg of Thiopental was injected the blood pressure fell by 10% and the heart rate rose by an equal amount.  Unfortunately, the same physiological consequences occurred if any other dose of Thiopental was injected.  Upon being introduced to the anesthesia community in 1969, the first anesthesia simulator was rejected as having no place in anesthesia training.

Dr. J. S. Gravenstein at the University of Florida resurrected the early technology in the late 1980s.  In concert with a team of computer scientists and engineers, the Human Patient Simulator [HPS] was created and introduced in the early 1990s.  What distinguishes the Human Patient Simulator from the first anesthesia simulator is that it is based upon modeling.  The software that runs the HPS contains complex mathematical equations. These equations define the many factors comprising the cardiovascular and respiratory systems of humans.  If a drug or event affects one or more factors, the new equation will describe the resulting changes.  Thus, if an intervention is correct and timely we will see improvement in the simulated patient’s condition.  If the intervention is incorrect the simulated patient’s condition will deteriorate and ultimately lead to cardiac arrest and death.