Simulation in Medicine

Introduction

Simulation is a technique for practice and learning that can be applied to many different disciplines and trainees. David Gaba, one of the pioneers of simulation technology in medicine, states, "Simulation is a technique, not a technology, to replace or amplify real experiences with guided experiences, often immersive in nature, that evoke or replicate substantial aspects of the real world in a fully interactive fashion. ‘‘Immersive’’ conveys the sense that participants have of being immersed in a task or setting as they would if it were the real world." [1] Simulation facilitates learning through immersion, reflection, feedback, and practice -- minus the risks inherent in a similar real-life experience. Simulations are used in varied industries that include aviation, nuclear power plants, space aeronautics, the military, business, and healthcare (McGaghie, 1999). The complexity of its use ranges from simple role play scenarios to highly technical, computer-driven models that are designed to respond to trainee actions as a real situation might.

In medicine, simulation is gradually becoming a standard part of professional training. As of 2005, 35% of US medical schools had mannequin-based simulation centers (Karmin, 2005) and that number continues to grow worldwide. Participants of simulation are immersed in these replicas of real-life experience and play roles in scenarios such as cardiac resuscitation teams, procedural performance, delivery of babies, providing anesthesia, surgical operations, dentistry, and nursing care, to name just a few.

Experts, Masters and Novices

In order to understand the significance of simulation in modern healthcare, it is useful to consider what factors influence greatness and expertise. K. Anders Ericsson, a cognitive psychologist, studied human performance by looking at the differences between novices and masters in fields such as athletics, music and games such as chess. The single difference between elite performers and lesser ones was the amount of deliberate practice they had, raising the concept that the dedication to practice may be more important than the innate talent for the skill itself. [13]

Turning to medicine, similar results of practice are seen.In the field of central venous catheter placement, complications are shown to fall off when doctors perform the procedure more than 50 times/year. Atul Gawande’s “Education of a Knife” describes this everyday struggle between making mistakes and mastery of one’s field that characterizes medical training as it stands in the apprenticeship model.

In the last couple of decades, medical education has started to rethink the extent to which practice happens on live patients. With the availability of simulated alternatives for learning, practice, and the inherent learning curve that comes with it, can begin to be shifted to low risk environments which are simulated.

History of Medical Simulators

Full body mannequin simulators originated in the field of anesthesia. The first realistic anesthesia simulator was produced in the late 1960s, based on work done by J.S. Denson and Stephen Abrahamson at the University of Southern California. This model, known as Sim One, was used mainly for the training of endotracheal intubation and the induction of anesthesia. The mannequin had outputs for peripheral pulses and heart sounds, but no outputs for electronic monitors. This system was eventually phased out. (Gaba 1999)

In the 1980s several independent groups developed anesthesia simulator systems. By this time, personal computers were relatively inexpensive, and other types of simulation software were available (eg, flight and driving simulators). The public became aware of simulation in a number of different fields, including military training, commercial aviation, nuclear power generation, and space flight. In the field of anesthesia, there was increased interest in the role of human factors issues such as ergonomics and human error. (Gaba 1999)

In the early 1990s, two realistic simulators were commercially produced, based on work at Stanford University (David Gaba) and University of Florida (Michael Good and JS Gravenstein). Gaba’s group produced the comprehensive anesthesia simulation environment, which was later to be commercialized as Medsim. Good and Gravenstein developed the Gainesville anesthesia simulator (GAS), later to become Medical Technologies Incorporated (METI). Stanford’s group was the first to incorporate aviation’s concept of crew resource management into anesthesia team training. Current full body simulator models incorporate computerized models that approximate the physiology seen in the human body. These models have uses beyond anesthesia and are now also used for surgery, critical care, obstetric, emergency medicine, and internal medicine. (Gaba, 1999)

The cost of creating a current day simulator environment currently ranges from $35,000 to several millions of dollars, depending on the environment created and the equipment used.

Fidelity

Medical simulations exist on a continuum of realism and technical complexity known as fidelity. Low fidelity simulations refer to low-tech scenarios, such as role play or the use of a plastic mannequin prop, where trainees are given a situation to enact without specific interaction from their prop. Fidelity increases in computer screen-based experiences, where trainees may be given a scenario of a patient with an abnormal heart rhythm and are actually shown the arrhythmia the same way it would appear on a monitor. The computer then prompts the trainee to make a decision about assessment and treatment, and, depending on their choice, the simulated patient and arrhythmia respond to the intervention. High fidelity simulation refers to a much higher level of immersion and technology with the goal of increased realism. For example, a team of trainees may be put in a scenario of a patient going into cardiac arrest, requiring resuscitation. The mannequin is computer driven, has eyes that open and close, pulses in all of the appropriate places, and can talk to the trainees. Before the cardiac event, the trainees can listen to the heart and lung sounds which approximate those of a real person, and, when epinephrine is administered during his cardiac arrest, his heart rhythm returns and his blood pressure can once again be measured as he begins to wake up and talk to the team.

Types of Simulators

Standardized Patients

Standardized Patients (SPs) are actors or lay persons who are trained to reliably play the role of a patient in a clinical encounter. SPs have been used for the last two decades, particularly in undergraduate medical education. SPs are usually trained to assess students using a checklist, and to provide feedback at the end of each session. Student-SP interactions are normally videotaped so that students can watch and reflect upon their performance. Sessions commonly conclude with a debriefing session from an experienced clinician. The utility of standardized patients includes the opportunity for students to practice communication and physical exam skills. They are also used for practice of sensitive topics and exam skills, such as “breaking bad news” or performing gynecological or breast examinations. SP simulation exercises are limited by the absence of reliable pathologic findings in actors (such as heart murmurs or abnormal lung sounds) compared with real patients. American medical students are now required to take an SP exam as part of the United States Medical Licensing Examination Step 2.

Computer (Screen) Based Systems and Virtual Reality

Computers and virtual reality currently allow users to interact with an environment whose output is through a computer screen. These outputs can be made more realistic by wearing special 3-D glasses or headsets. An example of this type of simulation is an endovascular catheterization or stenting procedure where doctors use their hands to manipulate catheters, which they watch on the screen, or bronchoscopy, in which the operator guides a scope looking into the airways of the lung, which is projected on the screen. These approximate the real life procedure which is actually viewed in 2D on a screen.

Part Task Trainers

Part task trainers are devices designed to replicate a particular part of the anatomy. These are used to practice specific, focused procedures or interventions. Examples include urinary catheter trainers, plastic arms for intravenous line placement, airway management heads, central line placement torsos, spinal columns (for spinal taps and epidural placement). Successful models also include store bought items such as pigs’ feet for suturing, oranges for skin biopsies, and watermelon for epidural anesthesia.

Hybrid Simulation

Hybrid simulation combines standardized patients with part task trainers. For instance, a nursing trainee may be asked to place a urinary catheter into a model which appears to be part of an actual person (standardized patient). Similarly, suture skills can be practiced on a plastic suture model which is affixed to the arm of a live standardized patient. This adds to the experience by training the student in communication and sensitivity to the patient while he or she performs the procedural skill.

Full Body Mannequin

Full body mannequin-based simulators are currently used primarily for training teams of doctors to respond to medical, emergency room, surgical, or obstetric patients. These simulators allow trainees from multiple disciplines to interact while managing problems of varying complexity, including cardiac arrest, complicated births, and difficult surgical complications. Students, nurses, respiratory technicians, doctors, and pharmacists can all participate around one decompensating “patient.” Full body mannequins are also the most technologically advanced simulators. They can interact with the learners through computer guided physiology that is programmed through computer software and manipulated in real time by technical staff. These mannequins can speak to the learners until they lose consciousness, breathe with realistic gases, have a measurable pulse and blood pressure, and urinate. Their eyes open and close and their pupils react to light. Their cardiac rhythms are visible on attached monitors, and medications administered to them may produce physiologically appropriate responses based on their programmed age and sex. After going through a simulation, learner teams meet with facilitators to debrief the experience. They can watch the events of the scenario on video and reflect on their performance while learning from experienced instructors.

Safety and Simulation

Healthcare safety can be compared to other high stakes industries such as aviation, the military, and nuclear power. In these industries, safety depends on the prevention of human error and on engineered redundancy, so that systems work without failing. Widespread morbidity and mortality can be clear consequences of safety failures in these environments. In healthcare, the Institute of Medicine report To Err is Human dramatically highlighted that healthcare is by no means free of error and its consequences. Experts estimated that 100,000 deaths occur each year in hospitals as a result of medical error. (Kohn, et al 1999) The utility of simulation in healthcare is most interesting to consider in the context of patient safety.

One important concept in medical safety is the paradigm of how one learns. Traditionally, medicine functions under the apprenticeship model. Trainees, such as residents, begin caring for patients on their first day of internship, under the supervision of more experienced providers, such as senior residents and attending physicians who provide a safety net for errors. Despite learning about medical care prior to assuming responsibility for their first patients, there must always be a first time for the performance of high-risk procedures, resuscitation, and implementing critical decision-making skills in real time on real patients.

Simulation provides a model for learning that can complement traditional clinically-based training. For uncommon scenarios, such as pericardial tamponade (where fluid surrounding the heart critically limits its ability to pump), or malignant hyperthermia (a reaction to anesthesia that causes extreme muscle contraction and breakdown, fever, and eventual death), physicians may have seen few or none of these events prior to facing them for the first time. Scheduled simulation experiences can assure that residents have exposure, although simulated, to such emergencies. For procedures, where it is shown that the volume of experience decreases patient complication rates (Sznajder, Zveibil et al. 1986), simulators allow for development of experience prior to performing on patients.

Evidence for Simulation as a Teaching Tool

Although traditional educational techniques such as classroom lectures or the apprenticeship model of residency training are not well studied, new and particularly resource intensive methods of teaching which invoke a paradigm shift are subject to higher scrutiny. A body of literature in this area is gradually emerging.

A BEME (Best Evidence Medical Education Collaborative) review of the literature from 1969-2003 concluded that the rigor and quality of research in simulation needs improvement, although high fidelity medical simulations are educationally effective and complement traditional training in patient care settings. The features of simulation which best facilitate learning include:

1. providing feedback
2. repetitive practice 
3. curriculum integration 
4. range of difficulty level (Issenberg, et al, 2005)
   

The educational benefits of simulation in medical education include the following:

1. deliberate practice with feedback
2. exposure to uncommon events 
3. reproducibility 
4. the opportunity for assessment of learners 
5. the absence of risk to patient
   

To date, there have been no studies to show that simulation training improves patient outcomes. There are several theories as to why this is the case. Life threatening complications are rare, and the number of cases needed to show a difference using simulation training can be prohibitive. Most hospitals have various quality improvement measures in place, and selecting for the impact of simulation on patient outcomes can be difficult.

Despite the absence of patient outcome data, a significant body of evidence exists for the benefit of simulation training in educational outcomes. Furthermore, several medical insurers offer malpractice insurance discounts for faculty who participate in simulator training, further enforcing its perceived impact in the healthcare environment.

Studies have shown that learners who go through simulations perform better on subsequent simulated tasks. For instance, a cohort study looked at medical students at 5 academic medical centers. The cohort were students who were exposed to 2 weeks of deliberate practice of cardiac bedside skills using the Harvey cardiology patient simulator followed by two weeks of traditional ward work vs. those who were exposed to 4 weeks of traditional ward work. The simulation group performed at twice the level of the ward group in half the training time. (Wooliscroft, 1987)

Michael Devita and his team of researchers were able to show that simulated patients have better outcomes if teams of doctors are trained to work together by reliably performing pre-assigned roles, such as medication manager, during a simulator exercise. (Devita, 2005)

Diane Wayne’s group showed that residents who were simulator trained in resuscitation of patients were more likely to adhere to American Heart Association guidelines for such resuscitation in live patients. Second year medicine residents who had gone through simulator training adhered to guidelines 68% of the time, as compared with 44% of the time for traditionally trained third year residents. (Wayne et al, 2007)

In surgery, a randomized, double-blind study showed the transfer of laparoscopic cholecystectomy (gall bladder surgery) skill from simulator to operating room. Virtual reality-trained residents made 6 times fewer intra-operative errors and performed the procedure 29% faster when dissecting the gallbladder from the liver bed, supporting the notion that significant improvement in skill can come from virtual reality training. (Seymour, 2002)

Simulation in Action

 

Future Directions/Innovations

As simulation continues its rapid evolution in medicine, there are several future directions to consider:

• At the 2007 Society for Simulation in Healthcare (SSH), one of the winning abstracts described using simulation to evaluate candidates for admission to medical school based on their noncognitive merits (Ziv, et al 2007) incorporating simulation in a nontraditional way to better evaluate applicants.

• A 2008 abstract winner incorporated simulation in situ in the OR to mitigate hazards of a new procedure of intraoperative radiation therapy, during the simulation identifying 20 defects in safe delivery of this procedure (including radiation safety, teamwork and communication, and equipment/supply problems) prior to trying it on patients. This allowed for changes to be made before performing the new procedure on patients. (Rodriquez-Paz et al, 2008) This creates a model for patient safety where future new innovations are translated into clinical environments.

 

• In 2004, the United States Food and Drug Administration (FDA) took the lead on simulation-based competency assessment for procedure performance. The FDA will only certify competency of a clinician to perform carotid stenting procedure of a patient if competency is demonstrated in a simulator first. (Henriksen and Dayton 2006) Future use of simulation to assess competency in healthcare professional training is a subject of avid interest.

 

• Designers continue to improve the technology of virtual reality, to make experiences seamless in realism.

Finally, David Gaba, one of the successful early pioneers of simulation in healthcare, describes two possibilities for the future of simulation in healthcare in the year 2025: one posits the successful integration of simulation throughout the fabric of healthcare; one hypothesizes simulation’s dismal failure, despite its early promise.  The Future of Simulation in Healthcare (Gaba, 2004)

Simulation Weblinks

Society For Simulation in Healthcare

www.ssih.org

Training Courses

Center for Medical Simulation

www.harvaradmedsim.org

Association for Standardized Patient Educators

www.aspeducators.org

Patient Safety Web Links

AHRQ Agency for Healthcare Research and Quality
www.ahrq.gov/qual/errorssix.htm

Web M&M

http://www.webmm.ahrq.gov/

ECRI Medical Safety Device Reports
www.mdsr.ecri.org

JCAHO Joint Commission on Accreditation of Healthcare Organizations
www.jcaho.org

IHI Institute for Healthcare Improvement
www.ihi.org

NPSF National Patient Safety Foundation
www.npsf.org

APSF Anesthesia Patient Safety Foundation Newsletter
ww.apsf.org

ISMP Institute for Safe Medical Practices
www.ismp.org

Veteran’s Administration
www.patientsafety.gov