From “simple” computer models to full body representations, lung simulators offer hands-on training for RTs

Stand up and lift your left foot. Easy, wasn’t it? You did not even have to think about it. Now walk to the nearest wall, turn, and place the outside edge of your right foot against the wall. Lift your left foot. You cannot do it?

The seemingly simple act of lifting your foot actually involves complex physics that belongs to the science of kinesiology. The above example illustrates the necessity of a weight shift to your right foot in order to lift your left foot. This would not be so easily noticed if not for the wall. The environmental constraint (wall) allows you to be conscious of the necessary weight-shift parameter. You did not have to know about it in order to lift your foot, but knowing has given you more insight into the act. This is the reason for and essence of human physiological simulation.

Simulation takes an action or event and provides a controllable environment whereby each discreet event that comprises the action can be observed, measured, and manipulated. Even time can be sped up or slowed down. One can know more about a specific action with varied parameters within varied environments. Simulation is manufactured reality, but reality nonetheless.

A Taxonomy of Simulation
Now take a breath. Breathing is just as seemingly easy as lifting your foot, but any of us who have taken a respiratory physiology class knows that breathing is one of the most complex physiological events.

Human simulation can provide a window into the complexity of respiratory mechanics, disease state, and clinical treatment. When we assess the benefits of simulation for professionals trying to enhance their skills, a breakdown of the different tasks that these professionals perform is helpful. A common taxonomy of tasks is:

• cognitive skills
• psychomotor skills
• situation management, interactions with others

Looking at allied health professionals and physicians in general, the taxonomy can be illustrated easily with some examples: Cognitive and Psychomotor. A lung simulator can act like a real patient when attached to a ventilator. This “patient” can be given disease states such as COPD1 or pulmonary fibrosis and then be placed on a ventilator. The equipment will ventilate the simulator as if it were a patient. The simulator can be programmed with specific breath patterns, resistance, compliance, etc or manipulated by the operator to vary the pulmonary dynamics in real time. A student can be tested in identifying urgent events such as resistance and compliance changes or selecting available technology (type of ventilator or ventilator mode) to optimize therapy.2

Situation/Interactions. The real-time interactivity allows for real-life dynamic interactions. Imagine an ER situation where a patient has been intubated in the field because of apnea due to chest trauma from a motor vehicle accident. Each breath of the lung simulator can be programmed, and clinical situations such as pneumothorax, ARDS, and airway obstruction can be simulated. This gives the caregivers the urgent feel and physical response that are missing in a lecture or computer-only simulation. Studies have shown that not only immediate learning is improved but also retention is better with this approach.2 In the case of the medical caregiver (similar to the situation of a pilot of a commercial jetliner or military aircraft), training includes preparation for tasks where successful performance decides issues of life and death. Training, therefore, must involve the actual development of skills such as intubation of a difficult airway patient and a desensitization to avoid the stress-related deterioration of task performance that can have serious consequences. Military trainers have long known that practice, drills, and exercises are the best method available to achieve this end, which also explains why military organizations embraced simulation in all its forms to a degree that is quite remarkable. For the above reasons, simulation is becoming one of the fastest-growing segments of medical education.3,4

As one of the indicators of this development, the most recent conference of the international Society for Simulation in Healthcare had a doubled attendance and membership. That increase indicates the society’s likely emergence as the major forum for experts in the new discipline of medical simulation. This new organization owes its origins to the Society for Technology in Anesthesia, which has for some time been the organization for those who work with human patient simulators and team-oriented simulation scenarios.

RT and Simulation
For respiratory professionals (similar to other caregivers), one of the significant learning objectives must be their ability to deliver trained behavior patterns that will make a significant contribution to rescuing a patient in a code situation.

While cognitive skills can be addressed in a multitude of ways using clinical simulation computer software, immersing a student into the hands-on aspects of a code situation is quite different. It is for this reason that simulations with varying degrees of realism for patient responses (tactile and response to treatment) become necessary. In fact, a classification of simulators in a pyramid of increasing fidelity (and cost) can be described (Figure, page 50).

Task trainers. Looking at the benefits and skill training power of the task trainer, an argument can be made, I believe, that this category of simulators should not be underrated in the popular quest to employ only the most high-level technology. Most respiratory caregivers have trained for basic life support or advanced cardiac life support on a mannequin-style task trainer. These trainers are not very interactive but do supply valuable feedback and psychomotor training in skills like intubation, bag-mask ventilation, or chest compressions. These skills are invaluable to obtain and maintain.

Computer models. These classic desktop computer sit-and-think simulations give the user various therapy paths and require clinical decisions to be made based on path-specific data. These are inexpensive and represent a more effective way of learning than lecture or reading alone.

Computerized lung models. These software-driven physical lung representations are the gold standard in respiratory simulation. These devices are somewhat expensive but are highly interactive and can be used for ventilator management education, human physiology education, drug and device research and development, and even clinical quality control. The devices are used in the various scenarios mentioned previously in this article.

Human patient simulators. These full-body (mostly), computerized, software-driven, physical representations of the human body are designed to develop skills that span the clinical realm from labor and delivery to pharmaceutical management of cardiac arrhythmia. These devices are the most expensive and tend to be found in simulation centers.

RTs’ Unique Roles
Constituting a specialty customer group, respiratory care professionals need to establish their positions in the evolving landscape of simulation centers. This might be helped by taking an inventory of the unique interactions RTs have with their patients and the skills that are critical to respiratory care professionals. Ask any resident and you will likely hear that pulmonary management is one of the more challenging aspects of medicine. Simulation centers can help them meet the challenges by creating scenarios specific to the course curriculum of the medical or respiratory therapy school. It is also beneficial to have an instrument to assess students’ critical thinking and problem-solving abilities.5

Respiratory care is at an advantage when it comes to guiding the design of simulations. Respiratory care touches most aspects of critical care medicine. The need for simulation is most often born out of the need to be better trained in a urgent or critical care setting. The goal is to be more effective, increase quality of patient care, and save time and money.

Acquiring data for feedback is not necessarily a “rocket science” endeavor, but rather requires RTs to insist on specific tools needed to perfect their respiratory care skills. An example is the necessity for feedback of peak pressure during bag-mask ventilation. Recent studies have illustrated the common clinical mistake of hyperventilation during CPR and the resulting mortality.6 In this case, direct feedback of airway patency, intrapulmonary pressure, tidal volume, and minute ventilation are desirable information when creating that type of scenario. The direct effect of this type of unique simulation training can be immediate and life saving.

Certain areas are more difficult than others to mimic in a simulation because of the simulation equipment fidelity required to do so. Training in ventilator management, for example, whether it is intended as task training specifically, or embedded in a larger patient scenario simulation, does require a simulator capable of contributing to the interactions between patient and ventilator associated with spontaneous breathing.7

Data that is indicative of success or failure of the respiratory treatment can be as simple as obtaining tidal volumes and minute ventilation, or, on the other hand, including more sophisticated derivatives of patient condition such as V/Q, blood gases, and cardiovascular information. Essentially, one of the biggest challenges of simulation development in medical education is to filter, condense, and otherwise simplify the myriad interconnections that exist in a real living organism and its connections to the outside world. Figure 2just a small snapshot of all the parameters one may have to consider when constructing a simulation.

Qualifying simulations as a useful tool for the transfer of skills to students is another challenge, one that is shared by respiratory care and any other branch of health care education (ACLS, physicians’ training). It is a two-step challenge. First, you would like to gather as much evidence, in a scientific way, on what works (and what does not), and second, you have to design a framework for this knowledge that sets out requirements for the design and evaluation of simulations to be acceptable in a curriculum. This can be accomplished through CME-style courses that can very effectively be structured using simulation technology.

Finally, keep in mind that respiratory simulation is still rather young. You have the opportunity to help direct its course. Specific simulation training standards, simulation disease state criteria, and outcome data need to be created. Take part in studies that involve simulation, partner with your nearest or affiliated simulation center to help create new scenarios, or even conduct your own studies.

Stefan Frembgen, PhD, is the founder and president of IngMar Medical Ltd, a producer of test lungs and breathing simulators based in Pittsburgh. He has been affiliated with the respiratory care device industry for 20 years and obtained his doctorate degree in safety engineering from the Bergische Universität Wuppertal, Germany.

1. Gremme M, Frembgen S. Active lung simulation with CO2 production and respiratory response to an end-tidal CO2 partial pressure. Presented at: the 38th Annual Conference of the German Society for Biomedical Engineering (Dr[yr,nrt 28, 2004. Münster University of Applied Sciences, Center for Biomedical Engineering.

2. Gordon JA, Brown DFM, Armstrong EG. Can a simulated critical care encounter accelerate basic science learning? Journal of the Society for Medical Simulation. 2006;1:13-17.

3. MacIntyre NR. Respiratory systems simulation and modeling. Respir Care. 2004;4:401-9.

4. Hinesly D. Breathing easy: the current state of lung simulators. RT the Journal for Respiratory Care Practitioners. 2005;18(9):40, 43-44.

5. Shelledy DC, Gardner DD, Carpenter ME, Murphy DL. Development of an instrument for the assessment of students’ critical thinking and problem solving ability. Respiratory Care Education Annual. 2004;13:15-23.

6. Aufderheide T, Lurie KG. Death by hyperventilation: a common and life-threatening problem during cardiopulmonary resuscitation. Crit Care Med. 2004;32(9 suppl):S345-S351.

7. Hosoya M, Mizutani T, Takahashi S, Toyooka H. Effects of pressure support ventilation or tube compensation, and tracheal tube size and length on tidal volume during spontaneous breathing—a simulator study. Anesthesiology. 2003;99:A428. ASAAbstracts 2003.