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11 Simulation Medicine
131
Simulator Considerations
A general consensus is emerging on the broad set of knowledge, skills, and abilities
comprising competent sonography. For example, Tolsgaard et al. [28] identied
seven ultrasound competencies agreed to by an international sample of experts from
specialties that use sonography: (a) indication for the examination, (b) applied
knowledge of ultrasound equipment, (c) image optimization, (d) systematic examination, (e) interpretation of images, (f) documentation of examination, and (g) medical decision-making. Skilled sonography is based on a complex interaction between
gross and ne probe manipulation in light of the sonographer’s knowledge of patient
anatomy, optimal views, diagnostic interpretation, disease states, artifacts, machine
settings, and individual differences.
As noted, simulations seek to approximate reality, requiring students to react to
problems or conditions faced in actual real-life patient care. A wide variety of simulation types exist, and most can be categorized into one of the following [1]:
• Standardized patients
• Partial-task trainers
• Mannequins (specically, high-delity patient simulators)
• Screen-based computer simulators
• Virtual-reality simulators
Simulators can also be classied as high-delity or low-delity, based on how
closely they replicate actual scanning in terms of real-time image display, image
quality, and haptic feedback [29]. There are inherent advantages and disadvantages
to each simulator, and the decision regarding which type(s) to incorporate into a
holistic curriculum or assessment tool must take into account many factors.
Wider adoption of point-of-care ultrasound has been hindered by the high opportunity cost of training users using traditional live instructor and model training.
Although not conceptually a primary consideration, cost is an important factor
when deciding what type of simulator to integrate into a teaching session or curriculum, and must be weighed against the cost of traditional live instructor and model
training.
Volunteer models by denition are free, though there are often opportunity costs
to nding willing models, and addressing secondary gains such as the desire to be
taught, pressure to please course instructors, and obtaining a free medical ultrasound scan. These are important factors that can result in unforeseen costs in real
money, instructor time, favors used, and risk management. At times, simulator operation may require skilled technicians who understand the mechanical aspects of the
product, and a fee may be assessed by the simulation center that employs these
technicians upon the learners. Clinical faculty are often relied upon to facilitate
simulation sessions and ensure learning objectives are achieved. Unfortunately, academic time is infrequently valued as a commodity, and clinicians are asked to volunteer their time at the expense of other academic or clinical responsibilities. This,
too, is an opportunity cost that must be taken into consideration.
132
B.P. Nelson and D. Katz
On the low end of the cost scale are “homemade” task trainers such as soft tissue
phantoms made from gelatin, candle wax, tofu, or meats. Paid models, often used to
teach pelvic or testicular examinations, can be inexpensive or quite costly, depending on whether a formal hiring service is used, if they are being employed to demonstrate known stable pathology, or other factors. Commercially purchased task
trainers and scanning phantoms are more expensive, but offer the benet of multiple
uses and decreased logistical overhead compared to those manufactured for a specic course. High-delity simulators are generally at the upper end of the cost scale,
ranging from several hundred dollars to over one hundred thousand dollars. A wide
array of benets is offered with such products, including expansive case banks with
real or simulated pathology, real-time feedback on probe placement or image acquisition, built-in tutorials, course management software to track learner progress, and
a host of other features depending on the model selected.
Finances aside, perhaps the most important consideration when selecting a simulation tool is the curricular goal. Simulation can augment didactics and allow for
asynchronous learning of core content. Some medical schools have described peerto- peer ultrasound instruction programs that decrease faculty involvement for each
learner [30–32]. Simulators with built-in tracking and learning content management
systems can act as immersive interactive textbooks of anatomy, physiology, pathology, and technique. These systems allow learners to access didactic content and
explore hands-on training cases in a self-directed fashion. Simulators can also facilitate hands-on learning as part of a larger course curriculum. Used in conjunction
with standardized patients and high-delity mannequins, or in a stand-alone fashion, simulators can augment the pathology offered in nonclinical learning environments. Within a simulated environment (e.g., trauma or critical care scenario),
simulators can portray vital ultrasound pathology and allow for controlled practice
in a safe environment, with immediate feedback on performance and medical
decision- making. Given the steep skill decay curves for sonography, simulation can
be used in a spaced-learning model for independent refresher training that follows
group sessions.
Simulation can be used to evaluate the effectiveness of a curriculum, and for
competency assessments at various time intervals of a training course, as continued
performance improvement, or as remediation for clinicians demonstrating a prociency gap. Current student competency assessment is hindered by a variety of
logistical constraints, such as lack of access to standardized patient pathology, illdened competency metrics, and the time and resources required to assess a multitude of variables dening competency. While commercial virtual training systems
for ultrasound provide can provide effective training, there is a growing demand to
further develop the capability to rapidly and efciently assess ultrasound competency across large number of users. In 2010, Frank etal. reported that “adopting
competency-based medical education on a larger scale would require new teaching
techniques, new modules, and new assessment tools to be practical and effective”
[33]. This was reinforced by the recent IOM report, which restated the need for new
11 Simulation Medicine
educational technologies to support performance-based teaching initiatives (IOM).
Diligently designed and executed academic and private industry partnerships that
leverage the guidance and expertise of medical educators and the private sector’s
ability to deliver scalable performance-based training solutions will be required to
implement large-scale, robust performance-based medical education solutions that
are responsive to stakeholder needs.
133
Commercially Available Simulators
In the context of the previously outlined simulator classication, some key questions surrounding educational objectives should be asked prior to making a decision
on which type of simulator to include in a training session:
1. Does the simulator reliably replicate the hand movements required to acquire an
image in real-time?
2. Does the displayed image reect a real or simulated ultrasound image?
3. Does the simulator offer a broad range of ultrasound applications (e.g., cardiac,
obstetric, musculoskeletal, e-FAST) and pathology?
4. Can the simulator be used for ultrasound-guided procedural skills training?
5. Can the simulator be used as part of a more comprehensive simulated patient
care scenario?
6. Can learners operate the simulator independently prior to or following a course
for the purpose of asynchronous learning or refresher training?
7. Can the simulator be used to help with medical decision-making training?
8. Can the simulator track student progress and provide metrics and feedback?
With these questions in mind, it is helpful to consider ultrasound simulators currently available in terms of the previously discussed categories of simulators.
Partial-Task Trainers: Phantoms
Hands-on training models are purpose-built for a single procedural task, such as
central venous access, nerve blocks, thoracentesis, and lumbar puncture. Used in
conjunction with any real ultrasound machine, these phantoms render simulated
ultrasound images. Because this group of products is often punctured with needles,
they are generally made from sturdy materials that necessitate some trade-offs in
image realism in comparison to real human tissue. Many low-cost, homemade alternatives to these task trainers have been described, and may be worth considering if
cost is an issue or when many simultaneous simulators are required for an educational activity [34–40] (Figs.11.1, 11.2, and 11.3).
134
a
Fig. 11.1 Blue Phantom (CAE Healthcare, Quebec, Canada) vascular access simulators use real
ultrasound equipment for real-time dynamic scanning through simulated patient anatomy
B.P. Nelson and D. Katz
b
Fig. 11.2 (a, b) Simulab (Seattle, WA) vascular access simulators use real ultrasound equipment
for real-time dynamic scanning through simulated patient anatomy
11 Simulation Medicine
Fig. 11.3 Limbs & Things
(Savannah, GA) vascular
access simulators use real
ultrasound equipment for
real-time dynamic
scanning through
simulated patient anatomy
Anatomic Simulator: Live Model
135
Simulation-based training utilizing live models has been the standard for ultrasound training courses. Standardized patients (SPs) can be utilized to evaluate a
learners’ global understanding of ultrasonography, examining their ability to
interpret and image and apply it to medical decision-making in the context of a
clinical scenario. They can also be used to evaluate a learner’s interaction with a
patient, including attentiveness to patient comfort (e.g., amount of pressure used
with probe manipulation). Volunteers can be sought among medical students, residents, or learners who take turns scanning each other. With the exception of incidental ndings or patients with previously identied abnormalities, the use of SPs
has been somewhat limited by their ability to depict pathology. Recently, however, radiofrequency communications technologies have been used to overcome
this barrier. Using a motion-sensing probe connected to an ultrasound graphic
user interface and anatomically labeled radiofrequency markers, simulated pathology can be projected into a healthy patient for a variety of applications, and
scanned in real-time (Figs. 11.4 and 11.5).
Anatomic Simulator: Phantom
Similar to the partial-task training phantoms described above, this group includes
durable hands-on training models for a variety of applications, including thorax,
abdomen, pelvis, and soft tissue. Once again, used in conjunction with any real
136
B.P. Nelson and D. Katz
Fig. 11.4 Laerdal (Stavenger, Norway) Laerdal-SonoSim Procedure Trainer - rst release includes
a vascular access simulator using real patient anatomy that features color, power, and spectral
Doppler tracings, automated real-time performance assessment, and virtual instruction. Anatomic
Simulator: Live Model
ultrasound machine, these phantoms render simulated ultrasound images with variable realism in image quality compared to real human tissue. In addition, these
models are static, limiting assessment of cardiac activity, lung movement, fetal heart
tones, and other dynamic images (Figs.11.6 and 11.7).
11 Simulation Medicine
Fig. 11.5 The SonoSim® LiveScan (SonoSim, Santa Monica, CA) anatomic simulator uses simu-
lated ultrasound equipment, real and simulated patient anatomy, and real-time dynamic scanning
through the imaging data set which is localized to the proper anatomic location using ID tags
placed on the model
137
Fig. 11.6 Blue Phantom anatomic simulators use real ultrasound equipment for real-time dynamic
scanning through simulated patient anatomy
138
Fig. 11.7 Kyoto Kagaku
(Kyoto, Japan) anatomic
simulators use real
ultrasound equipment for
real-time dynamic
scanning through
simulated patient anatomy
B.P. Nelson and D. Katz
Anatomic Simulator: Computer-Based
Multiple computer-based ultrasound simulators are available with variable degrees
of image and scanning delity. Some simulators display looped videos or static
images when a simulated probe makes contact with a scanning surface (Fig.11.8).
The opposite side of this spectrum includes simulators that offer ultrasound images
that can be manipulated in real-time through the movement of a hand-held probe.
An important distinction in computer-based ultrasound simulators surrounds the
ultrasound image itself. Some render computer graphic images (Figs. 11.9 and
11.10) while others use images and video from actual patient scans (Figs.11.11,
11.12, and 11.13). Although the use of computer graphic imagery renders visually
appealing images, this method often omits fundamental image artifacts and pathologic ndings critical to interpreting an ultrasound image. Breadth of content and
access to pathology are important considerations, as some simulators focus on core
applications such as thoracic, abdominal, and pelvic ultrasound, while others
include wider applications of point of care ultrasound such as ocular, soft tissue, or
musculoskeletal imaging. A host of other features is available among computerbased simulators, including interfaces that display the trajectory of the beam as it
penetrates the underlying anatomy, on-screen probe positioning guidance, advanced
imaging modes such as Doppler, “reel feel” haptic feedback, side-by-side CT/MRI
to ultrasound comparisons, metrics-based assessment, and robust tracking of performance using learning management systems.
11 Simulation Medicine
Fig. 11.8 Simulab
anatomic simulators use
simulated ultrasound
equipment, real patient
anatomy, and static,
landmark-based scanning
through the imaging
dataset
139
Fig. 11.9 The Vimedix system (CAE Healthcare) uses simulated ultrasound equipment, simulated
patient anatomy, and real-time dynamic scanning through the imaging data set
140
Fig. 11.10 The U/S Mentor (Simbionix, Airport City, Israel) anatomic simulator uses simulated
ultrasound equipment, simulated patient anatomy, and real-time dynamic scanning through the
imaging data set
B.P. Nelson and D. Katz
Fig. 11.11 The ScanTrainer (MedaPhor, South Glamorgan, United Kingdom) anatomic simulator
uses simulated ultrasound equipment, real patient anatomy, and real-time dynamic scanning
through the imaging data set with haptic feedback