Keywords
Diagnostic endoscopy
-
human cadaver endoscopy
-
simulation models
-
therapeutic endoscopy
Introduction
Computer-based simulation and animal-based models are increasingly being used for
training in diagnostic as well as therapeutic endoscopy. It offers a number of advantages
such as the opportunity to repeatedly practice the procedures and assessment of performance,
reducing the harm caused to patients by novices performing procedures directly on
them,[1]
[2]
[3]
[4] and an increase in performance efficiency by reducing the time needed to train in
the clinical environment.[5]
Available endoscopy training tools
Endoscopic training devices can be divided into mechanical simulators, those involving
animal tissue\(living or cadaveric) and virtual reality tools. Mechanical simulators
(Erlangen plastic mannequin, 1974) are limited by lack of variation.[6] Training models like EASIE (The Erlangen active simulator for interventional endoscopy,
ECE-Training GmbH, Erlangen, Germany), use specially prepared cadaveric animal model
which behave more like human but are limited by infrastructure and ethical concerns.[7],[8] Others such as GI-BRONCH Mentor (Simbionix, Cleveland, Ohio) and the CAE AccuTouch
(CAE Healthcare, Montreal, Quebec, Canada; previously marketed by Immersion Medical,
San Jose, California) are virtual reality tools which have lot of advantages: little
set up time, repeated use, and assessment of skills but still lack the feel and experience
of performing endoscopy on a real patient.[9],[10]
The relevance of these tools is more in a country like India where a large number
of doctors perform endoscopy, and there is no mandatory competency certification.[11] Availability of these models may provide valuable training opportunities for our
future endoscopists. Experience of endoscopy on a human cadaver may be closer to performing
endoscopy on a real patient compared than experience with an animal model or simulator.
It familiarizes with the normal human anatomy and the maneuvers required for negotiating
the endoscope. In addition, it has advantages similar to a simulator. We performed
a feasibility study on cadaver-based endoscopy and also compared the performance characteristics
with an endoscopic medical simulator.
Methods
Cadaver environment
At our center, the cadavers are preserved in a customized nonformalin-based solution
which retains organoleptic properties (preserve the color, feel, and inflation of
intestine) of the cadaver for up to 2 years. We used these for this study. The endoscope
and the accessories used were dedicated for use in cadaver laboratory.
Endoscopy on a simulator
Simulator (GI-BRONCH Mentor, Simbionix, Cleveland, Ohio) was used for diagnostic endoscopy
which gives the sense and feel of the tissue with varying levels of sophistication.
Simulator builds up hand-eye coordination, be reused multiple times, and gives feedback
of the endoscopic visualization.[12]
Ten junior trainees in gastroenterology and surgery who were novices in endoscopy
were the participants for this study between January 2017 and December 2017. None
of the participants had prior exposure to training on human cadaver before the study
commenced.
Training on human cadaver
Endoscopy was performed using forward-viewing single-channel gastroscope (PENTAX/EP
2940) using a light source processor PENTAX/EPM 3500 (Pentax U.K. Limited). The basic
steps included were as follows: endoscopy tip deflection by knob movement, push in/pull
back, right/left torque, air insufflation, and suction to achieve adequate examination
of the upper gastrointestinal (GI) tract. These were done on both simulator and human
cadaver model. The steps of (i) esophageal intubation, (ii) negotiating the pylorus,
(iii) maneuvering into the second part of the duodenum, and (iv) retroflexion in the
stomach for visualization of fundus were assessed with a questionnaire.
Endoscopic injection and submucosal dissection
Endoscopic injection (EI) was performed using Interject Boston Scientific 23G/240
cm needle for cadaver. The steps of EI scope positioning, needle sheath out, needle
out, submucosal injection, mucosal elevation, needle in, and sheath in were compared
between cadaver and simulator.
For endoscopic submucosal dissection (ESD), modular VIO generator (VIO 300D; Erbe
Elektromedizin, Tübingen, Germany) was used as surgical system. For the hybrid-knife
ESD, we used a water-jet hybrid knife (Erbe HybridKnife®, Erbe Elektromedizin, Tübingen,
Germany). The VIO mode ENDO CUT Q effect 2-cut duration3-cut interval 1 was used for
circumferential cutting and dissection. The steps of ESD training, marking the perimeter
of a made lesion with cautery, lifting up by submucosal injection around the perimeter
of the lesion, circumferential mucosal incision with electrocautery, and dissection
in the submucosal plane using water jet and knife without hemostasis were done only
in cadaver. The argon plasma coagulation (APC) mode FORCED APC 50 was used for marking
of lesions. Dissection with electrocautery was alternated with submucosal fluid injection
as many times as needed. The areas for resection were defined in an oval shape with
a size of approximately 25 mm in length and 20 mm in width in the antrum and body
of the stomach. The feasibility of ESD on human cadaver is tested.
The study was approved by the Institutional Ethical committee.
Discussion
Upper GI endoscopy is difficult to explain verbally and the skill assessment is very
subjective. However, endoscopy is a relatively invasive procedure carried out on examinee,
which can make practice and teaching difficult for trainees and instructors. The training
in endoscopy has changed along with the change of scopes used from large diameter
short fiber-optic scopes to small diameter long video endoscopes and from diagnostic
to more therapeutic indications. One-to-one training provides constant scrutiny and
feedback but depends on the relation between the mentor and the trainee.[13]
Simulation-based training programs found improved patient outcomes (better procedural
completion rates and a decrease in major complications) in a meta-analysis.[14]
However, simulators currently have limited benefit and useful in early training to
familiarize the scope and its maneuverability. Simulator technology will continue
to evolve and be more useful in advanced training in the future.[15]
Endoscopic training is often unstructured and in the current era of time-restricted
training, requires trainees
Table 1
Comparison of simulator and cadaver models in endoscopic training
|
Teaching Technique
|
Cadaver
|
Simulator
|
|
Score 0-5 (0 is bad and 5 is excellent). Proportion giving <;3/5 [Figure 7]
|
-
|
-
|
|
Visualisation of mucosa and spatial relations
|
80%
|
90%
|
|
Comfort level
|
50%
|
80%
|
|
Apprehension of cadaver
|
Similar to computer/video games
|
|
Basic steps: Tip deflection, push/pull/ torque of scope,
air insufflation and suction
|
80%
|
80%
|
|
Suction of fluid remnant in stomach can be done
|
Amount of air insufflation and pain feedback can be obtained
|
|
Esophageal intubation
|
20%
|
80%
|
|
Difficult due to supine positioning of cadaver
|
Easy
|
|
Negotiating pylorus and manoeuvring D2
|
80%
|
80%
|
|
Retroflexion in stomach
|
80%
|
60%
|
|
Endoscopic injection - positioning, needle in and out, mucosal elevation
|
90%
|
70% [Figures 9] and [10]
|
|
Regular accessories used Submucosal plane identified Realistic tactile feel noted
|
Though feedback is given, submucosal plane not identified
|
|
Endoscopic submucosal dissection - lesion marking, mucosal pre-cutting, inscision
& hemostasis
|
Only in cadaver [Figure 8]
|
NA
|
|
No hemostasis
|
|
90%
|
to acquire basic skills, and rapidly progresses to advance training as soon as possible.
Teaching complex skills like these on patients presents formidable obstacles as the
trainer’s role as an assistant is more limited as patient care is priority.
However, there are no reports of endoscopic training in human cadaver from India.
The current model can be used for training basic steps of endoscopy, needle injection,
tattooing, snare polypectomy, and few steps of ESD. It takes a lot of time to train
fellows, and if endoscopists are trying to maintain productivity, training fellows
may get in the way. Human cadavers give the tactile feedback, routine endoscopic accessories
can be used, and real-time anatomy and tissue can be handled as compared to a simulator.
Human cadavers have liquid stasis in fundus as compared to simulator and help in training
of suction and air/water insufflation buttons.
Competency in therapeutic endoscopy may consist of knowledge, skills, attitude, performance,
patient safety, quality initiatives, and cost consciousness.
Endoscopic techniques and technologies will continue to evolve, and there will be
further dissemination of procedures that most endoscopists are not currently performing.
It is important to keep endoscopy moving forward, as new technologies and techniques
may prove to be safer and more cost-efficient. Simulator training followed by cadaver
training can appropriately integrate simulators and cadavers into the learning curve
and maintain the benefits of both training methodologies.
Conclusions
Simulators help in gaining basic anatomy and provide feedback. Human cadaver can be
used for training therapeutic endoscopy. Diagnostic endoscopy, EI, and ESD can be
performed on the human cadaver. The human cadaver model and simulator can be used
as a bridge in training programs before proceeding to supervised training on patients.
Financial support and sponsorship
Nil.
