Keywords
endosonography - stomach - gastric outlet obstruction
In absence of dedicated fellowship in advanced endoscopy procedures like endoscopic
ultrasound (EUS) in our country, imparting adequate training in these procedures is
a challenge. These advanced procedures can be either trained in a formal way like
a structured fellowship in a dedicated tertiary training center for 6 to 24 months
or informally via endoscopy workshops, which usually include short hands-on experiences.
The hand-on experience can be either performed on models that are prepared using porcine
organs or devoid of animal material or on live pigs or on simulators.[1] However, these short-term learning modules have not been found to be cost-effective
learning procedures.[2] Therefore, many gastroenterologists are self-learning these procedures by watching
online videos and attending live sessions of the endoscopy workshops. However, this
self-learning of endoscopic procedures compromises the patient’s safety, and learning
in the absence of mentor is also suboptimal. Therefore, it is important to learn advanced
endoscopic procedures under expert supervision till one reaches the plateau of the
learning curve. Herein comes the concept of adequate competency and one way of assessing
the same is to quantify the number of procedures that are needed to reach the plateau
of learning curve. Assessing competence is of utmost importance for complex endoscopic
ultrasound (EUS) procedures like EUS-guided gastroenterostomy (EUS-GE) that are associated
with a higher risk of procedural complications.[3]
[4]
[5]
Gastric outlet obstruction (GOO) can have benign or malignant causes. The mainstay
of management in these patients is the relief of obstruction. In the past, surgery
was the only modality for treatment of these patients. However, surgical gastro-jejunostomy
has its own limitations, including prolonged hospital stay, and can only be offered
to surgically fit patients. Advancement in endoscopic therapy has led to the development
of of luminal self-expanding metallic enteric stents. This, in turn, has led to minimally
invasive approach for relieving GOO. Stent migration and occlusion are major limitations
of luminal self-expanding metallic stents (SEMS), and therefore there are increased
efforts to improve the results of endoscopic palliation. With the advent of EUS, newer
treatment approaches are on horizon. Therapeutic EUS-guided interventions like drainage
of pancreatic fluid collections, biliary and pancreatic duct drainage have revolutionized
the results of endotherapy, especially when conventional endoscopic methods fail.[5]
[6]
[7] EUS-GE is a new EUS-guided therapeutic procedure for the management of GOO.
The novel EUS-guided interventions are performed at few highly specialized tertiary
care centers. It is a matter of intense debate on what is the training needed to carry
out these interventions, how to judge for competence, and who can perform these newer
interventions. Lack of guidelines for assessing competency as well as structured training
curriculum for performing such interventions is a major drawback for widespread use
of these complex interventions. Expertise on procedures will also reduce these complications,
and therefore it is critical to perform initial procedures under expert supervision.
This has led to the concept of a learning curve for assessing the competence of the
endoscopist. It is based on the fact that with each new procedure, the time taken
to perform the procedure is more than the ideal time needed, and gradually by doing
more and more procedures, the time needed will start decreasing and reach a plateau,
which would be close to the ideal time.
EUS-GE is a complex and tedious procedure, and development of cautery-enhanced lumen-apposing
metallic fully covered stents (LAMS) (AXIOS stents [Boston Scientific, USA]) has improved
the safety profile of this procedure. The procedure has several variations including
the methods to identify the jejunal loops on EUS like direct puncture, balloon assisted,
and hybrid rendezvous with ultrathin endoscope. Therefore, there is lack of clarity
on the role and ways of assessing the learning curve for EUS-GE.[8] There is currently no data on the number of EUS-GE procedures needed to be conducted
in order to achieve competence. In this news and views, we are discussing two studies
that have assessed the learning curve for EUS-GE.
Tyberg et al aimed to study the learning curve of EUS-GE in 23 patients with GOO (etiology
was malignant in 48% patients) prospectively.[9] The methods to identify the small bowel loop were intraluminal balloon in 57%, hybrid
rendezvous with ultraslim scope in 26%, direct puncture in 13%, and reverse entero-gastrostomy
in the remaining 4% patients. They used cautery-enhanced LAMS in only seven patients.
The technical success was 96% and the clinical success was 95%. The median procedure
time was 88 minutes (45–140 minutes). The periprocedural complication was seen in
one patient (esophageal tear; repaired with clips), while minor post procedure complications
were seen in five patients. The reintervention for stent revision or removal was done
in four patients. The cumulative sum chart analysis showed that the procedure time
of 88 minutes was achieved at the seventh procedure. They also reported that even
after bridging the misdeployed LAMS, the procedure duration further reduced, with
consequent procedures suggesting improvement with experience (nonlinear regression
p < 0.0001). Small sample size, varied techniques used for small bowel access, and
electrocautery-enhanced LAMS being used in a small number of patients were important
limitations of study. The authors concluded that endoscopists achieve a reduction
in procedure time over successive cases, with a learning rate of seven cases.
Jovani et al published a retrospectively analyzed study of 87 consecutive GOO patients
(malignant etiology–88%) who underwent EUS-GE in a tertiary care center in the USA
from 2014–2020.[10] They excluded three patients for altered surgical anatomy and 11 patients for noncautery-enhanced
procedures to maintain homogeneity. They used freehand cautery-enhanced intervention
for the rest of the 73 patients. They injected 500 mL of saline, methylene blue and
contrast with the help of forward view endoscope. Later, under EUS guidance, 19G EUS
needle was used to aspirate blue-tinged fluid to confirm position in jejunum. This
was followed by free hand deployment of LAMS. The technical success was seen in 93%
patients, while clinical success was seen in 97% cases. The mean duration of the procedure
was 36 ± 24 minutes. Immediate adverse events were observed in four patients during
the initial 39 cases (misdeployment–3, conservatively managed hemoperitoneum–1). Late
adverse event was seen in only one patient (stent migration). The authors, on cumulative
sum analysis, found that experience of 25 cases was needed to attain proficiency and
40 cases for mastery. The mean procedural time for patients 25 to 39 and for patients
40 to 73 were significantly lower compared with the first 24 procedures. Retrospective
nature of study, small sample size, and lack of standard technique were important
limitations of this study.
Commentary
The learning curve is a good way to judge competency in any surgical or minimally
invasive procedures like EUS-guided innovative procedures. It is a graphical representation
of the relationship between the learning effort and outcome.[10] There should be two milestones for budding gastroenterology fellows in any endoscopic
intervention–proficiency and mastery. With new interventions, the learning curve should
always be determined, so as to minimize complications and have widespread acceptance
of the new technique. EUS-GE is an attractive option for patients in whom surgery
is contraindicated. However, there is no standardized technique for EUS-GE. It is
difficult to compare the mean time of procedure when the methods used to access a
small bowel loop are different. The expertise of the endoscopist also determines the
procedure time and technical success. Moreover, there is no structured training in
advanced EUS, with no agreed methods of assessing the competency. The above-discussed
studies have reported on the learning curve for EUS-GE at centers with extensive experience
in diagnostic and interventional EUS at a tertiary referral center. With improving
and changing medical education and training, more emphasis is being placed on competency-based
evaluation and promotion, which includes the assessment of important quality indicators.
It is also important to remember that the outcome measures are also determined by
the technological and procedural changes, and therefore the number of procedures required
to achieve competence as well as the procedural time are going to decrease with advancement
in technology and accessories.[11]
To conclude, the learning curve is a vital component for all interventions. It is
high time they should be incorporated in all the guidelines and be put to use for
the welfare of patients. As of now, there is no such guidance for the learning curve
of EUS-GE. The future lies in creating a curriculum for trainees, based on the learning
curves, so as to ensure performance of complex endoscopic procedures independently
with better outcomes and negligible adverse effects.
