Introduction
Peroral endoscopic myotomy (POEM) has recently emerged as a viable minimally invasive
endoscopic approach for the treatment of achalasia and other esophageal motility disorders
[1]
[2]. Pasricha et al [3] initially described the feasibility of an endoscopic submucosal esophageal myotomy
in a pig model in 2007 and the technique was subsequently developed and translated
into clinical practice by Inoue [4] in Japan in 2008. The technique has evolved and expanded around the world but hands-on
training for POEM in the United States is limited and without a structured curriculum
or standardized assessment tool.
There is a significant learning curve for POEM [5]
[6]
[7]
[8]
[9]
[10] and the number of cases required to achieve efficiency and mastery is highly variable
[5]
[6]
[7]
[8]
[9]
[10]
[11]. There are currently no published training guidelines or established quality metrics
for POEM, and POEM training during advanced endoscopy fellowship is limited and varies
significantly across programs. Length of procedure along with decreased adverse events
(AEs) are frequently referenced by studies when defining the learning curve associated
with POEM [5]
[6]
[7]
[8]
[9]
[10]. Furthermore, the learning curve can be shortened with mentorship and proctoring
[5]. Recently there has been a movement towards competency-based medical education rather
than a specific number of procedures to be done during endoscopic training [12]. Training to competency in POEM is critical and POEM trainees must acquire multiple
cognitive and technical skills to achieve proficiency. Kishiki and colleagues have
proposed a curriculum for pretesting and post-testing of trainees learning POEM [11] but a formal skills assessment tool for evaluating individual steps in performing
POEM has not been described.
The aim of this pilot study was to develop a POEM training and skills evaluation tool
to evaluate cognitive and technical skills for performing POEM.
Patients and methods
This pilot study was performed at a tertiary academic medical center in the United
States from May 2018 to November 2018. The study was approved by the Institutional
Review Board (IRB) at the University of Colorado. The aim of this study was to develop
a POEM training and skills evaluation tool.
Trainees included interventional endoscopy fellows with no prior hands-on experience
in endoscopic submucosal dissection (ESD) or POEM, and an interventional endoscopist
(1 year on university faculty after completion of an advanced endoscopy fellowship).
All participants were trained in interventional endoscopy during their 4th year advanced
endoscopy fellowship. As part of their advanced endoscopy fellowship, each trainee
had performed complex polypectomy, endoscopic mucosal resection, luminal stenting,
> 250 endoscopic ultrasound cases and > 300 endoscopic retrograde cholangiopancreatographies
(ERCPs). Before the study, trainees had listened to lectures on POEM and ESD as part
of their curriculum and attended endoscopy conferences where third space endoscopy
(TSE) concepts and techniques were discussed by senior experienced endoscopists. All
trainees had observed (but not performed) ESD and POEM cases during their fellowship,
and the faculty endoscopist who had completed his advanced endoscopy fellowship 1
year prior to the study had observed ESD cases performed by Japanese experts and performed
< 25 ESD cases.
The training protocol included performing POEM initially on explant porcine models
followed by live human cases, proctored by a single endoscopist (MSW) experienced
(> 150 POEM procedures) in POEM. Skills required for performing POEM were divided
into two groups: (1) cognitive skills and (2) technical skills ([Table 1]).
Table 1
Cognitive and technical skills for POEM.
|
Cognitive skills
|
Technical skills
|
|
1. Diagnostic endoscopic evaluation of GE junction and stomach
|
1. Submucosal entry
|
|
2. Appropriate site selection for mucosal incision
|
2. Submucosal tunneling
|
|
3. Identification of esophageal wall layers
|
3. Performance of myotomy
|
|
4. Identification of planes and orientation during submucosal tunneling
|
4. Management of bleeding (hemostasis)
|
|
5. Identification of anatomical planes and structures at GE junction and cardia
|
5. Management of mucosal injury or perforation
|
|
6. Identification of circular and longitudinal muscle planes
|
6. Incision closure
|
POEM, per-oral endoscopic myotomy; GE, gastroesophageal.
Cognitive skills included: (1) diagnostic endoscopic evaluation of the gastroesophageal
(GE) junction and stomach; (2) appropriate site selection for mucosal incision; (3) identification
of esophageal wall layers; (4) identification of planes and orientation during submucosal
tunneling; (5) identification of anatomical planes and structures at GE junction and
cardia; and (6) identification of circular and longitudinal muscle planes. Technical
skills included: (1) entry of the endoscope into the submucosal space; (2) submucosal
tunneling; (3) performance of myotomy; (4) management of bleeding; (5) managing of
mucosal injury or perforation; and (6) incision closure.
Trainees were graded for each of the cognitive and technical skills on a 5-point scale
as follows: 1 = trainer had to take over, 2 = trainer provided technical assistance,
but trainee was able to complete, 3 = trainer provided substantial verbal guidance,
4 = trainer provided minimal verbal guidance, and 5 = trainee performed completely
independently (Supplemental table).
Definitions
Acceptable passing level for each skill was considered at skill level ≥ 4 for that
skill. AEs were recorded per published American Society for Gastrointestinal Endoscopy
criteria [13].
Ex-vivo POEM procedures
All ex-vivo training was performed in explant porcine models comprising of esophagus,
stomach and duodenum assembled on a training tray. Technical steps of POEM were as
described below for human POEM cases.
Human POEM procedures
All patients had pre-procedure diagnostic upper endoscopy, barium esophagram and high-resolution
esophageal manometry, to confirm the diagnosis and rule out alternate and coexisting
conditions. Patients were asked to stay on a liquid diet for 2 days before the procedure
to allow adequate esophageal clearance for visualization during POEM and to minimize
risk of AEs.
POEM was performed in the supine position in the endoscopy unit under general anesthesia
with endotracheal intubation. Antibiotics were administered peri-procedurally, typically
a semi-synthetic penicillin with beta-lactamase inhibitor (ampicillin-sulbactam),
or a fluoroquinolone and metronidazole (if penicillin allergy). Technical steps of
POEM were as previously described [4]
[14]. A posterior submucosal tunnel with a posterior myotomy in the 5 o’clock position
was performed with the T-type Hybrid knife (ERBE USA, Marietta, GA). Bleeding during
the procedure was treated with the dissection knife and/or Coagrasper (Olympus America,
Center Valley, Pennsylvania, United States). The mucosal incision was closed with
endoscopic clips (Quick Clip Pro, Olympus America, Center Valley, Pennsylvania, United
States or Resolution 360 clips, Boston Scientific, Marlborough, Massachusetts, United
States).
All patients were admitted for overnight observation and an esophagram was obtained
the following morning to exclude leak after POEM. Patients were discharged on a liquid
diet and advanced to soft foods in 1 week. Oral antibiotics were continued for 7 days.
Patients were seen for clinic follow-up and surveillance upper endoscopy.
Results
Trainees completed a total of 18 procedures (8 cases on animal explant models and
10 human cases) and were evaluated by one experienced interventional endoscopist experienced
in POEM. Mean age of patients was 54.1 years (range 25 – 68 years) and 50 % were male.
Indications for POEM included achalasia type 1 (10 %), type 2 (50 %), type 3 (20 %)
and esophago-gastric junction outflow obstruction (EGJOO) (20 %). Mean submucosal
tunnel length was 14 cm (range 12 – 17) and mean myotomy length was 11.8 cm (range
8 – 16). Mean Eckardt score was 6.9 (range 4 – 10) on presentation and decreased to
mean score 0.88 (range 0 – 2) after POEM. No AEs were seen after POEM. One patient
with EGJOO had persistent hiccups after POEM but had significant improvement in Eckardt
score to 1 (with no dysphagia).
Cognitive skills assessment
All trainees were able to perform diagnostic endoscopic evaluation of the GE junction
and stomach with a score of ≥ 4 on their first porcine and first human procedure.
All trainees were able to select an appropriate site for mucosal incision with a score
of ≥ 4 on their first porcine and third human POEM case. Trainees required a mean
of 1.67 procedures (range 1 – 3) in porcine models and 1 human POEM procedure to achieve
a score of ≥ 4 for identification of esophageal wall layers. Trainees required a mean
of 1.67 procedures (range 1 – 3) in porcine models and three human POEM procedures
to achieve a score of ≥ 4 for identification of planes and orientation during submucosal
tunneling, and for identification of anatomical planes and structures at the GE junction
and cardia. Trainees required a mean of two procedures (range 1 – 3) in porcine models
and one human POEM procedure to achieve a score of ≥ 4 for identification of circular
and longitudinal muscle planes.
Technical skills assessment
Trainees achieved a score of ≥ 4 at a mean of 2.67 porcine procedures (range 2 – 3)
and eight human procedures for submucosal entry, and also for submucosal tunneling,
suggesting that these two steps were the most challenging steps. Myotomy was also
one of the more challenging steps of the procedure. Trainees required a mean of two
procedures (range 1 – 3) in porcine models and seven human procedures to achieve a
score of ≥ 4 for myotomy. Management of bleeding could only be assessed in human cases
and score ≥ 4 was achieved at the fourth human case where bleeding was encountered.
There were no mucosal perforations in either porcine or human cases in this study.
All trainees achieved a score ≥ 4 for mucosal incision closure with their first procedure
in both porcine and human cases. Esophagram obtained the day after human POEM confirmed
no leak in all human POEM cases.
Cognitive skills were acquired early in training with scores of ≥ 4 achieved by ≤ 3
cases. Technical skills required more cases and direction with scores ≥ 4 in technical
skills achieved by three porcine and eight human cases. Entry of the endoscope into
the submucosal space and submucosal tunneling were the most challenging steps followed
by myotomy ([Fig. 1]).
Fig. 1 Skills assessment during a submucosal entry, b submucosal tunneling, and c myotomy during human POEM procedures.
Discussion
TSE including ESD and POEM is a new addition to the endoscopic spectrum. Training
in these newer procedures such as POEM requires additional skills with a steep and
variable learning curve [5]
[6]
[7]
[8]
[9]
[10]. While there are advanced endoscopy training programs and established curricula
for ERCP and EUS [15]
[16]
[17] there is currently no standard curriculum for training in POEM. A proposed strategy
for training in these newer advanced endoscopic procedures such as ESD or POEM involves
observation of live procedures performed by experts, and then performing initial procedures
on animal models, followed by first human cases proctored by an experienced endoscopist
proficient in that specific procedure such as POEM [18]. However, it should be noted that these suggestions for training are opinions based
on individual endoscopist experiences and not validated in studies evaluating POEM
skills.
With the move to competency-based endoscopy training, evaluation of skills required
for performing POEM is crucial. We have created a POEM training and skills evaluation
tool and introduce it in this pilot study. The steps involved in the POEM procedure
were broken down into cognitive and technical skills and each skill was graded by
the proctoring endoscopist.
The technical challenge in entering the human submucosal space may be explained due
to limited submucosal dissection performed by the trainee due to concern for muscle
perforation after mucosal incision, hesitation by the trainee endoscopist in extending
the mucosotomy for entry, and management of mucosal and submucosal bleeding during
entry in human patients. Similarly, submucosal tunneling and myotomy were technically
challenging as well, likely due to difficulty in learning submucosal dissection while
preserving the overlying mucosa, management of intervening blood vessels during tunneling,
and concern for injury to deeper extra-esophageal structures during muscle incision.
The highlights of our study include stepwise evaluation of the entire POEM procedure
by deconstructing it into assessible individual cognitive and technical components.
This type of mentored evaluation and grading with a standardized tool may allow formal
training to achieve competence. This tool can be used by trainers to evaluate trainees
for competency in the various steps of the POEM procedure and will be essential to
institutions establishing their TSE programs.
We also acknowledge the limitations of our study. The main limitation is that the
study was performed at a single institution with a small number of trainees, limited
number of procedures, and with a single instructor. Hence our results are likely not
generalizable to all trainees and trainers, across different sites and experience
levels. Second, other cognitive aspects were not evaluated such as knowledge of accessories/knives,
electrosurgery settings, and injection solutions, often considered pre-requisites
for POEM training. Third, management of AEs was not adequately assessed in this small
study because overall AEs are rare and because bleeding could only be assessed in
human cases. Similarly, management of mucosal perforations was not assessed. In addition,
human cases did not include difficult anatomy such as sigmoid esophagus/end-stage
achalasia. Thus, results from this study may not be applicable to all POEM scenarios,
demonstrating potential selection bias. However, we believe this study introduces
the important concept of training for POEM to competency, with objective assessment
of every step in the procedure. Finally, we accept that the small number of trainees
and procedures in this pilot study makes assessing competency difficult, but it should
be emphasized that the goal of this study was to introduce a POEM training and skills
evaluation tool, rather than setting or defining competency standards. We hope that
this tool will lay the groundwork for future studies to assess POEM training and competency.
Conclusion
This pilot study introduces a POEM training and skills evaluation tool. Our study
shows that submucosal entry, tunneling, and myotomy were the most challenging to learn
while cognitive skills were learned early in training. Evaluation of POEM procedures
performed by more trainees at multiple sites will be necessary to further validate
the utility of this tool.
Supplementary Table
POEM training and skills evaluation tool.
|
Skill
|
|
Grading
|
|
(1) Trainer had to take over
|
(2) Trainer had to provide technical assistance, but trainee able to complete
|
(3) Trainer had to provide substantial verbal guidance
|
(4) Trainer provided minimal verbal guidance
|
(5) Trainee performed completely independently
|
|
1. Diagnostic endoscopic evaluation of GE junction and stomach
|
|
|
|
|
|
|
2. Appropriate site selection for mucosal incision
|
|
|
|
|
|
|
3. Submucosal entry
|
|
|
|
|
|
|
4. Submucosal tunneling
|
|
|
|
|
|
|
5. Identification of esophageal wall layers
|
|
|
|
|
|
|
6. Identification of planes and orientation during submucosal tunneling
|
|
|
|
|
|
|
7. Identification of anatomical planes and structures at GE junction and cardia
|
|
|
|
|
|
|
8. Identification of circular and longitudinal muscle planes
|
|
|
|
|
|
|
9. Performance of myotomy
|
|
|
|
|
|
|
10. Management of bleeding
|
|
|
|
|
|
|
11. Management of mucosal injury or perforation
|
|
|
|
|
|
|
12. Performance of incision closure at end of procedure
|
|
|
|
|
|
