Review for 10.1186/s12876-021-02089-6 (2022)

Title: Comparison of the innovative endoscopic oropharyngeal airway and the conventional
mouthpiece in elderly outpatients undergoing esophagogastroduodenoscopy under sedation: a
prospective and randomized study
Version: 1 Date: 11 Oct 2021
Reviewer's report:
Thank you for your novel and interesting study.
Please address the following items:
General:
Please edit the manuscript for English grammer and usage.
The commercial name of the device (“Endoscopy Protector”) should not appear in the abstract,
introduction, results or discussion section.  Refer to the novel device using a generic name such
as your term “endoscopic oropharyngeal airway.” The commercial name should appear only
once, in the methods section. There also list the manufacturer’s company name and address.
Methods:
Please add further detail about the randomization method. Randomization was in a 1:1 ratio:
what size were the randomization blocks (how many subjects per block)? Please also state when
subjects were allocated to their study group: was this prior to informed consent, prior to initiation
of sedation, prior to initiation of endoscopy, or at some other time? Was subject allocation to one
of the two study arms concealed prior to consent?  When and to whom was allocation revealed?
Please further clarify how the attending anesthesiologist and observer were blinded to subject
allocation.  Did the anesthethesiologist ever adjust nasal prongs, suction the patient, or in any
other way view the patient’s face and mouth?  Did you perform any prospective assessment of the
adequacy of blinding, for instance by asking the anesthesiologist and observer at the conclusion
of the procedure which study arm they thought the patient was randomized to?
Please state who placed the mouthpiece and endoscopic oropharyngeal airway in the subject’s
mouth, and add details about the technique was used to insert the endoscopic oropharyngeal
airway. When using a standard oral airway it is often inserted sideways, then rotated 90 degrees.
Was a similar method used or required? If not, why not?  How often was there some difficulty
in placing the novel device?  The fact that more propofol was administered prior to endoscopy
in the airway group suggests that placement of the endoscopic oropharyngeal airway may have
been difficult or stimulated the patient in some cases.  Your remarks about this on page 11
are confusing, because you attribute the higher dose of propofol in the airway group to the
gastroscope – but both patient groups underwent passage of a gastroscope. The higher propofol
dose in the airway group also suggests that blinding of the anesthesiologist may not have been
maintained.
Who moved the oxygen tubing to the novel device?  Would this have unblinded the
anethesiologist and observer?
Did all subjects routinely receive 5L/min of supplemental oxygen?  This is a higher dose than
used in most American and European centers. Was this aspect standardized?
Was capnography used?  As you know, hypoventilation during a short procedure may be masked
by supplemental oxygen administration, but acidosis can develop, which is itself a risk factor
for adverse outcomes.
What is the difference between the endoscopic oropharyngeal airway and the “special
oropharyngeal airway,” the “novel mouthpiece” and the “conventional mouthpiece” (page 6)?
Please use the same terms throughout the manuscript.
Page 4: The manuscript says that patients were given glue to drink prior to endoscopy.  Please
clarify.
Results:
Numerical results shown in Tables should not be repeated in the manuscript text.
It seems that 4 subjects were randomized and allocated but their data was then excluded from
analysis.  I am puzzled why this includes 2 subjects “lost to follow-up” since no follow-up visits
are described in the methods section.  Please clarify.  Please also describe the allocation and
sedation outcomes of the 2 who were excluded because endoscopy lasted more than 30 minutes.
Did any subject receive other sedating drugs such as narcotics, ketamine or benzodiazepenes?
What arrhythmias occurred, and did any of these require further evaluation or hospitalization?
Were there any adverse events requiring treatment beyond the duration of the procedure recovery
time?  Were there any deaths?
Discussion:
Please comment on limitations of your study design.  For instance, if capnography was not
used or capnography data were not collected, the possibility of hypoventilation and acidosis
should be discussed.  Limitations of blinding should also be discussed.  You should also discuss
the fact that there was no difference between groups in clinically significant adverse events
requiring management beyond the duration of the sedation, and that your measured outcomes
were surrogate markers or risk factors for clinically significant adverse events.