Title: Feasibility and repeatability of ultrasound-guided surface electroenterography to measure
colonic slow wave motility in healthy adults
Version: 1 Date: 16 Dec 2023
Reviewer's report:
The study investigated the efficacy of body-surface colonic recordings in ten human subjects.
Metrics derived from the frequency domain were compared between pre and postprandial states,
as well as between regions of the colon. Furthermore, a repeatability test was conducted in a
second session for each subject with the same protocols as the first session.  The main finding
was changes in metrics were observed depending on the meal state as well as region of the colon.
Reproducibility of the test was poor. I have made the following comments and suggestions for
the authors to consider in order to improve the manuscript.
Major
Line 100-13 Given the typical frequency of colonic slow wave activity is 2-6 cpm, a 20 min
recording would only contain between 40-120 cycles of events (likely towards the lower end), it
is questionable whether the duration is sufficient in capturing the pre and postprandial changes
of colonic slow waves. Furthermore, it is possible that the anticipation of meal and distention of
the stomach triggers neurohumoral pathways that affect the distal gut, the role of which should
be further discussed.
Line 145 – Would be more appropriate to consider a 2-way test (e.g., 2 way ANOVA) of
each sEEnG metric with meal-state (i.e., pre -and postprandial) as one factor and the region of
recording as the other factor? The problem of doing any one-way measures (e.g., Friendman
test) is it potentially misses the interaction between the two factors.
Line 190 – In addition to LCCC, it might be good to report the actual values of the different
metrics from the segment session to get an idea the magnitude of differences between the two
sessions. Also it could be more meaningful to consider comparing the normalized values of
metrics (e.g., frequency ratio between pre- and postprandial states) instead of the absolute values.
Line 307 – It is a bit unclear how the conclusion of the improved accuracy with ultrasound
guide was derived. Did the investigators specifically compare between guided and unguided
protocols? I would not consider the second session as ‘unguided’ since the anatomical locations
were documented based on ultrasound information in the first session. To be clear, I am not
questioning that improvement is made by ultrasound guided placement, just that it was not tested
in the present study.
Minor
Line 64 - ‘Colonic slow wave muscle activity’ should be just colonic slow wave activity, or the
authors may wish to specify whether it is the pacemaker or the muscle that is the origin of the
surface activity recorded.
Line 135 – A minor issue of taking the area average of power of 2 cpm centered around the
dominant frequency is when the dominant frequency is lower than 3.5 cpm, then the lower band
could go lower than the cutoff of 1.5 cpm. Similar could be applied to dominant frequencies
higher than 8 cpm, although it would be unlikely.
Title: Feasibility and repeatability of ultrasound-guided surface electroenterography to measure
colonic slow wave motility in healthy adults
Version: 1 Date: 16 Dec 2023
Reviewer's report:
The study investigated the efficacy of body-surface colonic recordings in ten human subjects.
Metrics derived from the frequency domain were compared between pre and postprandial states,
as well as between regions of the colon. Furthermore, a repeatability test was conducted in a
second session for each subject with the same protocols as the first session.  The main finding
was changes in metrics were observed depending on the meal state as well as region of the colon.
Reproducibility of the test was poor. I have made the following comments and suggestions for
the authors to consider in order to improve the manuscript.
Major
Line 100-13 Given the typical frequency of colonic slow wave activity is 2-6 cpm, a 20 min
recording would only contain between 40-120 cycles of events (likely towards the lower end), it
is questionable whether the duration is sufficient in capturing the pre and postprandial changes
of colonic slow waves. Furthermore, it is possible that the anticipation of meal and distention of
the stomach triggers neurohumoral pathways that affect the distal gut, the role of which should
be further discussed.
Line 145 – Would be more appropriate to consider a 2-way test (e.g., 2 way ANOVA) of
each sEEnG metric with meal-state (i.e., pre -and postprandial) as one factor and the region of
recording as the other factor? The problem of doing any one-way measures (e.g., Friendman
test) is it potentially misses the interaction between the two factors.
Line 190 – In addition to LCCC, it might be good to report the actual values of the different
metrics from the segment session to get an idea the magnitude of differences between the two
sessions. Also it could be more meaningful to consider comparing the normalized values of
metrics (e.g., frequency ratio between pre- and postprandial states) instead of the absolute values.
Line 307 – It is a bit unclear how the conclusion of the improved accuracy with ultrasound
guide was derived. Did the investigators specifically compare between guided and unguided
protocols? I would not consider the second session as ‘unguided’ since the anatomical locations
were documented based on ultrasound information in the first session. To be clear, I am not
questioning that improvement is made by ultrasound guided placement, just that it was not tested
in the present study.
Minor
Line 64 - ‘Colonic slow wave muscle activity’ should be just colonic slow wave activity, or the
authors may wish to specify whether it is the pacemaker or the muscle that is the origin of the
surface activity recorded.
Line 135 – A minor issue of taking the area average of power of 2 cpm centered around the
dominant frequency is when the dominant frequency is lower than 3.5 cpm, then the lower band
could go lower than the cutoff of 1.5 cpm. Similar could be applied to dominant frequencies
higher than 8 cpm, although it would be unlikely.
Please review this paper.
user
Title: Feasibility and repeatability of ultrasound-guided surface electroenterography to measure
colonic slow wave motility in healthy adults
Version: 1 Date: 16 Dec 2023
Reviewer's report:
The study investigated the efficacy of body-surface colonic recordings in ten human subjects.
Metrics derived from the frequency domain were compared between pre and postprandial states,
as well as between regions of the colon. Furthermore, a repeatability test was conducted in a
second session for each subject with the same protocols as the first session.  The main finding
was changes in metrics were observed depending on the meal state as well as region of the colon.
Reproducibility of the test was poor. I have made the following comments and suggestions for
the authors to consider in order to improve the manuscript.
Major
Line 100-13 Given the typical frequency of colonic slow wave activity is 2-6 cpm, a 20 min
recording would only contain between 40-120 cycles of events (likely towards the lower end), it
is questionable whether the duration is sufficient in capturing the pre and postprandial changes
of colonic slow waves. Furthermore, it is possible that the anticipation of meal and distention of
the stomach triggers neurohumoral pathways that affect the distal gut, the role of which should
be further discussed.
Line 145 – Would be more appropriate to consider a 2-way test (e.g., 2 way ANOVA) of
each sEEnG metric with meal-state (i.e., pre -and postprandial) as one factor and the region of
recording as the other factor? The problem of doing any one-way measures (e.g., Friendman
test) is it potentially misses the interaction between the two factors.
Line 190 – In addition to LCCC, it might be good to report the actual values of the different
metrics from the segment session to get an idea the magnitude of differences between the two
sessions. Also it could be more meaningful to consider comparing the normalized values of
metrics (e.g., frequency ratio between pre- and postprandial states) instead of the absolute values.
Line 307 – It is a bit unclear how the conclusion of the improved accuracy with ultrasound
guide was derived. Did the investigators specifically compare between guided and unguided
protocols? I would not consider the second session as ‘unguided’ since the anatomical locations
were documented based on ultrasound information in the first session. To be clear, I am not
questioning that improvement is made by ultrasound guided placement, just that it was not tested
in the present study.
Minor
Line 64 - ‘Colonic slow wave muscle activity’ should be just colonic slow wave activity, or the
authors may wish to specify whether it is the pacemaker or the muscle that is the origin of the
surface activity recorded.
Line 135 – A minor issue of taking the area average of power of 2 cpm centered around the
dominant frequency is when the dominant frequency is lower than 3.5 cpm, then the lower band
could go lower than the cutoff of 1.5 cpm. Similar could be applied to dominant frequencies
higher than 8 cpm, although it would be unlikely.
assistant