J Neurogastroenterol Motil 2024; 30(1): 119-120  https://doi.org/10.5056/jnm23163
Tagging an Air Swallow From the Bottom→Up Is More Efficient Than From the Top→Down
Frederick W Woodley1,2,3
1Center for Neurogastroenterology and Motility Disorders, Nationwide Children’s Hospital, Columbus, OH, USA; 2Division of Gastroenterology, Hepatology, and Nutrition, Nationwide Children’s Hospital, Columbus, OH, USA; and 3Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, USA
Published online: January 30, 2024
© The Korean Society of Neurogastroenterology and Motility. All rights reserved.

cc This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

TO THE EDITOR: Gastroesophageal reflux (GER) is widely assessed using some platform of combined multichannel intraluminal impedance with pH monitoring (MII-pH). Typically, GER (the intended use of the MII-pH software) are tagged by pressing and holding the control button and then left clicking the mouse to the left of the intended event in Z6, to the left of the event in Z1 and then to the right of the event in Z6.1 The “lollipops” are then pulled to the left or to the right, such that 50% of baseline is reached, at the start of bolus entry and at the point of bolus exit, in each channel in which the reflux bolus has ascended. In this manner, a “pyramid” shape is typically formed (Figure A).

Figure 1. Tagging air swallows. (A) The above figure depicts a gastroesophageal reflux (a) and an air swallow (b). (B) The images above depict an air swallow (tagged as a swallow [a]) that is transitioned to a “reflux” event when 4 channels are marked from the top→down (b). (C) The images above show that when the air swallow is marked from the bottom→up, only three channels need to be marked for the event to be transitioned from a “swallow” (a) to a “reflux” (b). The black solid arrows indicate the direction of intraluminal flow; the dashed black arrows indicate the direction in which the lollipop is pulled.

It was recently reported that MII software can be used to tag esophageal air events (EAE) like air swallows, gastric belches and supragastric belches.2,3 By flanking the event in a fashion similar to that used for GER, the EAEs can be tagged to appear as a “reflux” event. Subsequently, the tagged events can be assessed for their possible temporal association with symptoms.

Using the MMS/Laborie system (Enschede, the Netherlands), I have found that tagged events need not be marked in all 6 channels in order to be converted from a “swallow” to a “reflux.” This detail is important because EAEs, which are always tagged in separate copies of a tracing so as to access each EAE type individually,2,3 are often numerous and therefore time-consuming to tag.

I have also discovered that there is a difference depending upon whether I begin to process the event from the top→down or from the bottom→up. If I start from top (Z1) and moves down, 4 channels will typically need to be marked in order for the designation to switch from “unknown” or “swallow” to “reflux” (Figure B). However, if I start from the bottom (Z6) and move up, only 3 channels will need to be marked (Figure C). On rare occasion, holding the control button and right clicking the bottom left (Z6), top left (Z1) and then the bottom right (as described above), the “reflux” designation occurs immediately.

Because there are presently (to my knowledge) no commercially available MII systems that permit the autoscan and tagging of air swallows, manually marking events from the bottom→up appears to be the most efficient approach.


The author wishes to thank Dr Cheryl Gariepy for her review.

Financial support


Conflicts of interest


  1. Woodley FW. Missing the distal-most [Z6] impedance channel? The study can be salvaged!. J Neurogastroenterol Motil 2022;28:159-160.
    Pubmed KoreaMed CrossRef
  2. Woodley FW, Ciciora SL, Vaz K, Williams K, Di Lorenzo C, Jadcherla S. Novel use of impedance technology shows that esophageal air events can be temporally associated with gastroesophageal reflux disease-like symptoms. J Pediatr Gastroenterol Nutr 2020;70:e7-e11.
    Pubmed CrossRef
  3. Woodley FW, Williams K, Di Lorenzo C, Michel HK. Significant temporal association of esophageal air events (supragastric belches, air swallows, and gastric belches) with hiccups: a case study in an adolescent. JPGN Rep 2022;3:e209.
    Pubmed KoreaMed CrossRef

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