J Neurogastroenterol Motil 2024; 30(1): 121-122  https://doi.org/10.5056/jnm23164
Editing Multichannel Intraluminal Impedance-pH Tracings to Reduce Non-reflux-related Esophageal Acidification
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: Combined multichannel intraluminal impedance and pH (MII-pH) monitoring is the gold standard for assessing gastroesophageal reflux (GER) in infants and children, particularly due to the ability to study the intraluminal flow of reflux, independent of pH.1-3 One of the limitations of the MII-pH technology is the requirement of expertise for the analysis and editing of the MII-pH tracings.2,4

Esophageal acidification occurs due to (1) acid reflux (reflux-related esophageal acidification) and (2) feeds that are acidic (non-reflux related esophageal acidification). If not recognized, non-reflux related acidification can incrementally elevate the acid GER index (an important MII-pH metric) above critical threshold levels to signal an abnormal MII-pH study result.

To reduce the possibility of mistaking non-reflux related esophageal acidification as GER, many gastrointestinal motility centers will provide pre-test instructions, to both patients and parents/primary caregivers, to avoid acidic foods and drinks during the MII-pH test, even during feeding when such periods are excluded from analysis. An acidified esophagus can remain acidified even after the last swallow of acidic food or beverage, until subsequent swallowing of bicarbonate-rich saliva or secretion of bicarbonate from submucosal glands.5

Non-reflux-related esophageal acidification can occur in the analyzed tracing despite meal-time exclusion. If the “start meal” button is clicked after the meal has begun (without leaving a note in the diary), esophageal acidification due to feeding/drinking can occur. In Figure A, non-compliance is suggested with the swallow leading to the acidification (black arrow). Elimination of the non-reflux related esophageal acidification from the tracing can be accomplished by generating an artifact (Figure B).

Figure 1. Multichannel intraluminal impedance tracing illustrating pre- (A, B) and post-feeding acidification (C, D). In both instances (whether acidification occurs before or after the feed), artifact markers (B, D) were inserted to eliminate non-reflux-related esophageal acidification.

Also, a similar issue can arise at the end of a meal, if the “meal stop” button is pressed before the esophageal mucosa is completely neutralized (Figure C). Non-GER-related acidification is the time duration from the “stop meal” to the point when chemical clearance is completed (Figure D).

If acidification occurs either prior to or immediately after a meal, the analyst should insert artifact markers to exclude non-reflux-related acidifications to avoid mistaken generation of an abnormal test.

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