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, 16 (3), 327-30

How to Interpret Esophageal Impedance pH Monitoring


How to Interpret Esophageal Impedance pH Monitoring

Yu Kyung Cho. J Neurogastroenterol Motil.


Esophageal impedance pH monitoring provides quantitative data on esophageal acid exposure and has the ability to correlate the symptoms with acid exposure events. The nomenclature for the reflux patterns detected in impedance pH monitoring as well as the normal values have been determined. Data interpretation is similar to 24-hour pH monitoring, ie, searching for an increase in the number of reflux episodes, prolonged acid or volume exposure or increased numbers of proximal reflux events. In particular, the key clinical measurements for impedance testing on proton pump inhibitor therapy are the number of acid and non-acid reflux episodes and their relationship with the symptoms using the symptom index or symptom-association probability.

Keywords: Electric impedance; Gastroesophageal reflux; Reference values.

Conflict of interest statement

Conflicts of interest: None.


Figure 1
Figure 1
Esophageal impedance pH recordings showing examples of the 4 types of reflux. (A) Weakly acidic reflux, (B) acid reflux, (C) weakly alkaline reflux and (D) superimposed acid reflux.
Figure 2
Figure 2
Example of acid reflux. (A) Acid duration measured 5 cm above the lower esophageal sphincter. (B) Bolus duration measured 5 cm above the lower esophageal sphincter.

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