Impedance-pH monitoring helps evaluate esophageal chemical clearance, a response to reflux brought forth by the esophago-salivary reflex, through the post-reflux swallow-induced peristaltic wave (PSPW) index.

Mucosal integrity is determined through mean nocturnal baseline impedance (MNBI) and is considered to be a marker of GERD. The relationship between PSPW index and MNBI is not fully understood. The present study aimed to ascertain this relationship.

Investigators assessed impedance-pH tracings from 230 patients with GERD symptoms. ROC analysis and multivariate regression models were used to determine the association between acid exposure time (AET), total refluxes (TRs), PSPW index, and MNBI. Patients were classified using AET thresholds and symptom-reflux association indexes into the following categories: conclusive and inconclusive GERD, reflux hypersensitivity (RH), and functional heartburn (FH). Pathologic MNBI <2292 Ω was defined based on published outcome studies.

Findings from the study:

• There was a significant direct correlation between PSPW index and MNBI (0.759, p < 0.001).
• According to ROC analysis, PSPW index cut-off value of 53% could best differentiate between normal and pathologic MNBI values (sensitivity 88%, specificity 86.4%).
• As per AET cut-off of 4% or 6%, there was a sensitivity of 80.7% and 46%, and a specificity of 62.5% and 93.2%, respectively.
• A multivariate analysis revealed that AET >4% and PSPW index value <53% or <61% had a significant correlation with pathologic MNBI values.

To conclude, esophageal chemical clearance represents a key defense mechanism against reflux and if it impaired, it serves as a major determinant of reflux-associated damage to the mucosa.

Source: Ribolsi M, Frazzoni M, Cicala M, Savarino E. Association between post-reflux swallow-induced peristaltic wave index and esophageal mucosal integrity in patients with GERD symptoms. Neurogastroenterol Motil. 2022 Mar 3;e14344.