Lower oesophageal sphincter identification for gastro-oesophageal reflux monitoring: The step-up method revisited with use of basal impedance.

BACKGROUND

Oesophageal manometry is the gold standard for accurate positioning of multichannel intraluminal impedance pH (MII-pH) monitoring. The pH step-up method is not as accurate as oesophageal manometry and needs patients to be off proton pump inhibitor (PPI) therapy.

OBJECTIVE

This study aimed to evaluate the feasibility of the impedance step-up method for lower oesophageal sphincter (LOS) localisation.

METHODS

A total of 100 patients who underwent 24-hour MII-pH monitoring were enrolled. High-resolution manometry (HRM) was performed before MII-pH monitoring in order to locate the LOS by a different operator. The impedance step-up was defined as an increase of ≥50% with respect to gastric baseline. Lin's concordance correlation coefficient ( ) with 95% Bland-Altman limits of agreement (LOA) and Spearman's rho correlation coefficient were used when appropriate.

RESULTS

The median impedance step-up was on average 0.8 cm caudal to the manometric upper border of the LOS. Agreement between two step-up impedance performances and inter-observer agreement were excellent (  = 0.98 and 0.95), although the LOA ranges were wide (-2.4 to 4.0 cm). Impedance step-up performances were similar between patients off and on PPI.

CONCLUSIONS

We have described an alternative new method for pH impedance probe positioning using impedance step-up. Although less accurate than HRM in locating the LOS, it has excellent intra- and inter-observer agreement.