Discussing the influence of electrode location in the result of esophageal prolonged pH monitoring

BACKGROUND: There is a large consensus to preserve the distance of 5 cm above the proximal border of the lower esophageal sphincter (PBLES) as appropriate to the location of the electrode of the pH-metry. The main objective of this study is to determine whether placement of the electrode below the recommended location achieves a significant difference in the calculation of the DeMeester score. METHODS: The study was made up of 60 GERD patients and 20 control subjects. They were submitted to esophageal manometry and to pH-metric examination with two pH-metric catheters contained antimony electrodes - the distal was positioned 3 cm above the PBLES, leaving the other 5 cm away from it. RESULTS: LES pressure (LESP) in the GERD group was significantly lower than in the control group (P = 0.005). Normal mean DeMeester score was observed simultaneously in the control group, by both the electrodes, but abnormal DeMeester score was much more expressive when observed by the distal electrode in the GERD group. There were significant differences as for DeMeester score, of patients with GERD from that of the control group and of distal from the proximal electrode in the GERD group. CONCLUSIONS: Acid reflux is directly related to lower levels of LESP. Lower location of the catheter may strongly affect the results of prolonged esophageal pH monitoring in GERD patients.