Before pH measurement, manometry is recommended for precise pH probe positioning.
In this study, doctors from Germany investigated whether the pH probe could be positioned accurately using the pH step-up, the pH difference between the esophagus and the stomach.
|There were no differences in the fraction of the time pH was less than 4.|
|European Journal of Gastroenterology and Hepatology|
The team positioned probes 5 cm above either the manometrically determined upper lower esophageal sphincter margin or the pH step-up in healthy volunteers and reflux patients.
To determine the pH step-up, the pH probe was pulled back from the stomach until a sudden rise to pH greater than 4 occurred.
The team then compared probe position, reflux episodes and the fraction of the time pH was less than 4.
The pH step-up method was evaluated further during proton pump inhibitor therapy and after drug discontinuation.
The doctors found that the pH probe was positioned 2 cm and 1 cm closer to the stomach by the pH step-up method in the volunteers and reflux patients, respectively.
A small increase in upright reflux episodes, but not supine reflux episodes, was registered by the probe positioned by pH step-up.
The team did not find any significant differences in the fraction of the time pH was less than 4 between the 2 probes.
During proton pump inhibitor therapy, no pH step-up was detectable in 3 volunteers and in 1 patient. However, after discontinuing therapy, the pH step-up method immediately yielded clear-cut results.
Dr Christiana Pehl and colleagues concluded, "The pH probe for diagnostic 24-h pH-metry and, with some limitations, also for 24-h pH-metry for therapy control, can be positioned accurately by the pH step-up method".