pH probe positioning for 24-hour pH-metry by manometry or pH step-up.
OBJECTIVE
Before pH measurement, manometry is recommended for precise pH probe positioning. We investigated whether the pH probe could be positioned accurately by the pH difference between the oesophagus and the stomach (pH step-up).


METHODS
Dual-channel 24-h pH-metry with probes positioned 5 cm above either the manometrically determined upper lower oesophageal sphincter margin or the pH step-up was performed 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 four occurred. Probe position, reflux episodes and the fraction of the time pH was less than four were compared using the Wilcoxon test for difference and the Hodges-Lehman estimate inclusive confidence interval for equivalence. The pH step-up method was evaluated further during proton pump inhibitor therapy and after drug discontinuation.


RESULTS
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 in supine reflux episodes was registered by the probe positioned by pH step-up. No significant differences in the fraction of the time pH was less than four were obtained between the two probes. The Hodges-Lehman calculation proved equivalence for both methods of probe positioning for 24-h pH-metry. During proton pump inhibitor therapy, no pH step-up was detectable in three volunteers and in one patient. On the first day after discontinuing therapy, the pH step-up method yielded clear-cut results again.


CONCLUSIONS
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.
Pehl
Christian
C
Department of Gastroenterology, Hepatology and Gastrointestinal Oncology, Academic Teaching Hospital Bogenhausen, Munich, Germany. christian.pehl@extern.lrz-muenchen.de
Boccali
Ilona
I
Hennig
Michael
M
Schepp
Wolfgang
W
D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D000328:Adult; D000368:Aged; D001562:Benzimidazoles / Q000627:therapeutic use; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D005260:Female; D005745:Gastric Acidity Determination / Q000295:instrumentation; D005764:Gastroesophageal Reflux / Q000150:complications / Q000188:drug therapy / Q000378:metabolism*; D006551:Hernia, Hiatal / Q000150:complications; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008365:Manometry / Q000379:methods*; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000295:instrumentation* / Q000379:methods; D009853:Omeprazole / Q000031:analogs & derivatives; D000077402:Pantoprazole; D054328:Proton Pump Inhibitors; D013454:Sulfoxides / Q000627:therapeutic use
D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D001562:Benzimidazoles; D004791:Enzyme Inhibitors; D054328:Proton Pump Inhibitors; D013454:Sulfoxides; D000077402:Pantoprazole; D009853:Omeprazole