title: Ambulatory pH: monitoring with a wireless system.
abstract: BACKGROUND
  Currently, pH monitoring is the gold standard for assessing esophageal acid exposure in patients with gastroesophageal reflux disease (GERD). The shortcomings of 24-h pH-monitoring wires led to the development of a 48-h, catheter-free pH measurement system using the telemetry technique with the BRAVO capsule. This prospective study aimed to compare conventional 24-h pH monitoring with the BRAVO catheter-free pH-monitoring system in patients with GERD, patients after antireflux surgery, and a healthy control group.
  
  
  METHODS
  A sample of 133 participants were enrolled in the current trial and divided into three subgroups. Group 1 consisted of 10 healthy volunteers. Group 2 consisted of 123 patients with symptomatic gastroesophageal reflux and endoscopic signs of esophagitis. Group 3 consisted of 43 GERD patients (extracted from group 2) who underwent a laparoscopic 360 degree "floppy" Nissen fundoplication. All the patients underwent both conventional 24-h pH monitoring and BRAVO catheter-free pH monitoring. The data for both methods were recorded and compared in line with the different patient groups regarding their validity and reliability. Additionally, all the patients were interviewed with a standardized questionnaire concerning their subjective perception of the two different methods.
  
  
  RESULTS
  Both the 24-h pH monitoring and the 48-h BRAVO catheter-free pH monitoring could be successfully performed for all the patients. During measurement, 122 of the patients (92%) continued working or performing daily activities. A significant difference could not be found regarding objective outcome between the two measurement methods in the three patient groups. The two methods showed comparable results in terms of data and measurement reliability. The validity also was comparable, with no significant differences within the groups. Concerning the patients' subjective estimation of the two methods, the patients reported reduced regular activities and a higher level of discomfort during measurement with the conventional 24-h pH-monitoring system (p < 0.001 and p< 0.0001, respectively).
  
  
  CONCLUSIONS
  Both conventional 24-h pH monitoring and the 48-h catheter-free pH monitoring are valid and reliable recording devices for measuring esophageal acid exposure. However, from the patients' point of view, the BRAVO capsule affords less discomfort in the throat and allows more normal daily activities.
authors.affiliation: Department of General, Visceral, and Transplant Surgery, University Hospital of Tübingen, Hoppe-Seyler-Strasse 3, 72076, Tübingen, Germany. joachim.schneider@med.uni-tuebingen.de
authors.forename: J H
authors.initials: JH
authors.lastname: Schneider
authors.forename: K M
authors.initials: KM
authors.lastname: Kramer
authors.forename: A
authors.initials: A
authors.lastname: Königsrainer
authors.forename: F A
authors.initials: FA
authors.lastname: Granderath
mesh_terms: D000328:Adult; D000368:Aged; D004867:Equipment Design; D004947:Esophagus / Q000378:metabolism; D005260:Female; D018662:Fundoplication; D005744:Gastric Acid / Q000378:metabolism; D005764:Gastroesophageal Reflux / Q000175:diagnosis* / Q000378:metabolism / Q000601:surgery; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000295:instrumentation* / Q000379:methods; D017060:Patient Satisfaction; D011446:Prospective Studies; D015203:Reproducibility of Results; D013686:Telemetry / Q000295:instrumentation* / Q000379:methods