title: 24 Versus 48-hour bravo pH monitoring.
abstract: BACKGROUND
  Historical ambulatory pH monitoring systems for the evaluation of gastroesophageal reflux disease have been catheter based and uncomfortable for patients, commonly limiting both their diet and activities. Catheter-based studies have also been reported to underestimate the amount of reflux a patient may have in a normal, routine day. Compared with conventional catheter-based pH monitoring systems, wireless (Bravo) pH monitoring is better tolerated by patients and allows for an increased duration of pH recording. Currently, there is lack of data regarding the optimal duration of wireless studies and concern that day 1 results are not typical of a patient's routine lifestyle, given the effects of sedation. Few studies have evaluated the merits of 24 versus 48-hour wireless pH monitoring.
  
  
  OBJECTIVE
  The aims of this study were (1) to identify differences in reflux parameters between 24 versus 48-hour testing as measured by wireless pH monitoring and (2) to assess the effect of 48-hour studies on the number of reflux episodes and symptom correlation as compared with 24-hour studies.
  
  
  METHODS
  A retrospective chart review of 124 consecutive patients who underwent 48-hour wireless esophageal pH monitoring studies was prepared. All patients underwent esophagogastroduodenoscopy using intravenous conscious sedation before wireless capsule placement. Acid reflux variables (including total reflux time, number of reflux episodes, and total percent time of pH<4) and symptom-association probability (SAP) scores were compared for day 1 versus day 2 versus total.
  
  
  RESULTS
  Forty-eight-hour SAP scores were significantly higher when compared with the first 24 hours for all reported primary symptoms. SAP scores were calculated at 24 and 48 hours, respectively for heartburn (56 vs. 65, P<0.0001), regurgitation (65 vs. 80, P<0.0001), chest pain (59 vs. 78, P=0.0009), and cough (55 vs. 64, P=0.0027). In addition, the percentage of SAP scores >95 was significantly higher for both heartburn and regurgitation (34% vs. 48%, P=0.003 and 38% vs. 62%, P=0.005). As expected, 48-hour testing also captured a significantly higher number of reflux episodes as compared with day 1 results alone (97 vs. 47, P<0.0001). There were no statistical differences noted between the 2 days for total percent time of pH <4.
  
  
  CONCLUSIONS
  Forty-eight-hour wireless (Bravo) pH monitoring strengthens symptom correlation as compared with 24-hour results alone and yields a greater percentage of SAP scores >95 for typical symptoms of gastroesophageal reflux disease. Prolonged recording of patient symptoms and/or sedation effects may account for the better symptom correlation. Although there were no statistical differences seen in this study between 24 and 48-hour studies for total percent time pH <4, 48-hour studies captured significantly more reflux episodes as compared with 24 hours of monitoring alone. These results suggest that patients undergoing wireless pH monitoring should have 48-hour studies performed as a standard of practice.
authors.affiliation: Department of Medicine, Section of Digestive Diseases, Yale Center of Analytical Science, Yale School of Public Health, New Haven, CT, USA. Bani.chander@yale.edu
authors.forename: Bani
authors.initials: B
authors.lastname: Chander
authors.forename: Nicole
authors.initials: N
authors.lastname: Hanley-Williams
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Deng
authors.forename: Anish
authors.initials: A
authors.lastname: Sheth
mesh_terms: D000328:Adult; D000368:Aged; D053704:Capsule Endoscopy / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D016292:Procedural Sedation; D003371:Cough / Q000175:diagnosis; D050782:Esophageal pH Monitoring / Q000009:adverse effects / Q000295:instrumentation; D004945:Esophagoscopy / Q000009:adverse effects / Q000295:instrumentation; D005260:Female; D005764:Gastroesophageal Reflux / Q000175:diagnosis* / Q000503:physiopathology*; D006356:Heartburn / Q000175:diagnosis; D006801:Humans; D057045:Laryngopharyngeal Reflux / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D012189:Retrospective Studies; D013997:Time Factors; D055815:Young Adult