title: The role of impedance monitoring in patients with extraesophageal symptoms.
abstract: OBJECTIVE
  Ambulatory esophageal impedance monitoring is commonly employed to assess for nonacid reflux in patients with extraesophageal reflux. We aimed to determine if on therapy impedance data can be predicted from off therapy upper endoscopy, manometry, or pH parameters.
  
  
  METHODS
  Prospective Cohort Study.
  
  
  METHODS
  Patients with extraesophageal reflux symptoms and either partial- or nonresponders to twice-daily PPI underwent impedance monitoring on twice-daily PPI, as well as manometry, upper endoscopy, and 48-hour wireless pH monitoring off acid-suppressive medications for 1 week. Percent time pH < 4 and number of reflux episodes were obtained. Multivariable linear regression was used to determine association between the impedance data on therapy and upper endoscopy, manometry, and pH parameters measured off therapy.
  
  
  RESULTS
  Seventy-five patients (77% female, median BMI 29, 38% with hiatal hernia, and 19% with esophagitis) were studied both on and off therapy. Thirty-five percent had abnormal impedance monitoring on therapy and 84% had abnormal pH testing off therapy. There was no significant (P = 0.184) overall correlation between total number of impedance events and the baseline physiologic parameters of hiatal hernia, degree of acid reflux, or manometric findings, with only weak correlation (r = 0.54, P = 0.045) with % time pH < 4 among patients with esophagitis.
  
  
  CONCLUSIONS
  In patients with suspected extraesophageal reflux refractory to PPI therapy, impedance measures on therapy cannot be predicted from traditional baseline esophageal physiologic parameters. We recommend caution regarding over-interpretation of impedance data.
  
  
  METHODS
  2b.
authors.affiliation: Division of Gastroenterology, Hepatology and Nutrition, Vanderbilt University Medical Center, Nashville, Tennessee, U.S.A.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Kavitt
authors.forename: Elif Saritas
authors.initials: ES
authors.lastname: Yuksel
authors.forename: James C
authors.initials: JC
authors.lastname: Slaughter
authors.forename: C Gaelyn
authors.initials: CG
authors.lastname: Garrett
authors.forename: David
authors.initials: D
authors.lastname: Hagaman
authors.forename: Tina
authors.initials: T
authors.lastname: Higginbotham
authors.forename: Michael F
authors.initials: MF
authors.lastname: Vaezi
mesh_terms: D000328:Adult; D016145:Endoscopy, Digestive System; D050782:Esophageal pH Monitoring; D004941:Esophagitis / Q000188:drug therapy; D005260:Female; D005764:Gastroesophageal Reflux / Q000188:drug therapy*; D006551:Hernia, Hiatal / Q000188:drug therapy; D006801:Humans; D008297:Male; D008365:Manometry; D011446:Prospective Studies; D054328:Proton Pump Inhibitors / Q000627:therapeutic use*
chemical_list: D054328:Proton Pump Inhibitors
keywords: GERD; Impedance; refractory reflux