title: Efficacy of esophageal impedance/pH monitoring in patients with refractory gastroesophageal reflux disease, on and off therapy.
abstract: OBJECTIVE
  Intraluminal impedance monitoring has given new dimensions to the diagnosis of reflux disease. However, there is no defined algorithm for evaluating refractory reflux symptoms. We studied whether combined impedance/pH monitoring in patients on therapy can predict acid reflux in patients off therapy and whether testing should be carried out when patients are on or off therapy.
  
  
  METHODS
  Thirty-nine adults (mean age, 50 years; 24 female) with refractory reflux symptoms were evaluated by impedance/pH monitoring while on therapy, followed by wireless pH monitoring while off therapy. Non-acid reflux events in patients on therapy were correlated with acid reflux parameters studied off therapy. In addition, the likelihood of test abnormalities on and off therapy was determined.
  
  
  RESULTS
  In 25 of 39 patients (64%) on therapy, impedance testing was normal, with a median of 69 events (interquartile, 63.0-78.0). The percentage of time at pH <4 was within the normal range for all patients who were on therapy. The pH test results were abnormal in 28 of 39 patients (72%) when studied off therapy. Ninety-three of patients with abnormal impedance on therapy also had abnormal acid reflux off therapy. When both groups were off therapy, the patients with abnormal impedance parameters on therapy had significantly higher median (interquartile) 2-day baseline levels of esophageal acid exposure (8.7%, 6.9%-12.5%), compared with those of patients with normal impedance parameters while on therapy (6.0%, 2.8%-9.4%; P = .026).
  
  
  CONCLUSIONS
  Abnormal impedance in patients on therapy predicts acid reflux in patients off therapy. In patients with refractory reflux, combined impedance/pH monitoring might provide the single best strategy for evaluation of reflux symptoms.
authors.affiliation: Department of Internal Medicine, Voice Center, Vanderbilt University Medical Center, Nashville, Tennessee 37232-5280, USA.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Pritchett
authors.forename: Muhammad
authors.initials: M
authors.lastname: Aslam
authors.forename: James C
authors.initials: JC
authors.lastname: Slaughter
authors.forename: Reid M
authors.initials: RM
authors.lastname: Ness
authors.forename: C Gaelyn
authors.initials: CG
authors.lastname: Garrett
authors.forename: Michael F
authors.initials: MF
authors.lastname: Vaezi
mesh_terms: D000328:Adult; D016903:Drug Monitoring; D017097:Electric Impedance; D050782:Esophageal pH Monitoring; D004947:Esophagus / Q000473:pathology*; D005260:Female; D005764:Gastroesophageal Reflux / Q000188:drug therapy / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D054328:Proton Pump Inhibitors / Q000627:therapeutic use*
chemical_list: D054328:Proton Pump Inhibitors