Kavitt RT, Yuksel ES, Slaughter JC, et al. Laryngoscope. 2013 Jul.
OBJECTIVES: 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.
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.
CONCLUSION: 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.