title: Baseline impedance measured during high-resolution esophageal impedance manometry reliably discriminates GERD patients.
abstract: Baseline impedance measured with ambulatory impedance pH monitoring (MII-pH) and a mucosal impedance catheter detects gastroesophageal reflux disease (GERD). However, these tools are limited by cost or patient tolerance. We investigated whether baseline impedance measured during high-resolution impedance manometry (HRIM) distinguishes GERD patients from controls.
  
  
  
  Consecutive patients with clinical HRIM and MII-pH testing were identified. Gastroesophageal reflux disease was defined by esophageal pH <4 for ≥5% of both the supine and total study time, whereas controls had an esophageal pH <4 for ≤3% of the study performed off PPI. Baseline impedance was measured over 15 seconds during the landmark period of HRIM and over three 10 minute intervals during the overnight period of MII-pH.
  
  
  
  Among 29 GERD patients and 26 controls, GERD patients had a mean esophageal acid exposure time of 22.7% compared to 1.2% in controls (P<.0001). Mean baseline impedance during HRIM was lower in GERD (1061 Ω) than controls (2814 Ω) (P<.0001). Baseline mucosal impedance measured during HRIM and MII-pH correlated (r=0.59, P<.0001). High-resolution esophageal manometry baseline impedance had high diagnostic accuracy for GERD, with an area under the curve (AUC) of 0.931 on receiver operating characteristics (ROC) analysis. A HRIM baseline impedance threshold of 1582 Ω had a sensitivity of 86.2% and specificity of 88.5% for GERD, with a positive predictive value of 89.3% and negative predictive value of 85.2%.
  
  
  
  Baseline impedance measured during HRIM can reliably discriminate GERD patients with at least moderate esophageal acid exposure from controls. This diagnostic tool may represent an accurate, cost-effective, and less invasive test for GERD.
authors: Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA.
authors: K
authors: K
authors: Ravi
authors: Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA.
authors: D M
authors: DM
authors: Geno
authors: Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA.
authors: M F
authors: MF
authors: Vela
authors: Department of Gastroenterology and Hepatology, Mayo Clinic, Scottsdale, AZ, USA.
authors: M D
authors: MD
authors: Crowell
authors: Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA.
authors: D A
authors: DA
authors: Katzka
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017097:Electric Impedance; D050782:Esophageal pH Monitoring / Q000379:methods*; D005260:Female; D005764:Gastroesophageal Reflux / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008365:Manometry / Q000379:methods*; D008875:Middle Aged; D012372:ROC Curve; D055815:Young Adult
keywords: GERD; baseline impedance; mucosal impedance