title: Esophageal distension during bolus transport: can it be detected by intraluminal impedance recordings?
abstract: BACKGROUND
  Esophageal multiple intraluminal impedance (MII) measurement has been used to detect gastro-esophageal reflux and bolus transport. It is not clear if MII can detect changes in luminal cross sectional area (CSA) during bolus transport. Intraluminal ultrasound (US) images, MII, and high resolution manometry (HRM) were recorded simultaneously to determine temporal relationship between CSA and impedance during esophageal bolus transport and to define the relationship between peak distension and nadir impedance.
  
  
  METHODS
  Studies were conducted in five healthy subjects. MII, HRM, and US images were recorded 6 cm above LES. Esophageal distensions were studied during swallows and injections of 0.5 N saline bolus into the esophagus.
  
  
  RESULTS
  Temporal change in esophageal CSA correlates with changes in impedance (r-value: mean ± SD = -0.80 ± 0.08, range: -0.94 to -0.66). Drop in impedance during distension occurs as a two-step process; initial large drop associated with onset of CSA increase, followed by a small drop during which majority of the CSA increase occurs. Peak CSA and nadir impedance occur within 1 s of each other. Increase in swallow and injection volumes increased the CSA, had no effect on large drop but increased the small drop amplitude. We observed a significant correlation between peak CSA and nadir impedance (r = -0.90, p < 0.001) and a better correlation between peak CSA and inverse impedance (r = 0.94, p < 0.001).
  
  
  CONCLUSIONS
  Further studies are needed to confirm that intraluminal impedance recordings may be used to measure luminal CSA during esophageal bolus transport.
authors.affiliation: Department of Medicine, Division of Gastroenterology, San Diego VA Health Care System & University of California, San Diego, CA, USA; Departments of Internal Medicine, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: J H
authors.initials: JH
authors.lastname: Kim
authors.forename: R K
authors.initials: RK
authors.lastname: Mittal
authors.forename: N
authors.initials: N
authors.lastname: Patel
authors.forename: M
authors.initials: M
authors.lastname: Ledgerwood
authors.forename: V
authors.initials: V
authors.lastname: Bhargava
mesh_terms: D000328:Adult; D003679:Deglutition / Q000502:physiology*; D017097:Electric Impedance; D004947:Esophagus / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010528:Peristalsis / Q000502:physiology*
keywords: esophageal cross-sectional area; esophageal distension; esophageal peristalsis; multiple intra luminal esophageal impedance