title: Impedance signature of pharyngeal gaseous reflux.
abstract: BACKGROUND
  Pharyngeal impedance changes induced by various pharyngeal reflux events have not been characterized.
  
  
  OBJECTIVE
  To characterize pharyngeal impedance changes induced by participant-perceived belching events.
  
  
  METHODS
  We systematically evaluated pharyngeal impedance and pH changes related to 453 belch events in 11 gastroesophageal reflux disease, 10 reflux attributed-laryngitis patients and 16 controls.
  
  
  RESULTS
  Of 453 belch events, 362 were analyzable. Of these, 72% occurred within 10 s, 93% within 20 s, 99% within 30 s and 100% within 40 s of the time that participants marked a belch event. In 15% impedance changes in the pharynx preceded, in 12% they were simultaneous and in 73% they occurred after the start of the impedance change in the proximal esophagus. Time interval between the two events ranged between 0.4+/-0.03 and 0.7+/-0.1 s. In all, there were three types of belch-induced impedance changes: (a) impedance increase, (b) impedance decrease and (c) multiphasic. Twenty percent of impedance events associated with belching had less than 50% change from baseline, whereas in 51% changes exceeded or were equal to 50%. Among events with a drop in pharyngeal impedance, only two satisfied the criteria for the liquid reflux event.
  
  
  CONCLUSIONS
  Pharyngeal ventilation of gastric gaseous content seems to have a unique impedance signature. During pharyngeal gas reflux events, impedance changes may start before or after proximal esophageal changes. Belching may induce negative pharyngeal changes that do not meet the criteria for liquid reflux. These findings need to be taken into consideration in the analysis of pharyngeal reflux events.
authors.affiliation: Department of Endoscopy and Endoscopic Surgery, Gunma University Hospital, Maebashi, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Kawamura
authors.forename: Shailesh
authors.initials: S
authors.lastname: Bajaj
authors.forename: Muhammad
authors.initials: M
authors.lastname: Aslam
authors.forename: Candy
authors.initials: C
authors.lastname: Hofmann
authors.forename: Tanya
authors.initials: T
authors.lastname: Rittmann
authors.forename: Reza
authors.initials: R
authors.lastname: Shaker
mesh_terms: D000328:Adult; D000368:Aged; D017097:Electric Impedance; D004884:Eructation / Q000209:etiology / Q000503:physiopathology*; D050782:Esophageal pH Monitoring; D004947:Esophagus / Q000503:physiopathology; D005260:Female; D005764:Gastroesophageal Reflux / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D010614:Pharynx / Q000503:physiopathology*; D013997:Time Factors