title: Physical and pH properties of gastroesophagopharyngeal refluxate: a 24-hour simultaneous ambulatory impedance and pH monitoring study.
abstract: OBJECTIVE
  Frequency occurrence of nonacidic and nonliquid reflux events in the pharynx has not been systematically studied. The aim of the present study was to characterize the physical (liquid, gas, and mixed gas/liquid) and pH properties of the gastroesophagopharyngeal refluxate.
  
  
  METHODS
  We performed a total of 31 24-h simultaneous ambulatory pharyngoesophageal impedance and pH recordings in 11 GERD patients, 10 patients with reflux-attributed laryngitis, and 10 healthy controls.
  
  
  RESULTS
  On average, the total number of reflux events (all kinds) in the pharynx was less than half of that in the proximal esophagus (18 +/- 4 vs 50 +/- 4, p < 0.01). Most of the pharyngeal reflux events were gas events and were observed in all three studied groups. Prevalence of these gas reflux events ranged between 0 and 74. The number of gas reflux events accompanied by a minor pH drop in laryngitis patients (1 (0-36)) was significantly higher than those in GERD and controls (0 (0-2) and 0 (0-1), respectively, p < 0.05). There was no significant difference in the number of nonacidic gas reflux events among the three groups (GERD: 10 (2-57), laryngitis: 11.5 (0-51), controls: 10.5 (0-27)). Impedance recording identified a total number of 566 events in the pharynx. Of these, a total of 563 events were compatible with gas reflux events, 101 events were accompanied by minor drops in intrapharyngeal pH, whereas 460 events were not accompanied by any pharyngeal pH change.
  
  
  CONCLUSIONS
  Concurrent impedance and pH recordings detect significantly more events qualifying as reflux in the pharynx than pH recordings alone. A substantial majority of these events are gaseous refluxes both with and without minor pH drops. Gas reflux events with weak acidity appear to be more common among patients with reflux-attributed laryngeal lesions compared to GERD patients and controls.
authors.affiliation: MCW Dysphagia Institute, Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Osamu
authors.initials: O
authors.lastname: Kawamura
authors.forename: Muhammad
authors.initials: M
authors.lastname: Aslam
authors.forename: Tanya
authors.initials: T
authors.lastname: Rittmann
authors.forename: Candy
authors.initials: C
authors.lastname: Hofmann
authors.forename: Reza
authors.initials: R
authors.lastname: Shaker
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D015331:Cohort Studies; D017097:Electric Impedance; D005260:Female; D005744:Gastric Acid / Q000378:metabolism*; D005745:Gastric Acidity Determination; D005764:Gastroesophageal Reflux / Q000175:diagnosis / Q000378:metabolism* / Q000503:physiopathology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007827:Laryngitis / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory; D008991:Monitoring, Physiologic; D010614:Pharynx / Q000378:metabolism*; D011336:Probability; D012016:Reference Values; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index