title: Nonacid reflux episodes reaching the pharynx are important factors associated with cough.
abstract: BACKGROUND
  Gastroesophageal reflux is implicated in the pathogenesis of asthma and chronic cough. To date most studies have focused on acid reflux measured by pH below the upper esophageal sphincter (UES). The aim of this study was to assess the relationship between cough and reflux through the UES into the pharynx.
  
  
  METHODS
  Thirty-seven patients with asthma (19) and chronic cough (18) were recruited from the respiratory clinic. Reflux was monitored using a combined multichannel intraluminal impedance and pH probe by detecting (1) bolus reflux episodes within the esophagus and in the pharynx and (2) acidic reflux episodes within the esophagus and in the pharynx. All acid suppressive therapy was stopped for at least 7 days before the study. Demonstration of cough being linked to reflux was achieved using the symptom association probability (SAP). This was calculated using a 2-minute association window between symptoms and bolus entry into the esophagus. SAP was considered positive if >95%.
  
  
  RESULTS
  A positive SAP for cough was noted in 7/26 patients reporting symptoms on the day of monitoring. Compared with SAP-negative patients, SAP-positive patients had both a greater number [median (interquartile range), 5(2 to 8) vs. 2(0 to 4), P<0.05] and a higher proportion of reflux episodes crossing the UES into the pharynx [25%(14% to 28%) vs. 7% (2% to 14%), P<0.02]. There was no difference in the number of reflux episodes or acid exposure time in the distal esophagus between SAP-positive and SAP-negative patients. Only 1% to 2% of episodes were detected by the pharyngeal pH sensor.
  
  
  CONCLUSIONS
  Impedance detected pharyngeal reflux episodes are important factors in symptom production in cough patients.
authors.affiliation: Department of Medicine, Royal Hospitals, Grosvenor Road, Belfast, UK.
authors.forename: Neil
authors.initials: N
authors.lastname: Patterson
authors.forename: Inder
authors.initials: I
authors.lastname: Mainie
authors.forename: Gerard
authors.initials: G
authors.lastname: Rafferty
authors.forename: Lorcan
authors.initials: L
authors.lastname: McGarvey
authors.forename: Liam
authors.initials: L
authors.lastname: Heaney
authors.forename: Radu
authors.initials: R
authors.lastname: Tutuian
authors.forename: Donald
authors.initials: D
authors.lastname: Castell
authors.forename: Brian T
authors.initials: BT
authors.lastname: Johnston
mesh_terms: D000328:Adult; D000368:Aged; D001249:Asthma / Q000150:complications* / Q000503:physiopathology; D002908:Chronic Disease; D003371:Cough / Q000209:etiology* / Q000503:physiopathology; D004417:Dyspnea / Q000209:etiology / Q000503:physiopathology; D017097:Electric Impedance; D015154:Esophageal Motility Disorders / Q000150:complications* / Q000503:physiopathology; D049631:Esophageal Sphincter, Upper / Q000503:physiopathology*; D050782:Esophageal pH Monitoring; D005764:Gastroesophageal Reflux / Q000150:complications* / Q000503:physiopathology; D006685:Hoarseness / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D008365:Manometry; D008875:Middle Aged; D010614:Pharynx / Q000503:physiopathology*; D012135:Respiratory Sounds / Q000209:etiology / Q000503:physiopathology; D012307:Risk Factors