title: An impedance-manometry based method for non-radiological detection of pharyngeal postswallow residue.
abstract: BACKGROUND
  Postswallow residue is indicative of impaired pharyngeal bolus clearance. The integrated nadir impedance to impedance ratio (iZn/Z) is a novel functional variable that can be derived using automated impedance manometry (AIM). In this study, the postswallow pharyngeal iZn/Z was evaluated as a potential correlated postswallow residue and therefore predictor of ineffective swallowing.
  
  
  METHODS
  Optimal iZn/Z criteria were determine using a database of 50 randomly selected bolus swallows recorded with impedance, manometry, and videofluoroscopy. The iZn/Z was derived for a region of interest (ROI), spanning the mid-point of the pharyngeal stripping wave to the upper esophageal sphincter proximal margin, and from 0.25 to 1.25 s after the peak of the pharyngeal stripping wave. Videofluorscopy was scored by four experts using a six-point bolus residue scale (BRS) score. Optimized criteria for iZn/Z were then applied to a much larger database of 225 swallows scored for residue by one expert observer.
  
  
  RESULTS
  Among individual database, swallows iZn/Z was significantly correlated with average expert BRS score (r = 0.748, P < 0.0001). An iZn/Z of ≥ 500 was optimally predictive of swallows with residue defined by a BRS score of 4 or more. Within the larger cohort, iZn/Z was higher in dysphagia patient swallows compared with controls [2 (1, 4) vs 1 (1, 3), P < 0.005] and swallows with an iZn/Z ≥ 500 had higher bolus residue scores [4 (1, 6) vs 2 (1, 4), P < 0.001].
  
  
  CONCLUSIONS
  The AIM derived iZn/Z is an easily determined objective non-radiological marker of clinically relevant postswallow residue and therefore has potential diagnostic relevance as a predictor of ineffective swallowing.
authors.affiliation: Gastroenterology Unit, Child, Youth & Women's Health Service, North Adelaide, SA, Australia. taher.omari@adelaide.edu.au
authors.forename: T I
authors.initials: TI
authors.lastname: Omari
authors.forename: E
authors.initials: E
authors.lastname: Dejaeger
authors.forename: J
authors.initials: J
authors.lastname: Tack
authors.forename: D
authors.initials: D
authors.lastname: Vanbeckevoort
authors.forename: N
authors.initials: N
authors.lastname: Rommel
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003679:Deglutition / Q000502:physiology*; D003680:Deglutition Disorders / Q000175:diagnosis*; D017097:Electric Impedance; D004947:Esophagus / Q000503:physiopathology; D005260:Female; D005762:Gastroenterology / Q000379:methods*; D006801:Humans; D008297:Male; D008365:Manometry / Q000379:methods*; D008875:Middle Aged; D010614:Pharynx / Q000503:physiopathology; D055815:Young Adult