title: Automated impedance-manometry analysis detects esophageal motor dysfunction in patients who have non-obstructive dysphagia with normal manometry.
abstract: BACKGROUND
  Automated integrated analysis of impedance and pressure signals has been reported to identify patients at risk of developing dysphagia post fundoplication. This study aimed to investigate this analysis in the evaluation of patients with non-obstructive dysphagia (NOD) and normal manometry (NOD/NM).
  
  
  METHODS
  Combined impedance-manometry was performed in 42 patients (27F : 15M; 56.2 ± 5.1 years) and compared with that of 24 healthy subjects (8F : 16M; 48.2 ± 2.9 years). Both liquid and viscous boluses were tested. MATLAB-based algorithms defined the median intrabolus pressure (IBP), IBP slope, peak pressure (PP), and timing of bolus flow relative to peak pressure (TNadImp-PP). An index of pressure and flow (PFI) in the distal esophagus was derived from these variables.
  
  
  RESULTS
  Diagnoses based on conventional manometric assessment: diffuse spasm (n = 5), non-specific motor disorders (n = 19), and normal (n = 11). Patients with achalasia (n = 7) were excluded from automated impedance-manometry (AIM) analysis. Only 2/11 (18%) patients with NOD/NM had evidence of flow abnormality on conventional impedance analysis. Several variables derived by integrated impedance-pressure analysis were significantly different in patients as compared with healthy: higher PNadImp (P < 0.01), IBP (P < 0.01) and IBP slope (P < 0.05), and shorter TNadImp_PP (P = 0.01). The PFI of NOD/NM patients was significantly higher than that in healthy (liquid: 6.7 vs 1.2, P = 0.02; viscous: 27.1 vs 5.7, P < 0.001) and 9/11 NOD/NM patients had abnormal PFI. Overall, the addition of AIM analysis provided diagnoses and/or a plausible explanation in 95% (40/42) of patients who presented with NOD.
  
  
  CONCLUSIONS
  Compared with conventional pressure-impedance assessment, integrated analysis is more sensitive in detecting subtle abnormalities in esophageal function in patients with NOD and normal manometry.
authors.affiliation: Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, Adelaide, SA, Australia. quoc.nguyen@health.sa.gov.au
authors.forename: N Q
authors.initials: NQ
authors.lastname: Nguyen
authors.forename: R H
authors.initials: RH
authors.lastname: Holloway
authors.forename: A J
authors.initials: AJ
authors.lastname: Smout
authors.forename: T I
authors.initials: TI
authors.lastname: Omari
mesh_terms: D000465:Algorithms; D001331:Automation; D003680:Deglutition Disorders / Q000175:diagnosis* / Q000503:physiopathology*; D017097:Electric Impedance; D004947:Esophagus / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008365:Manometry / Q000379:methods*; D008875:Middle Aged; D012815:Signal Processing, Computer-Assisted