title: Esophageal impedance baseline is age dependent.
abstract: OBJECTIVE
  Esophageal impedance (multichannel intraluminal impedance [MII]) baseline (impedance baseline [IB]) has been recently considered to be related to esophageal integrity. The aim of this study was to analyze the age effect on IB in a large population of pediatric patients.
  
  
  METHODS
  A total of 816 children with symptoms of gastroesophageal reflux and submitted to MII were included. Mean IB was automatically calculated in the different MII channels (Chs) throughout 24-hour tracings by the specific software without removing any episode of increased/decreased IB. Acid and nonacid reflux parameters and age subgroups analysis were performed. Unpaired t test, Spearman rank correlation, polynomial and regression plot, multiple regression analysis, factorial analysis of variance, and the least mean squares method were used for statistical analysis and age-related percentile curves. P < 0.05 was considered as statistically significant.
  
  
  RESULTS
  Mean IB was significantly (P < 0.001) lower in younger compared with older children up to 48 months. The mean increase of IB per month was 2.9 Ω in Ch 1 and 2.3 Ω in Ch 6, but much higher in the first 36 months of life (47.5 Ω in Ch 1 and 29.9 Ω in Ch 6, respectively). From 48 months onward, there was no significant increase of the mean IB (P = 0.73). In the multiple regression analysis, only age and reflux index (but no other reflux parameters) significantly correlated with IB. Distal IB was significantly (P < 0.05) lower in patients with esophagitis and in subjects taking proton pump inhibitors compared with subjects off (any) treatment. Percentiles of IB in proximal and distal Chs were provided according to different age groups.
  
  
  CONCLUSIONS
  IB is significantly lower in infants (especially in the first months of life) compared with older children. Low IB in both proximal and distal esophagus in young infants may be related to anatomical and functional difference other than the presence of esophagitis.
authors.affiliation: *Department of Pediatrics, University of Insubria, Varese, Italy †UZ Brussel, Vrije Universiteit Brussel, Brussels ‡Systems and Modeling Unit, Montefiore Institute, University of Liege, Belgium §University of Naples "Federico II," Naples, Italy ||King Hussein Medical Center, Amman, Jordan.
authors.forename: Silvia
authors.initials: S
authors.lastname: Salvatore
authors.forename: Alessandro
authors.initials: A
authors.lastname: Salvatoni
authors.forename: Marieke
authors.initials: M
authors.lastname: Van Berkel
authors.forename: Kristel
authors.initials: K
authors.lastname: Van Steen
authors.forename: Dario
authors.initials: D
authors.lastname: Unmarino
authors.forename: Abdallah
authors.initials: A
authors.lastname: Ghanma
authors.forename: Bruno
authors.initials: B
authors.lastname: Hauser
authors.forename: Yvan
authors.initials: Y
authors.lastname: Vandenplas
mesh_terms: D000367:Age Factors; D002675:Child, Preschool; D017097:Electric Impedance; D004941:Esophagitis / Q000503:physiopathology*; D004947:Esophagus / Q000503:physiopathology*; D005764:Gastroesophageal Reflux / Q000503:physiopathology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D054328:Proton Pump Inhibitors / Q000627:therapeutic use; D012044:Regression Analysis
chemical_list: D054328:Proton Pump Inhibitors