title: Intestinal gas content and distribution in health and in patients with functional gut symptoms.
abstract: BACKGROUND
  The precise relation of intestinal gas to symptoms, particularly abdominal bloating and distension remains incompletely elucidated. Our aim was to define the normal values of intestinal gas volume and distribution and to identify abnormalities in relation to functional-type symptoms.
  
  
  METHODS
  Abdominal computed tomography scans were evaluated in healthy subjects (n = 37) and in patients in three conditions: basal (when they were feeling well; n = 88), during an episode of abdominal distension (n = 82) and after a challenge diet (n = 24). Intestinal gas content and distribution were measured by an original analysis program. Identification of patients outside the normal range was performed by machine learning techniques (one-class classifier). Results are expressed as median (IQR) or mean ± SE, as appropriate.
  
  
  RESULTS
  In healthy subjects the gut contained 95 (71, 141) mL gas distributed along the entire lumen. No differences were detected between patients studied under asymptomatic basal conditions and healthy subjects. However, either during a spontaneous bloating episode or once challenged with a flatulogenic diet, luminal gas was found to be increased and/or abnormally distributed in about one-fourth of the patients. These patients detected outside the normal range by the classifier exhibited a significantly greater number of abnormal features than those within the normal range (3.7 ± 0.4 vs 0.4 ± 0.1; p < 0.001).
  
  
  CONCLUSIONS
  The analysis of a large cohort of subjects using original techniques provides unique and heretofore unavailable information on the volume and distribution of intestinal gas in normal conditions and in relation to functional gastrointestinal symptoms.
authors.affiliation: Digestive System Research Unit, University Hospital Vall d'Hebron, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Barcelona, Spain.|Departament de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Cerdanyola del Vallès, Spain.
authors.forename: R A
authors.initials: RA
authors.lastname: Bendezú
authors.affiliation: Digestive System Research Unit, University Hospital Vall d'Hebron, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Barcelona, Spain.|Departament de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Cerdanyola del Vallès, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Barba
authors.affiliation: Digestive System Research Unit, University Hospital Vall d'Hebron, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Barcelona, Spain.|Departament de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Cerdanyola del Vallès, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Burri
authors.affiliation: Digestive System Research Unit, University Hospital Vall d'Hebron, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Barcelona, Spain.|Departament de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Cerdanyola del Vallès, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Cisternas
authors.affiliation: Digestive System Research Unit, University Hospital Vall d'Hebron, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Barcelona, Spain.|Departament de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Cerdanyola del Vallès, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Malagelada
authors.affiliation: Computer Vision Center, Bellaterra, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Segui
authors.affiliation: Digestive System Research Unit, University Hospital Vall d'Hebron, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Barcelona, Spain.|Departament de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Cerdanyola del Vallès, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Accarino
authors.affiliation: Radiology Department, University Hospital Vall d'Hebron, Barcelona, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Quiroga
authors.affiliation: Departamento de Lenguajes y Sistemas Informáticos, Universitat Politécnica de Catalunya, Barcelona, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Monclus
authors.affiliation: Departamento de Lenguajes y Sistemas Informáticos, Universitat Politécnica de Catalunya, Barcelona, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Navazo
authors.affiliation: Digestive System Research Unit, University Hospital Vall d'Hebron, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Barcelona, Spain.|Departament de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Cerdanyola del Vallès, Spain.
authors.forename: J-R
authors.initials: JR
authors.lastname: Malagelada
authors.affiliation: Digestive System Research Unit, University Hospital Vall d'Hebron, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Barcelona, Spain.|Departament de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Cerdanyola del Vallès, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Azpiroz
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005414:Flatulence / Q000503:physiopathology; D005740:Gases; D041981:Gastrointestinal Tract / Q000502:physiology* / Q000503:physiopathology; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000503:physiopathology; D000069550:Machine Learning; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
chemical_list: D005740:Gases
keywords: abdominal bloating; abdominal distension; functional gut disorders; intestinal gas