title: Accommodation of the abdomen to its content: integrated abdomino-thoracic response.
abstract: BACKGROUND
  We previously showed that changes in intra-abdominal content induce a volume-dependent muscular response of the anterior abdominal wall and the diaphragm. We aimed to determine the contribution of the thorax to abdominal accommodation and the influence of the intra-abdominal expansion rate.
  
  
  METHODS
  Gas (1440 mL total load) was infused into the colon of nine healthy subjects, while abdomino-thoracic perimeters (by tape measure), electromyography (EMG) activity of the diaphragm (via six ring electrodes over an esophageal tube in the hiatus), intercostals and anterior abdominal wall (via five pairs of surface electrodes) and the position of the diaphragm by ultrasonography were measured. Infusion rates of 24, 48, and 96 mL min(-1) were tested on separate days.
  
  
  RESULTS
  Gas infusion induced anterior abdominal wall contraction (18 ± 1% EMG increment; P < 0.001) with relatively modest girth increment (4.9 ± 0.9 mm; P = 0.001), diaphragmatic relaxation (by 15 ± 1%; P < 0.001) with cephalad displacement (by 23 ± 6 mm; P = 0.005), and intercostal contraction (by 19 ± 2%; P < 0.001) with increased thoracic perimeter (by 2.0 ± 0.5 mm; P = 0.009). Responses were similar with the three infusion rates.
  
  
  CONCLUSIONS
  Accommodation of intra-abdominal loads involves a volume-related integrated abdomino-thoracic response regardless of the expansion rate.
authors.affiliation: Digestive System Research Unit, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), University Hospital Vall d'Hebron, Barcelona, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Burri
authors.forename: D
authors.initials: D
authors.lastname: Cisternas
authors.forename: A
authors.initials: A
authors.lastname: Villoria
authors.forename: A
authors.initials: A
authors.lastname: Accarino
authors.forename: A
authors.initials: A
authors.lastname: Soldevilla
authors.forename: J-R
authors.initials: JR
authors.lastname: Malagelada
authors.forename: F
authors.initials: F
authors.lastname: Azpiroz
mesh_terms: D000005:Abdomen / Q000502:physiology*; D000328:Adult; D003964:Diaphragm / Q000502:physiology*; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009126:Muscle Relaxation / Q000502:physiology; D009130:Muscle, Smooth / Q000502:physiology*; D013909:Thorax / Q000502:physiology*; D055815:Young Adult