title: Mechanisms of bolus clearance in patients with laparoscopic adjustable gastric bands.
abstract: BACKGROUND
  The components of esophageal function important to success with laparoscopic adjustable gastric banding (LAGB) are not well understood. A pattern of delayed, however, successful bolus transit across the LAGB is observed.
  
  
  METHODS
  Successful LAGB patients underwent a high-resolution video manometry study in which bolus clearance, flow, and intraluminal pressures were recorded. Liquid and semi-solid swallows and stress barium (a combination of semi-solid swallows and liquid barium) were performed. A new measurement, the lower esophageal contractile segment (LECS), was defined and evaluated.
  
  
  RESULTS
  Twenty patients participated (mean age 48.3 +/- 12.0 years, four men, %excess weight loss 65.6 +/- 18.0). During semi-solid swallows, two patterns of esophageal clearance were observed: firstly, a native pattern (n = 10) similar to that which is expected in non-LAGB patients; secondly, a lower esophageal sphincter-dependent pattern (n = 7), where flow only occurred when the intrabolus pressure increased during the lower esophageal sphincter (LES) aftercontraction. In both patterns, if there was incomplete bolus clearance, reflux was observed and was usually followed by another swallow. A mean of 4.5 +/- 2.9 contractions were required to clear the semi-solid bolus. Contractions with an intact LECS demonstrated longer flow duration: 7.1 +/- 3.8 vs.1.6 +/- 3.2 s, p < 0.005. During the stress barium, an intrabolus pressure of 44.5 +/- 16.0 mm Hg leads to cessation of intake.
  
  
  CONCLUSIONS
  In LAGB patients, normal esophageal peristaltic contractions transition to a LES aftercontraction, producing trans-LAGB flow. Repeated contractions are required to clear a semi-solid bolus. Incorporating measurements of the LECS into assessments of esophageal motility in LAGB patients may improve the usefulness of this investigation.
authors.affiliation: Centre for Obesity Research and Education (CORE), Monash Medical School, The Alfred Hospital, Commercial Rd, Prahran, 3181, Melbourne, Australia. paul.burton@med.monash.edu.au
authors.forename: Paul Robert
authors.initials: PR
authors.lastname: Burton
authors.forename: Wendy A
authors.initials: WA
authors.lastname: Brown
authors.forename: Cheryl
authors.initials: C
authors.lastname: Laurie
authors.forename: Geoff
authors.initials: G
authors.lastname: Hebbard
authors.forename: Paul E
authors.initials: PE
authors.lastname: O'Brien
mesh_terms: D003679:Deglutition; D049630:Esophageal Sphincter, Lower / Q000503:physiopathology; D004947:Esophagus / Q000503:physiopathology*; D005260:Female; D015391:Gastroplasty; D006801:Humans; D010535:Laparoscopy; D008297:Male; D008365:Manometry; D008875:Middle Aged; D009119:Muscle Contraction; D009767:Obesity, Morbid / Q000503:physiopathology* / Q000601:surgery*; D010528:Peristalsis