title: Intraband pressure measurements describe a pattern of weight loss for patients with adjustable gastric bands.
abstract: BACKGROUND
  Individuals with adjustable gastric bands experience plateaus in weight loss. Patients commonly attribute this to a "loosening" of their band with time. We sought to elucidate a physiologic mechanism for this pattern in patient behavior and describe the feasibility of a pressure-based adjustment algorithm for adjustable gastric bands.
  
  
  METHODS
  Following IRB protocol, 100 consecutive patients undergoing placement of the Lap-Band (Inamed) were enrolled and followed prospectively for 12 months. Intraband pressure measurements at band volumes 0 to 4 mL were recorded intraoperatively and at each subsequent band adjustment. Band adjustments were made using the currently accepted volume-based postoperative protocol.
  
  
  RESULTS
  Seventy-nine patients were included in analysis. Mean percent excess weight loss for the study cohort was 36 +/- 17% at a median followup of 347 days. During the time between adjustments, there was a statistically significant decrease (p < 0.001) in intraband pressure without a corresponding decrease in band volume. This was a result of a substantial change in the pressure-volume relationship of the Lap-Band. As time progressed, the Lap-Band developed less intraband pressure per unit volume. This change was not a result of changes in the elastic properties of the band material itself.
  
  
  CONCLUSIONS
  Between adjustments, Lap-Band patients experience gradual loss of satiety and a loosening of their band, despite stable band volume. Their experience is substantiated by degradation in their intraband pressures with time. We have demonstrated that intraband pressures correlate with the patient's clinical history and have thereby established the foundation for a pressure-based adjustment protocol.
authors.affiliation: Department of Surgery, Section of Surgical Sciences, Vanderbilt University, Nashville, TN 37323-2577, USA. thomas.rauth@vanderbilt.edu
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Rauth
authors.forename: Aaron W
authors.initials: AW
authors.lastname: Eckhauser
authors.forename: Bonnie J
authors.initials: BJ
authors.lastname: LaFleur
authors.forename: Willie V
authors.initials: WV
authors.lastname: Melvin
authors.forename: Michael D
authors.initials: MD
authors.lastname: Holzman
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D005240:Feasibility Studies; D005260:Female; D015391:Gastroplasty; D006801:Humans; D010535:Laparoscopy; D008297:Male; D008365:Manometry; D008422:Materials Testing; D008875:Middle Aged; D009767:Obesity, Morbid / Q000601:surgery*; D011312:Pressure; D011446:Prospective Studies; D015431:Weight Loss