Physical Principles of Available Adjustable Gastric Bands: How they Work

Background: Commonly used adjustable gastric bands function on two different physical principles: low pressure-high volume and high pressure-low volume system. Methods: A study was carried out to investigate the theoretical and clinical levels of adjustable band volume-pressure features and their possible influence on band-related complications. The theoretical study had two objectives: to define physical principles of impact of the band balloon on the gastric wall at the stoma region, and to apply a physical formula for calculating this data. The objectives of the clinical part of the study were to construct a simple reliable measuring device, enabling data collection on an out-patient basis from patients who had undergone gastric banding with the two band systems, to support or refute the theoretically calculated results. Results: A physical formula calculated the pressure applied by the different band systems on the gastric wall in the stoma region. Calculations revealed a >100% difference in pressure caused by the respective bands. Invasive pressure measurements in 35 patients with the different balloon systems agreed with the calculated data, and found a >100% difference in pressure affecting the stoma wall both at rest and during meals. Conclusions: Differences in pressure on the gastric wall related to the physical system on which the bands operate may be a partial explanation for long-term complications of respective bands.