Evaluation of the barostat for recordings of gastrointestinal motility

The barostat has been used to investigate gastrointestinal motility. No detailed technical evaluation to characterize the properties of this device for motility recordings has been reported. We, therefore, aimed to test the barostat in vitro under standardized conditions.

Barostat and manometry recordings were performed using a combined catheter in a pressure chamber. Some of the experiments were made in pig sigmoid colon in order to mimic recordings in a hollow organ. Data are mean +/- SD.

Baseline changes of the bag volume under constant conditions were 3.9 +/- 2.0%. The bag volume increased by 4.5 +/- 1.1% with a temperature increase from 22 to 37 degrees C (p < 0.05). At external pressures above the bag operating pressure, the barostat bag collapsed, while only minimal volume reductions occurred at external pressures below the bag pressure. Barostat recordings of pressure events were delayed when compared with manometry and not linearly related to the pressure increases.

The influence of temperature changes on barostat recordings is small. The volume decrease in the barostat bag is not linearly related to the external pressure increase and influenced by the operating pressure in the bag. This experimental study provides insight and caveats for those planning to use the barostat device for motility recordings of the gastrointestinal tract.