Barostat
Barostat is derived from the ancient Greek βάρος báros “heaviness, weight” and στατός statos = “standing”, so it stands for a device (or in computer simulations a routine) for producing constant pressure .
In neurogastroenterological research, a barostat describes a pneumatic pump for providing constant pressures in a balloon . A barostat is used to measure compliance and tone of the intestinal wall or to determine sensory thresholds.
A specially designed piston pump is required because the intestinal wall - spontaneously and reflexively - can expand and contract extraordinarily. A balloon placed somewhere in the intestine then needs to be inflated or deflated quickly in order to maintain constant pressure.
Barostat balloon systems have been used throughout the digestive tract, including the esophagus , stomach , duodenum , colon, and rectum .
Computer- controlled barostats are often used to determine sensory and pain thresholds in the intestine. Pain threshold determination in the rectal ampulla has been proposed as a diagnostic test for irritable bowel syndrome .
A typical method is the so-called single random staircase or tracking procedure. This is a combination of two paradigms used in psychophysics : ascending stimuli (which tend to be biased) and random stimuli. Random stimuli are viewed as unethical , as pain thresholds are very different in different people and therefore random stimuli can be very painful in individual cases. In a tracking procedure, ascending stimuli are used until the threshold is reached for the first time. Then the tracking phase begins . If the test person rates the stimulus higher than the threshold, then the next stimulus is randomly selected to be either less or equally intense. If, on the other hand, the stimulus is rated lower than the threshold, then the next stimulus is just as intense or stronger. This makes the stimulus intensities unpredictable.