A barostat is a device used to maintain constant pressure in a closed chamber. Its main principle is providing constant

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...

s in a

balloon A balloon is a flexible bag that can be inflated with a gas, such as helium, hydrogen, nitrous oxide, oxygen, and air. For special tasks, balloons can be filled with smoke, liquid water, granular media (e.g. sand, flour or rice), or light so ...

by means of a pneumatic pump. Barostats are frequently used in

neurogastroenterology The enteric nervous system (ENS) or intrinsic nervous system is one of the main divisions of the autonomic nervous system (ANS) and consists of a mesh-like system of neurons that governs the function of the gastrointestinal tract. It is capable ...

research, where they are used for measuring

gut wall The gastrointestinal wall of the gastrointestinal tract is made up of four layers of specialised tissue. From the inner cavity of the gut (the lumen) outwards, these are: # Mucosa # Submucosa # Muscular layer # Serosa or adventitia The mucosa is ...

tension Tension may refer to: Science * Psychological stress * Tension (physics), a force related to the stretching of an object (the opposite of compression) * Tension (geology), a stress which stretches rocks in two opposite directions * Voltage or el ...

or sensory thresholds in the gut. A specially designed instrument is needed in neurogastroenterology research since the gut wall has an outstanding capacity to expand and

contract A contract is a legally enforceable agreement between two or more parties that creates, defines, and governs mutual rights and obligations between them. A contract typically involves the transfer of goods, services, money, or a promise to tr ...

spontaneously and by reflex. When this occurs, a balloon placed anywhere in the gut has to be inflated or deflated very rapidly in order to maintain a constant pressure in this balloon. Barostat-balloon systems have been used anywhere in the gut, including the

esophagus The esophagus ( American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to ...

, stomach, small bowel, colon (anatomy), colon, and the rectum, rectum ampulla. Computer-driven barostats have widely been used to assess sensation and pain thresholds in the gut. Assessment of pain thresholds in the ampulla recti has been proposed as medical diagnosis, diagnostic measure in irritable bowel syndrome. A typical method for measuring thresholds is the ''single random staircase'' or ''tracking procedure''. This is a blend of two paradigm (experimental), paradigms widely used in psychophysics, psychophysical research: ascending stimuli (prone to perception bias) and random stimuli. The latter is regarded as unethical since pain thresholds vary over a wide range in the gut, and therefore stimuli with random intensity can hurt very much. In a tracking procedure, ascending stimuli are used until the threshold is reached. Then the tracking phase begins. If the subject rates a stimulus to be above the threshold, the next stimulus will be chosen in a random process to be a 'stair' higher than the last one or of the same intensity. If, however, the subject rates the stimulus to be under the threshold, a less intense or similar stimulus will follow. Therefore, each stimulus is unpredictable in this phase. An extremely accurate high pressure barostat is also used as a pressure regulator in competition specification precharged pneumatic air rifles and pistols.

References

{{Reflist Gastroenterology

See also

References