Barostat

A barostat is a device used to maintain constant pressure in a closed chamber.[1] Their main principle is providing constant pressures in a balloon by means of a pneumatic pump.[2] Barostats are frequently used in neurogastroenterology research, where they are used for measuring gut wall tension or sensory thresholds in the gut.[3]

Rectal barostat balloon, partially inflated

A specially designed instrument is needed in neurogastroenterology research since the gut wall has an outstanding capacity to expand and contract 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,[4] stomach,[5] small bowel,[6] colon, and the rectum ampulla.[7]

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 diagnostic measure in irritable bowel syndrome.[8][9]

A typical method for measuring thresholds is the single random staircase or tracking procedure. This is a blend of two paradigms widely used in 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.

See also

References
  1. Jerzy Leszczynski (1 December 2011). Handbook of Computational Chemistry. Springer Science & Business Media. pp. 224–. ISBN 978-94-007-0710-8. Barostat Many of the approaches used for controlling the pressure are similar to those that are used for controlling the temperature. One approach is to maintain constant pressure by coupling the system to a constant pressure ...
  2. Kenneth William Hinchcliff; Andris J. Kaneps; Raymond J. Geor (2008). Equine Exercise Physiology: The Science of Exercise in the Athletic Horse. Elsevier Health Sciences. pp. 427–. ISBN 0-7020-2857-6. The principle of the barostat is to maintain a constant pressure within a plastic bag of infinite compliance, positioned within the lumen of the segment to be studied. When the internal pressure of the organ increases for any reason (for example, ...
  3. Anton Emmanuel; Eamonn M. M. Quigley (10 April 2013). Irritable Bowel Syndrome: Diagnosis and Clinical Management. Wiley. pp. 237–. ISBN 978-1-118-44474-0. The barostat is as instrument initially developed in our laboratory for measuring variations in gastric tone [28, 29]. ... With the tensostat it is possible to exert constant wall tension at predetermined levels and, consequently, conscious perception ...
  4. Marvin Meier Schuster; Michael D. Crowell; Kenneth L. Koch (2002). Schuster Atlas of Gastrointestinal Motility in Health and Disease. PMPH-USA. pp. 92–. ISBN 978-1-55009-104-5. Nifedipine has been studied using both standard balloon distention and barostat testing and has not been found to reliably ... Esophageal barostat experiments were able to measure a difference in tone between the smooth and striated ...
  5. Hamid M. Said (4 July 2012). Physiology of the Gastrointestinal Tract, Two Volume Set. Academic Press. pp. 952–. ISBN 978-0-12-382027-3. ... The barostat maintains a fixed pressure level within the stomach by adapting the intraballoon volume.4 Measurement of ...
  6. Practical Gastroenterology and Hepatology: Small and Large Intestine and Pancreas. John Wiley & Sons. 11 July 2011. pp. 179–. ISBN 978-1-4443-4786-9. Small and Large Intestine and Pancreas ... capacity can be estimated using the inflatable balloon mounted on a typical manometric assembly, these parameters can be most accurately and objectively measured using a barostat system [18].
  7. Donato F. Altomare; Filippo Pucciani (8 March 2008). Rectal Prolapse: Diagnosis and Clinical Management. Springer Science & Business Media. pp. 150–. ISBN 978-88-470-0684-3. This finding is in agreement with results of classic rectopexy and reflects the importance of preserving the rectal ampulla. ... A subgroup of patients underwent extensive manometry and rectal barostat to evaluate remaining anorectal function.
  8. Scott M. Fishman (29 March 2012). Bonica's Management of Pain. Lippincott Williams & Wilkins. pp. 888–. ISBN 978-1-4511-6140-3. This modality has been used extensively in studies of various functional bowel disorders, most notably irritable bowel syndrome, functional dyspep- sia, and NCCP. More than 40 years ago, intraesophageal balloon distension in humans was reported ... The introduction of the electronic barostat, a computer-driven ...
  9. Michael Camilleri; Robin C. Spiller (2002). Irritable Bowel Syndrome: Diagnosis and Treatment. W.B. Saunders. pp. 72–. ISBN 978-0-7020-2655-3. Evidence of ... increasing increments of pressure (delivered by a computer controlled pump, the barostat) until the patient first reports ...
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