Document Detail


Gastric flow and mixing studied using computer simulation.
MedLine Citation:
PMID:  15615685     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The fed human stomach displays regular peristaltic contraction waves that originate in the proximal antrum and propagate to the pylorus. High-resolution concurrent manometry and magnetic resonance imaging (MRI) studies of the stomach suggest a primary function of antral contraction wave (ACW) activity unrelated to gastric emptying. Detailed evaluation is difficult, however, in vivo. Here we analyse the role of ACW activity on intragastric fluid motions, pressure, and mixing with computer simulation. A two-dimensional computer model of the stomach was developed with the 'lattice-Boltzmann' numerical method from the laws of physics, and stomach geometry modelled from MRI. Time changes in gastric volume were specified to match global physiological rates of nutrient liquid emptying. The simulations predicted two basic fluid motions: retrograde 'jets' through ACWs, and circulatory flow between ACWs, both of which contribute to mixing. A well-defined 'zone of mixing', confined to the antrum, was created by the ACWs, with mixing motions enhanced by multiple and narrower ACWs. The simulations also predicted contraction-induced peristaltic pressure waves in the distal antrum consistent with manometric measurements, but with a much lower pressure amplitude than manometric data, indicating that manometric pressure amplitudes reflect direct contact of the catheter with the gastric wall. We conclude that the ACWs are central to gastric mixing, and may also play an indirect role in gastric emptying through local alterations in common cavity pressure.
Authors:
Anupam Pal; Keshavamurthy Indireshkumar; Werner Schwizer; Bertil Abrahamsson; Michael Fried; James G Brasseur
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Proceedings. Biological sciences / The Royal Society     Volume:  271     ISSN:  0962-8452     ISO Abbreviation:  Proc. Biol. Sci.     Publication Date:  2004 Dec 
Date Detail:
Created Date:  2004-12-23     Completed Date:  2005-03-29     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  101245157     Medline TA:  Proc Biol Sci     Country:  England    
Other Details:
Languages:  eng     Pagination:  2587-94     Citation Subset:  IM    
Affiliation:
Department of Mechanical Engineering, 205 Reber Building, The Pennsylvania State University, University Park, PA 16802, USA.
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MeSH Terms
Descriptor/Qualifier:
Computer Simulation
Gastric Juice / physiology*
Humans
Models, Anatomic*
Peristalsis / physiology*
Stomach / physiology*
Time Factors
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