| Mastoid and tympanic membrane as pressure buffers: a quantitative study in a middle ear cleft model. | |
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MedLine Citation:
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PMID: 14600460 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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HYPOTHESIS: The tympanic membrane (TM) and mastoid air cells are measurable pressure buffers of the middle ear (ME). BACKGROUND: Pressure homeostasis of the ME is maintained approximately atmospheric by mechanisms that neutralize (buffer) pressure fluctuations, two of which are the TM and mastoid. MATERIALS AND METHOD: Negative pressures were induced by volume changes in an artificial ME model. Those were recorded directly while using a rigid or a flexible TM with "mastoids" of various sizes. RESULTS: In the rigid TM model, the volume changes correlated linearly with the induced pressures and were confirmed to fit Boyle's law. In the flexible TM model, the pressure/volume correlation was nonlinear up to -50 mmH2O, where the TM was maximally displaced (approximately 25 mm3), became rigid, and constituted 75%, 41%, and 33% of the buffering gained in tandem with the "mastoid" in a model having a "mastoid" of 0, 5, and 10 mL, respectively. Altogether, a large "mastoid" required a greater volume change than a small one to induce the same pressure. CONCLUSIONS: The mastoid air volume "dilutes" pressure changes relatively to its size: the volume change required to alter a given pressure in an average (6 mL) mastoid is six-fold that which is needed in a small (1 mL) mastoid. ME volume reduction by TM retraction buffer negative ME pressures. This maximal ME volume change is constant for a "normal" TM. Therefore, it is the ME with the small mastoid that is most vulnerable to pressure changes and may develop compensatory buffering mechanisms, e.g., additional TM retraction (atelectasis) and/or ME volume reduction by fluid accumulation. |
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Authors:
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Udi Cinamon; Jacob Sadé |
Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology Volume: 24 ISSN: 1531-7129 ISO Abbreviation: Otol. Neurotol. Publication Date: 2003 Nov |
Date Detail:
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Created Date: 2003-11-05 Completed Date: 2004-01-05 Revised Date: 2004-11-17 |
Medline Journal Info:
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Nlm Unique ID: 100961504 Medline TA: Otol Neurotol Country: United States |
Other Details:
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Languages: eng Pagination: 839-42 Citation Subset: IM |
Affiliation:
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Ear Research Laboratory, Department of Bio-Engineering, Tel-Aviv University, Israel. udicin@hotmail.co.il |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Acoustic Impedance Tests Cholesteatoma, Middle Ear / etiology Ear, Middle / physiology* Humans Mastoid / physiology* Models, Biological* Otitis Media with Effusion / etiology Polymethyl Methacrylate Pressure Tympanic Membrane / physiology* |
| Chemical | |
Reg. No./Substance:
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9011-14-7/Polymethyl Methacrylate |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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