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Studies on Mathematical Modeling of Middle Ear Gas Exchange

Kanick, Stephen Chad (2005) Studies on Mathematical Modeling of Middle Ear Gas Exchange. Master's Thesis, University of Pittsburgh. (Unpublished)

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Middle ear (ME) pressure regulation is a topic of fundamental interest to the pediatric otolaryngology community since a lack of proper regulation is a precursor to middle ear disease. Development of mathematical models of ME gas exchange can improve understanding of the underlying ME physiology. Previous models were limited in their description of gas exchange (based on inputted empirical exchange constants) and in their application (few models posses capacity for clinical relevance in diagnosis). Here, we present investigations which improve and expand on previous models. The first study presents a global description of ME pressure regulation and applies the model to flight-related barotrauma. While a well functioning Eustachian tube has long been known to protect from barotrauma, the simulation results show that a variety of buffering mechanisms can reduce the demand placed on the efficiency of that function. Using these results, subclasses of ears with little risk for barotrauma were identified and an algorithm was developed that makes these assignments based on measurable variables. The second study outlines and analyzes a morphometric approach to describing transmucosal gas exchange within the middle ear. Implementation of the morphometric model requires the measurement of diffusional length (tao) for the ME mucosa which contributes to the mucosal diffusing capacity, a measure of the resistance to gas flow between airspace and capillary. Two methods for measuring tao have been proposed: the linear distance between air-mucosal boundary and capillary as described by Ars and colleagues, and the harmonic mean of all contributing pathway lengths as described by Weibel and colleagues. Here, oxygen diffusing capacity was calculated for different ME mucosal geometries using the two tao measures, and the results were compared to those predicted by a 2-dimensional finite element analysis. Predictive accuracy was improved by incorporating the tao measure described by Weibel which captures important information regarding variations in capillary shape and distribution. However, when compared to the oxygen diffusing capacity derived from the finite element analysis, both measures yielded non-linear, positively biased estimates. The morphometric techniques underestimate diffusion length by failing to account for the curvilinear gas flow pathways predicted by the finite element model.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Kanick, Stephen
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee CoChairMcCarthy, Joseph
Committee CoChairDoyle, William
Committee MemberVelankar,
Date: 28 January 2005
Date Type: Completion
Defense Date: 18 August 2004
Approval Date: 28 January 2005
Submission Date: 7 September 2004
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Chemical Engineering
Degree: MSChE - Master of Science in Chemical Engineering
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: analysis; barotrauma; diffusion length; eustachian tube; finite element; morphometric model
Other ID:, etd-09072004-100611
Date Deposited: 10 Nov 2011 20:01
Last Modified: 15 Nov 2016 13:50


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