Airway mechanics and pulmonary function tests : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Physics at Massey University, Palmerston North, New Zealand

dc.contributor.authorHolzhäuser, Ulrich
dc.date.accessioned2011-05-13T02:19:12Z
dc.date.available2011-05-13T02:19:12Z
dc.date.issued1999
dc.description.abstractMethods of engineering mechanics were applied to further the theoretical understanding of the elastic deformation of some specific components of the tracheobronchial tree when subject to a transmural pressure difference. The contribution of the epithelial basement membrane to airway collapse was analysed. The well-known approach based on the physics of a shell was extended to investigate the influence of a non-homogeneous stiffness of the basement membrane on airway collapse. Results were obtained for the fundamental "two-lobe" collapse. These indicate that the critical pressure at which collapse starts depends on the location of the region of maximal stiffness. A method was presented for analysing asymmetric stress-strain behaviour when the Young modulus of a material is different in compression than in tension. Results indicated that, if the basement membrane were stiffer in compression than in tension, the resulting collapsed structure would be slightly stiffer than in the case of no stiffness difference and thus the airway would be less narrowed and less compliant. The deformation of the trachea was analysed by using the same theory as used in the study of the folding of the epithelial membrane. Computations were made to investigate (i) a semi-circular "base-shape" as well as more complex, non-circular shapes, (ii) the effect of shortening of the posterior membrane, (iii) localised weakening of the cartilage ring. Good agreement between model predictions and published MRI microscopy data from rabbit tracheas was obtained. The concepts of fluid mechanics in elastic tubes were used to analyse the effects of airway remodelling on forced expiratory airflow and resistance to airflow. The tracheobronchial tree was modeled as a system of branching, elastic tubes. Flow behaviour through that system of tubes was analysed which allowed the simulation of pulmonary function tests, in particular forced expiration and response to a muscle agonist. Effects of thickening of the airway wall components (adventita, smooth muscle and the submucosa) on exiratory flow and airways resistance, were investigated. Results showed that thickening of the smooth muscle had the strongest effect on expiratory airflow and airway resistance, followed by thickening of the submucosal area. Model results were within a physiologically feasible range.en_US
dc.identifier.urihttp://hdl.handle.net/10179/2321
dc.language.isoenen_US
dc.publisherMassey Universityen_US
dc.rightsThe Authoren_US
dc.subjectPulmonary function testsen_US
dc.subjectRespiratory organsen_US
dc.subjectDiseasesen_US
dc.titleAirway mechanics and pulmonary function tests : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Physics at Massey University, Palmerston North, New Zealanden_US
dc.typeThesisen_US
massey.contributor.authorHolzhäuser, Ulrich
thesis.degree.disciplinePhysics
thesis.degree.grantorMassey University
thesis.degree.levelDoctoral
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophy (Ph.D.)
Files
Original bundle
Now showing 1 - 2 of 2
Loading...
Thumbnail Image
Name:
02_whole.pdf
Size:
4.73 MB
Format:
Adobe Portable Document Format
Description:
Loading...
Thumbnail Image
Name:
01_front.pdf
Size:
614.98 KB
Format:
Adobe Portable Document Format
Description:
License bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
license.txt
Size:
804 B
Format:
Item-specific license agreed upon to submission
Description: