Thesis supervisor: Joseph M. Reinhardt. Includes bibliographical references (p. 59-60).

Thesis (Ph.D.)--University of Western Australia, 2006.

published_or_final_version / Dentistry / Master / Master of Dental Surgery

No description available.

This research focuses on investigating the vibration characteristics of branched circular cylindrical shells with applications to airway passages. Analytical modelling is carried out based on Donnell-Mushtari equations of thin elastic membrane type of shells while numerical validation is conducted using the Finite Element Method (COSMOS/Works). Further validation of the results is performed using experimental investigation of tracheobronchial tissues dissected from pigs. The analytical, numerical and experimental results are in acceptable agreement. Further investigation of the vibration characteristics of the airways for cases which cannot be dealt with analytically is carried out using COSMOS/Works. Results show a strong trend relationship which suggests that the natural frequency of the trachea and the primary tracheobronchi is approximately 10 Hz. Radial resonances of lower bronchi are predictable through trends found in this work that the resonant frequency is a linear function in certain region of generations.

Thesis (M.D.S.)--University of Hong Kong, 1997. / Includes bibliographical references (leaves 244-306) Also available in print.

Objective: To determine the upper airway morphometry of Chinese adults by computed tomography. Study Design: This anatomical study consisted of radiological examination of Chinese adults’ upper airway and trachea using computed tomography and image analysis with the help of post-data capture processing software. Materials and Methods: A retrospective review of sixty-five Chinese adults who underwent computed tomography of head and neck region at a regional hospital in Hong Kong was conducted. Computed tomography performed by a Philips Gemini 16? PET/CTPhilips Gemini GXL 16 PET/CT Scanner. Post-data capture processing was performed on GE Advantage Window 4.3 workstation. Measurements were made on standard or oblique reformatted orthogonal planes. Results: 65 consecutive computed tomography scans of the head and neck region of Chinese adults werereviewed. The distance between lower incisor and vocal cords was 144.0mm (±12.1 SD) in men and 124.8mm (±10.4 SD) in women. The distance between the vocal cord and cricoid ring was 21.5mm (±5.8SD) in men and 16.1mm (±6.3SD) in women. The distance between the lower incisor and cricoid ring was 165.5mm (±10.7SD) in men and 140.9 mm (±11.1SD) in women. The distance between the vocal cord and carina was 142.4mm (±12.1SD) in men and 130.4mm (±12.6SD) in women. The distance between the cricoid ring and carina was 121.0mm (±12.7SD) in men and 114.3mm (±10.2SD) in women. All these measurements showed statistically significant gender difference. In men, the anteroposterior diameter of cricoid ring was 21.8mm (±1.4SD) and the transverse diameter was 17.0mm (±1.7SD). In women the anteroposterior diameter of cricoid ring was 17.4mm (±1.9SD) and the transverse diameter was 13.4mm (±1.8SD). Both were statistically different among men and women. The anteroposterior diameter of trachea of men was 21.1mm (±2.9 SD) and the transverse diameter was 17.8mm (±2.7 SD). While the corresponding anteroposterior diameter was 16.1mm (±2.2 SD) and the transverse diameter was 15.9mm (±1.6 SD) in women with statistically significant difference. Using the Pearson correlation, body height but not age of subjects was statistically correlated with all the airway measurements Conclusion: This study reports the tracheal morphometry and dimensions in a Chinese population and their correlation with body height. Details of these measurements will aid airway management and other upper airway procedures in this population. Conclusion: This study reports the tracheal morphometry and dimensions in a Chinese population and their correlation with body height. Details of these measurements will aid airway management and other upper airway procedures in this population. Conclusion: This study reports the tracheal morphometry and dimensions in a Chinese population and their correlation with body height. Details of these measurements will aid airway management and other upper airway procedures in this population. / published_or_final_version / Anatomy / Master / Master of Medical Sciences

published_or_final_version / Medicine / Master / Doctor of Medicine

Oscillatory velocity profiles and the pressure-flow relationship were measured in a 3:1 scale rigid model of the human central airways. A reciprocating pump provided flows with frequencies of 0.25, 1, 2 and 4 Hz and tidal volumes of 300, 500 and 1500 mL giving tracheal Womersley numbers up to 31 and peak tracheal Reynolds numbers up to 17000. A hot wire anemometer was used to measure velocities along two perpendicular diameters (one in the plane of the model and the other in the plane perpendicular to the model) at 10 stations distributed through the model. Velocities were also measured with and without a model larynx and with tracheal intubation in steady inspiratory flows. The flow distribution to the five lobar bronchi was identical in all experiments. / Oscillatory velocity profiles were compared with the steady velocity profiles at nearly identical Reynolds numbers. The flow in a branch was quasi-steady below a critical Strouhal number in agreement with an order of magnitude analysis. For quasi-steady oscillatory flows the velocity profile developed from an initially flat shape to the profiles characteristic of steady flow in branching tubes. Flows that were not quasi-steady exhibited relatively flat profiles over the entire respiratory cycle. The effects of tidal volume, frequency and the geometry of the airways on the velocity profiles were determined. / While the larynx produced a significant jet within the trachea it had no effect on the velocity profiles beyond the carina. The presence of a concentric endotracheal tube located halfway between the glottis and the carina had little effect on the velocity profiles in the main stem and the lobar bronchi. Inserting the tube further into the trachea altered the velocity profiles in the right upper lobar bronchus. / In oscillating flow the pressure was essentially uniform around the periphery of a branch in strong contrast to the results for steady flow. The pressure drop in oscillating flow was much larger than the pressure drop in steady flow at an equivalent flow rate. The functional form of the relationship between the pressure drop across the different branches of the model and the tracheal Reynolds number was similar to that suggested by earlier researchers, however the coefficients were very sensitive to the geometry of the model.

This research focuses on investigating the vibration characteristics of branched circular cylindrical shells with applications to airway passages. Analytical modelling is carried out based on Donnell-Mushtari equations of thin elastic membrane type of shells while numerical validation is conducted using the Finite Element Method (COSMOS/Works). Further validation of the results is performed using experimental investigation of tracheobronchial tissues dissected from pigs. The analytical, numerical and experimental results are in acceptable agreement. Further investigation of the vibration characteristics of the airways for cases which cannot be dealt with analytically is carried out using COSMOS/Works. Results show a strong trend relationship which suggests that the natural frequency of the trachea and the primary tracheobronchi is approximately 10 Hz. Radial resonances of lower bronchi are predictable through trends found in this work that the resonant frequency is a linear function in certain region of generations.