No description available.

Thesis (MEng--Engineering) -- Auckland University of Technology, 2004. / Also held in print (110 leaves, ill., 30 cm.) in Wellesley Theses Collection. (T 620.1123 HER)

Thesis (M. Phil.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 143).

Thesis (M.S.)--University of Michigan, 1982.

Thesis (M.S.)--University of Michigan, 1982.

No description available.

In addition to its usefulness in modeling and simulation processes, the modulus of elasticity is an index which is highly used in biomedical identifications and tissue characterizations. For many composite and viscoelastic materials an "accurate modulus" is an idealistic hypothesis and an "equivalent modulus" is normally of a high biomechanical significance. The composite shape of the trachea, which consists of the smooth muscles and cartilage rings, renders the fact that an equivalent modulus is in place for many applications. In this paper three in-vitro nondestructive testing techniques are presented to determine the Young modulus of elasticity of the trachea and the results are compared with the standard uniaxial state of stress method. These techniques are based on: (1) simulating the trachea as a pressurized vessel and deducing a special relationship between the pressure and the radial strain; (2) using two hydrophones and studying the variation in acoustic transmittance caused by the presence of the trachea in a water-bath; (3) considering the trachea as a thin cylindrical shell and determining the resonance vibration response. Elaborate discussion is presented to identify the "pros" and "cons" of each technique and final practical recommendations are made.

Intravenous application of high dose of capsaicin to the rat stimulates C-fiber neurons that innervate the airways to release tachykinins that produce acute inflammation in the mucosal tissue. Large amount of extravasated plasma is retained underneath the tracheal epithelium to form edema. Substance P (SP) is the most important inflammation-producing peptide of tachykinin family. The present study was to investigate time-dependent formation and remission of edema induced by SP (3 µg/ml/kg) by the use of digital morphometric analysis of montages of tracheal cross sections. Furthermore, 3-dimensional reconstruction of serial tracheal sections was carried out to analyze the relative distribution of subepithelial edematous loci. Two edema indexes were designated for evaluation of the status of edema. Edema length ratio was the ratio of the total length of edematous loci to the circumference of a tracheal section. Edema area ratio was the ratio of the total area of edematous loci to the area of tracheal epithelium and associated edema. The degree of edematous status in the mucosa exhibited a time-dependent change. Five min after application of SP, edema length ratio and edema area ratio in the trachea were 35.80¡Ó1.42% and 16.28¡Ó2.51%, that were 7.6 and 7.9 times, respectively, the values of vehicle control group. At 1 h after SP, edema length ratio and edema area ratio declined to 16.40¡Ó2.46% and 8.00¡Ó1.60%, 2.2 and 2.8 times the values of control, but still significantly different (P < 0.05). At 24 or 72 h after SP, the values of edema were not significantly different (P > 0.05) from the control values. Three- dimensional reconstruction study showed that, in the trachea of rats 5 min after receiving SP, there were many subepithelial edematous loci, evenly distributed along the inner circumference of trachea. They were interconnected. The number of edematous loci decreased drastically by 1 h after SP. Loci of edema were rarely found 24 or 72 h after SP. The close association of edema to the tracheal epithelium suggests that the mucosal surface may be the site for elimination of edema fluid.

Endotracheal suctioning is a procedure performed on a daily basis in hospitals, and is mostly take place in intensive care units (ICUs). (Annapoorna, 2005; Day et al, 2009). It helps removing sputum or secretion out from patients’ trachea. For patients who are under mechanical ventilation, this procedure is vital to maintain their airway patency when they are intubated with endotracheal tube or tracheostomized (Finucane & Santora, 2003). However, the procedure has its own risk and complications such as hypoxaemia, atelectasis, cardiovascular instability and more (Thomson, 2000). There are in general two types of endotracheal suctioning: open and closed system. As disconnection of mechanical ventilation from patients is needed for open endotracheal suctioning (OES), it has a higher risk of complications. However, the cost for OES is much cheaper compared to the closed system. Although OES is widely used in Hong Kong, there is no evidence-based guideline for nurses to follow. The guideline developed by American Association of Respiratory Care (2010) is lack of specificity on the target population and its recommendations were based on mixed literatures targeting on adult and infant patients. Therefore, the aim of this dissertation is to develop an evidence-based guideline for OES in adult patients under mechanical ventilation in ICU. To develop a guideline for OES, search was performed in multiple electronic databases (British Nursing Index, CINAHL, Cochrane Library, Ovid MEDLINE, and PubMed) with keywords related to OES and its complications. A total of 457 studies fulfilled the inclusion criteria and 11 of them were selected. The selected studies were evaluated by quality appraisal checklists, which are developed by Scottish Intercollegiate Guidelines Network (SIGN). Data were extracted for developing the guideline. Evidence have shown that the incidence of post-OES hypoxemia can be reduced by performing hyperoxygenation with 100% oxygen for 4-6 breaths prior and after each open endotracheal suction, accompanying with hyperinflation with 150% of patient’s tidal volume at most 8 breaths/40 seconds delivered by ventilator and prohibiting normal saline instillation into trachea for diluting the sputum. The grades of the recommendations in the guideline were rated with using of the SIGN grading system. The implementation potential was analyzed by the patients’ characteristics, transferability of the findings, feasibility of implementation and cost-benefit ratio. A 12-month implementation program was developed including communication with stakeholders, 4-week pilot testing, and training of ICU staffs, and implementation of OES guideline. The effectiveness of the guideline will be evaluated based on the primary outcome (i.e. oxygen level in blood) for detecting the incidence of hypoxemia. Also, the acceptability of the guideline, compliance of the guideline, financial cost reduction and better quality of service will be used as other evaluation indicators. / published_or_final_version / Nursing Studies / Master / Master of Nursing

In addition to its usefulness in modeling and simulation processes, the modulus of elasticity is an index which is highly used in biomedical identifications and tissue characterizations. For many composite and viscoelastic materials an "accurate modulus" is an idealistic hypothesis and an "equivalent modulus" is normally of a high biomechanical significance. The composite shape of the trachea, which consists of the smooth muscles and cartilage rings, renders the fact that an equivalent modulus is in place for many applications. In this paper three in-vitro nondestructive testing techniques are presented to determine the Young modulus of elasticity of the trachea and the results are compared with the standard uniaxial state of stress method. These techniques are based on: (1) simulating the trachea as a pressurized vessel and deducing a special relationship between the pressure and the radial strain; (2) using two hydrophones and studying the variation in acoustic transmittance caused by the presence of the trachea in a water-bath; (3) considering the trachea as a thin cylindrical shell and determining the resonance vibration response. Elaborate discussion is presented to identify the "pros" and "cons" of each technique and final practical recommendations are made.