Abstract Background: Hypoxaemia during tracheal intubation in obstetrics remains a lifethreatening complication. This study aimed to identify common clinical preinduction predictors of difficult intubation. Methods: A retrospective analysis was performed of data pertaining to tracheal intubation in patients requiring general anaesthesia for caesarean delivery, with a gestational age from 20 weeks, and until 7 days post-delivery, obtained from an obstetric airway management registry (ObAMR) at the University of Cape Town. Data was entered anonymously into a secure UCT REDCap database. Data categories were: patient and pregnancy characteristics, airway characteristics, details of management, and operator experience. The primary aim of the study was to identify anatomical and physiological risk factors for hypoxaemia. The primary outcome was defined as arterial desaturation to < 90% during obstetric airway management. For this purpose, multivariable binary logistic regression was performed. Hypoxaemia was thus used as a composite indicator of anatomical and physiological difficulty. Results: Data was collected for 1095 general anaesthetics in the ObAMR. Overall, 143/1091 of patients (13.1%, 95%CI 11.1 to 15.4%) experienced peripheral oxygen saturation below 90%. Univariate analysis showed that 91/142 (64.1%) of patients who desaturated were obese (body mass index [BMI]> 30 kg/m2 ), compared with 347/915 (37.9%) who were obese and did not experience desaturation (p< .001). A receiver operating curve (ROC) was constructed post hoc, which showed a cut-point for BMI of 29.76, and a sensitivity of 0.66, and specificity 0.62 for the prediction of hypoxaemia. Desaturation occurred in 17.0% of patients with hypertensive disorders of pregnancy, versus 11.0 % without (p=0.005). Increasing Mallampati class was associated with an increased incidence of hypoxaemia. The incidence of hypoxaemia was 25.8% for interns, compared with 8.0 % for consultant anaesthesiologists (p=0.005). In the multivariate analysis of factors associated with hypoxaemia, body mass index (p< 0.001), room air saturation prior to preoxygenation (p=0.008), and the presence of airway oedema (p=0.027), were independently associated with hypoxaemia. Conclusions: In this study, both anatomical and physiological predictors of hypoxaemia were identified. Using this concept, a predictive tool could be developed to aid in the identification of a difficult airway in obstetrics. Simple interventions such as face mask ventilation and the use of high flow nasal oxygenation, could be introduced to protect the parturient from the consequences of life-threatening hypoxaemia.

No description available.

Magister Scientiae Dentium - MSc(Dent) / Aim: The aim of this study was to assess the effect of retraction of anterior teeth on pharyngeal airway dimensions, after orthodontic treatment of bimaxillary protrusion cases by means of the extraction of four premolars. Method: A total of 88 lateral cephalometric radiograph pairs, consisting of a pre-treatment and post-treatment radiograph taken for orthodontic treatment of bimaxillary protrusion by means of extraction of four premolars, was used. The pharyngeal airway space, measured across three different levels, as well as the length of the maxilla and mandible were assessed for changes from pre-treatment to post-treatment. Pearson’s correlation coefficient was used to determine the degree to which the change in pharyngeal airway space was associated with the change in maxilla or mandible length. Results: The pre-treatment average pharyngeal airway space measurements were recorded as 15.23mm for the Superior Pharyngeal Airway Space, 11.63mm for the Middle Pharyngeal Airway Space and 13.56mm for the Inferior Pharyngeal Airway Space. The average reduction in the pharyngeal airway space was noted as 1.21mm, 1.64mm and 2.23mm respectively. All with statistically significant P values of <0.001.

Thymic stromal lymphopoietin (TSLP) is a pleotropic cytokine highly implicated in the pathophysiology of asthma and allergic diseases. Although there are robust data regarding the associations of TSLP polymorphisms with the development of allergy and asthma, there is very little information on how these TSLP variants functionally affect downstream effector pathways and disease phenotype. The overall objective of this thesis was to investigate how TSLP polymorphisms are linked to alterations in TSLP secretion and subsequent downstream cellular events. Initially, we investigated the influence of innate and adaptive stimuli on epithelial-derived TSLP expression and secretion, including effects on dendritic cells (DC). We show that polyinosinic:polycytidylic acid (polyI:C) and allergen-specific T cells induced enhanced TSLP secretion from asthmatic bronchial epithelial cells (BEC) compared to non-asthmatic BEC. Furthermore, activated-BEC culture supernatants induced TSLP-dependent CCL17 production from monocyte-derived DC in relation to clinical asthmatic status (Chapter 2). Next, we examined effects of TSLP on hemopoietic progenitor eosinophil-basophil (Eo/B) differentiation, demonstrating enhanced TSLP-mediated hemopoiesis ex vivo in relation to clinical atopic status. We further demonstrated p38MAPK-dependent autocrine signaling by TNFα in TSLP-mediated human Eo/B differentiation ex vivo (Chapter 3). Lastly, to explore the potential functional consequences of a key variant of the TSLP gene, we investigated associations between the rs1837253 TSLP variant and ex vivo production of TSLP in nasal epithelial cells (NEC). We showed that NEC derived from individuals with the “protective” minor allele have diminished TSLP secretion, which suggests that this rs1837253 polymorphism may be directly involved in the regulation of TSLP secretion (Chapter 4). The novel work presented herein provides further evidence for TSLP regulation of distinct immunological pathways in allergic immune inflammatory airway responses initiated at the epithelial surface, and thus (by implication) of allergic disease. These observations support the concept that TSLP is potentially an important biomarker and therapeutic target for allergic diseases characterized by increased Th2 and/or eosinophilic-basophilic inflammation. Continued investigations into the functional mechanisms linking TSLP variants to allergic disease phenotype are of critical importance. / Dissertation / Doctor of Science (PhD)

No description available.

No description available.

Approximately 7.5 million people suffer from voice disorders in the United States. Previous studies indicate that the quality of the fluid layer that coats the vocal folds appears to be different for people with voice disorders than for people whose voice is considered normal. These studies suggest that the composition and/or physical properties of the fluid layer may contribute to voice disorders. Despite these findings, little research has been undertaken to investigate the role of the fluid layer on voice, and in almost all cases, the fluid layer is considered to be insignificant. The purpose of this research was to investigate the role of the fluid layer and the potential it may have to influence voice production; particularly, to identify some aspects of the fluid layer that have the potential to contribute to voice disorders. In order to investigate the potential significance of the effects of a fluid layer on vocal fold operation, an existing lumped model was modified to incorporate the Newtonian squeeze-flow equation as a fluid model during the colliding portion of the oscillatory cycle. Results indicated that thicker films produced more significant deviations from the case with no fluid layer. Experimental testing was performed to validate existing analytical equations for squeezing flow of Newtonian and non-Newtonian fluids confined between parallel axisymmetric plates. Based on available published data on the rheological properties of the fluid layer found on the surface of the vocal folds, several fluids with a range of fluid properties were selected. Reasonable agreement was found for much of data collected for the Newtonian fluid cases within measurement tolerances. For the non-Newtonian cases, the constitutive equation was found to be in poor agreement with the measured physical characteristics of the selected non-Newtonian fluids. A summary of the collected experimental data is provided so that it can be used in for validation and comparison in future research. A preliminary computational model based on the classical two-mass vocal fold model was implemented which incorporated squeezing effects of a thin Newtonian film of fluid on the surface of the vocal folds. Results indicated that the fluid layer may not be insignificant, although further tests and modeling are required. Finally, different fluids were applied to a physical model of the vocal folds and measurements were taken to determine the effects of the application of fluid. The results showed significant changes in the vocal fold model response that indicated the fluid layer affects vocal fold operation in important ways. Some of the changes in response could not be attributed solely to the fluid layer. Suggestions regarding future work with physical model testing are given which may help clarify the effects of a fluid layer on vocal fold flow-induced vibration.

No description available.

Master of Science / Strangles is an extremely infectious disease of horses that has negative financial and health consequences. After infection, some horses form balls of concrete-like pus in a structure in an air-filled sac of the ear canal called guttural pouches (GPs). These concretions, called chondroids, allow affected horses to continue to pass on infection to other horses. Removal of chondroids is needed to stop disease transmission but current non-surgical and surgical removal techniques have limitations. Surgical laser passed through an endoscope (medical camera) allows minimally invasive surgery of the guttural pouches. We performed laser surgery on cadaver horse heads to create access to the GP, then evaluated our ability to remove chondroid-like beads from the GP using a custom-made 3D-printed instrument. Our results showed efficient and complete removal of the beads compared to lavage without the 3D-printed instrument, with little damage to the heads. These findings are an initial step to development of a new chondroid-removal technique and may allow surgeons to more efficiently remove chondroids without the need for invasive surgery.

22q11.2 Deletion Syndrome (22q) is the most common microdeletion known in humans. Studies have hypothesized that larger nasopharyngeal proportions lead to velopharyngeal dysfunction (VPD) in individuals in 22q.22q patients that undergo the pharyngeal flap surgery to correct their velopharyngeal insufficiency have been reported to experience an increased rate of surgical complications due to their complex anatomical differences.Treatment of velopharyngeal insufficiency among patients with 22q therefore requires quantitative anatomical data of the nasopharyngeal area for surgical planning. No studies to date have analyzed the nasopharyngeal volume in a non-sedated pediatric population with 22q. The aim of this study was to investigate the volumetric and linear characteristics of the nasopharyngeal port among children with 22q using a novel, non-sedated 3D imaging protocol. MRI data were obtained on 20 participants, 10 with a confirmed diagnosis of 22q and 10 control subjects. All participants were between 4-12 years of age. 3D MRI data were collected while the velum was relaxed as the participants lay in the supine position. The 3D scan involved a 0.8 in-plane isotropic resolution with an acquisition time of less than 5 minutes.MRI data were transferred into Amira 6 Visualization Volume Modeling software (Visage Imaging GmbH, Berlin, Germany). Both volumetric and linear measurements of the nasopharyngeal port were taken. The measures were selected based on relevance to speech resonance features and comparable studies in the literature. Linear measurements were taken of the velopharyngeal (VP) width, anterior cranial base angle (ACBA), pharyngeal depth, osseous pharyngeal depth, and adenoid-nasopharyngeal ratio (ANR). Volumetric measurements included adenoid volume (AV), nasopharyngeal volume (NPV), and oronasopharyngeal volume (ONV) . Independent samples t-tests were used to assess differences between the control and clinical groups. The total volume of the nasopharynx was found to be significantly larger in the 22q group (2890.70 mm3) compared to the control group (1542.10 mm3). Significant differences were additionally noted among linear measures, including a more obtuse angle of the ACBA in the 22q group. These results support our initial hypothesis regarding larger nasopharyngeal airways in patients with 22q compared to the control group. Quantitative anatomical data of nasopharyngeal proportions in children with 22q can be used to tailor surgery to provide a more personalized treatment approach to enhance speech and surgical outcomes in the 22q population.