No description available.

The human upper airway structure provides access of ambient air to the lower respiratory tract, and it as an efficient filter to cleanse inspired air of dust bacteria, and other environmental pollutants. When air passes through airway passages, it constantly changes direction, which may lead to flow separation, recirculation, secondary flow and shear stress variations along the airway surface. Therefore, it is essential to understanding the air transport processes within the upper airway system. The functions are respiratory defence mechanisms that protecting the delicate tissues of the lower airway from the often harsh conditions of the ambient air. While protecting the lower respiratory system, however, the upper airway itself becomes susceptible to various lesions and infections from filtration of environmental pollutants. Inhaled particle pollutants have been implicated as a potential cause of respiratory diseases. In contrast, inhalation of drug particles de posited directly to the lung periphery results in rapid absorption across bronchopulmonary mucosal membranes and reduction of the adverse reactions in the therapy of asthma and other respiratory disorders. For this purpose, it is desirable that the particles should not deposit in the upper airways before reaching the lung periphery. Therefore, accurate prediction of local and regional pattern of inhaled particle deposition in the human upper airway should provide useful information to clinical researchers in assessing the pathogenic potential and possibly lead to innovation in inhalation therapies. With the development of the increasing computer power and advancement of modeling software, computational fluid dynamics (CFD) technique to study dilute gas-particle flow problems is gradually becoming an attractive investigative tool. This research will provide a more complete picture of the detailed physical processes within the human upper airway system. Owing to the significant advancements in computer technologies, it will allow us to efficiently construct a full-scaled model integrating the various functional biological elements including the nasal, oral, laryngeal and more generations of the bifurcation of the human upper airway system through imagining methodologies. A significant advantage of this human model is that the differences in airway morphology and ventilation parameters that exist between healthy and diseased airways, and other factors, can be accommodated. This model will provide extensive experimental and numerical studies to probe significant insights to the particle deposition characte ristics within the complex airway passages and better understanding of any important phenomena associated with the fluid-particle flow. It will also lead to an improved understanding of fluid/particle transport under realistic physiological conditions. New concepts and numerical models to capture the main features observed in the experimental program and innovative techniques will be formulated. The ability to numerically model and a better physical understanding of the complex phenomena associated with the fluid dynamics and biological processes will be one of the major medical contributions especially targeting drug delivery and health risk analysis. Its biomedical engineering significance lies in the fact that this will enable us to accurately evaluate potential biological effects by the inhaled drug particles, facilitating new drug research and development.

Solitary extramedullary plasmacytomas are uncommon neoplasms. They occur most frequently in the upper aerodigestive tract and account for 4% of the nonepithelial tumors in this site. The evolution of a plasmacytoma is unsteady and symptoms at presentation have included dystonia, dysphagia, oral pain, cough, and dyspnea on exertion. Plasmaeytoma of the upper aerodigestive tract has not been previously reported as a cause of obstructive sleep apnea.

Obstructive sleep apnoea (OSA) is a common disorder characterized by repetitive closure of the upper airway during sleep and associated with significant adverse health effects including hypertension, heart disease and stroke. Current treatment with continuous positive airway pressure (CPAP) is highly effective but reduced compliance levels have resulted in suboptimal outcomes. Oral appliances such as mandibular advancement splints (MAS) are an alternative treatment and have potential advantages including greater patient compliance, comfort and portability. Although they have been shown to be successful across all categories of OSA severity, overall they are less effective than CPAP. A key limitation to its more widespread use has been the inability to predict which patients will be a treatment success. Prediction of treatment outcome would greatly enhance both MAS utilization and overall OSA management. However, little is known about the mechanisms of action of MAS therapy and a more detailed understanding is likely to improve patient selection and outcome. The aim of this thesis is to improve the prediction of treatment outcome through improved understanding of the mechanisms and site(s) of action of MAS therapy during sleep, through extrapolating this knowledge into daytime prediction tests and by developing prediction equations which can be tested prospectively. The work in this thesis presents novel ideas and findings. It is the first to examine and find that MAS therapy improves upper airway collapsibility during sleep. The site(s) of upper airway collapse was also examined and found to predict treatment outcome. Primary oropharyngeal collapse during sleep predicted treatment success and this was extrapolated into a simple daytime test hypothesized to reflect oropharyngeal function. These primary oropharyngeal collapsers were found to have characteristic awake flow-volume curves and this was then studied prospectively. Cephalometric X-rays and anthropomorphic measurements were also evaluated to formulate prediction equations for treatment outcome with MAS. These new findings together with their implications for clinical practice and future research are then summarized. It is concluded, however, that although many advancements have been made, the mechanisms of MAS action and prediction of treatment outcome remain incompletely understood reflecting the complex pathophysiology of the upper airway.

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.

Objective: We aim to improve our understanding of sleep physiology by describing the changes in mandibular position during sleep in normal subjects. Methods: We developed a novel method for mapping mandibular position simultaneously in three dimensions (anteroposterior, vertical and lateral) using magneto-resistive sensors strategically placed around 3 different moving joints on an external apparatus attached to the head and mandible. Spherical coordinates derived from these sensors provided information of jaw position in each of the three measurement planes. We assessed changes in jaw position in twelve healthy subjects (6 male, 6 female) aged (mean ± SD) 23 ± 7 years, Body Mass Index 22.5 ± 3.4 kg/m2, and with nasal resistance 3.24 ± 0.67 cmH2O/L/s by recording mandibular position simultaneously with overnight sleep polysomnography. Results: Jaw position was significantly influenced by sleep stage (p<0.001). The transition from wake to light sleep (stage one) was accompanied by significant jaw closure and jaw protrusion (p<0.05). As non-rapid-eye-movement (NREM) sleep deepened from stages 1 through slow wave sleep (SWS), vertical jaw opening (p<0.05) and posterior jaw movement progressively increased (p<0.05). REM sleep was associated with the greatest degree of jaw opening of all sleep stages (p<0.05). Lateral jaw position was not significantly different between sleep stages. Conclusion: This study describes, for the first time, an accurate method of measuring changes in mandibular position during sleep in all three dimensions. The observed changes during sleep in healthy subjects suggest a simultaneous modulation of upper airway muscular tone, which may be important in the understanding of upper airway occlusion in Obstructive Sleep Apnea. / Thesis (Master, Physiology) -- Queen's University, 2008-08-29 14:27:57.726

The role of dopamine in directly modulating somatic motoneuron excitability and hence muscle tone is unknown. We investigated whether dopamine influences the trigeminal motor pool (MoV) that innervates the masseter and tensor palatini muscles, both of which function to maintain upper airway patency. We hypothesized that dopamine facilitates motor outflow at the MoV. We focally applied apomorphine (nonspecific dopamine receptor agonist) at the MoV in anaesthetized rats. We also applied receptor-specific agonists and antagonists to determine the receptor subtype mediating dopaminergic mechanisms of action. We demonstrated that dopaminergic transmission at the MoV potently increased motor outflow via the D1-like receptor and facilitated masseter and tensor palatini muscle tone. It is unknown whether endogenous dopamine release on to airway motoneurons influences their activity to regulate muscle tone in natural sleep-wake behaviours. This issue warrants investigation because the neurochemical basis of upper airway motor dysfunction (e.g. obstructive sleep apnea) remains poorly characterized.

The role of dopamine in directly modulating somatic motoneuron excitability and hence muscle tone is unknown. We investigated whether dopamine influences the trigeminal motor pool (MoV) that innervates the masseter and tensor palatini muscles, both of which function to maintain upper airway patency. We hypothesized that dopamine facilitates motor outflow at the MoV. We focally applied apomorphine (nonspecific dopamine receptor agonist) at the MoV in anaesthetized rats. We also applied receptor-specific agonists and antagonists to determine the receptor subtype mediating dopaminergic mechanisms of action. We demonstrated that dopaminergic transmission at the MoV potently increased motor outflow via the D1-like receptor and facilitated masseter and tensor palatini muscle tone. It is unknown whether endogenous dopamine release on to airway motoneurons influences their activity to regulate muscle tone in natural sleep-wake behaviours. This issue warrants investigation because the neurochemical basis of upper airway motor dysfunction (e.g. obstructive sleep apnea) remains poorly characterized.

Upper airway endoscopy at rest has been the diagnostic method of choice for diagnosing equine upper respiratory tract (URT) disease since its development in the 1970´s. The development of high-speed treadmill endoscopy (HSTE) improved the sensitivity of URT endoscopy by allowing the examiner to observe the horse’s nasopharynx and larynx during exercise. However, the level of exertion achieved during HSTE may not always represent that achieved during normal exercise as surface, rider, tack, and environmental variables are altered. Recently, the development of dynamic overground endoscopy (DOE) has addressed some of those shortcomings. A retrospective study was undertaken to describe the upper airway abnormalities detected during DOE in horses presenting with poor performance and/or abnormal respiratory noise in South Africa. Patient records of Thoroughbred racehorses undergoing DOE from November 2011 to August 2012 by the Onderstepoort Veterinary Academic Hospital were reviewed. Data collected included signalment, primary complaint, distance exercised, maximum speed attained, and dynamic airway abnormalities detected. XIII A second study was carried out to evaluate agreement within and among examiners of three grading systems for laryngeal function at exercise. The grading systems assessed were an existing system for grading axial deviation of aryepiglottic folds (ADAF), a modified system for grading recurrent laryngeal neuropathy (RLN) at exercise, and a proposed system for grading vocal cord collapse (VCC). For investigation of intra-observer variability, recordings were watched by two of the investigators at the same time, on two different occasions, in real time, slow motion, and at frame-by-frame speed. To evaluate inter-observer variability, recordings were watched by four investigators on one occasion, as described for investigation of intra-observer variability, and scoring sheets completed. Kappa agreement was calculated for both intra- and inter-observer sessions. Fifty-two horses that underwent DOE for investigation of poor performance and/or abnormal respiratory noise were identified. The main abnormalities detected included dorsal displacement of the soft palate (DDSP) (13/52 horses, 25%); recurrent laryngeal neuropathy (RLN) (17/52 horses, 33%); axial deviation of the aryepiglottic folds (ADAF) (21/52 horses, 40%) and vocal cord collapse (VCC) (18/52 horses, 35%). A total of 40 horses presented one or more abnormalities of the URT (77%). Fifteen horses (29%) had a single abnormality, and 25 horses (48%) had multiple abnormalities. Results at frame-by-frame speed from the intra-observer evaluations for all the conditions showed substantial agreement for RLN by both observers (K = 74 - 80). Intra-observer evaluations for VCC were moderate to substantial (K 53 – 63). ADAF was the most difficult URT abnormality to assess for both observers, and agreement within observers was only fair to moderate (K = 36 - 52). Inter-observer evaluations for RLN showed substantial to moderate agreement (K = 62). Inter-observer evaluations for VCC showed moderate agreement (K = 47 – 54), and inter-observer evaluations for ADAF showed only slight to fair agreement and were the lowest for all the conditions (K = 14 – 22). This study showed that DOE is a useful technique for providing valuable information about disease of the URT. Finding multiple abnormalities in 48% of horses examined using DOE suggests that DOE may be indicated even for those horses with an obvious abnormality found during resting endoscopy. The intra-observer evaluations showed that RLN had higher agreement values than those for ADAF and VCC at all speeds, and that ADAF had lower agreement values than those for VCC and RLN at all speeds. Inter-observer agreement was less than intra-observer agreement, presumably because more observers were involved in the inter-observer assessment. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Companion Animal Clinical Studies / unrestricted