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Obstructive sleep apnea (OSA) is estimated to affect 2 to 4 percent of the adult population (Young T 1993, Skomro and Kryger 1999). However, an estimated 80 to 90 percent of adults with moderate to severe OSA may be clinically undiagnosed. Identification of those at risk and their subsequent diagnosis is, obviously, of great concern to clinicians. This investigation included three distinct research aims, which were the following: (1): In order to establish reliability of hemodynamic measures to be used during exercise testing, a study was conducted on the acetylene single-breath cardiac output (Qc) technique in 15 healthy subjects. This was completed in order to establish reliability of exercise Qc and total peripheral resistance (TPR), these responses could then be investigated acutely in the context of evaluating the relation of these measures to markers of disease in OSA patients. (2): The primary research aim was to describe the extent to which graded exercise testing may reveal abnormalities in hemodynamic function in obstructive sleep apnea (OSA) patients, particularly with respect to cardiac output (Qc), mean arterial pressure (MAP), and TPR that may be related to polysomnography (PSG) markers of OSA severity. Cardiorespiratory and hemodynamic responses that were evaluated included the following: peak oxygen consumption (VO2pk), end-tidal carbon dioxide production (PETCO2), end-tidal oxygen pressure (PETO2), heart rate (HR), blood pressure (systolic = SBP and diastolic = DBP), rate pressure product (RPP), TPR and its derivatives including MAP and Qc, in OSA patients. A global biochemical marker of vascular function, 24-hour urinary nitrite/ nitrate elimination was also determined for each patient. (3): The last aim was included in order to provide qualitative information concerning treatment, subjective sleep and daytime function, and physical activity levels of the OSA patients in this investigation as well as to give insights into the special challenges and potential for doing trials involving nCPAP and physical exercise training with OSA patients. Results from this study can be used to improve clinical evaluation procedures as well as to better understand underlying mechanisms relative to the link between cardiovascular disease and OSA / Ph. D.

Continuous positive airway pressure (CPAP) is the primary therapy administered for those afflicted with obstructive sleep apnea (OSA). We examined the effects of CPAP therapy on physiological variables during a ramped exercise. The five male, OSA patients had mean values and standard deviations for RDI=60.7 +/- 19.1, BMI=29.9 +/- 2.9, and age=56 +/- 16.1 yr. Subjects were examined before and after 4 wk of CPAP therapy. After 4 wk of CPAP therapy, patient responses to exercise showed a 17.6%, (p<0.05) improvement in rating of perceived exertion (RPE) at identical power outputs (60% of the individual's apparent functional capacity). Statistical significance was not attained (p>0.05) upon analysis of the following parameters at 60% of the individuals maximum workload although there was a trend showing a decrease in these variables: heart rate (6% improvement), VO2 (11.7% improvement) systolic blood pressure (4% improvement), and rate pressure product (8.6% improvement). This data shows that the decrease in RPE during 60% of the individual's maximum predicted HR reserve corresponded with an increase in sleep quality (mean increase of 40%, 3.2 units) as measured by the Pittsburgh Sleep Quality Index before and after 4 wk of CPAP therapy. It was concluded that the improvement in exercise tolerance could be attributed to the subjective feelings of improved sleep quality after 4 wk of CPAP therapy. Key Words: Obstructive sleep apnea---CPAP--- exercise---physiological responses. / Master of Science

In order to clarify the effects of a single night of CPAP titration on various cardiovascular, gas exchange, and perceptual measures, we conducted submaximal ramping exercise tests to an intensity of ~75% of the heart rate reserve in five male subjects. Means and standard deviation for their age and BMI were 57.0±14.7 years and 30.5±7.2, respectively. The baseline exercise test was administered immediately after the patients arose from bed, following an overnight PSG diagnostic evaluation. The exercise test was repeated within ~2 weeks of completion of an overnight CPAP evaluation trial. Patients reported experiencing improved sleep quality (50%) after the CPAP titration, based on comparison of morning questionnaire responses from the diagnostic PSG vs. CPAP titration. Statistical significance was not attained (p>0.05) upon analysis of the following parameters at 60% of the individuals maximum workload although there were changes in the mean values of the variables from the diagnostic PSG vs CPAP titration. The following changes were noted: heart rate increased by 6%, systolic blood pressure decreased by 6%, and the rate pressure product decreased by 5.8%. Respiratory variables changed as follows: VO2 decreased by 5.3% and VE decreased by 8.5%. The perceptual measure rate of perceived exertion (RPE) decreased by 17.5%. These preliminary findings demonstrate that self-reports of sleep quality in patients with diagnosed OSA improved after a single night of CPAP titration, even in a setting wherein the total time of CPAP sleep and reduction of apneas, hypopneas, and hypoxemic episodes are highly variable. Additionally, sleep structure revealed a marked increase in slow wave (53.2%) and REM (30.4%) sleep with CPAP titration in comparison to the diagnostic PSG. It was concluded that CPAP titration effectively improves sleep structure and patient ratings of sleep quality, but does not have significant effects on cardiorespiratory responses to submaximal endurance exercise. / Master of Science

Obstructive Sleep Apnea (OSA) is becoming an increasingly prevalent health problem, affecting 4% of men and 2% of women in North America. OSA is associated with many debilitating side-effects and co-morbidities; the most common being excessive daytime sleepiness (EDS), which effects the majority of OSA sufferers. EDS is negatively associated with physical activity (PA) and exercise. As a result, EDS may decrease the levels of PA performed by OSA patients. Previous research has revealed that the OSA population engages in less physical activity than the average healthy population. Studies show that CPAP treatment positively impacts EDS, and therefore; may impact PA. The primary purpose of this study was to objectively measure OSA patients' PA levels prior to CPAP treatment and 8 weeks after treatment initiation to assess whether CPAP treatment' impacts PA levels.Actigraph GT 1 M measures PA was assessed at baseline (prior to CPAP) and 8-weeks after. initiation of CPAP treatment. At each time frame, cardiovascular., blood data, body composition, and maximal cycle ergometer exercise measures were obtained. Also, subjective questionnaires, 1 reflective of sleep apnea and 1 regarding PA, were completed by the subjects.Six male subjects with severe OSA (AHI = 41.2 ± 28.4 events/hr) started and completed the study. No significant changes occurred in PA, represented as steps/day nor mean activity counts/day, throughout the 8 weeks of CPAP treatment. Significant changes were found in diastolic blood pressure, total cholesterol, high-density lipoprotein cholesterol, and Epworth sleepiness scale scores. No significant changes occurred in any other body composition, heart rate, systolic blood pressure, triglycerides, and blood glucose. Exercise parameters, total test time, peak Watts, and V02max trended toward an increase and maximal heart rate and blood pressure toward a decrease, but none changed significantly.In conclusion, these results demonstrated that 8 weeks of CPAP treatment was not successful in increasing PA levels of severe OSA patients. The OSA subjects were categorized as sedentary according to their steps/day. Compliance to CPAP could have been an issue with subjects' average nightly usage ranging from 1.85 – 6.6hours/night. Consequently, more research regarding OSA patients PA habits and CPAP treatments effects on PA should be investigated. / School of Physical Education, Sport, and Exercise Science

Childhood OSA is increasingly recognized to be associated with a variety of complications including neurocognitive and cardiovascular diseases. The intermediate link between OSA and end organ damage has been suggested to be inflammation, and both local airway and systemic inflammation have been described in adults with OSA. A non-invasive technique of sputum induction was utilised to show that children with OSA also have airway inflammation, as characterized by a significant increase in neutrophils, and the severity of OSA also correlated significantly with the degree of neutrophilic inflammation (Chapter 7). This finding may lead to research on the use of anti-inflammatory therapeutic agents or antibiotics for the treatment of childhood OSA. Another marker of inflammation, C-reactive protein (CRP) was measured in a cohort of children with OSA before and after treatment (Chapter 8). Children with OSA had higher CRP levels compared to their non-OSA counterparts, and the raised CRP decreased significantly following treatment suggesting that the inflammatory response is potentially reversible. The cardiovascular risk factors of insulin levels and blood pressure (BP) were evaluated and children with OSA had higher serum insulin and greater systolic and diastolic BP compared to healthy controls (Chapters 9 and 10). These findings suggest that children with OSA may be at risk of developing metabolic syndrome and its devastating consequence. (Abstract shortened by UMI.) / The original research studies undertaken were based on nocturnal sleep examinations to explore childhood OSA in two main aspects, namely its assessment, and a better understanding of its complications in children. The gold standard for diagnosing OSA is overnight polysomnography (PSG), which is an expensive investigation that is not routinely available at all public hospitals in Hong Kong. Alternative valid assessment tools for OSA that are more cost-effective are needed. The feasibility of using radiographic techniques to assess severity of OSA was explored, and the size of the upper airway, as reflected by the tonsillar pharyngeal (TP) ratio obtained from lateral neck radiograph, correlated well with the severity of OSA (Chapter 4). A defined TP cutoff could accurately predict moderate-to-severe OSA with high sensitivity and specificity. This method could be used in clinical practice to prioritize patients with suspected OSA for further evaluation. A locally applicable questionnaire scale was examined for its validity and accuracy in diagnosing children with OSA (Chapter 5). The presence of three symptoms (snoring, mouth breathing and nocturnal sweating) was found to have high predictive value in correctly identifying children with the condition. The question of whether a single night PSG study is adequate in diagnosing OSA was examined together with the assessment for the presence of night-to-night variability in PSG and respiratory parameters in childhood sleep (Chapter 6). Forty-four obese children and 43 age and sex-matched healthy controls underwent two consecutive nights PSG examination. Although a first night effect was clearly documented, a single night PSG study would have correctly identified over 80% of children with OSA. This finding has significant resource implications. / Albert Martin Li. / Adviser: Tony Nelson. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3420. / Thesis (M.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves xxxv-lxxx). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English only. / School code: 1307.

Obstructive Sleep Apnea Syndrome (OSAS) is defined as a sleep related breathing disorder that causes the body to stop breathing for about 10 seconds and mostly ends with a loud sound due to the opening of the airway. OSAS is traditionally diagnosed using polysomnography, which requires a whole night stay at the sleep laboratory of a hospital, with multiple electrodes attached to the patient&#039 / s body. Snoring is a symptom which may indicate presence of OSAS / thus investigation of snoring sounds, which can be recorded in the patient&#039 / s own sleeping environment, has become popular in recent years to diagnose OSAS. In this study, we aim to develop a new method to detect post-apnea snoring episodes with the goal of diagnosing apnea or creating a new criteria similar to apnea / hypopnea index. In this method, first segmentation is done to eliminate the silence parts and only deal with active. Then these episodes are represented by distinctive features / some of these features are available in literature but some of them are novel. Finally, these episodes are classified using supervised and unsupervised methods. We are especially interested in detecting post apnea episodes, hence the apnea periods. False alarm rates are reduced by adding additional constraints into the detection algorithm. These methods are applied to snoring sound signals of OSAS patients, recorded in Gulhane Military Medical Academy, to verify the success of our algorithms.

Thesis (Ph. D.)--University of North Texas, Aug., 2009. / Title from title page display. Includes bibliographical references.

Thesis (Ph. D.)--University of Sydney, 2008. / Title from title screen (viewed Mar. 12, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Discipline of Medicine, Faculty of Medicine. Degree awarded 2008; thesis submitted 2007. Includes bibliography. Also issued in print.