Snoring is a highly prevalent disorder affecting 20-40% of adult population. Snoring is also a major indicative of obstructive sleep apnea (OSA). Despite the magnitude of effort, the acoustical properties of snoring in relation to physiological states are not yet known. This thesis explores statistical properties of snoring sounds and their association with OSA. First, an unsupervised technique was developed to automatically extract the snoring sound segments from the lengthy recordings of respiratory sounds. This technique was tested over 5665 snoring sound segments of 30 participants and the detection accuracy of 98.6% was obtained. Second, the relationship between anthropometric parameters of snorers with different degrees of obstruction and their snoring sounds’ statistical characteristics was investigated. Snoring sounds are non-Gaussian in nature; thus second order statistical methods such as power spectral analysis would be inadequate to extract information from snoring sounds. Therefore, higher order statistical features, in addition to the second order ones, were extracted. Third, the variability of snoring sound segments within and between 57 snorers with and without OSA was investigated. It was found that the sound characteristics of non-apneic (when there is no apneic event), hypopneic (when there is hypopnea), and post-apneic (after apnea) snoring events were significantly different. Then, this variability of snoring sounds was used as a signature to discriminate the non-OSA snorers from OSA snorers. The accuracy was found to be 96.4%. Finally, it was observed that some snorers formed distinct clusters of snoring sounds in a multidimensional feature space. Hence, using Polysomnography (PSG) information, the dependency of snoring sounds on body position, sleep stage, and blood oxygen level was investigated. It was found that all the three variables affected snoring sounds. However, body position was found to have the highest effect on the characteristics of snoring sounds. In conclusion, snoring sounds analysis offers valuable information on the upper airway physiological state and pathology. Thus, snoring sound analysis may further find its use in determining the exact state and location of obstruction.

Objectif: Le syndrome d'apnée obstructive du sommeil (SAOS) est de plus en plus présent en Amérique du Nord et a été associé avec certaines maladies chroniques, particulièrement les maladies cardiaques. En première ligne, là où la prévalence de cooccurrence de maladies chroniques est très élevée, l'association potentielle avec l'apnée du sommeil est inconnue. L'objectif de cette étude était d'explorer l'association entre l'apnée obstructive du sommeil et 1) la présence et la gravité de la multimorbidité (cooccurrence de plusieurs maladies chroniques), et 2) des sous-catégories de multimorbidité. Méthode La technique d'échantillonnage en grappe a été utilisée pour recruter 120 patients atteints de SAOS à différents niveaux de gravité et ce, à partir de la base de données d'un laboratoire de sommeil. La gravité de la maladie a été établie grâce aux résultats de la polysomnographie. Les patients, qui furent invités à participer, ont reçu, par la poste, un questionnaire de renseignements sociodémographiques et le questionnaire auto-rapporté Disease Burden Morbidity Assessment (DBMA). L'envoi incluait un formulaire de consentement permettant l'accès au dossier médical afin d'obtenir plusieurs autres informations essentielles. Le DBMA a été utilisé pour avoir un score global de multimorbidité et des sous-scores de maladies qui affectent divers systèmes. Résultats Les analyses bivariées n'ont pas permis de démontrer une association entre l'apnée obstructive du sommeil et la multimorbidité (r = 0,117; p = 0,205). Par contre, le SAOS grave a été associé à la multimorbidité (odds ratio ajustés = 7,3 [1,7-32,2] ; p = 0,05). Le SAOS est modérément corrélé avec des sous-scores de multimorbidité vasculaire (r = 0,26 ; p = 0,01) et de syndrome métabolique (r = 0,26 ; p = 0,01). Conclusion Cette étude démontre que la gravité du SAOS est associée à la gravité de la multimorbidité et à des sous-scores de multimorbidité. Cette recherche ne permet pas d'établir un lien de causalité, d'autres recherches s'imposent pour confirmer ces associations. Toutefois, les intervenants de santé en première ligne devraient être au fait de cette association potentielle et devraient investiguer la présence de l'apnée du sommeil quand cela leur semble approprié.

Snoring is a highly prevalent disorder affecting 20-40% of adult population. Snoring is also a major indicative of obstructive sleep apnea (OSA). Despite the magnitude of effort, the acoustical properties of snoring in relation to physiological states are not yet known. This thesis explores statistical properties of snoring sounds and their association with OSA. First, an unsupervised technique was developed to automatically extract the snoring sound segments from the lengthy recordings of respiratory sounds. This technique was tested over 5665 snoring sound segments of 30 participants and the detection accuracy of 98.6% was obtained. Second, the relationship between anthropometric parameters of snorers with different degrees of obstruction and their snoring sounds’ statistical characteristics was investigated. Snoring sounds are non-Gaussian in nature; thus second order statistical methods such as power spectral analysis would be inadequate to extract information from snoring sounds. Therefore, higher order statistical features, in addition to the second order ones, were extracted. Third, the variability of snoring sound segments within and between 57 snorers with and without OSA was investigated. It was found that the sound characteristics of non-apneic (when there is no apneic event), hypopneic (when there is hypopnea), and post-apneic (after apnea) snoring events were significantly different. Then, this variability of snoring sounds was used as a signature to discriminate the non-OSA snorers from OSA snorers. The accuracy was found to be 96.4%. Finally, it was observed that some snorers formed distinct clusters of snoring sounds in a multidimensional feature space. Hence, using Polysomnography (PSG) information, the dependency of snoring sounds on body position, sleep stage, and blood oxygen level was investigated. It was found that all the three variables affected snoring sounds. However, body position was found to have the highest effect on the characteristics of snoring sounds. In conclusion, snoring sounds analysis offers valuable information on the upper airway physiological state and pathology. Thus, snoring sound analysis may further find its use in determining the exact state and location of obstruction.

BACKGROUND: In children, sleep-related airway obstruction by large tonsils and adenoids can cause obstructive sleep apnea (OSA). OSA may lead to poor growth, developmental delay, behaviour or learning problems. Recent evidence also suggests that children with OSA may develop cardiovascular complications, the mechanisms perhaps involving hypoxemia, the autonomic nervous system, apneas, and arousals. Surgical removal of tonsils and adenoids (adenotonsillectomy (T&A)) usually cures pediatric OSA. To diagnose OSA at all levels of severity, polysomnography is currently the best approach. The McGill Oximetry Score (MOS) is a validated measure based on nocturnal pulse oximetry. An abnormal MOS has a 97% positive predictive value at detecting moderate-severe OSA. Because the MOS was devised by measuring frequency of desaturations (<90%) and numbers of clusters of desaturations, it is not accurate at detecting OSA in children who do not have such drops in oxygen saturation. Accordingly, other measures applicable to a wider spectrum of children should be assessed. These measures should be simpler, less cumbersome, cheaper, and more accessible than polysomnography. / OBJECTIVES: To study alternative approaches that may be used to identify moderate-severe OSA in children, two studies were conducted. We examined one subjective measure - the OSA-18 parent questionnaire - and two objective measures - pulse rate and pulse rate variability. For the OSA-18 study, the goal was to determine whether it would accurately detect children with moderate-severe OSA as indicated by an abnormal MOS. For the pulse rate and pulse rate variability study, the goal was to determine if either or both would decrease after treatment with T&A for children with moderate-severe OSA. / METHODS: For the OSA-18 study, we used a cross-sectional design that included children 1-18 years old referred to a pediatric sleep laboratory for evaluation of suspected OSA. Alongside data from the OSA-18, we analyzed demographic and medical data (from a parent questionnaire) and information regarding adenotonsillar hypertrophy. We estimated sensitivity, specificity, positive and negative predictive values as well as receiver operating curves of the OSA-18 in detecting an abnormal MOS. We also conducted univariate and multivariate logistic regression analyses, using the MOS as the dependent variable and the OSA-18 score and others (age, gender, comorbidities, race) as independent variables. For the second study, we used a retrospective before-after design to compare pulse rate and pulse rate variability as measured by nocturnal pulse oximetry pre- and post-T&A of otherwise healthy children 1-18 years old with moderate-to-severe OSA. / RESULTS: For the OSA-18 study, we studied 334 children (58% male, mean age 4.6 +/- 2.2 years). The OSA-18 had a sensitivity of 40% and a negative predictive value of 73% for detecting an abnormal MOS. In addition, the area under the receiver operating curve was 0.611. While controlling for other independent variables in the logistic regression model, for each unit increase in the OSA-18 Score, the odds of having an abnormal MOS were increased by 2%. However, for each increase in age of 1 year, the odds of having an abnormal MOS were decreased by 17%. In the pulse rate and pulse rate variability study, 25 subjects (88% male; mean age 4.3 +/- 3.6 years) were enrolled. Following T&A, pulse rate and pulse rate variability decreased in 21 of 25 and 23 of 25 children, respectively. Mean pulse rate dropped from 99.7+/-11.2 to 90.1+/-10.7 bpm, p<0.001; age-standardized pulse rate (z-score) from 0.8 (0.4, 1.5) to 0.4 (0, 0.9), p=0.04). Pulse rate variability, as measured by the standard deviation of the pulse rate decreased from 10.3 +/- 2.1 to 8.2 +/- 1.6 bpm, p<0.001. As well, OSA symptomatology, parental concern about breathing during sleep and the MOS all improved. / CONCLUSIONS: Based on the first study we conclude that among children referred to a sleep laboratory, the OSA-18 does not accurately detect which children will have an abnormal MOS. The OSA-18 should not be used in place of objective testing to identify moderate-severe OSA in children. However, from the second study we conclude that measures of the autonomic nervous system such as pulse rate and pulse rate variability, as measured by pulse oximetry, decreased following surgical treatment of moderate-severe OSA. The results of this study potentially serve as important data for further work that would determine the accuracy of pulse rate and pulse rate variability measures and their diagnostic usefulness for OSA at all levels of severity.

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.

No description available.

Background: Obstructive sleep apnea is a common disorder, especially in men. Patients with this condition often snore and suffer from excessive daytime sleepiness. It is a treatable condition related to cardiovascular disease, road traffic accidents and obesity. Aims: To study whether snoring and witnessed sleep apnea are related to diabetes mellitus and whether sleepy subjects who snore or report sleep apneas drive more than others. To investigate whether sleep apnea is related to stroke, mortality and myocardial infarction in patients with coronary artery disease. To study the effect of ambient temperature on sleep apnea, morning alertness and sleep quality in patients with obstructive sleep apnea. Methods and results: Questions on snoring, sleep apnea, daytime sleepiness and yearly driving distance were included in the northern Sweden component of the WHO MONICA study. Analyzed were 7905 randomly selected men and women aged 25-79 years. Snoring and witnessed sleep apnea were related to diabetes mellitus in women, (OR 1.58, p = 0.041 and OR 3.29, p = 0.012 respectively), independent of obesity, age and smoking, but not in men. Sleepy snoring men drove a mean of 22566 km per year which was more than others who drove 17751 km per year independent of age, BMI, smoking and physical activity (p = 0.02). Sleepy men reporting sleep apnea also drove more (p = 0.01). 392 men and women with coronary artery disease referred for coronary angiography were examined with overnight sleep apnea recordings and followed for 10 years. Sleep apnea was recorded in 211 (54%) of patients at baseline. Stroke occurred in 47 (12%) patients at follow up. Sleep apnea was associated with an increased risk of stroke (HR 2.89, 95% CI 1.37 - 6.09, p = 0.005) independent of age , BMI, left ventricular function, diabetes mellitus, gender, intervention, hypertension, atrial fibrillation, a previous stroke or TIA and smoking. The risk of stroke increased with the severity of sleep apnea. 40 patients with obstructive sleep apnea were investigated with overnight polysomnography in ambient temperatures of 16°C, 20°C and 24°C in random order. Total sleep time was a mean of 30 minutes longer (p = 0.009), sleep efficiency higher (p = 0.012), patients were more alert in the morning (p = 0.028), but sleep apnea was more severe when sleeping in 16°C (p = 0.001) and 20°C (p = 0.033) vs. 24°C. The AHI was 30 ± 17 in 16ºC room temperature, 28 ± 17 in 20°C and 24 ± 18 in 24°C. Conclusions: Snoring and witnessed sleep apneas are related to diabetes mellitus in women. Sleepy men who snore or report sleep apnea drive more than others. Sleep apnea is independently associated with the risk of stroke among patients with coronary artery disease. Subjects with obstructive sleep apnea sleep longer, are more alert in the morning after a night’s sleep, but sleep apnea is more severe when sleeping in a colder environment.

Methadone is a long acting mu-opioid and is the most effective treatment for heroin addiction. However, opioids depress respiration and methadone maintenance treatment (MMT) patients have a higher mortality rate than the general population. Teichtahl et al conducted a pilot study and found 6 out of 10 MMT patients had central sleep apnea (CSA). But no definite conclusions were made regarding the prevalence and possible pathogenesis of CSA in the patients due to the small sample size and lack of blood toxicology data. The present project aims to confirm the preliminary results and further quantify the sleep disordered breathing (SDB) in stable MMT patients and to delineate the pathogenesis involved. (For complete abstract open document)

Obstructive Sleep Apnoea (OSA) is a disease characterised by repetitive upper airway obstructions which are manifest by desaturation and arousal from sleep. It has been known for many years that this interruption to the normal architecture of sleep may present to the clinician as excessive daytime somnolence often with a complaint of difficulties with concentration and short term memory. Previous work had demonstrated a relationship between variables of cognitive dysfunction in patients with obstructive sleep apnoea, however, little was known about which components of the syndrome contributed to this outcome and whether specific clinical thresholds of sleep disordered breathing could be defined for the development of cognitive dysfunction. In the context of this body of work cognitive dysfunction is defined as: a level of cognitive performance below normal derived values for a given cognitive test, when the subjects performance is controlled for age, sex and level of education.