Improving automatic detection of obstructive sleep apnea through nonlinear analysis of sustained speech

We present a novel approach for the detection of severe obstructive sleep apnea (OSA) based on patients' voices introducing nonlinear measures to describe sustained speech dynamics. Nonlinear features were combined with state-of-the-art speech recognition systems using statistical modeling techniques (Gaussian mixture models, GMMs) over cepstral parameterization (MFCC) for both continuous and sustained speech. Tests were performed on a database including speech records from both severe OSA and control speakers. A 10 % relative reduction in classification error was obtained for sustained speech when combining MFCC-GMM and nonlinear features, and 33 % when fusing nonlinear features with both sustained and continuous MFCC-GMM. Accuracy reached 88.5 % allowing the system to be used in OSA early detection. Tests showed that nonlinear features and MFCCs are lightly correlated on sustained speech, but uncorrelated on continuous speech. Results also suggest the existence of nonlinear effects in OSA patients' voices, which should be found in continuous speech.

Vocal tract settings in speakers suffering from obstructive sleep apnea síndrome

Automatic systems based on speech signal analysis for the early dete ction of obstructive sleep apnea (OSA) have achieved fairly high performance rates in recent years. However, a satisfactory explanation of these results has not been available. This presentation aims at explaining via an examination of the long-term spectra of OSA patients and normal control speakers these systems’ ability to discover OSA speakers on the base of all-purpose cepstral coefficients. An in terpretation of the long- term spectra in terms of the underlying tract settings suggests that the speech of OSA patients is characterized by a pharyngeal narrowing that may be captured by acoustic cues of the spectral contour of windowed speech frames. A novel interpretation of long-term spectra in terms of the first principal component of the temporal sequence of short-term amplitude-spectra is also discussed.

GMM-based classifiers for the automatic detection of obstructive sleep apnea

The aim of automatic pathological voice detection systems is to serve as tools, to medical specialists, for a more objective, less invasive and improved diagnosis of diseases. In this respect, the gold standard for those system include the usage of a optimized representation of the spectral envelope, either based on cepstral coefficients from the mel-scaled Fourier spectral envelope (Mel-Frequency Cepstral Coefficients) or from an all-pole estimation (Linear Prediction Coding Cepstral Coefficients) forcharacterization, and Gaussian Mixture Models for posterior classification. However, the study of recently proposed GMM-based classifiers as well as Nuisance mitigation techniques, such as those employed in speaker recognition, has not been widely considered inpathology detection labours. The present work aims at testing whether or not the employment of such speaker recognition tools might contribute to improve system performance in pathology detection systems, specifically in the automatic detection of Obstructive Sleep Apnea. The testing procedure employs an Obstructive Sleep Apnea database, in conjunction with GMM-based classifiers looking for a better performance. The results show that an improved performance might be obtained by using such approach.

Tratamiento quirúrgico del síndrome de apnea hipopnea obstructiva del sueño en la Clínica Rivas, Bogotá – Colombia

Introducción: El Síndrome de Apnea Hipopnea Obstructiva del Sueño es un trastorno respiratorio del sueño mayor ampliamente conocido, con importantes implicaciones para los pacientes y cuya incidencia ha venido en aumento durante los últimos años; comprende diversas manifestaciones clínicas que varían desde el ronquido hasta consecuencias cardiovasculares importantes. Objetivo: Describir la experiencia de los procedimientos quirúrgicos más utilizados para el tratamiento de pacientes con Trastornos Respiratorios del Sueño en la Clínica Rivas. Diseño: Estudio observacional descriptivo. Métodos: Revisión de 366 historias clínicas de pacientes con diagnóstico clínico y Polisomnográfico de SAHOS intervenidos quirúrgicamente debido al Trastorno Respiratorio del Sueño por rechazo de terapia de presión positiva en 3 años de observación. Resultados: Se evaluaron diferencias en medianas de los cambios del IAH, índice de Saturación de oxigeno basal y mínima, y el índice de microdespertares nocturnos tanto prequirúrgica como postquirúrgicamente. Como medida de evaluación secundaria se evaluaron las complicaciones quirúrgicas. Conclusión: En nuestra institución, como centro de referencia en apnea del sueño, la cirugía ha demostrado que disminuye de forma significativa gravedad del SAHOS y disminuye el riesgo de los pacientes con trastornos respiratorios del sueño que han rechazado el dispositivo de presión positiva.

Adjustment of apnea-hypopnea index with severity of obstruction events enhances detection of sleep apnea patients with the highest risk of severe health consequences

Introduction Presently, the severity of obstructive sleep apnea (OSA) is estimated based on the apnea-hypopnea index (AHI). Unfortunately, AHI does not provide information on the severity of individual obstruction events. Previously, the severity of individual obstruction events has been suggested to be related to the outcome of the disease. In this study, we incorporate this information into AHI and test whether this novel approach would aid in discriminating patients with the highest risk. We hypothesize that the introduced adjusted AHI parameter provides a valuable supplement to AHI in the diagnosis of the severity of OSA. Methods This hypothesis was tested by means of retrospective follow-up (mean ± sd follow-up time 198.2 ± 24.7 months) of 1,068 men originally referred to night polygraphy due to suspected OSA. After exclusion of the 264 patients using CPAP, the remaining 804 patients were divided into normal (AHI < 5) and OSA (AHI ≥ 5) categories based on conventional AHI and adjusted AHI. For a more detailed analysis, the patients were divided into normal, mild, moderate, and severe OSA categories based on conventional AHI and adjusted AHI. Subsequently, the mortality and cardiovascular morbidity in these groups were determined. Results Use of the severity of individual obstruction events for adjustment of AHI led to a significant rearrangement of patients between severity categories. Due to this rearrangement, the number of deceased patients diagnosed to have OSA was increased when adjusted AHI was used as the diagnostic index. Importantly, risk ratios of all-cause mortality and cardiovascular morbidity were higher in moderate and severe OSA groups formed based on the adjusted AHI parameter than in those formed based on conventional AHI. Conclusions The adjusted AHI parameter was found to give valuable supplementary information to AHI and to potentially improve the recognition of OSA patients with the highest risk of mortality or cardiovascular morbidity.

Polysomnografic findings of obstrutive sleep apnea in children with adenotonsillar hypertrophy

Serous Background: There are few studies assessing the clinical manifestations of sleep breathing disorders and polysomnograms in several pediatric age ranges. This studied aimed to assess polysomnography results such as apnea-hypopnea index, mean oxygen saturation and sleep efficiency in children presenting with airway obstruction and adenotonsillar hypertrophy complaints, and to establish whether they are correlated to age and sex. Methods: A retrospective study with children of both sexes, aged between 2 and 12 years, with clinically suspected obstructive sleep apnea syndrome and adenotonsillar hypertrophy, who underwent polysomnography before surgery. The children were allocated to groups according to their age range (Group I: 2 to 4 years old; Group II: 5 to 8 years old; Group III: 9 to 12 years old). Apnea-hypopnea index, mean oxygen saturation and sleep efficiency data were compared between sexes and among the three groups (Student’s t test, p < 0.05). Results: Of 167 children studied by polysomnography, 76.6% were of school age and 67% were male. For all studied age ranges, there was no difference between sexes for the investigated parameters (body mass index, apnea-hypopnea index, mean oxygen saturation and sleep efficiency). As regards mean oxygen saturation, Group I showed the lowest value (89.9 ± 6.2). Apnea-hypopnea indexes were higher in male children aged between 2 and 4 years (9.9 ± 5.2). Group III had the lowest sleep efficiency (84.1 ± 9.2). Conclusion: There was a predilection of more severe cases of obstructive sleep apnea syndrome for children younger than four years, shown by higher apnea-hypopnea index per hour and lower mean oxygen saturation in this age range.

Analysis of cerebral and autonomic response to respiratory events in patients with Sleep Apnea Syndrome

The arousal scoring in Obstructive Sleep Apnea Syndrome (OSAS) is important to clarify the impact of the disease on sleep but the currently applied American Academy of Sleep Medicine (AASM) definition may underestimate the subtle alterations of sleep. The aims of the present study were to evaluate the impact of respiratory events on cortical and autonomic arousal response and to quantify the additional value of cyclic alternating pattern (CAP) and pulse wave amplitude (PWA) for a more accurate detection of respiratory events and sleep alterations in OSAS patients. A retrospective revision of 19 polysomnographic recordings of OSAS patients was carried out. Analysis was focused on quantification of apneas (AP), hypopneas (H) and flow limitation (FL) events, and on investigation of cerebral and autonomic activity. Only 41.1% of FL events analyzed in non rapid eye movement met the AASM rules for the definition of respiratory event-related arousal (RERA), while 75.5% of FL events ended with a CAP A phase. The dual response (EEG-PWA) was the most frequent response for all subtypes of respiratory event with a progressive reduction from AP to H and FL. 87.7% of respiratory events with EEG activation showed also a PWA drop and 53,4% of the respiratory events without EEG activation presented a PWA drop. The relationship between the respiratory events and the arousal response is more complex than that suggested by the international classification. In the estimation of the response to respiratory events, the CAP scoring and PWA analysis can offer more extensive information compared to the AASM rules. Our data confirm also that the application of PWA scoring improves the detection of respiratory events and could reduce the underestimation of OSAS severity compared to AASM arousal.

Snoring and sleep apnea in children

Snoring is a primary and major clinical symptom of upper airway obstruction during sleep. Sleep-disordered breathing ranges from primary snoring to significant partial upper airway obstruction, and obstructive sleep apnea. Adult snoring and obstructive sleep apnea have been extensively studied, whereas less is known about these disorders in children. Snoring and more severe obstructive sleep apnea have been shown to have a harmful effect on the neurobehavioral development of children, but the mechanisms of this effect remains unknown. Furthermore, the correlation of this effect to objective sleep study parameters remains poor. This study evaluated the prevalence of snoring in preschool-aged children in Finland. Host and environmental risk factors, and neurobehavioral and neurocognitive symptoms of children suffering from snoring or obstructive sleep apnea were also investigated. The feasibility of acoustic rhinometry in young children was assessed. The prevalence and risk factors of snoring (I) were evaluated by a questionnaire. The random sample included 2100 children aged 1-6 years living in Helsinki. All 3- to 6-year-old children whose parents reported their child to snore always, often, or sometimes were categorized as snorers, and invited to participate to the clinical study (II-IV). Non-snoring children whose parents were willing to participate in the clinical study were invited to serve as controls. Children underwent a clinical ear-nose-throat examination. Emotional, behavioral, and cognitive performances were evaluated by Child Behavioral Checklist (CBCL), Wechsler Preschool and Primary Scale of Intelligence (WPPSI-R) and NEPSY-A Developmental Neuropsychological Assessment (NEPSY). Nasal volume was measured by acoustic rhinometry, and nasal resistance by rhinomanometry. Lateral and posteroanterior cephalometry were performed. A standard overnight ambulatory polysomnography was performed in the home environment. Twenty-six healthy children were tested in order to assess the feasibility of acoustic rhinometry in young children (V). Snoring was common in children; 6.3% of children snored always or often, whereas 81.3% snored never or occasionally. No differences were apparent between snorers and non-snorers regarding age, or gender. Pediatric snoring was associated with recurrent upper respiratory infections, otitis media, and allergic rhinitis. Exposure to parental tobacco smoke, especially maternal smoking, was more common among snorers. Rhinitis was more common among children who exposured to tobacco smoke. Overnight polysomnography (PSG) was performed on 87 children; 74% showed no signs of significant upper airway obstruction during sleep. Three children had obstructive apnea/hypopnea index (OAHI) greater than 5/h. Age, gender, or a previous adenoidectomy or tonsillectomy did not correlate with OAHI, whereas tonsillar size did correlate with OAHI. Relative body weight and obesity correlated with none of the PSG parameters. In cephalometry, no clear differences or correlations were found in PSG parameters or between snorers and non-snorers. No correlations were observed between acoustic rhinometry, rhinomanometry, and PSG parameters. Psychiatric symptoms were more frequent in the snoring group than in the nonsnoring group. In particular, anxious and depressed symptoms were more prevalent in the snoring group. Snoring children frequently scored lower in language functions. However, PSG parameters correlated poorly with neurocognitive test results in these children. This study and previous studies indicate that snoring without episodes of obstructive apnea or SpO2 desaturations may cause impairment in behavioral and neurocognitive functions. The mechanism of action remains unknown. Exposure to parental tobacco smoke is more common among snorers than non-snorers, emphasizing the importance of a smoke-free environment. Children tolerated acoustic rhinometry measurements well.

Oximetry alone versus portable polygraphy for sleep apnea screening before bariatric surgery.

BACKGROUND: Screening for obstructive sleep apnea (OSA) is recommended as part of the preoperative assessment of obese patients scheduled for bariatric surgery. The objective of this study was to compare the sensitivity of oximetry alone versus portable polygraphy in the preoperative screening for OSA. METHODS: Polygraphy (type III portable monitor) and oximetry data recorded as part of the preoperative assessment before bariatric surgery from 68 consecutive patients were reviewed. We compared the sensitivity of 3% or 4% desaturation index (oximetry alone) with the apnea-hypopnea index (AHI; polygraphy) to diagnose OSA and classify the patients as normal (<10 events per hour), mild to moderate (10-30 events per hour), or severe (>30 events per hour). RESULTS: Using AHI, the prevalence of OSA (AHI > 10 per hour) was 57.4%: 16.2% of the patients were classified as severe, 41.2% as mild to moderate, and 42.6% as normal. Using 3% desaturation index, 22.1% were classified as severe, 47.1% as mild to moderate, and 30.9% as normal. With 4% desaturation index, 17.6% were classified as severe, 32.4% as mild, and 50% as normal. Overall, 3% desaturation index compared to AHI yielded a 95% negative predictive value to rule out OSA (AHI > 10 per hour) and a 100% sensitivity (0.73 positive predictive value) to detect severe OSA (AHI > 30 per hour). CONCLUSIONS: Using oximetry with 3% desaturation index as a screening tool for OSA could allow us to rule out significant OSA in almost a third of the patients and to detect patients with severe OSA. This cheap and widely available technique could accelerate preoperative work-up of these patients.

Percepción de calidad de vida relacionada con la salud en pacientes con síndrome de apnea e hipoapnea obstructiva del sueño

El objetivo de esta investigación es describir la calidad de vida y la calidad del sueño en los pacientes con diagnóstico de Síndrome de Apnea Hipoapnea del sueño, mediante el uso de un grupo de cuestionarios para obtener datos demográficos, la evaluación del grado de somnolencia diurna percibida, la percepción de la calidad del sueño y la percepción de la calidad de vida relacionada con la salud con encuestas en sus respectivas versiones validadas para Colombia.

Complete denture wear during sleep in elderly sleep apnea patients-a preliminary study

There is no consensus in the literature about the impact of complete denture wear on obstructive sleep apnea (OSA). The goal of this randomized clinical study was to assess if complete denture wear during sleep interferes with the quality of sleep. Elderly edentulous OSA patients from a complete denture clinic were enrolled and received new complete dentures. An objective sleep analysis was determined with polysomnography performed at the sleep laboratory for all patients who slept either with or without their dentures. Twenty-three patients (74% females) completed the study with a mean age of 69.6 years and a mean body mass index of 26.7 kg/m(2). The apnea and hypopnea index (AHI) was significantly higher when patients slept with dentures compared to without (25.9 +/- 14.8/h vs. 19.9 +/- 10.2/h; p > 0.005). In the mild OSA group, the AHI was significantly higher when patients slept with the dentures (16.6 +/- 6.9 vs. 8.9 +/- 2.4; p < 0.05), while in moderate to severe OSA patients, the AHI was not significantly different when sleeping with dentures (.30.8 +/- 15.6 vs. 25.7 +/- 7.5; p = 0.2). The supine AHI in mild patients was related to a higher increase in AHI while wearing dentures (12.7 +/- 8.4/h vs. 51.9 +/- 28.6/h; p < 0.001). A limitation of the study is that the mild OSA patients had a higher BMI when compared to the moderate to severe OSA patients. Ten out of 14 patients who preferred to sleep with their upper and lower dentures showed an increase in their AHI while wearing dentures to sleep. Contrary to previous studies, we found that OSA patients may experience more apneic events if they sleep with their dentures in place. Specifically, in mild OSAS patients, the use of dentures substantially increases the AHI especially when in the supine position.