Bone mineral density alteration in obstructive sleep apnea by derived computed tomography screening

The association between obstructive sleep apnea (OSA) and bone mineral density (BMD) is poorly elucidated and has contradictory findings. Abdominal computed tomography (CT) for other indications can provide a valuable opportunity for osteoporosis screening. Thus, we retrospectively explored the association between OSA and BMD by examining abdominal CT vertebrae images for a multitude of conditions and indications. We included 315 subjects (174 with OSA and 141 without OSA) who performed at least two CT scans (under similar settings). Both groups had a similar duration between the first and second CT scans of 3.6 years. BMD decreased in those with OSA and increased age. A multivariate linear regression indicated that OSA is associated with BMD alterations after controlling for age, gender, and cardiovascular diseases. Here, we report that OSA is associated with BMD alterations. Further studies are required to untangle the complex affect of OSA on BMD and the possible clinical implications of vertebra-depressed or femoral neck fractures.

Obstructive sleep apnea and metabolic disorders in morbidly obese adolescents

BACKGROUND

Little known about the prevalence of obstructive sleep apnea (OSA) in morbid obese adolescents and the association between OSA and comorbid factors.

AIM

To examine the association between apnea-hypopnea index (AHI, a measure for OSA severity) and metabolic morbidity among morbidly obese adolescents.

METHODS

We performed a population-based retrospective cohort study by reviewing sleep study, metabolic indices, and comorbidity-related data of a cohort (n = 106) of adolescents referred to a bariatric surgery clinic. We compared subjects with moderate/severe OSA (AHI ≥ 5) versus no/mild OSA (AHI < 5) OSA and three groups of subjects with increasing body mass index (BMI) concerning sleep-study and metabolic indices using univariate analyses. To assess the link between AHI and ferritin levels a multivariate linear regression (adjusted for BMI and mean cell volume) was preformed.

RESULTS

A total of 71 patients met the inclusion criteria. Subjects with moderate/severe OSA (n = 32, 45%) had higher BMI, cholesterol, cholesterol/high-density lipoprotein (HDL) ratio, hemoglobin A1c, and serum ferritin levels (p < .05). AHI significantly increased across BMI strata (p = .02). Multivariate linear regression indicated that moderate/severe OSA was associated with higher levels of ferritin, unstandardized β = 49.1 (nIU/ml) (p = .025).

CONCLUSIONS

Morbidly obese adolescents with moderate/severe OSA versus no/mild OSA have a higher risk for metabolic complications. Therefore, OSA management should be considered in adolescents with morbid obesity, in addition to weight loss.

Changes in energy metabolism and respiration in different tracheal narrowing in rats

Why obstructive sleep apnea (OSA) treatment does not completely restore healthy metabolic physiology is unclear. In rats, the need for respiratory homeostasis maintenance following airway obstruction (AO) is associated with a loss of thermoregulation and abnormal metabolic physiology that persists following successful obstruction removal. Here, we explored the effect of two different types of tracheal narrowing, i.e., AO and mild airway obstruction (mAO), and its removal on respiratory homeostasis and metabolic physiology. We show that after ten weeks, mAO vs. AO consumes sufficient energy that is required to maintain respiratory homeostasis and thermoregulation. Obstruction removal was associated with largely irreversible increased feeding associated with elevated serum ghrelin, hypothalamic growth hormone secretagogue receptor 1a, and a phosphorylated Akt/Akt ratio, despite normalization of breathing and energy requirements. Our study supports the need for lifestyle eating behavior management, in addition to endocrine support, in order to attain healthy metabolic physiology in OSA patients.

Altered slow-wave sleep activity in children with rapid-onset obesity with hypothalamic dysregulation, hypoventilation, and autonomic dysregulation syndrome

STUDY OBJECTIVES

Rapid-onset obesity with hypothalamic dysregulation, hypoventilation, and autonomic dysregulation (ROHHAD) is a rare condition. Little is known about sleep/wake and slow-wave activity in this condition, although the central hypothalamic dysfunction associated with autonomic dysregulation would make the occurrence of SWA deregulation most likely.

METHODS

Two children with clinical presentation of ROHHAD syndrome were evaluated, diagnosed, and treated. Their polysomnographic studies were compared with 4 matched children with obstructive sleep apnea and 6 controls.

RESULTS

Children that were clinically diagnosed with ROHHAD exhibited significantly weaker slow-wave activity power and shallower slow-wave activity slopes during the first 2 sleep cycles compared with children with obstructive sleep apnea or controls.

CONCLUSIONS

This study shows that children with ROHHAD have suppressed slow-wave activity, possibly because of hypothalamic dysregulation that may contribute to their rapid-onset obesity and excessive daytime sleepiness.

0128 Mild Upper Airway Obstruction Leads to Increased Energy Intake and Growth Retardation that Persists After the Obstruction Removal

Introduction

Whereas pediatric obstructive sleep apnea may cause insufficient body weight gain and growth retardation, in some studies, metabolic syndrome and obesity were observed. Interestingly, treatment by adenotonsillectomy can lead to accelerated weight gain by an unclear mechanism. Here, we explored the effects of moderate upper airway obstruction (AO) and mild AO (mAO) and its removal (OR) on ventilation, resting energy expenditure (REE), food intake and growth during the diurnal cycle, from weaning to adulthood.

Methods

The trachea of 22-day-old rats was surgically narrowed to generate AO, mAO, and OR was performed after two weeks on mAO animals. Minute ventilation was recorded by whole body plethysmography and diurnal food intake, and REE was explored with metabolic cages 12 weeks post surgery.

Results

Following tracheal narrowing, inspiratory swings in esophageal pressure increased by 177% (p&lt;0.01) and 36% (p&lt;0.01) in AO and mAO rats, respectively, and was similar to the controls in the OR group. REE (Kcal/h/kg) was 3.7±0.1, 5.7±0.12 (p&lt;0.01), 4.1±0.08 (p&lt;0.01), and 3.6±0.15 in the control, AO, mAO, and OR groups, respectively. Increased EE in the AO and mAO groups was associated with up-regulation of ventilation by 133% and 56%, respectively (p&lt;0.01). In all groups, energy intake (EE) was higher during a 12 h active period compared to a sleep period (p&lt;0.01). EE during the lights on of AO and mAO animals increased by 136 % and 126%, respectively, and was similar to the control in the OR group. Active period EE increased by 19% in both obstructed groups (p&lt;0.01). Active period EE was 16.7 % higher in the OR group despite the normalization of ventilation and tracheal diameter to the control value. Increased REE was associated with hindrance of bone elongation (p&lt;0.01), and OR partially improved growth.

Conclusion

The need to maintain respiratory homeostasis during upper airway obstruction was associated with a persistent increase in energy intake. Surgical intervention may not be sufficient to correct the energy intake elevation, and endocrine regulation of feeding and growth may have greater impacts post intervention.

Support

This study was supported by the Israel Science Foundation grant no. 164/2018

Upper Airway Obstruction Elicited Energy Imbalance Leads to Growth Retardation that Persists after the Obstruction Removal

Upper airway obstruction can lead to growth retardation by unclear mechanisms. We explored the effect of upper airway obstruction in juvenile rats on whole-body energy balance, growth plate metabolism, and growth. We show that after seven weeks, obstructed animals’ ventilation during room air breathing increased, and animals grew less due to abnormal growth plate metabolism. Increased caloric intake in upper airway-obstructed animals did not meet increased energy expenditure associated with increased work of breathing. Decreased whole-body energy balance induced hindrance of bone elongation following obstruction removal, and array pathways regulating growth plate development and marrow adiposity. This is the first study to show that rapidly growing animals cannot consume enough calories to maintain their energy homeostasis, leading to an impediment in growth in the effort to save energy.

Irreversible metabolic abnormalities following chronic upper airway loading

STUDY OBJECTIVES

Treatment of obstructive sleep apnea increases obesity risk by an unclear mechanism. Here, we explored the effects of upper airway obstruction and its removal on respiratory homeostasis, energy expenditure, and feeding hormones during the sleep/wake cycle from weaning to adulthood.

METHODS

The tracheas of 22-day-old rats were narrowed, and obstruction removal was performed on post-surgery day 14. Energy expenditure, ventilation, and hormone-regulated feeding were analyzed during 49 days before and after obstruction.

RESULTS

Energy expenditure increased and body temperature decreased in upper airway obstruction and was only partially recovered in obstruction removal despite normalization of airway resistance. Increased energy expenditure was associated with upregulation of ventilation. Decreased body temperature was associated with decreased brown adipose tissue uncoupling protein 1 level, suppressed energy expenditure response to norepinephrine, and decreased leptin level. Upper airway obstructed animals added less body weight, in spite of an increase in food intake, due to elevated hypothalamic orexin and neuropeptide Y and plasma ghrelin. Animals who underwent obstruction removal fed more due to an increase in hypothalamic neuropeptide Y and plasma ghrelin.

CONCLUSIONS

The need to maintain respiratory homeostasis is associated with persistent abnormal energy metabolism and hormonal regulation of feeding. Surgical treatment per se may not be sufficient to correct energy homeostasis, and endocrine regulation of feeding may have a larger effect on weight change.

Reduced sleep pressure in young children with autism

Study Objectives

Sleep disturbances and insomnia are highly prevalent in children with Autism Spectrum Disorder (ASD). Sleep homeostasis, a fundamental mechanism of sleep regulation that generates pressure to sleep as a function of wakefulness, has not been studied in children with ASD so far, and its potential contribution to their sleep disturbances remains unknown. Here, we examined whether slow-wave activity (SWA), a measure that is indicative of sleep pressure, differs in children with ASD.

Methods

In this case-control study, we compared overnight electroencephalogram (EEG) recordings that were performed during Polysomnography (PSG) evaluations of 29 children with ASD and 23 typically developing children.

Results

Children with ASD exhibited significantly weaker SWA power, shallower SWA slopes, and a decreased proportion of slow-wave sleep in comparison to controls. This difference was largest during the first 2 hours following sleep onset and decreased gradually thereafter. Furthermore, SWA power of children with ASD was significantly negatively correlated with the time of their sleep onset in the lab and at home, as reported by parents.

Conclusions

These results suggest that children with ASD may have a dysregulation of sleep homeostasis that is manifested in reduced sleep pressure. The extent of this dysregulation in individual children was apparent in the amplitude of their SWA power, which was indicative of the severity of their individual sleep disturbances. We, therefore, suggest that disrupted homeostatic sleep regulation may contribute to sleep disturbances in children with ASD.

Oxygen and Carbon Dioxide Rhythms Are Circadian Clock Controlled and Differentially Directed by Behavioral Signals

Daily rhythms in animal physiology are driven by endogenous circadian clocks in part through rest-activity and feeding-fasting cycles. Here, we examined principles that govern daily respiration. We monitored oxygen consumption and carbon dioxide release, as well as tissue oxygenation in freely moving animals to specifically dissect the role of circadian clocks and feeding time on daily respiration. We found that daily rhythms in oxygen and carbon dioxide are clock controlled and that time-restricted feeding restores their rhythmicity in clock-deficient mice. Remarkably, day-time feeding dissociated oxygen rhythms from carbon dioxide oscillations, whereby oxygen followed activity, and carbon dioxide was shifted and aligned with food intake. In addition, changes in carbon dioxide levels altered clock gene expression and phase shifted the clock. Collectively, our findings indicate that oxygen and carbon dioxide rhythms are clock controlled and feeding regulated and support a potential role for carbon dioxide in phase resetting peripheral clocks upon feeding.

Sleep staging using nocturnal sound analysis

Sleep staging is essential for evaluating sleep and its disorders. Most sleep studies today incorporate contact sensors that may interfere with natural sleep and may bias results. Moreover, the availability of sleep studies is limited, and many people with sleep disorders remain undiagnosed. Here, we present a pioneering approach for rapid eye movement (REM), non-REM, and wake staging (macro-sleep stages, MSS) estimation based on sleep sounds analysis. Our working hypothesis is that the properties of sleep sounds, such as breathing and movement, within each MSS are different. We recorded audio signals, using non-contact microphones, of 250 patients referred to a polysomnography (PSG) study in a sleep laboratory. We trained an ensemble of one-layer, feedforward neural network classifiers fed by time-series of sleep sounds to produce real-time and offline analyses. The audio-based system was validated and produced an epoch-by-epoch (standard 30-sec segments) agreement with PSG of 87% with Cohen's kappa of 0.7. This study shows the potential of audio signal analysis as a simple, convenient, and reliable MSS estimation without contact sensors.

Abnormal Growth and Feeding Behavior in Upper Airway Obstruction in Rats

Pediatric obstructive sleep apnea (OSA) is a syndrome manifesting with snoring and increased respiratory effort due to increased upper airway resistance. In addition to cause the abnormal sleep, this syndrome has been shown to elicit either growth retardation or metabolic syndrome and obesity. Treating OSA by adenotonsillectomy is usually associated with increased risk for obesity, despite near complete restoration of breathing and sleep. However, the underlying mechanism linking upper airways obstruction (AO) to persistent change in food intake, metabolism, and growth remains unclear. Rodent models have examined the impact of intermittent hypoxia on metabolism. However, an additional defining feature of OSA that is not related to intermittent hypoxia is enhanced respiratory loading leading to increased respiratory effort and abnormal sleep. The focus of this mini review is on recent evidence indicating the persistent abnormalities in endocrine regulation of feeding and growth that are not fully restored by the chronic upper AO removal in rats. Here, we highlight important aspects related to abnormal regulation of metabolism that are not related to intermittent hypoxia per se, in an animal model that mimics many of the clinical features of pediatric OSA. Our evidence from the AO model indicates that obstruction removal may not be sufficient to prevent the post-removal tendency for abnormal growth.

Estimation of macro sleep stages from whole night audio analysis

During routine sleep diagnostic procedure, sleep is broadly divided into three states: rapid eye movement (REM), non-REM (NREM) states, and wake, frequently named macro-sleep stages (MSS). In this study, we present a pioneering attempt for MSS detection using full night audio analysis. Our working hypothesis is that there might be differences in sound properties within each MSS due to breathing efforts (or snores) and body movements in bed. In this study, audio signals of 35 patients referred to a sleep laboratory were recorded and analyzed. An additional 178 subjects were used to train a probabilistic time-series model for MSS staging across the night. The audio-based system was validated on 20 out of the 35 subjects. System accuracy for estimating (detecting) epoch-by-epoch wake/REM/NREM states for a given subject is 74% (69% for wake, 54% for REM, and 79% NREM). Mean error (absolute difference) was 36±34 min for detecting total sleep time, 17±21 min for sleep latency, 5±5% for sleep efficiency, and 7±5% for REM percentage. These encouraging results indicate that audio-based analysis can provide a simple and comfortable alternative method for ambulatory evaluation of sleep and its disorders.

Obstructive sleep apnea severity estimation: Fusion of speech-based systems

Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder. Previous studies associated OSA with anatomical abnormalities of the upper respiratory tract that may be reflected in the acoustic characteristics of speech. We tested the hypothesis that the speech signal carries essential information that can assist in early assessment of OSA severity by estimating apnea-hypopnea index (AHI). 198 men referred to routine polysomnography (PSG) were recorded shortly prior to sleep onset while reading a one-minute speech protocol. The different parts of the speech recordings, i.e., sustained vowels, short-time frames of fluent speech, and the speech recording as a whole, underwent separate analyses, using sustained vowels features, short-term features, and long-term features, respectively. Applying support vector regression and regression trees, these features were used in order to estimate AHI. The fusion of the outputs of the three subsystems resulted in a diagnostic agreement of 67.3% between the speech-estimated AHI and the PSG-determined AHI, and an absolute error rate of 10.8 events/hr. Speech signal analysis may assist in the estimation of AHI, thus allowing the development of a noninvasive tool for OSA screening.

Breathing and Snoring Sound Characteristics during Sleep in Adults

STUDY OBJECTIVES

Sound level meter is the gold standard approach for snoring evaluation. Using this approach, it was established that snoring intensity (in dB) is higher for men and is associated with increased apnea-hypopnea index (AHI). In this study, we performed a systematic analysis of breathing and snoring sound characteristics using an algorithm designed to detect and analyze breathing and snoring sounds. The effect of sex, sleep stages, and AHI on snoring characteristics was explored.

METHODS

We consecutively recruited 121 subjects referred for diagnosis of obstructive sleep apnea. A whole night audio signal was recorded using noncontact ambient microphone during polysomnography. A large number (> 290,000) of breathing and snoring (> 50 dB) events were analyzed. Breathing sound events were detected using a signal-processing algorithm that discriminates between breathing and nonbreathing (noise events) sounds.

RESULTS

Snoring index (events/h, SI) was 23% higher for men (p = 0.04), and in both sexes SI gradually declined by 50% across sleep time (p < 0.01) independent of AHI. SI was higher in slow wave sleep (p < 0.03) compared to S2 and rapid eye movement sleep; men have higher SI in all sleep stages than women (p < 0.05). Snoring intensity was similar in both genders in all sleep stages and independent of AHI. For both sexes, no correlation was found between AHI and snoring intensity (r = 0.1, p = 0.291).

CONCLUSIONS

This audio analysis approach enables systematic detection and analysis of breathing and snoring sounds from a full night recording. Snoring intensity is similar in both sexes and was not affected by AHI.

Breathing rate estimation during sleep using audio signal analysis

Sleep is associated with important changes in respiratory rate and ventilation. Currently, breathing rate (BR) is measured during sleep using an array of contact and wearable sensors, including airflow sensors and respiratory belts; there is need for a simplified and more comfortable approach to monitor respiration. Here, we present a new method for BR evaluation during sleep using a non-contact microphone. The basic idea behind this approach is that during sleep the upper airway becomes narrower due to muscle relaxation, which leads to louder breathing sounds that can be captured via ambient microphone. In this study we developed a signal processing algorithm that emphasizes breathing sounds, extracts breathing-related features, and estimates BR during sleep. A comparison between audio-based BR estimation and BR calculated using the traditional (gold-standard) respiratory belts during in-laboratory polysomnography (PSG) study was performed on 204 subjects. Pearson's correlation between subjects' averaged BR of the two approaches was R=0.97. Epoch-by-epoch (30 s) BR comparison revealed a mean relative error of 2.44% and Pearson's correlation of 0.68. This study shows reliable and promising results for non-contact BR estimation.

Can we discriminate between apnea and hypopnea using audio signals?

Obstructive sleep apnea (OSA) affects up to 14% of the population. OSA is characterized by recurrent apneas and hypopneas during sleep. The apnea-hypopnea index (AHI) is frequently used as a measure of OSA severity. In the current study, we explored the acoustic characteristics of hypopnea in order to distinguish it from apnea. We hypothesize that we can find audio-based features that can discriminate between apnea, hypopnea and normal breathing events. Whole night audio recordings were performed using a non-contact microphone on 44 subjects, simultaneously with the polysomnography study (PSG). Recordings were segmented into 2015 apnea, hypopnea, and normal breath events and were divided to design and validation groups. A classification system was built using a 3-class cubic-kernelled support vector machine (SVM) classifier. Its input is a 36-dimensional audio-based feature vector that was extracted from each event. Three-class accuracy rate using the hold-out method was 84.7%. A two-class model to separate apneic events (apneas and hypopneas) from normal breath exhibited accuracy rate of 94.7%. Here we show that it is possible to detect apneas or hypopneas from whole night audio signals. This might provide more insight about a patient's level of upper airway obstruction during sleep. This approach may be used for OSA severity screening and AHI estimation.

Detection of breathing sounds during sleep using non-contact audio recordings

Evaluation of respiratory activity during sleep is essential in order to reliably diagnose sleep disorder breathing (SDB); a condition associated with serious cardio-vascular morbidity and mortality. In the current study, we developed and validated a robust automatic breathing-sounds (i.e. inspiratory and expiratory sounds) detection system of audio signals acquired during sleep. Random forest classifier was trained and tested using inspiratory/expiratory/noise events (episodes), acquired from 84 subjects consecutively and prospectively referred to SDB diagnosis in sleep laboratory and in at-home environment. More than 560,000 events were analyzed, including a variety of recording devices and different environments. The system's overall accuracy rate is 88.8%, with accuracy rate of 91.2% and 83.6% in in-laboratory and at-home environments respectively, when classifying between inspiratory, expiratory, and noise classes. Here, we provide evidence that breathing-sounds can be reliably detected using non-contact audio technology in at-home environment. The proposed approach may improve our understanding of respiratory activity during sleep. This in return, will improve early SDB diagnosis and treatment.

Orexin Plays a Role in Growth Impediment Induced by Obstructive Sleep Breathing in Rats

STUDY OBJECTIVES

The mechanisms linking sleep disordered breathing with impairment of sleep and bone metabolism/architecture are poorly understood. Here, we explored the role of the neuropeptide orexin, a respiratory homeostasis modulator, in growth retardation induced in an upper airway obstructed (AO) rat model.

METHODS

The tracheae of 22-day-old rats were narrowed; AO and sham-control animals were monitored for 5 to 7 w. Growth parameters, food intake, sleep/wake activity, and serum hormones were measured. After euthanasia, growth plate (GP) histology, morphometry, orexin receptors (OXR), and related mediators were analyzed. The effect of dual orexin receptor antagonist (almorexant 300 mg/kg) on sleep and GP histology were also investigated.

RESULTS

The AO group slept 32% less; the time spent in slow wave and paradoxical sleep during light period and slow wave activity was reduced. The AO group gained 46% less body weight compared to the control group, despite elevated food intake; plasma ghrelin increased by 275% and leptin level decreased by 44%. The impediment of bone elongation and bone mass was followed by a 200% increase in OX1R and 38% reduction of local GP ghrelin proteins and growth hormone secretagogue receptor 1a. Sry-related transcription factor nine (Sox9), a molecule mediating cartilage ossification, was downregulated and the level of transcription factor peroxisome proliferator-activated receptor gamma was upregulated, explaining the bone architecture abnormalities. Administration of almorexant restored sleep and improved GP width in AO animals.

CONCLUSIONS

In AO animals, enhanced expression of orexin and OX1R plays a role in respiratory induced sleep and growth abnormalities.

Breath-by-breath detection of apneic events for OSA severity estimation using non-contact audio recordings

Obstructive sleep apnea (OSA) is a prevalent sleep disorder, characterized by recurrent episodes of upper airway obstructions during sleep. We hypothesize that breath-by-breath audio analysis of the respiratory cycle (i.e., inspiration and expiration phases) during sleep can reliably estimate the apnea hypopnea index (AHI), a measure of OSA severity. The AHI is calculated as the average number of apnea (A)/hypopnea (H) events per hour of sleep. Audio signals recordings of 186 adults referred to OSA diagnosis were acquired in-laboratory and at-home conditions during polysomnography and WatchPat study, respectively. A/H events were automatically segmented and classified using a binary random forest classifier. Total accuracy rate of 86.3% and an agreement of κ=42.98% were achieved in A/H event detection. Correlation of r=0.87 (r=0.74), diagnostic agreement of 76% (81.7%), and average absolute difference AHI error of 7.4 (7.8) (events/hour) were achieved in in-laboratory (at-home) conditions, respectively. Here we provide evidence that A/H events can be reliably detected at their exact time locations during sleep using non-contact audio approach. This study highlights the potential of this approach to reliably evaluate AHI in at home conditions.

OSA severity assessment based on sleep breathing analysis using ambient microphone

In this paper, an audio-based system for severity estimation of obstructive sleep apnea (OSA) is proposed. The system estimates the apnea-hypopnea index (AHI), which is the average number of apneic events per hour of sleep. This system is based on a Gaussian mixture regression algorithm that was trained and validated on full-night audio recordings. Feature selection process using a genetic algorithm was applied to select the best features extracted from time and spectra domains. A total of 155 subjects, referred to in-laboratory polysomnography (PSG) study, were recruited. Using the PSG's AHI score as a gold-standard, the performances of the proposed system were evaluated using a Pearson correlation, AHI error, and diagnostic agreement methods. Correlation of R=0.89, AHI error of 7.35 events/hr, and diagnostic agreement of 77.3% were achieved, showing encouraging performances and a reliable non-contact alternative method for OSA severity estimation.

Sleep/Wake Dynamics Changes during Maturation in Rats

Objectives

Conventional scoring of sleep provides little information about the process of transitioning between vigilance states. We applied the state space technique (SST) using frequency band ratios to follow normal maturation of different sleep/wake states, velocities of movements, and transitions between states of juvenile (postnatal day 34, P34) and young adult rats (P71).

Design

24-h sleep recordings of eight P34 and nine P71 were analyzed using conventional scoring criteria and SST one week following implantation of telemetric transmitter. SST is a non-categorical approach that allows novel quantitative and unbiased examination of vigilance-states dynamics and state transitions. In this approach, behavioral changes are described in a 2-dimensional state space that is derived from spectral characteristics of the electroencephalography.

Measurements and Results

With maturation sleep intensity declines, the duration of deep slow wave sleep (DSWS) and light slow wave sleep (LSWS) decreases and increases, respectively. Vigilance state determination, as a function of frequency, is not constant; there is a substantial shift to higher ratio 1 in all vigilance states except DSWS. Deep slow wave sleep decreases in adult relative to juvenile animals at all frequencies. P71 animals have 400% more trajectories from Wake to LSWS (p = 0.005) and vice versa (p = 0.005), and 100% more micro-arousals (p = 0.021), while trajectories from LSWS to DSWS (p = 0.047) and vice versa (p = 0.033) were reduced by 60%. In both juvenile and adult animals, no significant changes were found in sleep velocity at all regions of the 2-dimensional state space plot; suggesting that maturation has a partial effect on sleep stability.

Conclusions

Here, we present novel and original evidence that SST enables visualization of vigilance-state intensity, transitions, and velocities that were not evident by traditional scoring methods. These observations provide new perspectives in sleep state dynamics and highlight the usefulness of this technique in exploring the development of sleep-wake activity.

Sleep-wake evaluation from whole-night non-contact audio recordings of breathing sounds

STUDY OBJECTIVES

To develop and validate a novel non-contact system for whole-night sleep evaluation using breathing sounds analysis (BSA).

DESIGN

Whole-night breathing sounds (using ambient microphone) and polysomnography (PSG) were simultaneously collected at a sleep laboratory (mean recording time 7.1 hours). A set of acoustic features quantifying breathing pattern were developed to distinguish between sleep and wake epochs (30 sec segments). Epochs (n = 59,108 design study and n = 68,560 validation study) were classified using AdaBoost classifier and validated epoch-by-epoch for sensitivity, specificity, positive and negative predictive values, accuracy, and Cohen's kappa. Sleep quality parameters were calculated based on the sleep/wake classifications and compared with PSG for validity.

SETTING

University affiliated sleep-wake disorder center and biomedical signal processing laboratory.

PATIENTS

One hundred and fifty patients (age 54.0±14.8 years, BMI 31.6±5.5 kg/m2, m/f 97/53) referred for PSG were prospectively and consecutively recruited. The system was trained (design study) on 80 subjects; validation study was blindly performed on the additional 70 subjects.

MEASUREMENTS AND RESULTS

Epoch-by-epoch accuracy rate for the validation study was 83.3% with sensitivity of 92.2% (sleep as sleep), specificity of 56.6% (awake as awake), and Cohen's kappa of 0.508. Comparing sleep quality parameters of BSA and PSG demonstrate average error of sleep latency, total sleep time, wake after sleep onset, and sleep efficiency of 16.6 min, 35.8 min, and 29.6 min, and 8%, respectively.

CONCLUSIONS

This study provides evidence that sleep-wake activity and sleep quality parameters can be reliably estimated solely using breathing sound analysis. This study highlights the potential of this innovative approach to measure sleep in research and clinical circumstances.

Detection of Obstructive sleep apnea in awake subjects by exploiting body posture effects on the speech signal

Obstructive sleep apnea (OSA) is a common sleep disorder. OSA is associated with several anatomical and functional abnormalities of the upper airway. It was shown that these abnormalities in the upper airway are also likely to be the reason for increased rate of apneic events in the supine position. Functional and structural changes in the vocal tract can affect the acoustic properties of speech. We hypothesize that acoustic properties of speech that are affected by body position may aid in distinguishing between OSA and non-OSA patients. We aimed to explore the possibility to differentiate OSA and non-OSA patients by analyzing the acoustic properties of their speech signal in upright sitting and supine positions. 35 awake patients were recorded while pronouncing sustained vowels in the upright sitting and supine positions. Using linear discriminant analysis (LDA) classifier, accuracy of 84.6%, sensitivity of 92.7%, and specificity of 80.0% were achieved. This study provides the proof of concept that it is possible to screen for OSA by analyzing and comparing speech properties acquired in upright sitting vs. supine positions. An acoustic-based screening system during wakefulness may address the growing needs for a reliable OSA screening tool; further studies are needed to support these findings.

Chronic upper airway obstruction induces abnormal sleep/wake dynamics in juvenile rats

OBJECTIVES

Conventional scoring of sleep provides little information about the process of transitioning between vigilance-states. We used the state space technique to explore whether rats with chronic upper airway obstruction (UAO) have abnormal sleep/wake states, faster movements between states, or abnormal transitions between states.

DESIGN

The tracheae of 22-day-old Sprague-Dawley rats were surgically narrowed to increase upper airway resistance with no evidence for frank obstructed apneas or hypopneas; 24-h electroencephalography of sleep/wake recordings of UAO and sham-control animals was analyzed using state space technique. This non-categorical approach allows quantitative and unbiased examination of vigilance-states and state transitions. Measurements were performed 2 weeks post-surgery at baseline and following administration of ritanserin (5-HT2 receptor antagonist) the next day to stimulate sleep.

MEASUREMENTS AND RESULTS

UAO rats spent less time in deep (delta-rich) slow wave sleep (SWS) and near transition zones between states. State transitions from light SWS to wake and vice versa and microarousals were more frequent and rapid in UAO rats, indicating that obstructed animals have more regions where vigilance-states are unstable. Ritanserin consolidated sleep in both groups by decreasing the number of microarousals and trajectories between wake and light SWS, and increasing deep SWS in UAO.

CONCLUSIONS

State space technique enables visualization of vigilance-state transitions and velocities that were not evident by traditional scoring methods. This analysis provides new quantitative assessment of abnormal vigilance-state dynamics in UAO in the absence of frank obstructed apneas or hypopneas.

Role of orexin in respiratory and sleep homeostasis during upper airway obstruction in rats

STUDY OBJECTIVES

Chronic upper airway obstruction (UAO) elicits a cascade of complex endocrine derangements that affect growth, sleep, and energy metabolism. We hypothesized that elevated hypothalamic orexin has a role in maintaining ventilation during UAO, while at the same time altering sleep-wake activity and energy metabolism. Here, we sought to explore the UAO-induced changes in hypothalamic orexin and their role in sleep-wake balance, respiratory activity, and energy metabolism.

INTERVENTIONS

The tracheae of 22-day-old Sprague-Dawley rats were surgically narrowed; UAO and sham-operated control animals were monitored for 7 weeks. We measured food intake, body weight, temperature, locomotion, and sleep-wake activity. Magnetic resonance imaging was used to quantify subcutaneous and visceral fat tissue volumes. In week 7, the rats were sacrificed and levels of hypothalamic orexin, serum leptin, and corticosterone were determined. The effect of dual orexin receptor antagonist (almorexant 300 mg/kg) on sleep and respiration was also explored.

MEASUREMENTS AND RESULTS

UAO increased hypothalamic orexin mRNA and protein content by 64% and 65%, respectively. UAO led to 30% chronic sleep loss, excessive active phase sleepiness, decreased body temperature, increased food intake, reduction of abdominal and subcutaneous fat tissue volume, and growth retardation. Administration of almorexant normalized sleep but induced severe breathing difficulties in UAO rats, while it had no effect on sleep or on breathing of control animals.

CONCLUSIONS

In upper airway obstruction animals, enhanced orexin secretion, while crucially important for respiratory homeostasis maintenance, is also responsible for chronic partial sleep loss, as well as considerable impairment of energy metabolism and growth.

Automatic detection of whole night snoring events using non-contact microphone

Objective

Although awareness of sleep disorders is increasing, limited information is available on whole night detection of snoring. Our study aimed to develop and validate a robust, high performance, and sensitive whole-night snore detector based on non-contact technology.

Design

Sounds during polysomnography (PSG) were recorded using a directional condenser microphone placed 1 m above the bed. An AdaBoost classifier was trained and validated on manually labeled snoring and non-snoring acoustic events.

Patients

Sixty-seven subjects (age 52.5±13.5 years, BMI 30.8±4.7 kg/m², m/f 40/27) referred for PSG for obstructive sleep apnea diagnoses were prospectively and consecutively recruited. Twenty-five subjects were used for the design study; the validation study was blindly performed on the remaining forty-two subjects.

Measurements and Results

To train the proposed sound detector, >76,600 acoustic episodes collected in the design study were manually classified by three scorers into snore and non-snore episodes (e.g., bedding noise, coughing, environmental). A feature selection process was applied to select the most discriminative features extracted from time and spectral domains. The average snore/non-snore detection rate (accuracy) for the design group was 98.4% based on a ten-fold cross-validation technique. When tested on the validation group, the average detection rate was 98.2% with sensitivity of 98.0% (snore as a snore) and specificity of 98.3% (noise as noise).

Conclusions

Audio-based features extracted from time and spectral domains can accurately discriminate between snore and non-snore acoustic events. This audio analysis approach enables detection and analysis of snoring sounds from a full night in order to produce quantified measures for objective follow-up of patients.

Sleep-quality assessment from full night audio recordings of sleep apnea patients

In this work, a novel system (method) for sleep quality analysis is proposed. Its purpose is to assist an alternative non-contact method for detecting and diagnosing sleep related disorders based on acoustic signal processing. In this work, audio signals of 145 patients with obstructive sleep apnea were recorded (more than 1000 hours) in a sleep laboratory and analyzed. The method is based on the assumption that during sleep the respiratory efforts are more periodically patterned and consistent relative to a waking state; furthermore, the sound intensity of those efforts is higher, making the pattern more noticeable relative to the background noise level. The system was trained on 50 subjects and validated on 95 subjects. The system accuracy for detecting sleep/wake state is 82.1% (epoch by epoch), resulting in 3.9% error (difference) in detecting sleep latency, 11.4% error in estimating total sleep time, and 11.4% error in estimating sleep efficiency.

Increased prevalence of obstructive lung disease in patients with obstructive sleep apnea

STUDY PURPOSES

This study aims to determine whether there is an increased prevalence of obstructive lung diseases (OLDs) in patients with obstructive sleep apnea (OSA). We also determined whether among the OLD patients there is a difference in the prevalences of specific chronic disease co-morbidities between patients with and without OSA.

METHODS

The prevalences of COPD, asthma, and COPD combined with asthma (ICD-9 coding) were compared between 1,497 adult OSA patients and 1,489 control patients, who were matched for age, gender, geographic location, and primary care physician. The prevalences of specific co-morbidities were measured in the OLD groups between patients with OSA and the matched control group.

RESULTS

COPD, asthma, and COPD combined with asthma were found to be more prevalent among OSA patients compared to the matched controls. Prevalences among patients with and without OSA, respectively, were COPD-7.6 and 3.7 % (P<0.0001), asthma-10.4 and 5.1 % (P<0.0001), COPD plus asthma-3.3 and 0.9 % (P<0.0001). The Charlson Comorbidity Index was greater for OSA patients (2.3 ± 0.2) than for controls (1.9 ± 1.8; P<0.0001). These trends held for all severity ranges of OSA. Patients with OSA and COPD were characterized by more severe hypoxia at night compared with the OSA patients without OLD.

CONCLUSION

OSA was associated with an increased prevalence of OLDs.

Obstructive apnea hypopnea index estimation by analysis of nocturnal snoring signals in adults

STUDY OBJECTIVE

To develop a whole-night snore sounds analysis algorithm enabling estimation of obstructive apnea hypopnea index (AHI(EST)) among adult subjects.

DESIGN

Snore sounds were recorded using a directional condenser microphone placed 1 m above the bed. Acoustic features exploring intra-(mel- cepstability, pitch density) and inter-(running variance, apnea phase ratio, inter-event silence) snore properties were extracted and integrated to assess AHI(EST).

SETTING

University-affiliated sleep-wake disorder center and biomedical signal processing laboratory.

PATIENTS

Ninety subjects (age 53 ± 13 years, BMI 31 ± 5 kg/m(2)) referred for polysomnography (PSG) diagnosis of OSA were prospectively and consecutively recruited. The system was trained and tested on 60 subjects. Validation was blindly performed on the additional 30 consecutive subjects.

MEASUREMENTS AND RESULTS

AHI(EST) correlated with AHI (AHI(PSG); r(2) = 0.81, P < 0.001). Area under the receiver operating characteristic curve of 85% and 92% for thresholds of 10 and 20 events/h, respectively, were obtained for OSA detection. Both Altman-Bland analysis and diagnostic agreement criteria revealed 80% and 83% agreements of AHI(EST) with AHI(PSG), respectively.

CONCLUSIONS

Acoustic analysis based on intra- and inter-snore properties can differentiate subjects according to AHI. An acoustic-based screening system may address the growing needs for reliable OSA screening tool. Further studies are needed to support these findings.

Financial incentive increases CPAP acceptance in patients from low socioeconomic background

Objective

We explored whether financial incentives have a role in patients′ decisions to accept (purchase) a continuous positive airway pressure (CPAP) device in a healthcare system that requires cost sharing.

Design

Longitudinal interventional study.

Patients

The group receiving financial incentive (n = 137, 50.8±10.6 years, apnea/hypopnea index (AHI) 38.7±19.9 events/hr) and the control group (n = 121, 50.9±10.3 years, AHI 39.9±22) underwent attendant titration and a two-week adaptation to CPAP. Patients in the control group had a co-payment of $330–660; the financial incentive group paid a subsidized price of $55.

Results

CPAP acceptance was 43% greater (p = 0.02) in the financial incentive group. CPAP acceptance among the low socioeconomic strata (n = 113) (adjusting for age, gender, BMI, tobacco smoking) was enhanced by financial incentive (OR, 95% CI) (3.43, 1.09–10.85), age (1.1, 1.03–1.17), AHI (>30 vs. <30) (4.87, 1.56–15.2), and by family/friends who had positive experience with CPAP (4.29, 1.05–17.51). Among average/high-income patients (n = 145) CPAP acceptance was affected by AHI (>30 vs. <30) (3.16, 1.14–8.75), living with a partner (8.82, 1.03–75.8) but not by the financial incentive. At one-year follow-up CPAP adherence was similar in the financial incentive and control groups, 35% and 39%, respectively (p = 0.82). Adherence rate was sensitive to education (+yr) (1.28, 1.06–1.55) and AHI (>30 vs. <30) (5.25, 1.34–18.5).

Conclusions

Minimizing cost sharing reduces a barrier for CPAP acceptance among low socioeconomic status patients. Thus, financial incentive should be applied as a policy to encourage CPAP treatment, especially among low socioeconomic strata patients.

Impaired behavioral and neurocognitive function in preschool children with obstructive sleep apnea

OBJECTIVE

We aimed to examine the hypothesis that behavioral and neurocognitive functions of preschool children with Obstructive Sleep Apnea Syndrome (OSAS) are impaired compared to healthy children, and improve after adenotonsillectomy (TA).

METHODS

A comprehensive assessment battery was used to assess cognitive and behavioral functions, and quality of life in children with OSAS compared to matched controls.

RESULTS

45 children (mean age 45.5 ± 9 months, 73% boys, BMI 15.7 ± 2) with OSAS were compared to 26 healthy children (mean age 48.6 ± 8 months, 46% boys, BMI 16.4 ± 2). Mean AHI in the OSAS group was 13.2 ± 10.7 (ranging from 1.2 to 57). Significantly impaired planning and fluency (executive function) were found in children with OSAS, as well as impaired attention and receptive vocabulary. Parents and teachers described the OSAS group as having significantly more behavior problems. Quality of life questionnaire in children with OSAS (mean 2.3, range 0.7-4.3) was significantly worse compared to controls (mean 0, range: 0-4), P < 0.004. One year following TA, 23 children with OSAS and 18 controls were re-evaluated. Significant improvement was documented in verbal and motor fluency, sustained attention, and vocabulary. After TA, fewer behavioral problems were seen.

CONCLUSIONS

Preschool children with OSAS present significantly impaired executive functions, impaired attention and receptive vocabulary, and more behavior problems. One year after TA, the prominent improvements were in behavior and quality of life. These findings suggest that the impact of OSAS on behavioral and cognitive functions begins in early childhood.

Role of growth hormone-releasing hormone in sleep and growth impairments induced by upper airway obstruction in rats

Upper airway obstruction (UAO) can lead to abnormal growth hormone (GH) homeostasis and growth retardation but the mechanisms are unclear. We explored the effect of UAO on hypothalamic GH-releasing hormone (GHRH), which has a role in both sleep and GH regulation. The tracheae of 22-day-old rats were narrowed; UAO and sham-operated animals were sacrificed 16 days post-surgery. To stimulate slow-wave sleep (SWS) and GH secretion, rats were treated with ritanserin (5-HT(2) receptor antagonist). Sleep was measured with a telemetric system. Hypothalamic GHRH, hypothalamic GHRH receptor (GHRHR) and GH receptor, and orexin were analysed using ELISA, real-time PCR and Western blot. UAO decreased hypothalamic GHRH, GHRHR and GH receptor levels, while orexin mRNA increased (p<0.01). In UAO rats, the duration of wakefulness was elevated and the duration of SWS, paradoxical sleep and slow-wave activity was reduced (p<0.001). Ritanserin alleviated these effects, i.e. normalised hypothalamic GHRH content, decreased wake duration, increased duration and depth of SWS, and attenuated growth impairment (p<0.001). Here, we present evidence that growth retardation in UAO is associated with a reduction in hypothalamic GHRH content. Our findings show that abnormalities in the GHRH/GH axis underlie both growth retardation and SWS-disorder UAO.

Nocturnal sound analysis for the diagnosis of obstructive sleep apnea

A novel method for screening obstructive sleep apnea syndrome (OSAs) based on nocturnal acoustic signal is proposed. Full-night audio signals from sixty subjects were segmented into snore, noise and silence events using semi-automatic algorithm based on Gaussian mixture models which achieves more than 90% (92%) sensitivity (specificity) and produces an average of 2,000 snores per subject. A classification into 3 groups is proposed for the diagnosis: comparison group - non-OSA subjects (apnea hypopnea index, AHI < 10), mild to moderate OSA (10 < AHI < 30) and severe OSA (AHI>30). A Bayes classifier was implemented, fed with five acoustic features, all correlated with the severity of the syndrome: (1) Inter Event Silence, which quantifies segments suspicious as apnea; (2) Mel Cepstability, measures the entire night stability of the spectrum, expressed using mel-frequency cepstrum; (3) Energy Running Variance, a criterion for the variation of the nocturnal acoustic pattern; (4) Apneic Phase Ratio, exploiting the finding that snores around apnea events expressing larger acoustic variation; and (5) Pitch Density. Correct classification of 92% for resubstitution method and 80% for 5-fold cross validation method was achieved. Moreover, in a case of two groups with a threshold of AHI=10, a sensitivity (specificity) of 96.5% (90.6%) and 87.5% (82.1%) for resubstitution and cross-validation respectively were obtained.

Determinants of elevated healthcare utilization in patients with COPD

BACKGROUND

Chronic obstructive pulmonary disease (COPD) imparts a substantial economic burden on western health systems. Our objective was to analyze the determinants of elevated healthcare utilization among patients with COPD in a single-payer health system.

METHODS

Three-hundred eighty-nine adults with COPD were matched 1:3 to controls by age, gender and area of residency. Total healthcare cost 5 years prior recruitment and presence of comorbidities were obtained from a computerized database. Health related quality of life (HRQoL) indices were obtained using validated questionnaires among a subsample of 177 patients.

RESULTS

Healthcare utilization was 3.4-fold higher among COPD patients compared with controls (p < 0.001). The "most-costly" upper 25% of COPD patients (n = 98) consumed 63% of all costs. Multivariate analysis revealed that independent determinants of being in the "most costly" group were (OR; 95% CI): age-adjusted Charlson Comorbidity Index (1.09; 1.01-1.2), history of: myocardial infarct (2.87; 1.5-5.5), congestive heart failure (3.52; 1.9-6.4), mild liver disease (3.83; 1.3-11.2) and diabetes (2.02; 1.1-3.6). Bivariate analysis revealed that cost increased as HRQoL declined and severity of airflow obstruction increased but these were not independent determinants in a multivariate analysis.

CONCLUSION

Comorbidity burden determines elevated utilization for COPD patients. Decision makers should prioritize scarce health care resources to a better care management of the "most costly" patients.

Sleep quality predicts quality of life in chronic obstructive pulmonary disease

Purpose

Chronic obstructive pulmonary disease (COPD) patients may suffer from poor sleep and health-related quality of life. We hypothesized that disturbed sleep in COPD is correlated with quality of life.

Methods

In 180 patients with COPD (forced expired volume in 1 second [FEV₁] 47.6 ± 15.2% predicted, 77.8% male, aged 65.9 ± 11.7 years), we administered general (Health Utilities Index 3) and disease-specific (St George’s Respiratory) questionnaires and an index of disturbed sleep (Pittsburgh Sleep Quality Index).

Results

Overall scores indicated poor general (Health Utilities Index 3: 0.52 ± 0.38), disease- specific (St George’s: 57.0 ± 21.3) quality of life and poor sleep quality (Pittsburgh 11.0 ± 5.4). Sleep time correlated with the number of respiratory and anxiety symptoms reported at night. Seventy-seven percent of the patients had Pittsburg scores >5, and the median Pittsburgh score was 12. On multivariate regression, the Pittsburgh Sleep Quality Index was an independent predictor of both the Health Utilities Index 3 and the St George’s scores, accounting for 3% and 5%, respectively, of the scores. Only approximately 25% of the patients demonstrated excessive sleepiness (Epworth Sleepiness Scale >9).

Conclusions

Most patients with COPD suffer disturbed sleep. Sleep quality was correlated with general and disease-specific quality of life. Only a minority of COPD patients complain of being sleepy.

Automatic detection of obstructive sleep apnea using speech signals

Obstructive sleep apnea (OSA) is a common disorder associated with anatomical abnormalities of the upper airways that affects 5% of the population. Acoustic parameters may be influenced by the vocal tract structure and soft tissue properties. We hypothesize that speech signal properties of OSA patients will be different than those of control subjects not having OSA. Using speech signal processing techniques, we explored acoustic speech features of 93 subjects who were recorded using a text-dependent speech protocol and a digital audio recorder immediately prior to polysomnography study. Following analysis of the study, subjects were divided into OSA (n=67) and non-OSA (n=26) groups. A Gaussian mixture model-based system was developed to model and classify between the groups; discriminative features such as vocal tract length and linear prediction coefficients were selected using feature selection technique. Specificity and sensitivity of 83% and 79% were achieved for the male OSA and 86% and 84% for the female OSA patients, respectively. We conclude that acoustic features from speech signals during wakefulness can detect OSA patients with good specificity and sensitivity. Such a system can be used as a basis for future development of a tool for OSA screening.

[Obstructive sleep apnea syndrome in young infants]

Obstructive sleep apnea syndrome (OSAS) has been reported among children aged 3-6 years. Adenotonsillar hypertrophy is the most common cause of OSAS. The upper airway obstruction results in repeated obstructive apneas and hypopneas, associated with oxygen desaturations and sleep fragmentation. OSAS in children is associated with higher respiratory morbidity as well as significant clinical consequences, mainly neurocognitive and behavioral problems, impaired growth and cardiac dysfunction. The objectives of the present study were to determine the clinical and sleep characteristics of OSAS in children younger than 2 years, and to evaluate morbidity and health care utilization of infants with OSAS. This retrospective study included 35 children younger than 2 years of age, referred for polysomnography because of suspected OSAS. The controL group included healthy children, matched by age, gender and pediatrician.

RESULTS

A total of 33 infants were diagnosed with OSAS. Mean apnea/hypopnea index [AHI) was 18.7 +/- 18.1 events/ hour [range 1.3-90.2]. In 10 infants a pattern of intermittent hypoxemia was observed. Infants with OSAS demonstrated a higher number of primary care clinic visits (20.8 +/- 14 vs. 12.1 +/- 6.6, P < 0.02). A higher percentage of children with OSAS visited the emergency room (60.6% vs. 32.2%, P < 0.03), and was hospitalized (36.3% vs. 12.9%, P < 0.03). Duration of hospitalization was also higher in the OSAS group [23.2 +/- 14.1% vs. 3 +/- 2.1%, P < 0.05). The number of drug prescriptions was higher among the study group [25.9 +/- 21.8% vs. 13.6 +/- 10.1, P < 0.03). Thirteen patients underwent adenoidectomy with or without tonsillectomy, resulting in improvement of AHI, decreasing from 26.4 +/- 24 before to 3.6 +/- 4.5 events per hour after surgery (p < 0.01).

CONCLUSIONS

OSAS can be found in infants younger than 2 years of age. OSAS at this young age is characterized by a higher morbidity in comparison to healthy children. Early diagnosis and treatment may prevent morbidity in young children with OSAS.

Low socioeconomic status is a risk factor for CPAP acceptance among adult OSAS patients requiring treatment

STUDY OBJECTIVE

To evaluate whether socioeconomic status (SES) has a role in obstructive sleep apnea syndrome (OSAS) patients' decision to accept continuous positive airway pressure (CPAP) treatment.

DESIGN

Cross-sectional study; patients were recruited between March 2007 and December 2007.

SETTING

University-affiliated sleep laboratory.

PATIENTS

162 consecutive newly diagnosed (polysomnographically) adult OSAS patients who required CPAP underwent attendant titration and a 2-week adaptation period.

RESULTS

40% (n = 65) of patients who required CPAP therapy accepted this treatment. Patients accepting CPAP were older, had higher apnea-hypopnea index (AHI) and higher income level, and were more likely to sleep in a separate room than patients declining CPAP treatment. More patients who accepted treatment also reported receiving positive information about CPAP treatment from family or friends. Multiple logistic regression (after adjusting for age, body mass index, Epworth Sleepiness Scale, and AHI) revealed that CPAP purchase is determined by: each increased income level category (OR, 95% CI) (2.4; 1.2-4.6), age + 1 year (1.07; 1.01-1.1), AHI ( > or = 35 vs. < 35 events/hr) (4.2, 1.4-12.0), family and/or friends with positive experience of CPAP (2.9, 1.1-7.5), and partner sleeps separately (4.3, 1.4-13.3).

CONCLUSIONS

In addition to the already known determinants of CPAP acceptance, patients with low SES are less receptive to CPAP treatment than groups with higher SES. CPAP support and patient education programs should be better tailored for low SES people in order to increase patient treatment initiation and adherence.

Upper airway loading induces growth retardation and change in local chondrocyte IGF-I expression is reversed by stimulation of GH release in juvenile rats

Chronic resistive airway loading (CAL) impairs growth in juvenile rats. The effects of CAL on epiphyseal growth plate (EGP) structure and insulin-like growth factor (IGF)-I gene expression have not been explored. Little is known about whether stimulants of endogenous growth hormone (GH) secretion can normalize this growth impairment. This study explored the effect of CAL on circulating and EGP GH/IGF-I pathway GH and the effect of ritanserin (endogenous GH stimulant) on somatic growth and the GH/IGF-I axis. We hypothesized that CAL would lead to a decrease in body temperature (Tb) and alterations of GH/IGF-I pathways, consequently leading to growth retardation. The tracheae of 22-day-old male rats were obstructed by tracheal banding (38 sham-operated control, 42 CAL). Tibial EGP morphometry, liver and EGP IGF mRNA, and serum GH and IGF-I levels were analyzed with quantitative real-time PCR and ELISA. Tb and locomotion activity (MA) were measured with telemetric transmitters inserted into the abdominal cavity. CAL animals had lower Tb and MA despite preserved food consumption. CAL impaired both tibial and tail length gains. Tail and tibial length gains inversely correlated with tracheal resistance. Circulating GH and IGF-I, liver and EGP IGF-I mRNA, and EGP width were decreased in the CAL group. Ritanserin administration to CAL animals normalized circulating and local EGP GH and IGF-I levels and minimized the longitudinal growth impairment. We conclude that CAL causes growth delay associated with alterations in the GH/IGF-I axis. Stimulation of GH release by ritanserin restored both global and local GH/IGF-I pathways, yet growth parameters were only partially restored.

The effect of obstructive sleep apnea on morbidity and health care utilization of middle-aged and older adults

OBJECTIVES

To determine whether elderly subjects with obstructive sleep apnea (OSA) had different morbidity and health care utilization than elderly subjects without OSA and middle-aged patients with OSA 2 years before diagnosis.

DESIGN

Case-control study between January 2001 and April 2003.

SETTING

Two sleep-wake disorders centers.

PARTICIPANTS

One hundred fifty-eight elderly and 1,166 middle-aged (aged 67-89 and 40-64, respectively) patients with OSA were matched 1:1 with healthy controls according to age, sex, geographic area, and primary physician.

MEASUREMENTS

Polysomnography, medical diagnoses, and healthcare utilization.

RESULTS

Healthcare costs 2 years before diagnosis were more than 1.8 times as high for elderly and middle-aged patients with OSA as for controls (P<.001). Expenditures of elderly patients with OSA were 1.9 times as high as for middle-aged patients with OSA (P<.001). Multiple logistic regression analysis (adjusting for age, body mass index, and apnea hypopnea index) revealed that cardiovascular disease (CVD) (odds ratio (OR)=4.1, 95% confidence interval (CI)=1.8-9.3) and use of psychoactive drugs (OR=3.8, 95% CI=1.5-10.1) are independent determinants for the top-third most-costly elderly patients with OSA.

CONCLUSION

Elderly patients with OSA have high healthcare utilization because of CVD morbidity and use of psychoactive medications. Therefore, OSA has clinical significance in elderly people.

Elevated healthcare utilisation in young adult males with obstructive sleep apnoea

The aim of the present study was to explore morbidity and healthcare utilisation among young adult males with obstructive sleep apnoea (OSA) compared with middle-aged OSA patients over the 5-yr period preceding diagnosis. A prospective case-control study was performed; 117 young (22-39-yr-old) males with OSA were matched with 117 middle-aged (40-64-yr-old) OSA males for body mass index, apnoea/hypopnoea index, arterial oxygen saturation, arousal and awakening index, and Epworth Sleepiness Scale score. Each OSA patient was matched with controls by age, geographic area and physician. Young adult males with OSA showed no increase in specific comorbidity compared with controls. Middle-aged OSA patients exhibited increased risk of cardiovascular disease. Healthcare utilisation for the 5-yr period was >or=1.9 times higher among young and middle-aged male OSA patients than among controls. Multiple logistic regression analysis revealed that hyperlipidaemia in young adults and a body mass index of >37 kg x m(-2) and cardiovascular disease in middle-aged adults are the only independent determinants of the upper third, most costly, OSA patients. Compared with middle-aged males with obstructive sleep apnoea, in whom increased expenditure was related to cardiovascular disease and body mass index, utilisation was not related to any specific disease in younger cases.

Gender differences in morbidity and health care utilization among adult obstructive sleep apnea patients

STUDY OBJECTIVE

To explore gender differences in morbidity and total health care utilization 5 years prior to diagnosis of obstructive sleep apnea (OSA).

DESIGN

Case-control study; patients were recruited between January 2001 and April 2003.

SETTING

Two university-affiliated sleep laboratories.

PATIENTS

289 women (22-81 years) with OSA were matched with 289 men with OSA for age, body mass index (BMI), and apnea-hypopnea index (AHI). All OSA patients were matched 1:1 with healthy controls by age, geographic area, and primary physician.

MEASUREMENTS AND RESULTS

Women with OSA compared to men with OSA have lower perceived health status and Functional Outcomes of Sleep Questionnaire score (54.5% vs. 28.4%, P <0.05 and 67.5+/-21.4 vs. 76+/-20.1, P <0.05, respectively). Compared to men with OSA, women with OSA have higher risk of hypothyroidism (OR 4.7; 95% CI, 2.3-10) and arthropathy (OR 1.6, 95% CI, 1.1-2.2) and lower risk for CVD (OR 0.7; 95% CI, 0.5-0.91). Compared to controls, both women and men with OSA had 1.8 times higher 5-year total costs (P <0.0001). Compared to men with OSA, expenditures for women with OSA are 1.3 times higher (P <0.0001). The multiple logistic regression (adjusting for BMI, AHI) revealed that age (OR 1.04; 95% CI, 1.01-1.07), antipsychotic and anxiolytic drugs (OR 2.3; 95% CI, 1.2-4.4), and asthma (OR 2.4; 95% CI, 1.1-5.6) are independent determinants for "most costly" OSA women.

CONCLUSION

Compared to men with similar OSA severity, women are heavier users of health care resources. Low FOSQ score and poor perceived health status in addition to overuse of psychoactive drugs are associated with high health care utilization among women with OSA.