Relationship between obstructive sleep apnea and diurnal leptin rhythms

STUDY OBJECTIVES: Several studies have reported an association between obstructive sleep apnea and leptin, a hormone that influences satiety and body weight. We evaluated the relationship of leptin levels and the overnight change in levels with sleep apnea. DESIGN: Cross-sectional analysis of data from a prospective cohort study. SETTING: Case Western Reserve University General Clinical Research Center. PATIENTS OR PARTICIPANTS: A total of 138 individuals participating in the Cleveland Family Study--59% women, 45% African-American, with mean apnea-hypopnea index (AHI) of 6.9 (range 0-106)--were studied. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Serum leptin was measured at 10:00 pm to 11:00 pm and at 7:00 am to 8:00 am. Leptin levels in both the morning and evening were positively correlated with apnea-hypopnea index (AHI) in age-, sex-, and race-adjusted analyses (P < .0001) but not after additional adjustment for body mass index. The evening/morning leptin ratio, however, was associated with AHI independent of age, sex, race, body mass index, and waist-hip ratio (P = .03). Conversely, AHI was an independent predictor of the leptin ratio (P = .001) and more predictive than arousal index, oxygenation indices, time asleep, or sleep-stage distribution. An AHI > 15 was associated with a 23% increase in leptin ratio. CONCLUSIONS: These findings suggest that sleep apnea may suppress secretion of leptin in the morning. Alternatively, the relative elevation in evening leptin may influence apnea pathogenesis.     

Associations between sleep apnea and advanced brain aging in a large-scale population study

Advanced brain aging is commonly regarded as a risk factor for neurodegenerative diseases, for example, Alzheimer’s dementia, and it was suggested that sleep disorders such as obstructive sleep apnea (OSA) are significantly contributing factors to these neurodegenerative processes. To determine the association between OSA and advanced brain aging, we investigated the specific effect of two indices quantifying OSA, namely the apnea–hypopnea index (AHI) and the oxygen desaturation index (ODI), on brain age, a score quantifying age-related brain patterns in 169 brain regions, using magnetic resonance imaging and overnight polysomnography data from 690 participants (48.8% women, mean age 52.5 ± 13.4 years) of the Study of Health in Pomerania. We additionally investigated the mediating effect of subclinical inflammation parameters on these associations via a causal mediation analysis. AHI and ODI were both positively associated with brain age (AHI std. effect [95% CI]: 0.07 [0.03; 0.12], p-value: 0.002; ODI std. effect [95% CI]: 0.09 [0.04; 0.13], p-value: < 0.0003). The effects remained stable in the presence of various confounders such as diabetes and were partially mediated by the white blood cell count, indicating a subclinical inflammation process. Our results reveal an association between OSA and brain age, indicating subtle but widespread age-related changes in regional brain structures, in one of the largest general population studies to date, warranting further examination of OSA in the prevention of neurodegenerative diseases.     

Relationship between REM density, duty cycle, and obstructive sleep apnea in children

STUDY OBJECTIVES: The pattern and distribution of rapid eye movement (REM) sleep changes during development, yet there have been few studies of REM density in children. Although children with obstructive apnea syndrome (OSAS) obstruct primarily during REM sleep, the relationship between REM density and obstructive apnea has not been established for this population. We hypothesized that (i) REM density and REM cycle duration increases over the course of the night in children, (ii) the duty cycle (inspiratory time divided by respiratory cycle time) increases over the course of the night in children with suspected OSAS, and (iii) the increase in REM density over the course of the night is associated with increased severity of obstructive apnea. DESIGN: REM density and respiratory parameters were measured during polysomnography. SETTING: Sleep laboratory PATIENTS: 76 children with suspected OSAS. INTERVENTIONS: NA MEASUREMENTS AND RESULTS: REM density and the duration of REM cycles increased over the course of the night until the fifth REM cycle, and then stabilized. The duty cycle increased across the first 6 REM cycles. However, the apnea hypopnea index (AHI) did not increase across REM cycles, and was not affected by the changes in REM density or duty cycle. We speculate that the increase in the duty cycle is a compensatory response to increased upper airway loads during sleep, and that this may lead to ventilatory or upper airway muscle fatigue.     

Association between habitual naps and sleep apnea

STUDY OBJECTIVES: Taking an afternoon nap (siesta) is a common habit. A number of studies have shown an increased cardiovascular mortality in habitual nappers. Afternoon nappers have anthropometric characteristics similar to those of patients with sleep apnea. Nappers appear to suffer from more sleep apnea, which could contribute to cardiovascular disorders. Our aim was therefore to determine the association between sleep apnea and napping, as well as to analyze the relationship of sleep apnea and napping with hypertension. DESIGN: Case-control study. SETTING: Residents in the town of Caceres (Spain) with a population of 100,000 inhabitants. PARTICIPANTS: Four hundred five individuals were initially selected (186 nappers and 219 nonnappers). INTERVENTIONS: Telephone interviews were conducted to contact habitual nappers and nonnappers. Out of the total population selected, 90 nappers and 88 nonnappers completed the study protocol (personal interview and polysomnography). MEASUREMENTS AND RESULTS: The nappers had a higher frequency of sleep apnea at the 3 cutoff points studied (apnea and hypopnea index > or = 5, > or = 10, > or = 15). The adjusted odds ratio was between 2.8 (confidence interval, 1.3-5.8) and 5.5 (confidence interval, 2.3-13). Napping was associated with hypertension in the univariate analysis (odds ratio: 2.1; confidence interval, 1.1-4), but this association disappeared once sleep apnea was included as a covariate in the multivariate modeling (odds ratio dropped to 1.1). CONCLUSIONS: Our findings suggest that napping could be regarded as a marker of sleep apnea, which could account for the cardiovascular diseases observed in nappers. Given that napping is common and that sleep apnea is treatable, more attention should be focused on this population.     

Association between atrial fibrillation and central sleep apnea

BACKGROUND: We previously described an association between atrial fibrillation and central sleep apnea in a group of patients with congestive heart failure. We hypothesized that the prevalence of atrial fibrillation might also be increased in patients with central sleep apnea in the absence of other cardiac disease. METHODS AND RESULTS: We compared the prevalence of atrial fibrillation in a series of 60 consecutive patients with idiopathic central sleep apnea (apnea-hypopnea index > 10 events per hour, > 50% central events) with that in 60 patients with obstructive sleep apnea (apnea-hypopnea index > 10, > 50% obstructive events) and 60 patients without sleep apnea (apnea-hypopnea index < 10), matched for age, sex, and body mass index. Subjects with a history of congestive heart failure, coronary artery disease, or stroke were excluded from the study. The prevalence of atrial fibrillation among patients with idiopathic central sleep apnea was found to be significantly higher than the prevalence among patients with obstructive sleep apnea or no sleep apnea (27%, 1.7%, and 3.3%, respectively, P < .001). However, hypertension was most common and oxygen desaturation most extreme among patients with obstructive sleep apnea. CONCLUSIONS: We conclude that there is a markedly increased prevalence of atrial fibrillation among patients with idiopathic central sleep apnea in the absence of congestive heart failure. Moreover, the high prevalence of atrial fibrillation among patients with idiopathic central sleep apnea is not explainable by the presence of hypertension or nocturnal oxygen desaturation, since both of these were more strongly associated with obstructive sleep apnea.     

Association between smoking and drinking and sleep duration

In a study of lifestyles and health of the adult population of some Oxfordshire villages, data were collected upon the usual sleep duration and quality, smoking and drinking habits of 725 men and 759 women.

A strong negative association has been found between cigarette smoking and sleep duration in both sexes, and between alcohol consumption and sleep duration in men. There is no equivalent association between drinking or smoking and reported poor quality sleep.

While these findings do not prove a causal relationship, the a bsence of complaints of poor quality sleep among the smokers and drinkers suggests that these habits are not simply the correlates of underlying psychological problems leading to insomnia.     

Snoring & sleep apnea: a population study in Italian women

The aim of this cross-sectional study was to evaluate the prevalence of sleep-disordered breathing by means of a validated portable instrument (MESAM IV) and to investigate the relationship between snoring and sleep apnea in a sample of Italian middle-aged female population. We randomly chose 750 subjects aged 40 to 65 years and 365 agreed to participate to the study. In this group, 19.7% of subjects were every-night snorers according to the questionnaire; when recorded, 54.2% snored for more than 10% of the night, and 7.1% for more than 50% of the night. Sleep apnea was also common: 10.7% of subjects had a respiratory disturbances per hour (RDI) between 5 and 9, 7.7% an RDI between 10 and 19, and 2.2% had an RDI > or =20. Snoring percentage and RDI were significantly correlated. However, 50% of subjects who snored for more than half the night had no evidence of sleep apnea. Snoring amount >50% resulted influenced by body mass index, while RDI>10 was influenced by neck diameter. We concluded that in middle-aged women, both snoring and sleep apnea are very common. A high percentage of snoring is not essential for the occurrence of sleep apnea, nor it necessarily indicates the presence of sleep apnea.     

Association between polysomnographic sleep measures and health-related quality of life in obstructive sleep apnea

Many facets of health-related quality of life are diminished in obstructive sleep apnea (OSA) as they are in other chronic medical conditions. We speculated that impairment in health-related quality of life (HRQoL) might result from the fatigue and daytime somnolence associated with the sleep disorder, as an indirect result from the fragmentation of night-time sleep in OSA. Our hypothesis was that sleep fragmentation measures would correlate with poorer HRQoL measured by medical outcomes study (MOS) subscales. Thirty-nine patients with polysomnographically-confirmed OSA participated in this study. Pearson's correlations were performed with the following sleep architecture variables: wake after sleep onset, the total number of brief arousals, the number of respiratory-related arousals, the rate of respiratory events per hour, and total sleep time. To our surprise, although the total number of arousals was associated with health distress (r=-0.481, P < 0.005), it did not correlate with any other subscales indicating poorer physical and mental health. The relatively insensitive measure of total sleep time (TST) correlated in the expected direction with most subscales. However, after controlling for age and gender, respiratory disturbance indices (RDI) and/or number of arousals emerged as significantly associated with mobility, cognitive functioning, social functioning, energy and fatigue, and health distress. Our findings suggest that polysomnographic indicators of sleep quality and sleep continuity may be an important influence determining many aspects of HRQoL in OSA patients.     

The use and effectiveness of adaptive servo ventilation in central sleep apnea: a study of consecutive sleep clinic patients

The use of adaptive servo ventilation to treat central sleep apnea in the clinical setting is incompletely understood and could be under‐utilized. We reviewed our experience of adaptive servo ventilation use in patients with central sleep apnea. This study shows the effectiveness of adaptive servo ventilation in treating patients with central sleep apnea, irrespective of a predisposing factor, as assessed during a 4‐week treatment trial. Results show that adaptive servo ventilation was effective and superior to continuous positive airway pressure in controlling central sleep apnea and improving symptoms. Only a small proportion of these patients had comorbid heart failure. Early treatment with adaptive servo ventilation may improve long‐term adherence to therapy. These findings highlight the utility of adaptive servo ventilation in the management of central sleep apnea.     

No relation between apolipoprotein E alleles and obstructive sleep apnea

Apolipoprotein E (ApoE) is a genetic risk factor influencing the development of cardiovascular diseases and Alzheimer's disease. Patients with obstructive sleep apnea (OSA) suffer an excess mortality and morbidity from cardiovascular diseases. The frequencies of ApoE alleles were determined in 291 patients with OSA and 728 controls. The distribution of ApoE alleles and genotypes showed no difference between OSA and controls.     

Obstructive sleep apnea syndrome: differences between children and adults

The obstructive sleep apnea syndrome is a common cause of morbidity in childhood. The clinical presentation, pathophysiology, polysomnographic characteristics and treatment differ between children and adults. Measurements of the upper airway pressure-flow characteristics can be useful in evaluating upper airway function in patients with OSAS as well as the normal population.     

Obstructive sleep apnea

Obstructive sleep apnea is an increasingly well-recognized disease characterized by periodic collapse of the upper airway during sleep. This leads to either complete or partial obstruction of the airway, resulting in apneas, hypopneas, or both. This disorder causes daytime somnolence, neurocognitive defects, and depression. It affects almost every system in the body, resulting in an increased incidence of hypertension, cardiovascular disease, stroke, pulmonary hypertension, cardiac arrhythmias, and altered immune function. It also increases the risk of having an accident, presumably as a result of associated somnolence. The gold standard for the diagnosis of sleep apnea is an overnight polysomnogram. Split-night studies are becoming increasingly common and allow for quicker implementation of therapy at a reduced cost. Treatment options for sleep apnea include weight loss, positional therapy, oral devices, continuous positive airway pressure (CPAP), and upper airway surgery. CPAP is the most efficacious and widely used therapy. Its complications include nasal congestion or dryness, mask discomfort, and claustrophobia. Heated humidifiers, newer types of masks, and nasal steroids have improved tolerance of this therapy. Bilevel positive-pressure therapy can be considered for patients who find it difficult to exhale against the consistently increased pressure of CPAP. The disease requires aggressive treatment to improve quality of life and prevent its complications.     

The Epworth sleepiness scale: Reliably unreliable in a sleep clinic population

The Epworth Sleepiness Scale is used frequently to measure excessive daytime sleepiness in research and clinical settings, although there is limited evidence on test–retest reliability, particularly among sleep clinic populations. The objective of this study was to evaluate the reliability of this instrument among adult patients recruited from a public hospital sleep clinic in Sydney, Australia. English‐speaking participants self‐completed the Epworth Sleepiness Scale on two occasions, at the specialist clinic visit and on the night of diagnostic polysomnography. Of the 108 participants included in the study, the majority were male (64%) and the mean age was 51 years. The median retest interval was 64 days. The primary outcome of test–retest reliability as measured using the intraclass correlation coefficient was 0.73 (95% confidence interval, 0.61–0.82). Despite moderate statistical reliability and a low mean difference of 1.1, Bland‐Altman analysis showed an unacceptably wide distribution of between‐score differences. The 95% limits of agreement were ?8.5 to +10.6, and an absolute difference in scores of at least 3 was observed in 60 (56%) of the participants. Our results suggest that the Epworth Sleepiness Scale should not be used in clinical settings to make individual‐level comparisons, such as the effect of therapeutic interventions, or to prioritise access to services.     

The reliability of the Epworth Sleepiness Score in a sleep clinic population

Despite the Epworth Sleepiness Score being widely used, there are limited studies of its reliability in clinical practice. The aim of this study was to assess the reliability of the Epworth Sleepiness Score in a clinical population. The study included patients referred to Middlemore Hospital sleep service between October and November 2014, aged over 17 years, with at least two Epworth Sleepiness Score measurements at up to three different points on the diagnostic pathway: on General Practitioner referral (GP Epworth Sleepiness Score); at overnight oximetry assessment (Oximetry Epworth Sleepiness Score); and at a specialist clinic (Specialist Epworth Sleepiness Score). No treatment was administered between scores. One‐hundred and thirty‐three patients were included in the study. There was a median of 91 days from GP Epworth Sleepiness Score to Oximetry Epworth Sleepiness Score, and 11 days from Oximetry Epworth Sleepiness Score to Specialist Epworth Sleepiness Score. There was poor test–retest reliability between GP Epworth Sleepiness Score and Specialist Epworth Sleepiness Score; 72.4% and 17.8% of patients had an absolute difference of more than 2 and 8 Epworth Sleepiness Score points, respectively. A Bland–Altman plot of mean Epworth Sleepiness Score versus the difference between GP Epworth Sleepiness Score and Specialist Epworth Sleepiness Score demonstrated a wide scatter of data and 95% confidence interval for the difference in Epworth Sleepiness Score for an individual patient of ?14 to +10. There was similar variability between GP Epworth Sleepiness Score and Oximetry Epworth Sleepiness Score. The reliability of the Epworth Sleepiness Score is unproven in clinical settings. This study shows poor test–retest reliability of Epworth Sleepiness Score, particularly between primary and secondary care, arguing against the use of Epworth Sleepiness Score for clinical decision‐making or prioritisation of services without first assessing the reliability of the Epworth Sleepiness Score in the relevant clinical population.     

Prevalence of obstructive sleep apnea symptoms and risk factors in an Armenian population sample

Aim

Obstructive sleep apnea (OSA) is a common medical condition with significant adverse consequences. OSA awareness among the general population and physicians in Armenia is quite low. This study aimed to estimate the prevalence of OSA symptoms and risk factors in Armenia, which has not been investigated so far.

Patients and methods

This was a cross-sectional study of 1,500 randomly selected adults from the capital city and regions of the country. The instrument used to assess the risk of OSA was the Berlin questionnaire.

Results

Of the 1,500 respondents, 44% (49% of men and 37% of women) were identified as being at high risk of OSA. In both genders the risk of OSA increased with age achieving the maximum level of 60% at the age of 50?C69?years and declining to 45% after the age of 70?years. Before the age of 50?years, men were at higher risk of OSA than women (42% vs. 19%, p?<?0.001). After 50 the risk of having OSA was almost the same in men and women (57% vs. 56%).

Conclusion

Almost every second Armenian male and every third female citizen could benefit from evaluation for OSA.     

Lung volumes and mean apnea duration in obstructive sleep apnea

Former studies suggested that lung volumes might play a role in pathomechanisms of obstructive sleep apnea (OSA). Mean apnea duration (MAD) is a rarely investigated parameter in OSA but is possibly a surrogate of arousal threshold. The aim of this study was to evaluate the influence of lung volumes to MAD in OSA. In 69 patients with obstructive sleep apnea (51 male und 18 female, BMI 34.2 ± 6.0 kg/m², age 53.6 ± 9.7 years, AHI 43.1 ± 21.1/h) we performed a polysomnography and pulmonary function testing in daytime. There was a significant correlation between MAD and residual volume (RV) (r = 0.51; p < 0.001), which was the highest correlation we found. In linear regression analysis RV remained the only independent variable with significant influence on MAD (p < 0.001). We could show that RV seems to play a role in the mechanisms of apnea termination in terms of MAD. MAD reflects the time until a specific negative intrathoracic pressure is reached to induce an arousal. In this process dependency on RV could explain our results. Despite some limitations these results provide some new aspects in understanding pathophysiology of OSA.