Predictors of obstructive sleep apnoea in patients admitted for acute coronary syndrome.

Identifying undiagnosed obstructive sleep apnoea (OSA) patients in cardiovascular clinics could improve their management. Aiming to build an OSA predictive model, a broad analysis of clinical variables was performed in a cohort of acute coronary syndrome (ACS) patients.Sociodemographic, anthropometric, life-style and pharmacological variables were recorded. Clinical measures included blood pressure, electrocardiography, echocardiography, blood count, troponin levels and a metabolic panel. OSA was diagnosed using respiratory polygraphy. Logistic regression models and classification and regression trees were used to create predictive models.A total of 978 patients were included (298 subjects with apnoea-hypopnoea index (AHI) <15 events·h-1 and 680 with AHI ≥15 events·h-1). Age, BMI, Epworth sleepiness scale, peak troponin levels and use of calcium antagonists were the main determinants of AHI ≥15 events·h-1 (C statistic 0.71; sensitivity 94%; specificity 24%). Age, BMI, blood triglycerides, peak troponin levels and Killip class ≥II were determinants of AHI ≥30 events·h-1 (C statistic of 0.67; sensitivity 31%; specificity 86%).Although a set of variables associated with OSA was identified, no model could successfully predict OSA in patients admitted for ACS. Given the high prevalence of OSA, the authors propose respiratory polygraphy as a to-be-explored strategy to identify OSA in ACS patients.

Undiagnosed obstructive sleep apnea is independently associated with reductions in quality of life in middle-aged, but not elderly men of a population cohort.

PURPOSE: Obstructive sleep apnea (OSA) is now highly prevalent but largely undiagnosed. Quality of life is an indicator of both the impact of undiagnosed OSA and the need for strategies to increase OSA diagnosis. We determined age-related impacts of undiagnosed OSA on health-related quality of life (HRQL) and whether this was independent of sleepiness and comorbidities. METHODS: In 2010-2012, 837 participants from the Men Androgen Inflammation Lifestyle Environment and Stress Study (population cohort n = 1869, ≥40 years, Adelaide, Australia), without a prior OSA diagnosis underwent full in-home polysomnography (Embletta X100) and completed the Epworth Sleepiness Scale and SF-36 questionnaire. The effects of the apnea-hypopnea index (AHI) on SF-36 physical (PCS) and mental (MCS) component summary scores and standardized SF-36 scale z-scores were estimated using multiple linear regression adjusted for major comorbidities and sleepiness, stratified by age. RESULTS: Men ≤69 years demonstrated significant (p < 0.05) decrements/event increase in AHI in PCS score [unstandardized B coefficient (SE) = -0.068 (0.023)], physical functioning, role physical, general health, and vitality z-scores in fully adjusted models. Severe OSA (AHI ≥30) was associated with significant reductions in PCS [B = -4.1 (1.1)] and MCS score [B = -3.6 (1.2)] independent of sleepiness and comorbidities which were attenuated but persisted in men <69 years without depression. In men aged ≥70 years, statistically significant AHI-associated impairments were generally not seen. CONCLUSIONS: Undiagnosed OSA was a major independent contributor to HRQL impairments in men <69 years. Improved strategies to identify undiagnosed OSA are indicated that may require a reduced focus on daytime sleepiness.

Comparative Effectiveness of Supine Avoidance versus Continuous Positive Airway Pressure for Treating Supine-isolated Sleep Apnea: A Clinical Trial.

Rationale: About 20-35% of patients with obstructive sleep apnea (OSA) have supine-isolated OSA, for which supine sleep avoidance could be an effective therapy. However, traditional supine discomfort-based methods show poor tolerance and compliance to treatment and so cannot be recommended. Supine alarm devices show promise, but evidence to support favorable adherence to treatment and effectiveness at reducing excessive daytime sleepiness compared with continuous positive airway pressure (CPAP) remains limited. Objectives: To establish if alarm-based supine-avoidance treatment in patients with supine-isolated OSA is noninferior to CPAP in reducing daytime sleepiness. Methods: After baseline questionnaire administration and in-home supine-time and polysomnography assessments, patients with supine-isolated OSA and Epworth Sleepiness Scale scores ⩾8 were randomized to ⩾6 weeks of supine-avoidance or CPAP treatment, followed by crossover to the remaining treatment with repeat assessments. Noninferiority was assessed from change in Epworth Sleepiness Scale with supine avoidance compared with CPAP using a prespecified noninferiority margin of 1.5. Average nightly treatment use over all nights and treatment efficacy and effectiveness at reducing respiratory disturbances were also compared between treatments. Results: The reduction in sleepiness score with supine avoidance (mean [95% confidence interval], -1.9 [-2.8 to -1.0]) was noninferior to that with CPAP (-2.4 [-3.3 to -1.4]) (supine avoidance-CPAP difference, -0.4 [-1.3 to 0.6]), and the lower confidence limit did not cross the noninferiority margin of 1.5 (P = 0.021). Average treatment use was higher with supine avoidance compared with CPAP (mean ± standard deviation, 5.7 ± 2.4 vs. 3.9 ± 2.7 h/night; P < 0.001). Conclusions: In patients with supine-isolated OSA, vibrotactile supine alarm device therapy is noninferior to CPAP for reducing sleepiness and shows superior treatment adherence. Clinical trial registered with www.anzctr.org.au (ACTRN 12613001242718).

Investigating obstructive sleep apnoea: will the health system have the capacity to cope? A population study.

OBJECTIVE: To obtain prevalence estimates of clinical features of obstructive sleep apnoea (OSA) and identify the dimensions of the public health problem requiring further investigation for an Australian population. METHODS: The South Australian Health Omnibus Survey is an annual representative population survey of South Australians aged≥15 years, conducted via interviewer-administered questionnaire. In 2009, 3007 participants were asked the STOP-BANG instrument measure of obstructive sleep apnoea risk, which includes symptoms of loud snoring, frequent tiredness during daytime, observed apnoea, and high blood pressure (STOP), and measured body mass index, age, neck circumference and gender (BANG). Three or more positive response categorises a person at high risk for OSA. RESULTS: Snoring was reported by 49.7% of adults. Tiredness after sleep more than 3 - 4 times per week was reported by 24.8%, and during wake-time by 27.7% of adults, with 8.8% reporting having fallen asleep while driving. Over half of the surveyed men (57.1%, n=566) and 19.3% (n=269) of the women were classified at high-risk of OSA with the STOP-BANG measure. In multivariable models, high risk was associated with less education, lower income, and residence in a regional rather than metropolitan area. CONCLUSION: The high prevalence of adults at risk for OSA suggests that the capacity currently available within the healthcare system to investigate and diagnose OSA is likely to be inadequate, particularly outside urban areas. This highlights an important public health problem that requires further detailed study and trials of new models of care.

Upper airway function and arousability to ventilatory challenge in slow wave versus stage 2 sleep in obstructive sleep apnoea.

UNLABELLED: Patients with obstructive sleep apnoea (OSA) have reduced event rates during slow wave sleep (SWS) compared with stage 2 sleep. To explore this phenomenon, ventilatory and arousal timing responses to partial and complete airflow obstruction during SWS versus stage 2 sleep were examined. METHODS: Ten patients, mean+/-SD apnoea-hypopnoea index (AHI) 49.7+/-16.5 events/h with reduced OSA frequency during SWS (SWS AHI 18.9+/-14.0 events/h) slept with an epiglottic pressure catheter and nasal mask/pneumotachograph. Patients underwent rapid continuous positive airway pressure (CPAP) dialdowns to three subtherapeutic levels and brief airway occlusions in random order. RESULTS: Post-dialdown, there were marked reductions in peak flow and minute ventilation, and progressive increases in inspiratory effort (p<0.001), but with limited ventilatory recovery and no differences between sleep stages. CPAP versus peak flow relationships on the third and second to last breath pre-arousal were not different between sleep stages. Arousals occurred later and post-dialdown arousal probability was lower during SWS compared with stage 2 sleep, Cox hazard ratio (95% CI) 0.65 (0.48 to 0.88), p=0.006. During SWS occlusions, time to arousal (mean+/-SEM) was prolonged (23.0+/-2.6 vs 17.1+/-1.7 s, p=0.02). Inspiratory effort developed more rapidly (-1.0+/-0.2 vs -0.6+/-0.1 cm H(2)O/s, p=0.019) and was more negative (-28.7+/-2.7 vs -20.3+/-1.6 cm H(2)O, p<0.001) on the breath preceding arousal. CONCLUSIONS: Except for a heightened ventilatory drive response during airway occlusion, airway function and ventilatory compensation to ventilatory challenge appear to be similar, but with consistently and substantially delayed arousal responses, in SWS versus stage 2 sleep.

Making errors at work due to sleepiness or sleep problems is not confined to non-standard work hours: results of the 2016 Sleep Health Foundation national survey.

Almost one-third of Australians report having made errors at work that are related to sleep issues. While there is significant literature investigating the role of sleep in workplace health and safety in shiftworking and nightwork operations, long working hours, work-family conflict, and commute times getting longer also impact day workers' sleep behaviors and opportunities. The aim of this study was to examine the relationship between sleep duration and disorders, sleep health and hygiene factors, work-related factors and errors at work in Australian workers. From a sample of 1011 Australian adults, age-adjusted binary logistic regression analyses were conducted in 512 workers who provided responses to the question "Thinking about the past three months, how many days did you make errors at work because you were too sleepy or you had a sleep problem?" A number of sleep behaviors and poor sleep hygiene factors were linked with work errors related to sleepiness or sleep problems, with age-adjusted odds of errors (confidence intervals) up to 11.6 times higher (5.4-25.1, p < 0.001) in those that snored, 7.7 (4.6-12.9) times higher in those reporting more than three sleep issues (p < 0.001), 7.0 times higher (3.4-14.8) in short (≤5 hours/night) sleepers (p < 0.021), 6.1 times higher (2.9-12.7) in those staying up later than planned most nights of the week (p< 0.001) and 2.4 times higher (1.6-3.7) in those drinking alcohol ≥3 nights/week before bed (p < 0.001). More than 40% of participants working non-standard hours reported making errors at work, and they were more likely to be young (compared to the main sample of workers) and more likely to engage in work activities in the hour before bed. Sleep factors (other than clinical sleep disorders) were associated with an increased likelihood of sleep-related work errors. Both day workers and those working non-standard hours engage in work, sleep and health behaviors that do not support good sleep health, which may be impacting safety and productivity in the workplace through increased sleepiness-related errors.

Effects of continuous positive airway pressure on depression and anxiety symptoms in patients with obstructive sleep apnoea: results from the sleep apnoea cardiovascular Endpoint randomised trial and meta-analysis.

BACKGROUND: Whether continuous positive airway pressure (CPAP) treatment can improve depression or anxiety symptoms in obstructive sleep apnoea (OSA) patients remains uncertain. METHODS: Secondary analysis of the Sleep Apnea Cardiovascular Endpoints (SAVE) trial, combined with a systematic review of randomised evidence. The SAVE secondary analyses involved 2410 patients with co-existing moderate-severe OSA and established cardiovascular disease randomly allocated to CPAP treatment plus usual care or usual care alone and followed up for 3·7 (SD 1·6) years. We evaluated the effect of CPAP treatment on depression and anxiety caseness (scores ≥ 8 on the Hospital Anxiety and Depression Scale depression and anxiety subscales [HADS-D and HADS-A]) for OSA patients. FINDINGS: CPAP treatment was associated with reduced odds of depression caseness (adjusted odds ratio [OR] 0·80, 95% confidence interval [CI] 0·65-0·98, P = 0·031) compared to usual care in the SAVE trial and the treatment effect was greater in those with pre-existing depression symptoms. A systematic review of 20 randomised trials including 4255 participants confirmed a benefit of CPAP in reducing depression symptoms in OSA patients: the overall effect (standardised mean difference) was - 0·18 (95% CI - 0·24 to - 0·12). No effect of CPAP treatment on anxiety caseness was found both in patients of the SAVE study (adjusted OR 0·98, 95% CI 0·78-1·24, P = 0·89) and the systematic review. INTERPRETATION: CPAP reduces depression symptoms in patients with co-existing OSA and CVD independently of improvements in sleepiness.

Variability of QT interval duration in obstructive sleep apnea: an indicator of disease severity.

STUDY OBJECTIVE: To determine OSA-related changes in variability of QT interval duration and in heart rate variability (HRV), and to evaluate the relationship of these parameters to disease severity. DESIGN: Retrospective analysis of diagnostic sleep records. SETTINGS: Clinical sleep laboratory in a hospital setting. PATIENTS: Twenty patients (12 males and 8 females) without significant comorbidities who were undergoing polysomnography were studied. MEASUREMENTS AND RESULTS: Standard heart rate variability measures and QT variability (Berger algorithm) were computed over consecutive 5-minute ECG epochs throughout the night. The effect of sleep stage and the relationship between these parameters and the severity of OSA as determined by the respiratory disturbance index (RDI) were explored. Further, a linear regression model of QT variability was developed. Severity of OSA (RDI) was 49 +/- 28 (range from 17-107) events/ hr. QT variability was the only ECG measure significantly correlated with RDI (both log-transformed; r = 0.6, P = 0.006). Further, QT variability was correlated with the minimum oxygen saturation (r = -0.55, P = 0.01). Sleep stage showed a significant effect on HRV, but not on QT variability. In the regression model, RDI was the strongest predictor of QT variability (R2 increase 38%), followed by high and low frequency power of HRV (R2 increase 10% each). CONCLUSION: Obstructive sleep apnea is associated with changes in QT interval variability during sleep. The variance of beat-to-beat QT intervals correlates more strongly with the severity of OSA (as determined by RDI) than standard measures of heart rate variability, and is correlated with blood oxygenation, but not sleep stage.

Prevalence and comorbidity of sleep conditions in Australian adults: 2016 Sleep Health Foundation national survey.

OBJECTIVE: To determine the prevalence of sleep conditions (obstructive sleep apnea [OSA], insomnia symptoms, simple snoring, and restless legs) and their associated burden of chronic conditions in a community sample. DESIGN: Cross-sectional national adult online survey. SETTING: Community-based sample. PARTICIPANTS: Australian adults ≥18 years, N = 1011. MEASUREMENTS: A cross-sectional national online survey assessed diagnosed OSA, OSA symptoms, insomnia symptoms, sleep problems, excessive daytime sleepiness (Epworth Sleepiness Scale ≥11), and physician-diagnosed health conditions (heart disease, diabetes, hypertension, reflux disease, lung disease, depression, anxiety/panic disorder, arthritis). Possible undiagnosed OSA was estimated using self-reported frequent loud snoring and witness apneas. International Criteria for Sleep Disorders-3 criteria identified insomnia symptoms. Logistic regression models adjusted for age, sex, obesity, and smoking determined correlates of sleep disorders. RESULTS: Comorbid sleep conditions were common, with 56% of participants demonstrating ≥1 condition. Reporting ≥1 mental health condition (depression and/or anxiety) was independently associated with diagnosed OSA (odds ratio [95% confidence interval {CI}]: 6.6 [3.2-13.6]), undiagnosed OSA (3.2 [1.8-5.8]), simple snoring (2.4 [1.2-4.5]), insomnia symptoms (4.3 [2.5-7.3]), and restless legs (1.9 [1.2-3.1]). Diagnosed OSA was significantly associated with ≥1 cardiometabolic condition (2.9 [1.4-6.0]) and arthritis (3.6 [1.8-7.2]). ESS ≥11 was associated with diagnosed (3.1 [1.4-6.8]) and undiagnosed OSA (6.2 [3.4-11.4]), insomnia symptoms (2.6 [1.4-4.9]), and restless legs (2.3 [1.4-4.0]), and these sleep conditions were also significantly associated with ≥2 diagnosed medical problems. CONCLUSION: Strategies to facilitate the diagnosis and management of often comorbid sleep disorders in primary care are required to reduce the significant sleep-related disparities in cardiometabolic and mental health.

Sleep health of Australian adults in 2016: results of the 2016 Sleep Health Foundation national survey.

OBJECTIVE: To measure the prevalence and social impacts of sleep problems in Australia. DESIGN: Cross-sectional national adult online survey. SETTING: Community-based sample. PARTICIPANTS: Australian adults ≥18 years, n=1011. RESULTS: Self-reported inadequate sleep, of either duration or quality, and its daytime consequences affect 33%-45% of adults. Diagnosed sleep apnea is reported by 8%, significant insomnia by 20%, and restless legs by18% of adults. Besides specific clinical sleep disorders, poor sleep habits were common. Average reported sleep time is 7 hours, although 12% sleep less than 5½hours and 8% over 9 hours. Three-quarters (76%) of those who sleep less than 5½hours report frequent daytime impairment or sleep-related symptoms. Frequent, loud snoring is reported by 24% of men and 17% of women. Among these, 70% report daytime impairment or other sleep-related symptoms. Twenty-six percent report Internet use most or every night just before bed and frequent sleep difficulties or daytime impairments. Similarly, 16% of working adults do work just before bed and also have frequent sleep difficulties or daytime sleep-related symptoms. Younger adults (18-34 years) sleep around 1 hour longer before non-work days than working days compared with 18 minutes in older age groups. In the past 3 months, 29% of adults report making errors at work due to sleepiness or sleep problems. Driving while drowsy at least every month is reported by 29% of people, 20% have nodded off while driving, and 5% have had an accident in the past year because they dozed off. CONCLUSION: Sleep problems and daytime consequences are endemic among Australian adults. A focus on healthy sleep at a policy level as well as increased clinician and public awareness may be warranted.

Sickness absenteeism is associated with sleep problems independent of sleep disorders: results of the 2016 Sleep Health Foundation national survey.

INTRODUCTION: Sleep disorders are associated with sickness absenteeism (SA), at significant economic cost. Correlates of absenteeism are less well described in nonclinical samples. PARTICIPANTS AND METHODS: We determined the relationship between markers of inadequate sleep and SA in a sample of 551 working adults aged ≥18 years across Australia. We considered diagnosed obstructive sleep apnea (OSA) and insomnia symptoms, daytime symptoms, and sleepiness with respect to sickness absenteeism (missing ≥1 day of work in the past 28 days because of problems with physical or mental health). RESULTS: Sickness absenteeism was reported by 27.0% of participants and was more frequent in younger participants, university graduates, and those experiencing financial stress. Sickness absenteeism was independently associated with insomnia (odds ratio [OR]=2.5, confidence interval [CI]=1.5-4.0], OSA (OR=9.8, CI=4.7-20.7), sleep aid use (OR=3.0, CI=1.9-4.7), and daytime symptoms (OR=3.0, CI=2.0-4.6) and inversely associated with perception of getting adequate sleep (OR=0.6, CI=0.4-0.9). Associations persisted in the population free of insomnia and/or OSA. CONCLUSIONS: In adults without clinical sleep disorders, sleep behaviors are contributing to sickness absenteeism. An increased focus at an organizational level on improvement of sleep hygiene is important to reduce lost work performance.

Erectile dysfunction is independently associated with apnea-hypopnea index and oxygen desaturation index in elderly, but not younger, community-dwelling men.

OBJECTIVE(S): To examine the association between obstructive sleep apnea (OSA) and other sleep indices using polysomnography (PSG) data and erectile dysfunction (ED) in a representative cohort of men. DESIGN: Cross-sectional. SETTING: Community-based. PARTICIPANTS: Aged 40+ years (n=734; mean age [SD], 60.8 [10.9]). MEASUREMENTS: Men with no prior OSA diagnosis who underwent in-home PSG (Embletta X100; 2010-11) and ED assessment (Global Impotence Rating) were selected. Un-adjusted and multi-adjusted regression models of ED were fitted against PSG measures, along with qualifying sociodemographic, lifestyle, and health-related covariates. Mediation effects were examined using the Baron-Kenny method. RESULTS: Of the men examined, 24.7% (n=181) had ED, most notably in men older than 65years (cf. men 35-49 and 50-64years; P<.001). There was no significant association between ED and any of the PSG measures for allaged men. Given an observed ageinteraction within OSA categories (P=.005), analyses were repeated in age-stratified samples (<65 years; 65+ years). In men younger than 65years, only severe OSA was found to have an association with ED (2.01; 1.13-4.69) in unadjusted models. For men aged 65+ years, an independent association with ED was found for apnea-hyponea index (AHI; 1.55;1.02-2.36), moderate (AHI:10.0-19.9; 1.79;1.18-2.43), and severe (AHI:20.0+; 4.84;2.56-9.93) OSA, and oxygen desaturation index (ODI; both continuous [1.48;1.03-1.99] and >16 seconds [2.79;1.23-6.32]). The effect of AHI on ED was shown to be primarily mediated through ODI (63.4%, Sobel P value=.29). CONCLUSIONS: In younger, community-based men, there appeared no independent relationship between objective measures of sleep and ED. However, there appears a strong, independent relationship between OSA, ODI, and ED in men 65 years and older.

Mild hypoxia does not suppress auditory arousal from NREM sleep.

STUDY OBJECTIVES: The depressive effects of hypoxia on the central nervous system are well known. The purpose of this study was to determine the influence of mild overnight hypoxia on the ability of healthy individuals to arouse from non-rapid-eye-movement (NREM) sleep to auditory tones. DESIGN: Randomized cross-over. SETTING: Participants slept in a sound-insulated room with the physiologic recordings and experimental interventions controlled from a separate room. PARTICIPANTS: Eleven healthy men aged 18 to 24 years. INTERVENTIONS: On separate nights, participants were exposed to mild overnight hypoxia (SaO2 approximately 90%) or medical air in single-blind fashion. During established sleep, subjects were administered 1 of 10 auditory tones (500 Hz, 54-90 dB, 5 seconds duration) via earphones, or a sham tone (recording period with no tone). MEASUREMENTS AND RESULTS: The probability and intensity of arousal responses in the 30 seconds following tones or shams were compared between gas conditions and between stage 2 and slow-wave sleep. Arousal probability and intensity increased with tone intensity and were significantly lower during slow-wave compared with stage 2 sleep but were not different between hypoxia and normoxia nights. CONCLUSION: These data suggest that mild overnight hypoxia does not impair the neural mechanisms involved in arousal from sleep to auditory stimuli.

Nocturia, Other Lower Urinary Tract Symptoms and Sleep Dysfunction in a Community-Dwelling Cohort of Men.

OBJECTIVES: To examine the influence of obstructive sleep apnea (OSA) on nocturia, controlling for their shared co-morbidities, in a population of community-based middle aged to elderly men. METHODS: Participants were drawn from a randomly selected, community-dwelling cohort of men in Adelaide, Australia. Seven hundred and eight men (mean: 60.7 [41.6-88.2] years) who had polysomnography recordings, complete lower urinary tract symptoms (LUTS) measures (International Prostate Symptom Score), without prostate or bladder cancer and/or surgery, and no prior OSA diagnosis were selected. Nocturia was defined as ≥2 voids per main sleep. Unadjusted and multi-adjusted regression models of nocturia were combined with OSA, wake after sleep onset, total sleep period, excessive daytime sleepiness (EDS), and sleep quality (SQ) data, together with socio-demographic, and health-related factors. RESULTS: Men with nocturia were found to have higher levels of OSA (32.2% [n = 65]), wake after sleep onset time (97.2 ± 52.9 minutes), sleep period (467.3 ± 58.4 minutes), EDS (18.2% [n = 37]), and poorer SQ (54.3% [n = 108]). Multiple-adjusted models showed nocturia was positively associated with OSA (odds ratio:1.64, 95% confidence interval [1.03,2.55]), EDS (1.72 [1.01,2.93]), and poorer SQ (1.65 [1.10,2.48]). Including other storage and voiding LUTS attenuated the effect of OSA and strengthened the association with EDS (2.44 [1.45,4.10] and 2.24 [1.19,4.22]), whereas voiding LUTS also strengthened the association with poorer SQ (2.61 [1.63,4.17]). Men with increasing nocturic frequency spent less time in N2 and rapid eye movement stage sleep. CONCLUSION: Nocturia is strongly associated with OSA in community-based men. Nocturia also reduces sleep efficiency/SQ, N2, and rapid eye movement sleep time, while increasing EDS. Other LUTS increase EDS through non-OSA means.

The association of obstructive sleep apnea (OSA) and nocturnal hypoxemia with the development of abnormal HbA1c in a population cohort of men without diabetes.

AIM: To examine the relationship between indices of undiagnosed OSA and the development of abnormal glycaemic control in community-dwelling men free of diabetes. METHODS: The Men, Androgens, Inflammation, Lifestyle, Environment, and Stress (MAILES) Study is a population-based cohort study in Adelaide, South Australia. Clinic visits at baseline (2002-06) and follow-up (2007-10) identified abnormal glycaemic metabolism [HbA1c 6.0 to <6.5% (42 to <48mmol/mol)] in men without diabetes. At follow-up (2010-11), n=837 underwent assessment of OSA by full in-home unattended polysomnography (Embletta X100). RESULTS: Development of abnormal glycaemic metabolism over 4-6 years (n=103 "incident" cases, 17.0%) showed adjusted associations [odds ratio (95% CI)] with the 1st [1.7 (0.8-3.8)], 2nd [2.4 (1.1-4.9)], and 3rd [2.3 (1.1-4.8)] quartiles of mean oxygen saturation (SaO2) compared to the highest quartile. Prevalent abnormal glycaemic metabolism (n=140, 20.8%) was independently associated with the third and fourth quartiles of percentage of sleep time with oxygen saturation <90% and lowest quartile of mean SaO2. Linear regression analysis showed a significant reduction in HbA1c [unstandardized B, 95% CI: -0.02 (-0.04, -0.002), p=0.034] per percentage point increase in mean SaO2. OSA as measured by the apnea-hypopnea index showed no adjusted relationship with abnormal glycaemic metabolism. CONCLUSIONS: Development of abnormal glycaemic metabolism was associated with nocturnal hypoxemia. Improved management of OSA and glycaemic control may occur if patients presenting with one abnormality are assessed for the other.

Noninvasive cardiovascular markers of acoustically induced arousal from non-rapid-eye-movement sleep.

STUDY OBJECTIVES: Changes in cardiovascular measures such as heart rate (HR) and pulse transit time (PTT) have been advocated as sensitive markers of autonomic arousal from sleep. In animal studies, alerting stimuli produce particularly marked skin vascular responses. We hypothesized that changes in skin vascular conductance would provide more sensitive markers of autonomic arousal during sleep compared to central cardiovascular response measures such as HR and PTT. DESIGN: Cardiovascular responses to auditory-induced arousals were recorded during overnight sleep studies. SETTING: Sleep disorders unit in a 270-bed teaching hospital. PARTICIPANTS: Eleven young healthy male subjects. INTERVENTIONS: Throughout ovemight sleep studies, auditory tones (5-second duration, 54-90 decibels, 22-56 per subject) were presented during non-rapid-eye-movement sleep. Beat-by-beat HR, PTT, laser-Doppler fingertip skin blood flow (SBF) and finger and ear photoplethysmogram pulse wave amplitudes (PWA) were measured in the 20 seconds preceding and 30 seconds following each tone and compared to control measurements obtained during 50-second periods of recording with no stimulus (no tone, 6-22 per subject). Electroencephalographic (EEG) arousals were scored according to standard criteria (American Sleep Disorders Association) into no discemible, 3- to 10-second duration, or 10- to 15-second duration arousals. Poststimulus cardiovascular measurements were expressed as a percentage of the prestimulus mean and response magnitudes quantified from peak responses and the area under the poststimulus response curve. The ability of each cardiovascular response measure to discriminate EEG arousals (EEG changes lasting more than 3 seconds) was assessed from the area under the receiver operating characteristic (ROC) curve. MEASUREMENTS AND RESULTS: There were no significant changes in any cardiovascular parameter during control recordings. In contrast to all other parameters, finger PWA and SBF decreased following tones that produced no discernible EEG arousal (P < 0.05). A significant HR rise and decreases in all cardiovascular measures occurred with greater than 3-second arousals, with longer duration arousals generally exhibiting larger responses. Conventional EEG arousals (greater than 3 seconds) were relatively poorly detected from HR responses (ROC area HR rise 0.80 +/- 0.04) compared to changes in SBF (0.85 +/- 0.02), PTT (0.85 +/- 0.03) and finger PWA (0.90 +/- 0.01). CONCLUSIONS: Decreases in skin vascular conductance (finger PWA and SBF) provide sensitive markers of autonomic arousal during sleep. They are at least as sensitive as PTT for detecting conventionally scored EEG arousals and may be more sensitive in detecting "subcortical" arousals.

The relationship between functional health literacy and obstructive sleep apnea and its related risk factors and comorbidities in a population cohort of men.

STUDY OBJECTIVES: To examine the relationship between functional health literacy (FHL) and obstructive sleep apnea (OSA), its diagnosis, related risk factors, and comorbidities. DESIGN: Population cohort study. SETTING: Adelaide, South Australia, 2011-12. PARTICIPANTS: 1,021 Men Androgen Inflammation Lifestyle Environment and Stress Study participants aged ≥ 40 years, of whom 627 were identified with OSA by self-report (n = 184 previously diagnosed) or with in-home polysomnography in 837 randomly selected participants without self-reported OSA (n = 443 previously undiagnosed). INTERVENTIONS: The Newest Vital Sign assessed FHL in 88% of participants. Full in-home unattended polysomnography (Embletta X100) was scored by 2007 AASM (alternative) criteria. MEASUREMENTS AND RESULTS: FHL was adequate in 75.3% (n = 122) of previously diagnosed and 68.3% (n = 261) of previously undiagnosed OSA. Not having a previous diagnosis was independently associated with inadequate FHL (odds ratio [OR]:2.84, 95% confidence interval [CI]:1.25-6.45) and workforce participation (OR = 2.04, 95% CI = 1.01-4.00), and inversely associated with previous snoring (OR = 0.48, 95% CI = 0.29-0.81), obesity (OR = 0.35, 95% CI = 0.15-0.81), and cardiovascular disease (OR = 0.45, 95% CI = 0.24-0.85). In polysomnography participants, inadequate FHL was independently associated with previously undiagnosed OSA (OR = 2.43, 95% CI = 1.40-4.20). In undiagnosed men, less than adequate FHL was independently associated with sedentary lifestyle (OR = 2.42, 95% CI = 1.36-4.29), and depression (OR = 2.50, 95% CI = 1.23-5.09) and inadequate FHL was associated with current smoking (OR = 2.87, 95% CI = 1.21-6.84). The depression association was attenuated after additional adjustment for comorbidities and general health (OR = 2.04, 95% CI = 0.93-4.49, P = 0.076). In previously diagnosed OSA, less than adequate FHL was independently associated with cardiovascular disease (OR = 2.76, 95% CI = 1.09-7.01). CONCLUSIONS: Limited functional health literacy was independently associated with obstructive sleep apnea (OSA), OSA diagnosis, lifestyle factors and comorbidities, highlighting the importance of developing and promoting national disease-specific health literacy policies.

Treating obstructive sleep apnea with hypoglossal nerve stimulation.

BACKGROUND: Reduced upper airway muscle activity during sleep is fundamental to obstructive sleep apnea (OSA) pathogenesis. Hypoglossal nerve stimulation (HGNS) counteracts this problem, with potential to reduce OSA severity. STUDY OBJECTIVES: To examine safety and efficacy of a novel HGNS system (HGNS, Apnex Medical, Inc.) in treating OSA. PARTICIPANTS: Twenty-one patients, 67% male, age (mean ± SD) 53.6 ± 9.2 years, with moderate to severe OSA and unable to tolerate continuous positive airway pressure (CPAP). DESIGN: Each participant underwent surgical implantation of the HGNS system in a prospective single-arm interventional trial. OSA severity was defined by apnea-hypopnea index (AHI) during in-laboratory polysomnography (PSG) at baseline and 3 and 6 months post-implant. Therapy compliance was assessed by nightly hours of use. Symptoms were assessed using the Epworth Sleepiness Scale (ESS), Functional Outcomes of Sleep Questionnaire (FOSQ), Calgary Sleep Apnea Quality of Life Index (SAQLI), and the Beck Depression Inventory (BDI). RESULTS: HGNS was used on 89% ± 15% of nights (n = 21). On these nights, it was used for 5.8 ± 1.6 h per night. Nineteen of 21 participants had baseline and 6-month PSGs. There was a significant improvement (all P < 0.05) from baseline to 6 months in: AHI (43.1 ± 17.5 to 19.5 ± 16.7), ESS (12.1 ± 4.7 to 8.1 ± 4.4), FOSQ (14.4 ± 2.0 to 16.7 ± 2.2), SAQLI (3.2 ± 1.0 to 4.9 ± 1.3), and BDI (15.8 ± 9.0 to 9.7 ± 7.6). Two serious device-related adverse events occurred: an infection requiring device removal and a stimulation lead cuff dislodgement requiring replacement. CONCLUSIONS: HGNS demonstrated favorable safety, efficacy, and compliance. Participants experienced a significant decrease in OSA severity and OSA-associated symptoms. CLINICAL TRIAL INFORMATION: NAME: Australian Clinical Study of the Apnex Medical HGNS System to Treat Obstructive Sleep Apnea. REGISTRATION NUMBER: NCT01186926. URL: http://clinicaltrials.gov/ct2/show/NCT01186926.

Continuous positive airway pressure treatment improves pulmonary hemodynamics in patients with obstructive sleep apnea.

Daytime pulmonary hypertension (PH) is relatively common in obstructive sleep apnea (OSA) and is thought to be associated with pulmonary vascular remodeling (PRm). The extent to which PH is reversible with treatment is uncertain. To study this, we measured pulmonary hemodynamics (Doppler echocardiography) in 20 patients with OSA (apnea-hypopnea index [AHI] 48.6 +/- 5.2/h, mean +/- SEM) before and after 1 and 4 mo of CPAP treatment (compliance 4.7 +/- 0.5 h/night). Patients had normal lung function, and no cardiac disease or systemic hypertension. Doppler studies were performed at three levels of inspired oxygen concentration (11%, 21%, and 50%) and during incremental increases in pulmonary blood flow (10, 20, and 30 microg/kg/min dobutamine infusions). Treatment resulted in a decrease in pulmonary artery pressure (Ppa, 16.8 +/- 1.2 mm Hg before CPAP versus 13.9 +/- 0.6 mm Hg after 4 mo CPAP, p < 0.05) and total pulmonary vascular resistance (231.1 +/- 19.6 versus 186.4 +/- 12.3 dyn. s. cm(-)(5), p < 0.05). The greatest treatment effects occurred in the five patients who were pulmonary hypertensive at baseline. The pulmonary vascular response to hypoxia decreased after CPAP (DeltaPpa/DeltaSa(O(2)) 10.0 +/- 1.6 mm Hg before versus 6.3 +/- 0.8 mm Hg after 4 mo CPAP, p < 0.05). The curve of Ppa versus cardiac output (Q), derived from the incremental dobutamine infusion, shifted downward in a parallel fashion during treatment. Systemic diastolic blood pressure also fell significantly. Improvements in pulmonary hemodynamics were not attributable to changes in left ventricular diastolic function or Pa (O(2)). We conclude that CPAP treatment reduces Ppa and hypoxic pulmonary vascular reactivity in OSA and speculate that this may be due to improved pulmonary endothelial function.