Association of sleep-disordered breathing and the occurrence of stroke

Validation of an automated algorithm for detecting apneas and hypopneas by acoustic analysis of breath sounds

BACKGROUND

Sleep-disordered breathing (SDB) is common and is associated with increased risk for cardiovascular disease. However, most patients remain undiagnosed due to lack of access to sleep laboratories. We therefore tested the validity of a single-channel monitoring setup that captures and analyzes breath sounds (BSs) to detect SDB.

METHODS

BS were recorded from 50 patients undergoing simultaneous polysomnography (PSG). Using custom-designed automatic software, BS were subjected to a set of pattern recognition rules to identify apneas and hypopneas from which the acoustic apnea-hypopnea index (AHI-a) was calculated. Apneas and hypopneas from PSG were scored blindly by three technicians according to two criteria; one relying solely on the drop of the respiratory signal by >90% for an apnea and by 50% to 90% for a hypopnea (TV50 criteria), and another that also required a desaturation or an arousal for a hypopnea (American Association of Sleep Medicine [AASM] criteria). PSG AHI (AHI-p) was calculated for each technician according to both criteria.

RESULTS

There was no significant difference between AHI-p scores according to TV50 and AASM criteria. AHI-a was strongly correlated with AHI-p according to both TV50 (R=94%) and AASM criteria (R=93%). Bland-Altman plot analysis revealed that 98% and 92% of AHI-a fell within the limits of agreement for AHI-p according to TV50 and AASM criteria, respectively. Based on a diagnostic cutoff of AHI-p≥10 for SDB, overall accuracy of AHI-a reached 88% and negative predictive value reached 100%.

CONCLUSION

Acoustic analysis of BS is a reliable method for quantifying AHI and diagnosing SDB compared to simultaneous PSG.

The Relationship between Obstructive Sleep Apnea and Atrial Fibrillation: A Complex Interplay

In recent years, growing evidence suggests an association between obstructive sleep apnea (OSA), a common sleep breathing disorder which is increasing in prevalence as the obesity epidemic surges, and atrial fibrillation (AF), the most common cardiac arrhythmia. AF is a costly public health problem increasing a patient's risk of stroke, heart failure, and all-cause mortality. It remains unclear whether the association is based on mutual risk factors, such as obesity and hypertension, or whether OSA is an independent risk factor and causative in nature. This paper explores the pathophysiology of OSA which may predispose to AF, clinical implications of stroke risk in this cohort who display overlapping disease processes, and targeted treatment strategies such as continuous positive airway pressure and AF ablation.

Arterial stiffness and endothelial function in obstructive sleep apnoea/hypopnoea syndrome

BACKGROUND

Obstructive sleep apnoea-hypopnoea syndrome (OSAHS) is associated with increased cardiovascular morbidity and mortality. Our study examined arterial stiffness and endothelial function in subjects with OSAHS with no known cardiovascular disease compared to well-matched controls.

METHODS

Twenty subjects with OSAHS (defined as apnoea-hypopnoea index [AHI] > or =15 and Epworth Sleepiness Scale score > or =11) without cardiovascular disease and 20 well-matched controls underwent a comprehensive evaluation of arterial stiffness and endothelial function. Arterial stiffness was measured by applanation tonometry and cardiovascular magnetic resonance imaging (MRI) and endothelial function assessed by measuring vascular reactivity after administration of glyceryl trinitrate and salbutamol.

RESULTS

Subjects with OSAHS had increased arterial stiffness (augmentation index 19.3 [10.9] vs. 12.6 (10.2)%; p=0.017) and impaired endothelial function (change in augmentation index following salbutamol -4.3 (3.2) vs. -8.0 (4.9)%; p=0.02) compared to controls. Aortic distensibility, a measure of arterial stiffness, was negatively correlated with the AHI.

CONCLUSIONS

Our findings suggest that even in the absence of known cardiovascular disease, subjects with OSAHS have increased arterial stiffness and impaired endothelial function and are at increased risk for cardiovascular disease.

Cerebral hemodynamic changes in obstructive sleep apnea syndrome after continuous positive airway pressure treatment

BACKGROUND

Patients with obstructive sleep apnea syndrome (OSAS) are at increased risk for cerebrovascular diseases. The underlying mechanisms remain obscure. It may occur through a reduction in cerebral vascular reactivity. Continuous positive airway pressure (CPAP) is effective in reducing the occurrence of apneas. We hypothesized that treatment with CPAP improves cerebral vascular reactivity.

METHODS

This is a prospective study with OSAS patients. The apnea test (ApT) was calculated as an increase of mean artery velocity during apnea: [Artery velocity in apnea minus Resting artery velocity]/Resting artery velocity expressed as percentage. After 2 years of CPAP treatment, the test was repeated.

RESULTS

Seventy-six patients represented the study pool. After 2 years of treatment with CPAP, we were able to conduct a reassessment in 65 patients. Of the 65 patients who finished the clinical study, 56 were men, and 9 were women, with an average age of 48.1 ± 10.4 years. There was an improvement in the ApT after CPAP treatment (30.8 ± 12.1 vs 39.8 ± 15.1; p:0.000). The values of cerebral blood flow velocities, diastolic blood pressure in apnea, and basal heart rate decreased.

CONCLUSIONS

Cerebral vascular reactivity in OSAS patients measured by ApT improved after 2 years of CPAP.

The more the merrier? Working towards multidisciplinary management of obstructive sleep apnea and comorbid insomnia

OBJECTIVES

The goal of this article was to provide an overview of the diagnostic considerations, clinical features, pathophysiology, and treatment approaches for patients with obstructive sleep apnea (OSA) and comorbid insomnia.

METHOD

We begin with a review of the literature on OSA and comorbid insomnia. We then present a multidisciplinary approach using pulmonary and behavioral sleep medicine treatments.

RESULTS

OSA and insomnia co-occur at a high rate and such patients have distinct clinical features. Empirically supported treatments are available for OSA and insomnia independently but there are no standards or guidelines for how to implement these treatments for patients who suffer from both disorders.

CONCLUSIONS

Multidisciplinary treatment holds promise for patients with comorbid sleep disorders. Further research should be aimed at optimizing treatments and developing standards of practice for this population.

Obstructive sleep apnea as a risk factor for silent cerebral infarction

Previous studies have suggested that obstructive sleep apnea (OSA) may be a risk factor for stroke. In this study, we assessed that OSA is an independent risk factor of silent cerebral infarction (SCI) in the general population, and in a non-obese population. This study recruited a total of 746 participants (252 men and 494 women) aged 50-79 years as part of the Korean Genome and Epidemiology Study (KoGES); they underwent polysomnography, brain magnetic resonance imaging and health screening examinations. SCI was assessed by subtypes and brain regions, and lacunar infarction represented lesions <15 mm in size in the penetrating arteries. Moderate-severe OSA was determined by apnea-hypopnea index ≥15. The results indicated that 12.06% had moderate-severe OSA, 7.64% of participants had SCI and 4.96% had lacunar infarction. Moderate-severe OSA was associated positively with SCI [odds ratio (OR): 2.44, 95% confidence interval (CI): 1.03-5.80] and lacunar infarction (OR: 3.48, 95% CI: 1.31-9.23) in the age ≥65-year group compared with those with non-OSA. Additionally, in the basal ganglia, OSA was associated with an increase in the odds for SCI and lacunar infarction in all age groups, and especially in the ≥65-year age group. In the non-obese participants, OSA was also associated positively with SCI in the ≥65-year age group, lacunar infarction in all age groups, and especially in the ≥65-year age group. There was also a positive association with the basal ganglia. Moderate-severe OSA was associated positively with SCI and lacunar infarction in elderly participants. Treatment of OSA may reduce new first-time cerebrovascular events and recurrences.

Memory and obstructive sleep apnea: a meta-analysis

STUDY OBJECTIVES

To examine episodic memory performance in individuals with obstructive sleep apnea (OSA).

DESIGN

Meta-analysis was used to synthesize results from individual studies examining the impact of OSA on episodic memory performance. The performance of individuals with OSA was compared to healthy controls or normative data.

PARTICIPANTS

Forty-two studies were included, comprising 2,294 adults with untreated OSA and 1,364 healthy controls. Studies that recorded information about participants at baseline prior to treatment interventions were included in the analysis.

MEASUREMENTS

PARTICIPANTS WERE ASSESSED WITH TASKS THAT INCLUDED A MEASURE OF EPISODIC MEMORY: immediate recall, delayed recall, learning, and/or recognition memory.

RESULTS

The results of the meta-analyses provide evidence that individuals with OSA are significantly impaired when compared to healthy controls on verbal episodic memory (immediate recall, delayed recall, learning, and recognition) and visuo-spatial episodic memory (immediate and delayed recall), but not visual immediate recall or visuo-spatial learning. When patients were compared to norms, negative effects of OSA were found only in verbal immediate and delayed recall.

CONCLUSIONS

This meta-analysis contributes to understanding of the nature of episodic memory deficits in individuals with OSA. Impairments to episodic memory are likely to affect the daily functioning of individuals with OSA.

Interaction between Sleep-Disordered Breathing and Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Sleep-disordered breathing (SDB) is suggested to be strongly associated with ischemic strokes. Risk factors, stroke subtypes, stroke lesion distribution, and the outcome of SDB in stroke patients remain unclear in Korea.

METHODS

We prospectively studied 293 patients (159 men, 134 women; age 68.4±10.5) with acute ischemic stroke. Cardiovascular risk factors, stroke severity, sleep-related stroke onset, distribution of stroke lesions, and 3-month score on the modified Rankin Scale (mRS) were assessed. Stroke severity was assessed by the US National Institutes of Health Stroke Scale (NIHSS) and the mRS. The apnea-hypopnea index (AHI) was determined 6.3±2.2 days after stroke onset with the Apnea Link portable sleep apnea monitoring device.

RESULTS

The prevalence of SDB (defined as an AHI of ≥10) was 63.1% (111 men, 74 women). Those in the SDB group were older, had higher NIHSS and mRS scores, greater bulbar weakness, and a higher incidence of sleep-associated stroke onset. Among risk-factor profiles, alcohol consumption and atrial fibrillation were significantly related to SDB. The stroke outcome was worse in patients with SDB than in those without SDB. The lesion location and specific stroke syndrome were not correlated with SDB.

CONCLUSIONS

SDB is very common in acute cerebral infarction. Different risk-factor profiles and sleep-related stroke onsets suggest SDB as a cause of ischemic stroke. The higher NIHSS score and greater bulbar involvement in the SDB group seem to show the influence of ischemic stroke on the increased SDB prevalence.

Early sleep apnea screening on a stroke unit is feasible in patients with acute cerebral ischemia

Early screening for sleep apnea (SA) is rarely considered in patients with acute cerebral ischemia. We aimed to evaluate the feasibility of early SA screening on a stroke unit, its impact on post-discharge SA care and the relation of SA to clinical features. Patients with acute ischemic stroke (AIS) and transient ischemic attack (TIA) prospectively underwent overnight cardiorespiratory polygraphy within 3 ± 2 days of symptom-onset. Feasibility was defined as analyzable polygraphy in 90 % of studied patients. We enrolled 61 patients (84 % AIS, 16 % TIA): mean age 66 ± 8 years, 44 % men, median NIHSS 1 (0-15), median ESS 5 (0-13). Analyzability was given in 56/61 (91.8 %; one-sided 95 % CI, lower-bound 86.0 %) patients indicating excellent feasibility of early SA screening with no significant differences in stroke severity (100 % in TIA, 91 % minor stroke, 83 % major stroke, p = 0.474). Ninety-one percent (51/56) had an apnea-hypopnea index ≥ 5/h (median: 20/h [0-79]); 32 % (18/56) mild, 30 % (17/56) moderate, and 29 % (16/56) severe SA. When comparing sleep-related ischemic stroke (SIS) and non-SIS patients, no differences were found regarding the presence (95 vs. 89 %, p = 0.49) or severity (e.g., severe SA: 32 vs. 27 %, p = 0.69) of SA. After 12 months, 27/38 (71 %) patients given specific recommendations completed in-laboratory sleep work-up and 7/27 (25 %) were prescribed for non-invasive ventilatory correction. In conclusion, early SA screening is feasible in patients with acute cerebral ischemia and may have a positive impact on post-discharge SA care. Given the high frequency and atypical presentation of SA, early screening for SA should be considered in all acute cerebral ischemia patients.

Obstructive sleep apnoea and cardiovascular disease

Obstructive sleep apnoea (OSA) is a common health concern caused by repeated episodes of collapse of the upper airway during sleep. The events associated with OSA lead to brain arousal, intrathoracic pressure changes, and intermittent episodes of hypoxaemia and reoxygenation. These events activate pathways such as oxidative stress, sympathetic activation, inflammation, hypercoagulability, endothelial dysfunction, and metabolic dysregulation that predispose patients with OSA to hypertension and atherosclerosis. OSA is a common cause of systemic hypertension and should be suspected in hypertensive individuals, especially those with resistant hypertension. In patients with OSA, continuous positive airway pressure (CPAP) treatment reduces blood pressure, and its effects are related to compliance and baseline blood pressure. Evidence suggests that OSA is a risk factor for stroke and heart failure. An association between coronary heart disease and OSA seems to be limited to middle-aged men (30-70 years). Cardiac rhythm disorders occur in about half of patients with OSA, but their clinical relevance is still unknown. The association of OSA with cardiovascular risk is mainly based on studies in men, and an association has yet to be established in women. Data on older patients is similarly scarce. Currently, there is not enough evidence to support treatment with CPAP for primary or secondary prevention of cardiovascular disease.

Biomarkers of sleep apnea

Obstructive sleep apnea (OSA) is a condition of repetitive upper airway collapse, which occurs during sleep. Recent literature has emphasized the role of OSA in contributing to glucose intolerance, dyslipidemia, and hypertension. OSA is associated with the development of cardiovascular disease, although definitive data are sparse with regard to the prevention of cardiovascular disease and CPAP therapy. CPAP provides effective treatment for OSA, but patient adherence remains challenging. Aside from daytime symptom improvement, it is difficult to monitor the adequacy of treatment response. Thus, the search for a biomarker becomes critical. The discovery of an ideal biomarker for OSA has the potential to provide information related to diagnosis, severity, prognosis, and response to treatment. In addition, because large-scale randomized controlled trials are both ethically and logistically challenging in assessing hard cardiovascular outcomes, certain biomarkers may be reasonable surrogate outcome measures. This article reviews the literature related to potential biomarkers of OSA with the recognition that an ideal biomarker does not exist at this time.

Sleep apnea syndrome: experience of the pulmonology department in Ibn Sina Hospital, Rabat, Morocco

INTRODUCTION

Sleep apnea syndrome is a highly prevalent disorder that is still underdiagnosed and undertreated and whose obstructive form is the most common. The diagnosis is suspected on clinical signs collected by interrogation and questionnaires (Berlin questionnaire and Epworth sleepiness scale), then confirmed by objective sleep study findings (polygraphy or polysomnography). It is necessary to conduct studies in each context on the characteristics and management of sleep apnea syndrome comprising the testing of reliability of the questionnaires.

METHODS

Prospective and descriptive study of 104 patients addressed to sleep consultation at pulmononology Department of Ibn Sina Hospital, Morocco over a period of 5 years (January 2006 to December 2010), agreed to participate in the study, responded to a predetermined questionnaire, and benefited from clinical examination and paraclinical tests including a polygraphy or a polysomnography

RESULTS

59(56.7%) patients had an obstructive sleep apnea-hypopnea syndrome with a similar prevalence in both sexes. 32.2% of patients were obese and 28,8% had cardio-vascular diseases. Snoring, excessive daytime sleepiness and witnessed apnea were found in respectively 79.7%, 50.8% and 16.9%. Berlin questionnaire and Epworth sleepiness scale had an acceptable internal consistency against apnea hypopnea index with a Cronbach's alpha coefficient respectively 0.79 and 0.78. Depending on severity, clinical impact and results of investigations, the adequate treatment has been proposed based on the 2010 recommendations for clinical practice.

CONCLUSION

This study has provided an idea about the profile and the management of patients having an obstructive sleep apnea-hypopnea syndrome and showed that both Berlin questionnaire and Epworth sleepiness scale are two simple and reliable methods in our context. A larger and further study across the country should be considered.

Association of metabolic factors with high-sensitivity C-reactive protein in patients with sleep-disordered breathing

Sleep-disordered breathing (SDB) such as snoring or obstructive sleep apnea and metabolic syndrome are both related to cardiovascular diseases. Being a surrogate marker of high risk for cardiovascular disorder, the high-sensitivity C-reactive protein (hs-CRP) level is thought to be elevated in patients with both SDB and metabolic syndrome. To understand better the development of cardiovascular disease in patients with SDB, we examined the association of metabolic variables with hs-CRP levels in adult patients with symptoms of SDB and without any previous treatment, who were selected to participate in the study. Metabolic parameters including fasting blood glucose, lipid profile and hs-CRP were measured following an overnight polysomnography. Laboratory and polysomnographic data were analyzed to identify variables related to high hs-CRP levels. A total of 309 patients with SDB participated in this study. Of these, 139 presented with hs-CRP <1 mg/L and 52 presented with hs-CRP >3 mg/L. Patients with high hs-CRP showed a higher apnea-hypopnea index (AHI), body mass index (BMI), fasting glucose, and triglyceride level, and a lower mean and minimal oxygen saturation and HDL-cholesterol level. However, ordinal regression analysis demonstrated that only a higher BMI and fasting glucose level and a lower HDL-cholesterol level were independent risk factors for cardiovascular diseases (OR = 1.076, 95 % CI = 1.009-1.147, p = 0.005; OR = 1.011, 95 % CI = 1.004-1.019, p = 0.008; OR = 0.966, 95 % CI = 0.947-0.984, p < 0.001, respectively). The results showed that elevated hs-CRP is common in patients with SDB but is not independently associated with the severity of SDB. Metabolic factors such as a higher BMI and fasting blood glucose and a lower HDL-cholesterol level were more strongly associated with elevated hs-CRP rather than with SDB severity, suggesting that metabolic parameters are important contributors to cardiovascular diseases and should be corrected in patients with SDB.

Meta-analysis of the association between obstructive sleep apnoea and postoperative outcome

BACKGROUND

Obstructive sleep apnoea (OSA) is often undiagnosed before elective surgery and may predispose patients to perioperative complications.

METHODS

A literature search of PubMed-Medline, Web of Science, Scopus, EMBASE, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials up to November 2010 was conducted. Our search was restricted to cohort or case-control studies in adults diagnosed with OSA by screening questionnaire, oximetry, or polysomnography. Studies without controls, involving upper airway surgery, and with OSA diagnosed by ICD-9 codes alone were excluded. The primary postoperative outcomes were desaturation, acute respiratory failure (ARF), reintubation, myocardial infarction/ischaemia, arrhythmias, cardiac arrest, intensive care unit (ICU) transfer, and length of stay.

RESULTS

Thirteen studies were included in the final analysis (n=3942). OSA was associated with significantly higher odds of any postoperative cardiac events [45/1195 (3.76%) vs 24/1420 (1.69%); odds ratio (OR) 2.07; 95% confidence interval (CI) 1.23-3.50, P=0.007] and ARF [33/1680 (1.96%) vs 24/3421 (0.70%); OR 2.43, 95% CI 1.34-4.39, P=0.003]. Effects were not heterogeneous for these outcomes (I(2)=0-15%, P>0.3). OSA was also significantly associated with higher odds of desaturation [189/1764 (10.71%) vs 105/1881 (5.58%); OR 2.27, 95% CI 1.20-4.26, P=0.01] and ICU transfer [105/2062 (5.09%) vs 58/3681 (1.57%), respectively; OR 2.81, 95% CI 1.46-5.43, P=0.002]. Both outcomes showed a significant degree of heterogeneity of the effect among studies (I(2)=57-68%, P<0.02). Subgroup analyses had similar conclusions as main analyses.

CONCLUSIONS

The incidence of postoperative desaturation, respiratory failure, postoperative cardiac events, and ICU transfers was higher in patients with OSA.

Sleep and stroke

Obstructive Sleep-Disordered Breathing (OSDB) is an under-recognized risk factor for stroke. OSDB is associated with traditional vascular risk factors such as hypertension, obesity, and diabetes, and can influence the risk for stroke through direct and indirect mechanisms. Untreated OSDB may also influence rehabilitation efforts and functional outcome following a stroke, as well as the risk for stroke recurrence. Stroke risk is greatly reduced if the OSDB is adequately treated. Conversely, OSDB may be exacerbated or caused by stroke. Increasing awareness and improving screening for OSDB is paramount in the primary and secondary prevention of stroke, and in improving stroke outcomes. The following review article is intended to highlight the current basics of epidemiology, clinical characteristics, pathophysiology, diagnosis, and treatment of OSDB in relation to stroke.

The relationship between obstructive sleep apnea and self-reported stroke or coronary heart disease in overweight and obese adults with type 2 diabetes mellitus

STUDY OBJECTIVES

Type 2 diabetes mellitus (T2DM) and obstructive sleep apnea (OSA) are common, increasingly recognized as comorbid conditions, and individually implicated in the development of cardiovascular disease (CVD). We sought to determine the association between OSA and CVD in an overweight and obese population with T2DM.

DESIGN

Cross-sectional.

SETTING

Ancillary study to the Look AHEAD trial.

PARTICIPANTS

Three hundred five participants of the Sleep AHEAD study who underwent unattended full polysomnography at home with measurement of the apnea-hypopnea index (AHI).

MEASUREMENTS AND RESULTS

Self-reported prevalent CVD was obtained at the initial assessment of the parent study and included a history of the following conditions: stroke, carotid endarterectomy, myocardial infarction, coronary artery bypass grafting, and percutaneous coronary intervention. Logistic regression was used to assess the association of OSA, measured continuously and categorically, with prevalent CVD. OSA was present (AHI ≥ 5) in 86% of the population, whereas the prevalence of all forms of CVD was just 14%. The AHI was associated with stroke with an adjusted odds ratio (95% confidence interval) of 2.57 (1.03, 6.42). Neither the continuously measured AHI nor the categories of OSA severity were significantly associated with the other forms of CVD assessed.

CONCLUSIONS

We found suggestive evidence of a greater prevalence of stroke at greater values of the AHI. OSA was not associated with prevalent coronary heart disease in the Sleep AHEAD trial. Future studies should confirm the link between OSA and stroke and examine mechanisms that link OSA to stroke in adults with T2DM.

Central sleep apnea is associated with increased risk of ischemic stroke in the elderly

OBJECTIVES

Sleep apnea/hypopnea syndrome is a well-recognized independent risk factor for stroke in middle-aged population, but controversy remains in older subjects. We examined the possible association between different respiratory parameters and risk of stroke in a prospective population-based cohort of 394 stroke-free elderly subjects.

MATERIAL AND METHODS

Fully overnight polysomnography was performed at baseline. Over the 6 year follow-up period, 20 ischemic strokes occurred. Differences in stroke-free survival between subjects according to central apnea index (CAI) were assessed.

RESULTS

We just observed association with incident ischemic stroke on central sleep apnea (CSA) episodes. Obstructive sleep apnea, time passed under 90% oxygen saturation, or arousal index were not associated. The event-free survival was lowest in the highest CAI group. This association was independent of any other vascular risk factors.

CONCLUSIONS

CSA is the specific respiratory event associated with stroke in the elderly. Additionally, CSA could be a marker of silent brain ischemia, as a sign of disturbed regulation of central respiratory mechanisms, tentatively of ischemic origin.

Polysomnography underestimates altered cardiac autonomic control in patients with obstructive sleep apnea

BACKGROUND

Repetitive nocturnal sympathetic activation during episodes of apnea and postapneic hyperventilation increases cardiovascular risk. The effects of hypopnea and non-apneic, non-hypopneic intervals before and after hypopnea/apnea on sympathico-vagal balance have not been assessed yet.

HYPOTHESIS

Hypopnea and non-apneic, non-hypopneic intervals before and after hypopnea/apnea cause increased sympathetic activity when compared to normal respiration in nonREM stages 2–4.

METHODS

A total of 34 patients were studied using in-laboratory polysomnography including continuous ECG recording. Absolute spectral power of heart rate variability in the very low (VLF), low (LF), and high frequency (HF) bands and low frequency to high frequency power ratio (LF/HF ratio) were analyzed during apnea, hypopnea, and during the pre- and post-phases of such respiratory episodes and compared to spectral powers during normal respiration in nonREM sleep 2–4.

RESULTS

Patients with hypopnea and/or obstructive apnea showed higher power of VLF and the LF/HF ratio in intervals of hypopnea/apnea and in non-apneic, non-hypopneic intervals before and after hypopnea/apnea compared to normal respiration in nonREM stages 2–4.

CONCLUSION

The effect of sleep-disordered breathing on alteration of autonomic tone in patients with hypopnea and obstructive apnea is more severe than estimated by conventional polysomnographic assessment of apnea and hypopnea. Patients with sleep apnea show a sympathetic overdrive not only during phases of hypopnea and obstructive apnea but also in non-apnea, non-hypopnea intervals before and after hypopnea, and obstructive apnea.

Obstructive sleep apnea and stroke

Obstructive sleep apnea (OSA) is a common disorder that has been associated with many cardiovascular disease processes, including hypertension and arrhythmias. OSA has also been identified as an independent risk factor for stroke and all-cause mortality. OSA is highly prevalent in patients with transient ischemic attacks and stroke. Routinely screening patients with transient ischemic attacks or stroke for sleep apnea is becoming more common. In stroke patients with OSA, treatment with continuous positive airway pressure may prevent subsequent cardiovascular events and improve neurologic outcomes. This review explores the pathophysiology of the association between OSA and stroke, and the clinical implications of identification and treatment of OSA in patients with stroke.

Association of obstructive sleep apnea with risk of serious cardiovascular events: a systematic review and meta-analysis

BACKGROUND

The relationship between obstructive sleep apnea (OSA) and cardiovascular events remains unclear. We conducted a systematic review to determine the incident risk of cardiovascular events among patients with OSA.

METHODS AND RESULTS

We searched MEDLINE and EMBASE in January 2011 for prospective studies that followed up patients with OSA for incident ischemic heart disease, stroke, and cardiovascular mortality. Outcomes data were pooled using random effects meta-analysis and heterogeneity assessed with the I(2) statistic. Regression analysis was performed to evaluate the effects of different gradations of OSA severity based on apnea-hypopnea index. We identified 9 relevant studies from 1731 citations. OSA was associated with incident stroke in a meta-analysis of 5 studies (8435 participants), odds ratio (OR) 2.24; 95% confidence interval (CI), 1.57-3.19; I(2)=7%. A significant association was seen in studies that were predominantly on men; OR, 2.87; 95% CI, 1.91-4.31, whereas data on women were sparse. In the overall analysis of 6 studies (8785 participants), OSA was nonsignificantly associated with ischemic heart disease (OR, 1.56; 95% CI, 0.83-2.91), with significant findings in the 5 studies that recruited mainly men (OR, 1.92; 95% CI, 1.06-3.48). Substantial heterogeneity was noted (I(2)=74%). OSA was linked to cardiovascular death in 2 studies involving 2446 participants (OR, 2.09; 95% CI, 1.20-3.65, I(2)=0%). Regression analysis showed greater likelihood of stroke or cardiovascular events with increasing apnea-hypopnea index values.

CONCLUSIONS

OSA appears to be associated with stroke, but the relationship with ischemic heart disease and cardiovascular mortality needs further research.

Daytime sleepiness and risk of stroke and vascular disease: findings from the Northern Manhattan Study (NOMAS)

BACKGROUND

Recent studies have suggested that poor quality and diminished quantity of sleep may be independently linked to vascular events although prospective and multiethnic studies are limited. This study aimed to explore the relationship between daytime sleepiness and the risk of ischemic stroke and vascular events in an elderly, multiethnic prospective cohort.

METHODS AND RESULTS

As part of the Northern Manhattan Study, the Epworth Sleepiness Scale was collected during the 2004 annual follow-up. Daytime sleepiness was trichotomized using previously reported cut points of no dozing, some dozing, and significant dozing. Subjects were followed annually for a mean of 5.1 years. Cox proportional hazards models were used to calculate hazard ratios and 95% confidence intervals for stroke, myocardial infarction, and death outcomes. We obtained the Epworth Sleepiness Scale on 2088 community residents. The mean age was 73.5 ± 9.3 years; 64% were women; 17% were white, 20% black, 60% Hispanic, and 3% were other. Over 44% of the cohort reported no daytime dozing, 47% some dozing, and 9% significant daytime dozing. Compared with those reporting no daytime dozing, individuals reporting significant dozing had an increased risk of ischemic stroke (hazard ratio, 2.74 [95% confidence interval, 1.38-5.43]), all stroke (3.00 [1.57-5.73]), the combination of ischemic stroke, myocardial infarction, and vascular death (2.38 [1.50-3.78]), and all vascular events (2.48 [1.57-3.91]), after adjusting for medical comorbidities.

CONCLUSIONS

Daytime sleepiness is an independent risk factor for stroke and other vascular events. These findings suggest the importance of screening for sleep problems at the primary care level.

Sleep medicine knowledge, attitudes, and practices among medical students in Guangzhou, China

PURPOSE

This study aimed to describe the knowledge, attitudes, and practices of Chinese medical students towards sleep medicine.

METHODS

The authors surveyed medical students at Southern Medical University in 2009. Students completed a questionnaire before and after attending a 3-h sleep disorders course.

RESULTS

All 324 questionnaires were returned. Less than one half of the students were aware that restless legs syndrome, somniloquy, and teeth grinding are sleep disorders. Only a small percentage of students knew that sleep disorders are related to diabetes, anemia, hyperlipidemia, and attention deficit syndrome. After the 3-h sleep disorders course, the percentage of students who regarded snoring, restless legs syndrome, nightmares, and somniloquy as sleep disorders increased from 64.9 to 92.7 %, 40.8 to 64.4 %, 48.0 to 60.3 %, and 33.5 to 59.9 % (P < 0.001), respectively. Sleep problems were considered to be a significant issue by 93.8 % of the students. The students thought that people with sleep disorders should seek treatment. Of the students, 81.3 % were interested in sleep medicine. The students considered that it is necessary to set up specialized sleep medicine departments to manage sleep disorders. Of the students, 76.8 % thought they or their friends had sleep problems, and 44.8 % consulted physicians about sleep problems. Greater than two thirds of the students (67.1 %) did not have formal education about sleep medicine. Few students were aware of medical schools offering a course in sleep medicine. Most of the students liked learning in the form of elective courses, lectures, or online course. The students also realized that having sleep medicine knowledge is needed as a physician.

CONCLUSIONS

Chinese medical students attached importance to sleep disorders, but knew little about sleep disorders. Knowledge of sleep medicine can be improved with a short training course.

Altered global and regional brain mean diffusivity in patients with obstructive sleep apnea

Obstructive sleep apnea (OSA) is a common and progressive disorder accompanied by severe cardiovascular and neuropsychological sequelae, presumably induced by brain injury resulting from the intermittent hypoxia and cardiovascular processes accompanying the syndrome. However, whether the predominant brain tissue pathology is acute or chronic in newly-diagnosed, untreated OSA subjects is unclear; this assessment is essential for revealing pathological processes. Diffusion tensor imaging (DTI)-based mean diffusivity (MD) procedures can detect and differentiate acute from chronic pathology and may be useful to reveal processes in the condition. We collected four DTI series from 23 newly-diagnosed, treatment-naïve OSA and 23 control subjects, using a 3.0-Tesla magnetic resonance imaging scanner. Mean diffusivity maps were calculated from each series, realigned, averaged, normalized to a common space, and smoothed. Global brain MD values for each subject were calculated using normalized MD maps and a global brain mask. Mean global brain MD values and smoothed MD maps were compared between groups by using analysis of covariance (covariate: age). Mean global brain MD values were significantly reduced in OSA compared with controls (P = 0.01). Multiple brain sites in OSA, including medullary, cerebellar, basal ganglia, prefrontal and frontal, limbic, insular, cingulum bundle, external capsule, corpus callosum, temporal, occipital, and corona radiata regions showed reduced regional MD values compared with controls. The results suggest that global brain MD values are significantly reduced in OSA, with certain regional sites especially affected, presumably a consequence of axonal, glial, and other cell changes in those areas. The findings likely represent acute pathological processes in newly-diagnosed OSA subjects.

Respiratory perioperative management of patients with obstructive sleep apnea

Obstructive sleep apnea (OSA) has become a major public health problem in the United State and Europe. However, perioperative strategies regarding diagnostic options and management of untreated OSA remain inadequate. Preoperative screening and identification of patients with undiagnosed OSA may lead to early perioperative interventions that may alter cardiopulmonary events associated with surgery and anesthesia.(1) Hence, clinicians need to become familiar with the preoperative screening and diagnosis of OSA. Perioperative management of a patient with OSA should be modified and may include regional anesthesia and alternative analgesic techniques such as nonsteroidal anti-inflammatory drugs that may reduce the need for systemic opioids. Additionally, supplemental oxygen and continuous pulse oximetry monitoring should be utilized to maintain baseline oxygen saturation. Postoperatively patients should remain in a semi-upright position and positive pressure therapy should be used in patients with high-risk OSA.

Subjective sleepiness and daytime functioning in bariatric patients with obstructive sleep apnea

PURPOSE

The purpose of this study was to evaluate associations between obstructive sleep apnea (OSA) severity and self-reported sleepiness and daytime functioning in patients considering bariatric surgery for treatment of obesity.

METHODS

Using a retrospective cohort design, we identified 342 patients who had sleep evaluations prior to bariatric surgery. Our final sample included 269 patients (78.6 % of the original cohort, 239 females; mean age = 42.0 ± 9.5 years; body mass index = 50.2 ± 7.7 kg/m(2)) who had overnight polysomnography and completed the Epworth Sleepiness Scale (ESS) and the Functional Outcomes of Sleep Questionnaire (FOSQ). Patients' OSA was classified as none/mild (apnea-hypopnea index (AHI) < 15, n = 112), moderate (15 ≤ AHI < 30, n = 77), or severe (AHI ≥ 30, n = 80). We calculated the proportion of unique variance (PUV) for the five FOSQ subscales. ANOVA was used to determine if ESS and FOSQ were associated with OSA severity. Unpaired t tests compared ESS and FOSQ scores in our sample with published data.

RESULTS

The average AHI was 29.5 ± 31.5 events per hour (range = 0-175.8). The mean ESS score was 6.3 ± 4.8, and the mean global FOSQ score was 100.3 ± 18.2. PUVs for FOSQ subscales showed moderate-to-high unique contributions to FOSQ variance. ESS and global FOSQ score did not differ by AHI group. Only the FOSQ vigilance subscale differed by OSA severity with the severe group reporting more impairment than the moderate and none/mild groups. Our sample reported less sleepiness and daytime impairment than previously reported means in patients and controls.

CONCLUSIONS

Subjective sleepiness and functional impairment were not associated significantly with OSA severity in our sample of patients considering surgery for obesity. Further research is needed to understand individual differences in sleepiness in patients with OSA. If bariatric patients underreport symptoms, self-report measures are not an adequate substitute for objective assessment and clinical judgment when evaluating bariatric patients for OSA. Patients with severe obesity need evaluation for OSA even in the absence of subjective complaints.

Sleep apnea-plus: prevalence, risk factors, and association with cardiovascular diseases using United States population-level data

OBJECTIVES

The purpose of this study was to estimate the prevalence of, to identify sociodemographic risk factors for, and to examine the association of cardiovascular diseases with sleep apnea-plus (i.e., comorbid insomnia and sleep apnea) in the general United States population.

METHODS

A population-based multi-year cross-sectional study design was used with data from the 2005-2008 United States National Health and Nutrition Examination Surveys (NHANES) (n=12,593).

RESULTS

The prevalence of insomnia among individuals with sleep apnea (n=236/546 or 43%) was higher compared to individuals without sleep apnea (n=3550/12,047 or 30%). Among individuals with sleep apnea, women (OR 2.19, 95% CI 1.07-4.48) and individuals with symptoms of depression (OR 3.53, 95% CI 1.49-8.35) were significantly more likely, and individuals ages 60+ years (OR 0.43, 95% CI 0.20-0.94) and individuals with morbid obesity (OR 0.27, 95% CI 0.09-0.75) were significantly less likely, to have sleep apnea-plus. After controlling for confounders, the odds of health professional-diagnosed self-reported hypertension (OR 0.64, 95% CI 0.29-1.44), diabetes (OR 1.02, 95% CI 0.33-3.11), congestive heart failure (OR 0.67, 95% CI 0.19-2.44), myocardial infarction (OR 1.80, 95% CI 0.49-6.67), and stroke (OR 0.82, 95% CI 0.18-3.77), as well as objectively measured risk factors for these conditions, were not significantly different between individuals with sleep apnea-plus and individuals with sleep apnea-alone.

CONCLUSIONS

The prevalence of insomnia in sleep apnea is high, and substantially greater than in the general population, and this has important implications for the management of sleep apnea patients. Similar to sleep apnea-alone, individuals with sleep apnea-plus have elevated rates of cardiovascular diseases compared to the general population. Given the elevated rates of cardiovascular diseases among individuals with sleep apnea-plus, along with their known poor CPAP compliance, identification of individuals with sleep apnea-plus and treatment of their concomitant insomnia is important.

Sleep-related problems in neurologic diseases

There is a strong association between sleep-related problems and neurologic diseases. Neurologic diseases of the CNS can directly cause sleep problems when sleep-wake mechanisms associated with the ascending reticular activating system are involved. The major sleep disorders associated with neurologic problems are outlined in the International Classification of Sleep Disorders, 2nd edition, as hypersomnias of central origin, sleep-related breathing disorders, the insomnias, circadian rhythm sleep disorders, sleep-related movement disorders, parasomnias, and sleep-related epilepsy. In a patient with CNS disease and excessive sleepiness, sleep-related breathing disorders should be a first concern, given the known association between obstructive sleep apnea (OSA) and cerebrovascular disease and the potential confounding effects that OSA might have on an otherwise compromised ischemic CNS penumbra. A basic knowledge of the anatomy and physiology of the sleep-wake mechanisms provides a rationale for pharmacologic intervention. Nonpharmacologic treatments are also important, especially when sleep-related breathing disorders are a concern. In addition, as patients with neurologic diseases are often prone to the adverse effects of many medications, the specific treatment regimen for any given individual should always include good sleep hygiene practices that use cognitive behavioral therapy.

Sleep disordered breathing and depression among U.S. adults: National Health and Nutrition Examination Survey, 2005-2008

STUDY OBJECTIVE

To determine if symptoms of sleep disordered breathing (SDB) are associated with depression symptomology in a national sample.

DESIGN

National Health and Nutrition Examination Survey.

SETTING

U.S., 2005-2008.

PARTICIPANTS

9,714 adults (≥ 18 years).

MEASUREMENTS

Respondents were asked about frequency of snoring and snorting, gasping, or stopping breathing while asleep and completed the PHQ-9 (a 9-item depression screener). Odds ratios (OR) and 95% confidence intervals (CI) for SDB symptom-associated probable major depression (defined as a PHQ-9 score ≥ 10) were obtained from sex-specific logistic regression analyses adjusted for body mass index, age, race/ethnicity, and education.

RESULTS

Among men, 6.0% reported physician-diagnosed sleep apnea, 37.2% snored ≥ 5 nights/week, 7.1% snorted/stopped breathing ≥ 5 nights/week, and 5.0% had PHQ-9 scores ≥ 10. Among women, 3.1% reported sleep apnea, 22.4% snored ≥ 5 nights/week, 4.3% snorted/stopped breathing ≥ 5 nights/week, and 8.4% had PHQ-9 scores ≥ 10. Sleep apnea was associated with probable major depression (OR = 2.4; 95% CI: 1.5, 3.6 among men; OR = 5.2; 95% CI: 2.7, 9.9 among women). Snoring was not associated with depression symptoms in men or women. Snorting/stopping breathing ≥ 5 nights/week compared to never was strongly associated with probable major depression in men (OR = 3.1; 95% CI: 1.8, 5.2) and women (OR = 3.0; 95% CI: 1.6, 5.4).

CONCLUSION

Frequent snorting/stopping breathing was associated with probable major depression by the PHQ-9 in a national sample of adults. Additional research may be needed to determine whether regular screening for these conditions by mental health professionals and sleep specialists should be recommended.

Accuracy of ECG-based screening for sleep-disordered breathing: a survey of all male workers in a transport company

Purpose

Sleep-disordered breathing (SDB) is associated with increased risk for cardiovascular morbidity and mortality and for sleepiness-related accidents, but >75 % of the patients remain undiagnosed. We sought to determine the diagnostic accuracy of ECG-based detection of SDB when used for population-based screening.

Methods

All male workers, mostly truck drivers, of a transport company (n = 165; age, 43 ± 12 years) underwent standard attended overnight polysomnography. Cyclic variation of heart rate (CVHR), a characteristic pattern of heart rate associated with SDB, was detected from single-lead ECG signals during the polysomnography by a newly developed automated algorithm of autocorrelated wave detection with adaptive threshold (ACAT).

Results

Among 165 subjects, the apnea–hypopnea index (AHI) was ≥5 in 62 (38 %), ≥15 in 26 (16 %), and ≥30 in 16 (10 %). The number of CVHR per hour (CVHR index) closely correlated with AHI [r = 0.868 (95 % CI, 0.825–0.901)]. The areas under the receiver operating characteristic curves for detecting subjects with AHI ≥5, ≥15, and ≥30 were 0.796 (95 % CI, 0.727–0.855), 0.974 (0.937–0.993), and 0.997 (0.971–0.999), respectively. With a predetermined criterion of CVHR index ≥15, subjects with AHI ≥15 were identified with 88 % sensitivity and 97 % specificity (likelihood ratios for positive and negative test, 30.7 and 0.12). The classification performance was retained in subgroups of subjects with obesity, hypertension, diabetes mellitus, dyslipidemia, and decreased autonomic function.

Conclusions

The CVHR obtained by the ACAT algorithm may provide a useful marker for screening for moderate-to-severe SDB among apparently healthy male workers.

A prospective cohort study of the long-term effects of CPAP on carotid artery intima-media thickness in obstructive sleep apnea syndrome

OBJECTIVE

To examine the long-term effect of CPAP on carotid artery intima-media thickness (IMT) in patients with Obstructive sleep apnea syndrome(OSAS).

METHODS

A prospective observational study over 12 months at a teaching hospital on 50 patients newly diagnosed with OSAS who received CPAP or conservative treatment (CT). Carotid IMT was assessed with B-mode Doppler ultrasound from both carotid arteries using images of the far wall of the distal 10 mm of the common carotid arteries at baseline, 6 months and 12 months. MEASUREMENTS AND RESULTS [MEAN (SE)]: Altogether 28 and 22 patients received CPAP and CT respectively without significant differences in age 48.8(1.8) vs 50.5(2.0)yrs, BMI 28.2(0.7) vs 28.0(1.2)kg/m2, ESS 13.1(0.7) vs 12.7(0.6), AHI 38(3) vs 39(3)/hr, arousal index 29(2) vs 29(2)/hr, minimum SaO2 75(2) vs 77(2)% and existing co-morbidities. CPAP usage was 4.6(0.3) and 4.7(0.4)hrs/night over 6 months and 1 year respectively. Carotid artery IMT at baseline, 6 months, and 12 months were 758(30), 721(20), and 705(20)micron for the CPAP group versus 760(30), 770(30), and 778(30)micron respectively for the CT group, p = 0.002. Among those free of cardiovascular disease(n = 24), the carotid artery IMT at baseline, 6 months and 12 months were 722(40), 691(40), and 659(30)micron for the CPAP group (n = 12) with usage 4.5(0.7) and 4.7(0.7) hrs/night over 6 months and 12 months whereas the IMT data for the CT group(n = 12) were 660(20), 685(10), and 690(20)micron respectively, p = 0.006.

CONCLUSIONS

Reduction of carotid artery IMT occurred mostly in the first 6 months and was sustained at 12 months in patients with reasonable CPAP compliance.

[Neurological aspects of chronic heart failure]

Chronic heart failure (CHF) is one of the leading causes of hospitalization, morbidity and mortality. Moreover, there is a high rate of neurological as well as neuropsychological comorbidities, namely ischemic stroke, structural brain alterations, cognitive impairment, sleep apnea and possible side-effects of HF medication such as delirium or (intracerebral) hemorrhage. The higher stroke risk in patients with HF increases further with age, concomitant arterial hypertension or atrial fibrillation (AF). In women the stroke risk increases with reduced ejection fraction (EF). In general stroke in HF patients is associated with a poor outcome and higher mortality, which is increased more than 2-fold. Furthermore, approximately 25-80% of all patients with CHF experience cognitive impairments such as decreased attention and concentration, memory loss, diminished psychomotor reaction time and decreased executive functions. Cognitive impairment in patients with HF has been linked to losses in gray matter, (silent) ischemic strokes, decreased cerebral perfusion and higher mortality. Moreover, sleep apnea occurs in more than half of all patients with CHF and reduced EF. However, prospective studies are needed to test whether early detection and optimal treatment of HF reduces the burden of neurological and neuropsychological sequelae.

Sleep disorders and stroke

The purpose of this review is to highlight existing literature on the epidemiology, pathophysiology, and treatments of stroke sleep disorders. Stroke sleep disorders are associated with many intermediary vascular risk factors leading to stroke, but they may also influence these risk factors through direct or indirect mechanisms. Sleep disturbances may be further exacerbated by stroke or caused by stroke. Unrecognized and untreated sleep disorders may influence rehabilitation efforts and poor functional outcomes following stroke and increase risk for stroke recurrence. Increasing awareness and improving screening for sleep disorders is paramount in the primary and secondary prevention of stroke and in improving stroke outcomes. Many vital questions about the relationship of sleep disorders and stroke are still unanswered and await future well-designed studies.

An investigation into the relationship between sleep-disordered breathing, the metabolic syndrome, cardiovascular risk profiles, and inflammation between South Asians and Caucasians residing in the United Kingdom

BACKGROUND

The aim of this study was to determine the prevalence of sleep-disordered breathing (SDB) in a South Asian and a Caucasian population and to compare the cardiovascular risk factors in those with SDB within these ethnic groups and determine if SDB is independently associated with the metabolic syndrome and markers of inflammation.

METHODS

A total of 1,598 participants within a U.K. multiethnic population underwent an oral glucose tolerance test, completed the Berlin Sleep Questionnaire, and provided anthropometric data and fasting bloods. Metabolic syndrome was classified according to National Cholesterol Education Program Adult Treatment Panel III criteria.

RESULTS

The prevalence of SDB was 28.3% and did not differ between the two ethnic groups. South Asians with SDB had a higher body fat percentage (38.4±10% vs. 35.6±9%, P=0.016), glycosylated hemoglobin (5.6±0.5% vs. 5.6±0.5%, P=0.001) and lower high-density lipoprotein cholesterol (1.21±0.23 mmol/L vs. 1.29±0.34 mmol/L, P=0.002) compared to Caucasians with SDB, who were older (59.6±8.6 years vs. 50.4±10.3 years, P<0.001) and had higher systolic blood pressure (139.8±18.5 mmHg vs. 131.7±18.6 mmHg, P<0.001). SDB was associated with metabolic syndrome after adjustment for age, gender, ethnicity, and waist circumference (odds ratio=1.54, 95% confidence interval 1.12-2.09, P=0.01). There was no independent association between SDB and markers of inflammation.

CONCLUSION

The relationship between SDB and metabolic syndrome is not driven via the inflammatory pathway. The prevalence of SDB is significantly higher in those with metabolic syndrome although these South Asians had a greater cardiovascular disease (CVD) risk profile the relationship is independent of ethnicity. Routine screening for SDB within primary/secondary care may have a role in the prevention of CVD and type 2 diabetes mellitus.