Association of sleep-disordered breathing and the occurrence of stroke

Prevalence of risk factors for atrial fibrillation and stroke among 1210 patients with sleep disordered breathing

AIMS

This study sought to identify the prevalence of risk factors for atrial fibrillation and stroke in a sleep apnea population.

METHODS

Study participants included 1210 consecutive adults who were referred with suspicion of sleep apnea. Statistical analysis was used to determine the relationship between sleep apnea syndrome and risk factors for atrial fibrillation and stroke.

RESULTS

Among 1210 enrolled patients, 65.8% had severe sleep apnea (Apnea/hypopnea Index--AHI>30), 25.2% had mild to moderate sleep apnea (AHI 5 to 30), and 8.8% had no sleep apnea (AHI<5). At baseline, the mean apnea-hypopnea index in patients with sleep apnea syndrome was 35. Compared to patients with an AHI<5, those with an AHI>30 were older (47.3±11.4 vs. 52.74±12.4, p<0.001) and had a higher body mass index (BMI) (30.7±7.3 vs. 33.83±10.1, p<0.001), a higher prevalence of hypertension (38 vs. 16%, p<0.001), and a higher CHADS2 (congestive heart failure, hypertension, age, diabetes and prior stroke) score (0.59±0.8 vs. 0.28±0.64, p<0.001).

CONCLUSIONS

Patients with severe sleep apnea have a higher prevalence of risk factors for atrial fibrillation and stroke when compared with subjects without sleep apnea.

Healthcare providers' knowledge of disordered sleep, sleep assessment tools, and nonpharmacological sleep interventions for persons living with dementia: a national survey

A large proportion of persons with dementia will also experience disordered sleep. Disordered sleep in dementia is a common reason for institutionalization and affects cognition, fall risk, agitation, self-care ability, and overall health and quality of life. This report presents findings of a survey of healthcare providers' awareness of sleep issues, assessment practices, and nonpharmacological sleep interventions for persons with dementia. There were 1846 participants, with the majority being from nursing and rehabilitation. One-third worked in long-term care settings and one-third in acute care. Few reported working in the community. Findings revealed that participants understated the incidence of sleep deficiencies in persons with dementia and generally lacked awareness of the relationship between disordered sleep and dementia. Their knowledge of sleep assessment tools was limited to caregiver reports, self-reports, and sleep diaries, with few using standardized tools or other assessment methods. The relationship between disordered sleep and comorbid conditions was not well understood. The three most common nonpharmacological sleep interventions participants identified using were a regular bedtime routine, increased daytime activity, and restricted caffeine. Awareness of other evidence-based interventions was low. These findings will guide evidence-informed research to develop and test more targeted and contextualized sleep and dementia knowledge translation strategies.

[Cardiovascular morbidity associated with obstructive sleep apnea syndrome]

INTRODUCTION

The obstructive sleep apnoea syndrome (OSAS) had become a major public health concern in modern society due to its high prevalence but, above all, to its associated morbidity, especially cardiovascular.

BACKGROUND

Untreated OSAS is associated with an increased incidence of fatal (myocardial infarction and stroke) (odds ratio: 2.87) and non-fatal cardiovascular events (myocardial infarction, stroke, coronary artery bypass surgery and coronary angiography) (odds ratio: 3.17). Moreover, the prevalence of hypertension in patients with OSAS is high, between 35 and 80%. The pathophysiological mechanisms leading to these complications are mainly due to intermittent hypoxia secondary to repeated episodes of apnoea/hypopnoea during sleep. These mechanisms include sympathetic hyperactivation, impairment of vasomotor reactivity, vascular inflammation, oxidative stress and metabolic disorders. In patients with OSAS, the impact of continuous positive pressure is proven in terms of prevention of cardiovascular events although blood pressure reduction is limited. Obviously these effects are proportional to observance.

CONCLUSION

OSAS does increase the cardiovascular risk, independently of other risk factors. Although the impact of treatment is relatively low in decreasing blood pressure, it seems essentially effective in preventing cardiovascular morbidity. Therefore, OSAS screening, and the association of specific treatments in cardio-metabolic patients and OSAS patients respectively, should be included in clinical strategies.

Cardiovascular complications of sleep apnea: role of oxidative stress

Obstructive sleep apnea (OSA) occurs in 2% of middle-aged women and 4% of middle-aged men with a higher prevalence among obese subjects. This condition is considered as an independent risk factor for cerebrovascular and cardiovascular diseases. One of the major pathophysiological characteristics of OSA is intermittent hypoxia. Hypoxia can lead to oxidative stress and overproduction of reactive oxygen species, which can lead to endothelial dysfunction, a hallmark of atherosclerosis. Many animal models, such as the rodent model of intermittent hypoxia, mimic obstructive sleep apnea in human patients and allow more in-depth investigation of biological and cellular mechanisms of this condition. This review discusses the role of oxidative stress in cardiovascular disease resulting from OSA in humans and animal models.

Challenges and motivating factors related to positive airway pressure therapy for post-TIA and stroke patients

Challenges adapting to continuous positive airway pressure (CPAP) therapy are largely unexplored in patients with stroke or transient ischemic attack. This study, nested within a randomized controlled trial of CPAP use, employed qualitative methods to explore challenges and motivators related to CPAP at two time points: prior to initiating therapy and at a 1-month follow up. Emergent thematic analysis, an inductive, qualitative approach, revealed variations in how patients experienced and adapted to CPAP across five phases: (a) interpreting the sleep apnea diagnosis, (b) contemplating CPAP therapy, (c) trying CPAP therapy, (d) making mid-course adjustments, and (e) experiencing benefits from CPAP therapy. Patients all had mild to moderate sleep apnea, and frequently did not experience sleep apnea symptoms. A salient motivator for adhering to CPAP therapy for these patients was the desire to reduce the risk of subsequent cerebrovascular events. Self-determination theory guided the interpretation of results.

Insights into obstructive sleep apnea research

Moderate to severe obstructive sleep apnea (OSA) occurs in 10-17% of middle aged men and 3-9% of middle-aged women with a higher prevalence among obese subjects. This condition is an independent risk factor for many cardiovascular diseases. Intermittent hypoxia is a major pathophysiologic character of OSA; it can lead to oxidative stress and inflammation, which in their turn cause endothelial dysfunction, a hallmark of atherosclerosis. Many animal models have been designed to mimic OSA in human patients to allow more in-depth investigation of biological and cellular mechanisms of this condition. This review discusses the cardiovascular outcomes of OSA and some of the animal models that are being used to investigate it.

Severity of obstructive sleep apnea is associated with elevated plasma fibrinogen in otherwise healthy patients

PURPOSE

Obstructive sleep apnea (OSA) has been implicated in both cardiovascular and cerebrovascular diseases. Systemic inflammation and coagulation may be related to cardiovascular pathophysiology in patients with OSA. Fibrinogen is a major coagulation protein associated with inflammation, and long-term elevated plasma fibrinogen is associated with an increased risk of major cardiovascular diseases. We assessed whether severity of OSA is associated with levels of fibrinogen in newly diagnosed, untreated, and otherwise healthy OSA patients.

METHODS

We studied 36 men with OSA and 18 male control subjects (apnea-hypopnea index [AHI]<5 events/h). OSA patients were divided into mild (AHI≥5<15 events/h) and severe (AHI≥15 events/h) OSA groups. Morning fibrinogen levels in OSA patients were compared to those in control subjects of similar age, body mass index, blood pressure, smoking habits, and alcohol consumption.

RESULTS

Fibrinogen levels were significantly elevated in patients with severe OSA compared to both control (P=0.003) and mild OSA (P=0.02) subjects after adjustment for covariates. However, there were no significant differences in fibrinogen levels between mild OSA and control subjects. Fibrinogen levels were directly related to AHI and arousal index and inversely related to mean and lowest oxygen saturation during sleep.

CONCLUSIONS

Severity of OSA was associated with increased fibrinogen level independent of other factors, suggesting that apneic events and oxygen desaturation during sleep are mechanisms for increased fibrinogen levels in patients with OSA.

Untreated obstructive sleep apnea and the risk for serious long-term adverse outcomes: a systematic review

BACKGROUND

Reports on the association between obstructive sleep apnea (OSA) and risk of death, cardiovascular (CV) events, diabetes and depression have been inconsistent.

METHODS

We conducted a systematic review of the prognostic value of clinical and polysomnographic (PSG) characteristics of OSA for adverse long-term outcomes of untreated OSA in adult patients. A comprehensive search strategy for prognosis studies, OSA, CV events, mortality, depression and diabetes was developed in collaboration with a medical information specialist. All English language studies, from Jan 1999 to Dec 2011, with longitudinal design in adults with OSA diagnosed by PSG recording, found through Medline, Embase and bibliographies of identified articles, were considered eligible. Quality was assessed using published guidelines.

RESULTS

Among 26 articles, ten evaluated the association of OSA with mortality, 9 with a composite CV outcome, 4 with stroke, 2 with diabetes and 1 with depression. Significant relationships between the apnea-hypopnea index (AHI) and outcomes of interest were reported in 18 studies: seven for all-cause mortality, six for composite CV events, three for stroke, one for diabetes and one for depression. The effect of AHI was attenuated by female gender, older age, absence of daytime sleepiness and higher body mass index. Due to clinical heterogeneity between studies, meta-analyses were not performed.

CONCLUSION

Evidence exists in men for a relationship between OSA and all-cause mortality and a composite CV outcome. Associations between OSA and other outcomes remain uncertain. Among OSA-specific markers, only AHI was a consistent predictor. Other consistent predictors were traditional CV risk factors. Research is required to identify effect modifiers and the predictive ability of various AHI threshold values and hypopnea definitions. An enhanced set of OSA-specific predictors will allow better risk stratification to guide OSA treatment.

Influence and predicting variables of obstructive sleep apnea on cardiac function and remodeling in patients without congestive heart failure

STUDY OBJECTIVE

Obstructive sleep apnea syndrome (OSAS) has been considered to be an important predisposing factor for cardiovascular disease. This study aims to investigate the impact of OSAS on cardiac function and remodeling in patients without congestive heart failure.

METHODS

A total of 79 patients with sleep disordered breathing, preserved systolic function, and normal pro-brain natriuretic peptide level were enrolled. Sixty-five patients were classified to have moderate to severe OSAS (apnea-hypopnea index [AHI] ≥ 15/h), while the other 14 patients with mild or no OSAS (AHI < 15/h) served as control subjects. Baseline clinical and polysomnographic variables as well as tissue Doppler imaging and three-dimensional echocardiographic parameters were obtained.

RESULTS

The body mass index, neck circumference, Epworth Sleepiness Scale, desaturation index, arousal index, and snoring index were significantly higher in patients with moderate to severe OSAS than those without (p < 0.05). The left atrial size, mitral A-wave velocity, and left ventricular end-diastolic volume were significantly larger, while E/A ratio was lower in patients with moderate to severe OSAS than those without (p < 0.05). Notably, AHI in REM sleep was significantly correlated with the aortic root size, E/A ratio, left ventricular volume, and stroke volume. In addition, the area under the receiver operator characteristic curve for AHI in REM sleep ≥ 32.3/h was 0.647 (95% CI [0.525, 0.769]) in predicting the development of left ventricular diastolic dysfunction. AHI in REM sleep ≥ 32.3/h was the only independent variant in predicting diastolic dysfunction after adjusting the variables including age, gender, hypertension, and body mass index.

CONCLUSIONS

Patients with moderate to severe OSAS tend to have cardiac dysfunction revealed by echocardiography. High AHI in REM sleep is significantly associated with cardiovascular remodeling and ventricular diastolic dysfunction, and may be a potential variable to predict cardiac dysfunction.

The effect of sleep disordered breathing on the outcome of stroke and transient ischemic attack: a systematic review

STUDY OBJECTIVES

The primary objective was to systematically review the literature on how sleep disordered breathing (SDB) affects recurrence and death among stroke or transient ischemic attack (TIA) patients. A secondary objective was to evaluate how treatment of SDB with continuous positive airway pressure (CPAP) affects the risk of recurrence and death in these patients.

METHODS

Adults (18+) with a stroke or TIA diagnosis were eligible for inclusion. Case groups consisted of patients with a sleep disorder. The outcomes of interest were all-cause mortality, recurrent vascular events, and case fatality.

RESULTS

Ten articles covering 1,203 stroke and TIA patients were included in the review. The results generally support a dose-response relationship between severity of SDB and risk of recurrent events and all-cause mortality in stroke and TIA patients. Three small-scale articles with substantial risk of bias evaluated the effects of CPAP therapy, and the results are inconclusive. Data on case fatality is too sparse to be conclusive.

CONCLUSIONS

Existing studies provide sufficient data to establish obstructive SDB as a negative predictor of all-cause mortality and recurrent vascular events following stroke or TIA. The ability of CPAP treatment to lower the risk of serious adverse outcomes after stroke remains controversial because of substantial risk of bias identified in most of the eligible studies addressing this relation. Additional studies are needed.

Relationship of obesity and insulin resistance with the cerebrovascular reactivity: a case control study

Background

Obesity is associated with increased risk for stroke. The breath-holding index (BHI) is a measure of vasomotor reactivity of the brain which can be measured with the transcranial Doppler (TCD). We aim to evaluate obesity as an independent factor for altered cerebrovascular reactivity.

Methods

Cerebrovascular hemodynamics (mean flow velocities MFV, pulsatility index, PI, resistance index, RI, and BHI) was determined in 85 non-obese (Body Mass Index, BMI ≤27 kg/m²) and 85 obese subjects (BMI ≥35 kg/m²) without diabetes mellitus and hypertension. Anthropometric and metabolic variables, and scores to detect risk for obstructive sleep apnea (OSA) were analyzed for their association with the cerebrovascular reactivity.

Results

The BHI was significantly lower in subjects with obesity according to BMI and in subjects with abdominal obesity, but the PI and RI were not different between groups. There was a linear association between the BMI, the HOMA-IR, the Matsuda index, the waist circumference, and the neck circumference, with the cerebrovascular reactivity. After adjusting for insulin resistance, neck circumference, and abdominal circumference, obesity according to BMI was negatively correlated with the cerebrovascular reactivity.

Conclusions

We found a diminished vasomotor reactivity in individuals with obesity which was not explained by the presence of insulin resistance.

Obstructive sleep apnea and other sleep-related syndromes

Obstructive sleep apnea syndrome (OSAS) is a common disorder characterized by repetitive episodes of breathing cessation due to complete or partial collapse of the upper airway therefore affecting ventilation. It is quite common, with a prevalence of about 2-4%, has a strong genetic component, and creates a proinflammatory state with elevated TNFα and other cytokines. If untreated, OSA can lead to significant neurological problems that include stroke, cognitive decline, depression, headaches, peripheral neuropathy, and nonarteritic ischemic optic neuropathy (NAION). Treatment reverses some of these neurological problems. Treatment includes continuous positive airway pressure and its variants, oral appliances, weight loss, upper airway surgery, and rarely maxillofacial procedures. Other sleep breathing disorders such as hypoventilation, central sleep apnea, complex sleep apnea, and Cheyne-Stokes respiration are less common and are sometimes associated with neuromuscular disorders causing diaphragmatic paralysis, but can also be seen in opiate exposure and severe obesity.

Sleep Apnea and Inflammation - Getting a Good Night's Sleep with Omega-3 Supplementation

Obstructive sleep apnea (OSA) is a multifactorial sleep disorder associated with an increased risk of cardiovascular mortality and morbidity. Several mechanisms have been proposed to explain the association between OSA and cardiovascular dysfunction. One of the proposed mechanisms is an inflammatory response to OSA mediated by tumor necrosis factor (TNF-α). Patients with OSA have higher plasma, serum, and intracellular levels of TNF-α, which may be reduced after apnea treatment with continuous positive airway pressure (CPAP). Because TNF-α plays an important role in OSA related cardiovascular morbidity, the present review aims to identify other preventive measures, in addition to CPAP, that may minimize the inflammatory process in OSA and consequently the risk of premature death due to cardiovascular dysfunction. Thus, we hypothesized that a nutritional immunology profile, i.e., supplementation with omega-3 fatty acids, may be valuable for individuals with OSA.

Association of sleep apnea with clinically silent microvascular brain tissue changes in acute cerebral ischemia

The aim of this study was to determine the importance of sleep apnea in relation to clinically silent microvascular brain tissue changes in patients with acute cerebral ischemia. Patients with acute cerebral ischemia prospectively underwent nocturnal respiratory polygraphy within 5 days from symptom-onset. Sleep apnea was defined as apnea-hypopnea-index (AHI) ≥5/h. Experienced readers blinded to clinical and sleep-related data reviewed brain computed tomography and magnetic resonance imaging scans for leukoaraiosis and chronic lacunar infarctions. Ischemic lesions were considered clinically silent when patients did not recall associated stroke-like symptoms. Functional outcome was assessed with modified Rankin Scale at discharge, 6 and 12 months. Fifty-one of 56 (91 %) patients had sleep apnea of any degree. Patients with moderate-to-severe leukoaraiosis (Wahlund score ≥5) were found to have higher mean AHI than those with none or mild leukoaraiosis (34.4 vs. 12.8/h, p < 0.001). Moderate-to-severe sleep apnea (AHI ≥15/h) was found to be an independent predictor of moderate-to-severe leukoaraiosis (adjusted OR 6.03, 95 % CI 1.76-20.6, p = 0.0042) and of moderate-to-severe leukoaraiosis associated with clinically silent chronic lacunar infarctions (adjusted OR 10.5, 95 % CI 2.19-50.6, p = 0.003). The higher the Wahlund score and the AHI, the more likely unfavorable functional outcome resulted over time (p = 0.0373). In acute cerebral ischemia, sleep apnea is associated with clinically silent microvascular brain tissue changes and may negatively influence functional outcome. Routine sleep apnea screening and further investigation of possible long-term effects of non-invasive ventilatory treatment of sleep apnea appear warranted in this at-risk population.

Obstructive sleep apnea and risk of cardiovascular disease and all-cause mortality: a meta-analysis of prospective cohort studies

BACKGROUND

The association between obstructive sleep apnea (OSA) and the incidence of cardiovascular disease (CVD) has been examined in many studies. However, the findings are not entirely consistent across studies. Our goal was to evaluate the association between OSA and risk of CVD and all-cause mortality by performing a meta-analysis of prospective cohort studies.

METHODS

We used generalized least squares regression models to estimate the dose-response relationship. Heterogeneity, subgroup, and sensitivity analyses and publication bias were performed.

RESULTS

Twelve prospective cohort studies involving 25,760 participants were included in the meta-analysis. The overall combined relative risks for individuals with severe OSA compared with individuals with an AHI of <5 were 1.79 (95% confidence interval [CI]: 1.47 to 2.18) for CVD, 1.21 (95% CI: 0.75 to 1.96) for incident fatal and non-fatal coronary heart disease, 2.15 (95% CI: 1.42 to 3.24) for incident fatal and non-fatal stroke, and 1.92 (95% CI: 1.38 to 2.69) for deaths from all-causes. A positive association with CVD was observed for moderate OSA but not for mild OSA. The results of the dose-response relationship indicated that per 10-unit increase in the apnea-hypopnea index was associated with a 17% greater risk of CVD in the general population.

CONCLUSIONS

This meta-analysis of prospective cohort studies suggests that severe OSA significantly increases CVD risk, stroke, and all-cause mortality. A positive association with CVD was observed for moderate OSA but not for mild OSA.

Neural control of the upper airway: integrative physiological mechanisms and relevance for sleep disordered breathing

The various neural mechanisms affecting the control of the upper airway muscles are discussed in this review, with particular emphasis on structure-function relationships and integrative physiological motor-control processes. Particular foci of attention include the respiratory function of the upper airway muscles, and the various reflex mechanisms underlying their control, specifically the reflex responses to changes in airway pressure, reflexes from pulmonary receptors, chemoreceptor and baroreceptor reflexes, and postural effects on upper airway motor control. This article also addresses the determinants of upper airway collapsibility and the influence of neural drive to the upper airway muscles, and the influence of common drugs such as ethanol, sedative hypnotics, and opioids on upper airway motor control. In addition to an examination of these basic physiological mechanisms, consideration is given throughout this review as to how these mechanisms relate to integrative function in the intact normal upper airway in wakefulness and sleep, and how they may be involved in the pathogenesis of clinical problems such obstructive sleep apnea hypopnea.

Classification of vibratory patterns of the upper airway during sleep

Upper airway (UA) narrowing and collapse during sleep results in obstructive sleep apnea (OSA). We hypothesize that vibratory patterns of snoring can distinguish simple snorers from those with OSA. Samples of breath sounds were collected from 7 snorers without OSA and 5 with OSA. Snoring pitch (F0) contours were found using the robust algorithm for pitch tracking (RAPT). The OSA snoring contours showed fluctuating patterns as compared to the smoother patterns of simple snorers. This suggests that snoring reveals the underlying instabilities of UA tissue in OSA. Conditional random fields, a statistical sequence classifier, gave 75% accuracy in distinguishing the 2 groups.

Self-reported sleep duration in relation to incident stroke symptoms: nuances by body mass and race from the REGARDS study

BACKGROUND

To determine, among employed persons with low risk for obstructive sleep apnea (OSA), if sleep duration is associated with incident stroke symptoms, independent of body mass index (BMI), and if sleep duration mediates racial differences in stroke symptoms.

METHODS

In 2008, 5666 employed participants (US blacks and whites, ≥45 years) from the longitudinal and nationally representative Reasons for Geographic And Racial Differences in Stroke study self-reported their average sleep duration. Participants had no history of stroke, transient ischemic attack, or stroke symptoms and were at low risk for OSA. After the sleep assessment, self-reported stroke symptoms were collected at 6-month intervals, up to 3 years (M = 751 days). Interval-censored, parametric survival models were conducted to estimate hazard ratios predicting time from sleep duration measurement (<6, 6-6.9, 7-7.9 [reference], 8-8.9, ≥9 hours) to first stroke symptom. Adjusted models included demographics, stroke risk factors, psychological symptoms, health behaviors, and diet.

RESULTS

During follow-up, 224 participants reported 1 or more stroke symptoms. In the unadjusted model, short sleep (<6 hours) significantly predicted increased risk of stroke symptoms but not in adjusted models. Stratification by BMI revealed a significant association between short sleep duration and stroke symptoms only for normal BMI persons in unadjusted (hazard ratio: 2.93, 95% confidence interval: 1.38-6.22) and fully adjusted models (hazard ratio: 4.19, 95% confidence interval: 1.62-10.84). The mediating effect of sleep duration on the relationship between race and stroke symptoms was borderline significant in normal weight participants.

CONCLUSIONS

Among middle-aged to older employed individuals of normal weight and low risk of OSA, self-reported short sleep duration is prospectively associated with increased risk of stroke symptoms.

Intermittent hypoxia impairs glucose homeostasis in C57BL6/J mice: partial improvement with cessation of the exposure

OBJECTIVES

Obstructive sleep apnea is associated with insulin resistance, glucose intolerance, and type 2 diabetes mellitus. Although several studies have suggested that intermittent hypoxia in obstructive sleep apnea may induce abnormalities in glucose homeostasis, it remains to be determined whether these abnormalities improve after discontinuation of the exposure. The objective of this study was to delineate the effects of intermittent hypoxia on glucose homeostasis, beta cell function, and liver glucose metabolism and to investigate whether the impairments improve after the hypoxic exposure is discontinued.

INTERVENTIONS

C57BL6/J mice were exposed to 14 days of intermittent hypoxia, 14 days of intermittent air, or 7 days of intermittent hypoxia followed by 7 days of intermittent air (recovery paradigm). Glucose and insulin tolerance tests were performed to estimate whole-body insulin sensitivity and calculate measures of beta cell function. Oxidative stress in pancreatic tissue and glucose output from isolated hepatocytes were also assessed.

RESULTS

Intermittent hypoxia increased fasting glucose levels and worsened glucose tolerance by 67% and 27%, respectively. Furthermore, intermittent hypoxia exposure was associated with impairments in insulin sensitivity and beta cell function, an increase in liver glycogen, higher hepatocyte glucose output, and an increase in oxidative stress in the pancreas. While fasting glucose levels and hepatic glucose output normalized after discontinuation of the hypoxic exposure, glucose intolerance, insulin resistance, and impairments in beta cell function persisted.

CONCLUSIONS

Intermittent hypoxia induces insulin resistance, impairs beta cell function, enhances hepatocyte glucose output, and increases oxidative stress in the pancreas. Cessation of the hypoxic exposure does not fully reverse the observed changes in glucose metabolism.

Association between the -1438G/A and T102C polymorphisms of 5-HT2A receptor gene and obstructive sleep apnea: a meta-analysis

The serotonin 2A (5-HT2A) receptor has been implicated in obstructive sleep apnea (OSA). Single nucleotide polymorphisms (SNPs) in the 5-HT2A gene have been found in OSA, the most common being -1438G/A and T102C; however, studies of the association between 5-HT2A SNPs and OSA risk have reported inconsistent findings. A meta-analysis was performed to quantitatively review the association between -1438G/A and T102C SNPs and OSA. Five studies, including 791 subjects for -1438G/A genotype and 1,068 subjects for T102C genotype, were selected. Pooled data analysis of the -1438G/A genotype indicated a significantly increased OSA risk was associated with two variant genotypes (AA vs. AG+GG: OR 3.023, 95 % CI 2.169-4.213, P = 0.506 for heterogeneity; A allele carriers vs. GG: OR 1.938, 95 % CI 0.879-4.274, P = 0.012 for heterogeneity). Stratification analysis by gender supported the association in males, but not females. For the T102C genotype, no significantly increased OSA risk was associated with the two variant genotypes (CC vs. CT+TT: OR 1.065, 95 % CI 0.787-1.442, P = 0.361 for heterogeneity; C allele carriers vs. TT: OR 0.979, 95 % CI 0.737-1.3, P = 0.9 for heterogeneity).In conclusions, meta-analysis indicated that the -1438G/A, and not T102C, polymorphism of 5-HT2A is a positive risk factor of OSA, especially in males.

Sleep apnoea and the heart

Sleep apnoea is associated with significant daytime functioning impairment and marked cardiovascular morbidities, leading to a significant increase in mortality. Sympathetic activation, oxidative stress and systemic inflammation have been shown to be the main intermediary mechanisms associated with sleep apnoea and intermittent hypoxia. There are now convincing data regarding the association between hypertension, arrhythmias, coronary heart disease, heart failure, increased cardiovascular mortality and sleep apnoea. This has been evidenced in sleep apnoea patients and is supported by experimental data obtained in intermittent hypoxia. Whether treating sleep apnoea enables chronic cardiovascular consequences to be reversed is not fully established as regard coronary heart disease, arrhythmias and heart failure. In this late condition, complex bidirectional relationships occur, with obstructive sleep apnoea being a risk factor for heart failure whilst central sleep apnoea mainly appears as a consequence of heart failure. It remains to be established in adequately designed studies, i.e. large randomised controlled trials, whether treating sleep apnoea can improve heart failure morbidity and mortality.

Sleeping over a sleep disorder - Awareness of obstructive sleep apnoea as a modifiable risk factor for hypertension and stroke: A survey among health care professionals and medical students

Background:

Obstructive sleep apnoea (OSA) syndrome is an established and modifiable but under recognized risk factor for common disorders like stroke and hypertension.

Objective:

To assess awareness level of health care practitioners and medical students about OSA as a risk factor for stroke and hypertension.

Methods:

Questionnaire based survey with multiple response type and fill in the blanks type questions. The data was compiled and analyzed using SPSS version 19.

Results:

180 participants completed the survey questionnaire. Only 24 (13.3%) identified OSA as a reversible risk factor for ischemic stroke. 11 (6%) participants only could answer OSA as an identified risk factor for hypertension as per Seventh Joint National Committee report.

Conclusion:

This study reveals dismal level of awareness, among health professionals and medical students, about OSA being an established and modifiable risk factor for hypertension and ischemic stroke.

Reversal of the neurological deficit in acute stroke with the signal of efficacy trial of auto-BPAP to limit damage from suspected sleep apnea (Reverse-STEAL): study protocol for a randomized controlled trial

Background

Although the negative impact of sleep apnea on the clinical course of acute ischemic stroke (AIS) is well known, data regarding non-invasive ventilation in acute patients are scarce. Several studies have shown its tolerability and safety, yet no controlled randomized sequential phase studies exist that aim to establish the efficacy of early non-invasive ventilation in AIS patients.

Methods/design

We decided to examine our hypothesis that early non-invasive ventilation with auto-titrating bilevel positive airway pressure (auto-BPAP) positively affects short-term clinical outcomes in AIS patients. We perform a multicenter, prospective, randomized, controlled, third rater- blinded, parallel-group trial. Patients with AIS with proximal arterial obstruction and clinically suspected sleep apnea will be randomized to standard stroke care alone or standard stroke care plus auto-BPAP. Auto-BPAP will be initiated within 24 hours of stroke onset and performed for a maximum of 48 hours during diurnal and nocturnal sleep. Patients will undergo unattended cardiorespiratory polygraphy between days three and five to assess sleep apnea. Our primary endpoint will be any early neurological improvement on the NIHSS at 72 hours from randomization. Safety, tolerability, short-term and three-months functional outcomes will be assessed as secondary endpoints by un-blinded and blinded observers respectively.

Discussion

We expect that this study will advance our understanding of how early treatment with non-invasive ventilation can counterbalance, or possibly reverse, the deleterious effects of sleep apnea in the acute phase of ischemic stroke. The study will provide preliminary data to power a subsequent phase III study.

Trial registration

Clinicaltrials.gov Identifier: NCT01812993

Targeted case finding for OSA within the primary care setting

STUDY OBJECTIVES

The aim was to determine the feasibility of using an unattended 2-channel device to screen for obstructive sleep apnea in a population of high-risk patients using a targeted, case-finding strategy. The case finding was based on the presence of risk factors not symptoms in the studied population.

METHODS

The study took place from June 2007 to May 2008 in rural and metropolitan Queensland and New South Wales. Family doctors were asked to identify patients with any of the following: BMI > 30, type 2 diabetes, treated hypertension, ischemic heart disease. Participants applied the ApneaLink+O2 at home for a single night. The device recorded nasal flow and pulse oximetry. Data were analyzed by proprietary software, then checked and reported by either of two sleep physicians.

RESULTS

1,157 patients were recruited; mean age 53 ± 14.6, M/F% = 62/38, mean BMI = 31.8, obesity = 35%, diabetes = 16%, hypertension = 39%, IHD = 5%, Mean Epworth Sleepiness Scale score (ESS) = 8.3. The prevalence of unrecognized OSA was very high: 71% had an AHI > 5/h, 33% had an AHI > 15/h, and 16% had an AHI > 30/h. The ApneaLink+O2 device yielded technically adequate studies in 93% of cases.

CONCLUSION

The study shows that a "real world" simple low cost case finding and management program, based on unattended home monitoring for OSA, can work well in a population with risk factors and comorbidities associated with OSA, independent of the presence of symptoms. The prevalence of unrecognized OSA was very high.

Vascular Dementia

The purpose of this review is to highlight existing literature on the epidemiology, pathophysiology, and novel risk factors for vascular dementia. We further examine the evidence linking chronic brain hypoperfusion induced by a variety of cardiovascular diseases to the development of vascular dementia. In the elderly, in whom cerebral perfusion is diminished by the aging process, additional reduction in cerebral blood flow stemming from exposure to potentially modifiable vascular risk factors increases the probability of developing vascular dementia. Finally, we discuss the association between obstructive sleep apnea, an underrecognized risk factor for stroke, and vascular dementia. Obstructive sleep apnea is linked to cerebrovascular disease through many intermediary vascular risk factors and may directly cause cerebrovascular damage through microvacular disease. Insight into how cardiovascular risk factors induce vascular dementia offers an enhanced understanding of the multifactorial pathophysiology by this disorder and ways of preventing and managing the cerebrovascular precursors of vascular dementia. Many vital questions about the relation of obstructive sleep apnea with stroke and vascular dementia are still unanswered and await future well-designed studies.

Race/ethnic differences in obstructive sleep apnea risk in patients with acute ischemic strokes in south Florida

PURPOSE

Obstructive sleep apnea (OSA) is a risk factor for ischemic stroke, but it may differ between race/ethnic groups. The goal of our study was to examine the pre-stroke risk of OSA between three race/ethnic groups admitted for acute ischemic stroke in a tertiary urban hospital in South Florida.

METHODS

Our sample was composed of patients with acute ischemic strokes evaluated at a teaching hospital over a 3-year period. Race/ethnicity was defined by self-identification, modeled after the US census and categorized into non-Hispanic whites, non-Hispanic blacks, and Hispanics. Pre-stroke risk of OSA was assessed with the Berlin questionnaire and categorized into high- or low-risk categories. We performed binary logistic regression to evaluate the pre-stroke risk of OSA in Hispanics and non-Hispanic blacks with non-Hispanic whites as the reference, adjusting for age, body mass index, hypertension, diabetes, and smoking.

RESULTS

There were 176 patients with acute ischemic strokes of which 44 % were Hispanics, 44 % non-Hispanic Blacks, and 12 % non-Hispanic whites. A higher frequency of patients at high risk for OSA was seen in 60 % of Hispanics, 54 % of non-Hispanic blacks, and 33 % of non-Hispanic whites. Hispanics (OR, 2.6; 95 % CI 1.1-6.4) had a higher frequency of patients at high risk for OSA compared to non-Hispanic whites, adjusting for covariates. There were no differences between non-Hispanic blacks (OR, 1.2; 0.5-2.9 and non-Hispanic whites.

DISCUSSION

We observed higher frequency of patients at high risk for OSA in Hispanics with acute ischemic strokes in South Florida.

Carotid intima-media thickness increase in patients with habitual simple snoring and obstructive sleep apnea syndrome is associated with metabolic syndrome

OBJECTIVES

Sleep disorders are emerging risk factors for atherosclerosis. Increased carotid intima-media thickness (CCA-IMT) is a surrogate marker of cardiovascular risk. The aim of the present study was to investigate the relationship between CCA-IMT and habitual simple snoring or obstructive sleep apnea syndrome (OSAS) and the other cardiovascular risk factors.

METHODS

Sleep disorders were diagnosed and staged by polysomnography. Patients were then classified into either habitual simple snoring (n = 20, group 1) or OSAS (n = 67, group 2), which was subclassified as mild-moderate (n = 27) or severe (n = 40). CCA-IMT was measured by B-mode ultrasonography. The other major risk factors were investigated.

RESULTS

The mean CCA-IMT was 0.65 ± 0.02 mm (mean ± SD) in group 1 versus 0.75 ± 0.02 mm in group 2 (p = 0.03). Using CCA-IMT ≥ 0. 9 mm as the threshold value also yielded significant results between the two groups (p = 0.03). The mean CCA-IMT did not differ between patients with mild-moderate and severe OSAS, whereas metabolic risk factors and metabolic syndrome (MS) were more prominent in the latter. Age, MS, neck and waist circumference, waist/ hip circumference, and fasting glucose level were higher in patients with CCA-IMT ≥ 0.9 mm.

CONCLUSIONS

CCA-IMT increase was associated with OSAS, but did not correlate with its severity, which could be due to the higher incidence of MS in this group.

Association of sleep disordered breathing and cognitive deficit in APOE ε4 carriers

STUDY OBJECTIVES

The aim of the study was to determine whether apolipoprotein E epsilon 4 genotype (APOE4) modifies the association of sleep disordered breathing (SDB) with cognitive function in a middle-aged population.

DESIGN

Cross-sectional analysis of a community-dwelling cohort.

SETTINGS

Sleep laboratory at the Clinical Research Unit of the University of Wisconsin Hospitals and Clinics.

PARTICIPANTS

There were 755 adults from the Wisconsin Sleep Cohort who provided a total of 1,843 polysomnography and cognitive evaluations (most participants were assessed multiple times at approximately 4-y intervals); 56% males, average age 53.9 years (range 30-81 years).

INTERVENTIONS

None.

MEASUREMENT AND RESULTS

In-laboratory overnight polysomnography was used to assess SDB. Cognition was evaluated by a battery of six neurocognitive tests assessing memory and learning, attention, executive function, and psychomotor efficiency. The APOE4 genotype (ε3/ε4 or ε4/ ε4) was identified in 200 participants. Data were analyzed using linear mixed-effects models, accounting for multiple observations per participant. Cognitive test scores were regressed on SDB categories (AHI < 5, 5 ≤ AHI < 15, AHI ≥ 15); APOE4 and their interaction; and age, education, sex, and body mass index. There was no statistically significant association between SDB and cognitive performance among APOE4-negative individuals. However, in APOE4-positive individuals, those with AHI ≥ 15 had significantly worse performance on the Auditory Verbal Learning Test and the Controlled Oral Word Association Test.

CONCLUSIONS

In APOE4-positive individuals, moderate to severe sleep disordered breathing (AHI ≥ 15) was associated with poorer performance on cognitive tests that require both memory and executive function engagement.

Morbidities associated with obstructive sleep apnea

Obstructive sleep apnea (OSA)-induced biological changes include intermittent hypoxia, intermittent hypercapnia, intrathoracic pressure changes, sympathetic activation and sleep fragmentation. OSA can cause metabolic dysregulation, endothelial dysfunction, systemic inflammation, oxidative stress and hypercoagulation, and neurohumoral changes. There is evidence suggesting that OSA is independently associated with metabolic syndrome. OSA has been shown to increase the risk for systemic hypertension, pulmonary vascular disease, ischemic heart disease, cerebral vascular disease, congestive heart failure and arrhythmias. Although there are evidences accumulating that there may be a causal relationship between OSA and cardiovascular disorders, there is a need for more data from randomized controlled intervention trials to confirm this relationship. Many risk factors of OSA (age, male gender and obesity) are also known risk factors for cardiovascular disease. Severe OSA-hypopnea significantly increases the risk of fatal and nonfatal cardiovascular events in both men and women, and continuous positive airway pressure treatment reduces this risk in both. Neurocognitive consequences of OSA include daytime sleepiness, loss of alertness, memory deficit, reduced vigilance, impaired executive function, increased risk for automobile and occupational accidents, and decreased quality of life.

Obstructive sleep apnea and cardiovascular risk: meta-analysis of prospective cohort studies

BACKGROUND

Previous studies suggest obstructive sleep apnea (OSA) may increase cardiovascular risk, but the results are inconclusive due to various limitations. We aimed to systematically evaluate the effect of OSA on the incidence of cardiovascular events by a meta-analysis of prospective cohort studies.

METHODS

We searched multiple electronic databases for studies that examined the prospective relationship between OSA and incidence of coronary heart disease (CHD), stroke, or total cardiovascular diseases (CVD) among adults. Either fixed- or random-effects models were used to calculate the pooled risk estimates. Sensitivity analysis was conducted to examine the robustness of pooled outcomes.

RESULTS

Of 17 studies included, 9 reported results on total CVD, 7 reported on fatal or non-fatal CHD, and 10 reported on fatal or non-fatal stroke. The pooled relative risks (95% confidence interval) for individuals with moderate-severe OSA compared with the reference group were 2.48 (1.98-3.10) for total CVD, 1.37 (0.95-1.98) for CHD, and 2.02 (1.40-2.90) for stroke. These results did not materially change in the sensitivity analyses according to various inclusion criteria.

CONCLUSIONS

In conclusion, findings from this meta-analysis supported that moderate-severe OSA significantly increased cardiovascular risk, in particular stroke risk.

Obstructive sleep apnea and cardiovascular disease in blacks: a call to action from the Association of Black Cardiologists

Obstructive sleep apnea (OSA) has emerged as a new and important risk factor for cardiovascular disease (CVD). Over the last decade, epidemiologic and clinical research has consistently supported the association of OSA with increased cardiovascular (CV) morbidity and mortality. Such evidence prompted the American Heart Association to issue a scientific statement describing the need to recognize OSA as an important target for therapy in reducing CV risk. Emerging facts suggest that marked racial differences exist in the association of OSA with CVD. Although both conditions are more prevalent in blacks, almost all National Institutes of Health-funded research projects evaluating the relationship between OSA and CV risk have been conducted in predominantly white populations. There is an urgent need for research studies investigating the CV impact of OSA among high-risk minorities, especially blacks. This article first examines the evidence supporting the association between OSA and CVD and reviews the influence of ethnic/racial differences on this association. Public health implications of OSA and future directions, especially regarding minority populations, are discussed.

Obstructive sleep apnea screening and postoperative mortality in a large surgical cohort

OBJECTIVE

A recent investigation at Barnes-Jewish Hospital located in St. Louis, Missouri, found that an estimated 22% of adults presenting for inpatient surgery screened as high risk for obstructive sleep apnea (OSA). Surgical patients with OSA have multiple comorbidities and are at increased risk for perioperative complications. Our objective was to determine if a prior diagnosis of OSA or a positive screen for OSA was associated with increased risk for 30-day and one-year mortality.

METHODS

B-J APNEAS (Barnes-Jewish Apnea Prevalence in Every Admission Study) was a prospective cohort study. Unselected adult surgical patients at Barnes Jewish Hospital were prospectively enrolled between February 2006 and April 2010. All patients completed preoperative OSA screening and those who were at risk for OSA according to a combination of the Berlin and Flemons screening tools received targeted postoperative interventions. STOP (loud Snoring, daytime Tiredness, Observed apneas, and high blood Pressure) and STOP-BANG (STOP, plus body mass index [BMI], age, neck circumference, and gender) scores also were obtained.

RESULTS

Overall, the sample included 14,962 patients, of whom 1939 (12.9%) reported a history of OSA. All four screening tools identified a high prevalence of undiagnosed patients at risk for OSA (9.5%-41.6%), but agreement among screens was not strong with κ statistic ranging from 0.225 to 0.611. There was no significant difference in 30-day postoperative mortality between patients with possible OSA (based on their history or on a positive OSA screen with any of the four instruments) and the rest of the surgical population. Significant differences in one-year mortality were noted between the low-risk and high-risk groups as identified by the Flemons' (4.96% vs 6.91%; p<0.0001), STOP (5.28% vs 7.57%; p<0.0001) and STOP-BANG (4.13% vs 7.45%; p<0.0001) screens. After adjusting for risk factors, none of the OSA screening tools independently predicted mortality rate up to one year postoperatively.

CONCLUSION

Neither a prior diagnosis of OSA nor a positive screen for OSA risk was associated with increased 30-day or one-year postoperative mortality. Differences in 1 year postoperative mortality were noted with three of the screening tools. The results of our study highlight uncertainties and research priorities for the medical community.

Tae-eum type as an independent risk factor for obstructive sleep apnea

Obstructive sleep apnea (OSA) is prevalent and associated with several kinds of chronic diseases. There has been evidence that a specific type of Sasang constitution is a risk factor for metabolic and cardiovascular diseases that can be found in patients with OSA, but there are no studies that address the association between the Sasang constitution type (SCT) and OSA. The purpose of this study was to investigate the association between the SCT and OSA. A total of 652 participants were included. All participants were examined for demographic information, medical history, and completed an interviewer-administered questionnaire on life style and sleep-related variables. Biochemical analyses were performed to determine the glucose and lipid profiles. An objective recording of OSA was done with an unattended home PSG using an Embla portable device. The apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) were significantly higher in the Tae-eum (TE) type as compared to the So-eum (SE) and the So-yang (SY) types. Even after adjusting for confounding variables, the TE type still had a 2.34-fold (95% CI, 1.11–4.94; P = 0.0262) increased risk for OSA. This population-based cohort study found that the TE constitutional type is an independent risk factor for the development of OSA.