Sleep apnea in patients with transient ischemic attack and stroke: a prospective study of 59 patients

The impact of ageing and sex on the association between sleepiness and sleep disordered breathing

The aim of our study was to investigate age-related changes in sleepiness symptoms associated with sleep disordered breathing (SDB). Wisconsin Sleep Cohort participants were assessed using polysomnography, the Epworth Sleepiness Scale (ESS) and the multiple sleep latency test (MSLT). SDB was defined as an apnoea/hypopnoea index ≥15 events·h(-1), and sleepiness as ESS ≥10 and MSLT ≤5 min. Odds ratios were calculated using generalised estimating equations associating sleepiness with SDB, and conditional logistic regression examining changes in longitudinal sleepiness status (ESS only). Models were a priori stratified by sex. ESS was measured in 1,281 participants and MSLT in 998 at multiple time-points (ESS n=3,695; MSLT n=1,846). Significant interactions were found between SDB and age in males, but not females. The odds ratios modelled for sleepiness in a 40-yr-old male with SDB were significant compared to a male without SDB (ESS 2.1 and MSLT 2.9); however, these associations were not significant at 60 yrs of age. The within-subject odds ratio for sleepiness was also significant at 40 yrs of age (OR 3.4), but not at 60 yrs of age. The age-related reductions in the association between sleepiness and SDB may have clinical implications for the diagnosis and treatment of SDB in older people as sleepiness is often used as a therapeutic target.

Treatment of risk factors to prevent stroke

Much of the decline in stroke incidence and mortality for the past several decades in Western countries has been attributed to better treatment of risk factors. Many epidemiological studies and clinical trials confirmed the importance of managing hypertension. Comparative trials of anti-hypertensive drugs or drug classes have not yielded clear results, but blood pressure variability may play an important role beyond the absolute value of blood pressure. Diabetes therapy remains a conundrum. Although diabetes is clearly a risk factor for ischemic stroke, treatment trials targeting different glycemic goals have not indicated that glucose lowering results in stroke prevention. Trials focused on insulin resistance are ongoing and they may be able to help establish the management of diabetes/impaired glucose tolerance. Evidence for treatment of dyslipidemia has contrasted science to diabetes mellitus. Dyslipidemia has not been strongly or consistently linked to ischemic stroke but the Stroke Prevention by Aggressive Reduction in Cholesterol Levels (SPARCL) trial showed the impact of statin treatment in stroke prevention. The results of clinical trials investigating dabigatran and rivaroxaban clearly indicate alternative strategies to vitamin K antagonists in stroke prevention for persons with atrial fibrillation. Evidence for stroke prevention by life style modification, treating metabolic syndrome, sleep disordered breathing, lipoprotein (a), hyperhomocysteinemia, and coagulation disorders are also discussed.

Obstructive sleep apnea: a risk factor for cardiovascular disease

Obstructive sleep apnea (OSA) is a condition in which the upper airway becomes constricted or occluded during sleep, leading to decreased or absent airflow, hypoxia, and sympathetic activation. This chain of events, occurring dozens of times an hour, can contribute to the development of hypertension, coronary artery disease, heart failure, and stroke. This article discusses the epidemiology of comorbid OSA and cardiovascular disease, the pathophysiology of OSA, how it acts as a risk factor for cardiovascular problems, and how appropriate treatment of OSA ameliorates the consequences. The importance of having a high suspicion for OSA in people with risk factors (including obesity, middle age, male or postmenopausal female) or symptoms (snoring, excessive daytime sleepiness, difficulty concentrating) is pointed out. The article concludes with clinical and research implications.

Sleep-disordered breathing and arterial blood flow steal represent linked therapeutic targets in cerebral ischaemia

The pathogenic link between sleep-disordered breathing and early neurological deterioration in acute ischaemic stroke patients is now a subject of clinical investigations. Vasomotor reactivity and intracranial blood flow steal in response to changing vasodilatory stimuli like carbon dioxide play a pivotal role in clinical deterioration with reversed Robin Hood syndrome. A mechanical ventilatory correction in selected acute stroke patients might have a beneficial effect on sleep-disordered breathing and brain perfusion. This is a novel therapeutic target and the missing link in the pathogenesis of early neurological deterioration and stroke recurrence.

Obstructive sleep apnea, stroke, and cardiovascular diseases

BACKGROUND

Obstructive sleep apnea (OSA) is gaining recognition as a cardiovascular and cerebrovascular risk factor. Sleep apnea is now implicated in the etiopathogenesis of stroke, coronary artery disease, hypertension, and congestive heart failure.

REVIEW SUMMARY

OSA exerts its negative cardiovascular consequences through its unique pattern of intermittent hypoxia and arousals. The putative mechanisms involved in the pathogenesis of cardiovascular disease in OSA include fibrinolytic imbalance, endothelial dysfunction, oxidative stress, and inflammation. This study discusses the known cellular and molecular processes that promote atherogenesis and vascular dysfunction in patients with OSA, and their implications for cardiovascular disease and prevention in that patient population.

CONCLUSION

Neurologists should familiarize themselves with the symptoms and signs of OSA and the pathophysiology of the association between untreated OSA and cardiovascular disease, including stroke. OSA should be ruled out in patients with cardiovascular disease and be regarded as an important modifiable risk factor. Knowledge of this association is of prime public health importance and can result in primary and secondary prevention of cardiovascular events. This study will also help neurologists in providing patient education and treatment.

The relationship between sleep disorders and stroke

Although sleep appears to be a quiescent, passive state externally, there are a multitude of physiological changes occurring during sleep that can affect cerebral homeostasis and predispose individuals to cerebrovascular disorders. Therefore, it is not surprising that sleep-disordered breathing causes significant nocturnal perturbations, such as obstructive sleep apnea (OSA), that can lead to cerebrovascular disorders. There is evidence to suggest that OSA is a risk factor for stroke, although studies have not been able to clearly discern the absence or presence of OSA before the stroke event. Sleep-disordered breathing, such as OSA and central sleep apnea, can occur as a consequence of stroke. Fortunately, treating OSA appears to decrease morbidity and possibly mortality. Unfortunately, continuous positive airway pressure compliance in this population group is low, and significant efforts and resources may be needed to improve compliance and adherence. Various other sleep disorders, such as insomnia, fatigue, hypersomnia, and parasomnia, can occur following a stroke, and physicians treating patients following a stroke need to be aware of these disorders in order to effectively treat such patients.

Nocturnal cerebral hemodynamics in snorers and in patients with obstructive sleep apnea: a near-infrared spectroscopy study

STUDY OBJECTIVES

Sleep disordered breathing (SDB) of the obstructive type causes hemodynamic consequences, leading to an increased cerebrovascular risk. The severity of SDB at which detrimental circulatory consequences appear is matter of controversy. Aim of the present study is the investigation of cerebral hemodynamics in patients with SDB of variable severity using near-infrared spectroscopy (NIRS).

DESIGN

N/A.

SETTING

Sleep laboratory.

PATIENTS OR PARTICIPANTS

Nineteen patients with SDB.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Patients underwent nocturnal videopolysomnography (VPSG) coupled with cerebral NIRS. NIRS data were averaged for each patient, and a new method (integral) was applied to quantify cerebral hemodynamic alterations. Nocturnal VPSG disclosed various severities of SDB: snoring (7 patients, apnea-hypopnea index [AHI] = 2 +/- 2/h, range: 0.5-4.5); mild SDB (7 patients, AHI = 14 +/- 8/h, range: 6.3-28.6); and severe obstructive sleep apnea syndrome (5 patients, AHI = 79 +/- 20/h, range: 39.6-92.9). Relative changes of NIRS parameters were significantly larger during obstructive apneas (compared with hypopneas; mean deoxygenated hemoglobin [HHb] change of 0.72 +/- 0.23 and 0.13 +/- 0.08 micromol/L per sec, p value = 0.048) and in patients with severe SDB (as compared with patients with mild SDB and simple snorers; mean HHb change of 0.84 +/- 0.24, 0.02 +/- 0.09, and 0.2 +/- 0.08 micromol/L per sec, respectively, p value = 0.020). In this group, NIRS and concomitant changes in peripheral oxygen saturation correlated.

CONCLUSIONS

The results of this study suggest that acute cerebral hemodynamic consequences of SDB lead to a failure of autoregulatory mechanisms with brain hypoxia only in the presence of frequent apneas (AHI > 30) and obstructive events.

Risk factors for periodic breathing in acute stroke: tracheobronchial infection

BACKGROUND AND PURPOSE

Despite evidence from clinical and population studies, the aim of the present study was to suggest that multiple factors contribute to periodic breathing (PB). However, little information has been focused on episodes of tracheobronchial infections (TBI) preceding PB onset.

METHODS

Thirty subjects with acute stroke who had PB and 41 subjects with acute stroke that of a sex- and age-matched control group without PB were retrospectively evaluated. Stroke location, extent of stroke (demonstrated on CT or MRI), and characteristics of TBI before PB were assessed. PB diagnosis was carried out using a portable device and a pulse oximeter. Risk factors for patients with PB were compared with those without PB by univariate and multivariate analysis.

RESULTS

Twenty-four TBI in 30 patients with PB and 11 TBI in 41 patients with non-PB were diagnosed. There was no significant difference in age, sex, body mass index, stroke type, stroke location, or underlying diseases between the two groups (P > 0.05). There was a significant difference in snoring, first recurrent stroke, Glasgow Coma Scale, congestive heart failure, TBI, and inflammatory responses between the PB and non-PB group (P < 0.05). Multiple logistic regression analyses showed a difference in the prevalence of snoring (OR = 10.813, CI = 2.131-54.866, P < 0.01), TBI (OR = 5.313, CI = 1.241-22.740, P < 0.05), and inflammatory responses (OR = 7.315, CI = 1.253-43.123, P < 0.05) between the two groups.

CONCLUSIONS

In addition to snoring, TBI and inflammatory responses are the two independent predictors for PB in patients with acute stroke. Clinicians should be encouraged to systematically evaluate TBI and inflammatory responses before PB in patients with acute stroke.

Dissociation of obstructive sleep apnea from hypersomnolence and obesity in patients with stroke

BACKGROUND AND PURPOSE

Obstructive sleep apnea (OSA) is seldom considered in the diagnostic investigation in the poststroke period although it is a stroke risk factor and has adverse prognostic implications after stroke. One reason might be that widely used clinical criteria for detection of OSA in the general community are not applicable in patients with stroke. We hypothesized that patients with stroke report less sleepiness and are less obese than subjects from a community sample with the same severity of OSA.

METHODS

We performed polysomnography in 96 consecutive patients with stroke admitted to a stroke rehabilitation unit and in a community sample of 1093 subjects without a history of stroke. We compared the degrees of subjective sleepiness assessed by the Epworth Sleepiness Scale and body mass index between the 2 samples according to OSA categories assessed by the frequency of apneas and hypopneas per hour of sleep (<5, no OSA; 5 to <15 mild OSA; and >or=15, moderate to severe OSA).

RESULTS

Compared with the community sample, patients with stroke with OSA had significantly lower Epworth Sleepiness Scale scores and body mass index for mild OSA (Epworth Sleepiness Scale 9.3+/-0.3 versus 5.6+/-0.5, P<0.001 and body mass index 33.1+/-0.5 versus 28.5+/-1.1, P<0.048) and for moderate to severe OSA (Epworth Sleepiness Scale 9.7+/-0.4 versus 7.1+/-0.9, P=0.043 and body mass index 36.4+/-0.8 versus 27.2+/-0.8 kg/m(2), P<0.025).

CONCLUSIONS

For a given severity of OSA, patients with stroke had less daytime sleepiness and lower body mass index than subjects without stroke. These factors may make the diagnosis of OSA elusive in the poststroke period and preclude many such patients from the potential benefits of OSA therapy.

Obstructive sleep apnea and stroke

Obstructive sleep apnea (OSA) and stroke are frequent, multifactorial entities that share risk factors, and for which case-control and cross-sectional studies have shown a strong association. Stroke of respiratory centers can lead to apnea. Snoring preceding stroke, documentation of apneas immediately prior to transient ischemic attacks, the results of autonomic studies, and the circadian pattern of stroke, suggest that untreated OSA can contribute to stroke. Although cohort studies indicate that OSA is a stroke risk factor, controversy surrounds the cost-effectiveness of the screening for and treatment of OSA once stroke has occurred.

Cerebrovascular Diseases and Sleep-Disordered Breathing

Sleep-disordered breathing (SDB) is more probably the cause rather than the consequence of stroke because: apneas are essentially obstructive rather than central, the frequency of SDB is not different between transient ischemic attack and cerebral infarction; and previous excessive daytime sleepiness is significantly more frequent among stroke patients with SDB than those without. The presence of SDB in stroke patients could lead to a poor outcome. Pathophysiological relationships between strokes and SDB are multiple. Experimental and clinical studies have shown that both short- and long-term factors may play a role in increasing the susceptibility to stroke in patients with obstructive sleep apnea syndrome. The former include changes in cerebral hemodynamics, hematologic alterations, and cardiocirculatory dysfunctions that typically and repeatedly occur during apnea episodes and also may persist during wakefulness. Regarding long-term factors, some changes in the anatomical characteristics of carotid arteries wall have been recognized in SDB patients. This finding seems to suggest that the link between SDB and cerebrovascular disease might be explained, at least in part, by an increase in the progression of the atherosclerosis process involving cerebral vessels. There are several practical implications from the demonstrated significant role of sleep apnea in increasing the predisposition to developing stroke. Specific investigation is fundamental in the presence of a clinical suspect of SDB, especially in patients with history of transient ischemic attacks and stroke. Specific treatment of SDB may reduce the possibility of further cerebrovascular disturbances.

Obstructive sleep apnea and cardiovascular disease

Over the past few decades, sleep apnea has emerged as an important potential etiologic factor in a broad range of cardiac and vascular diseases. These disease conditions include hypertension, coronary artery disease, myocardial infarction, heart failure, and stroke. Recognition of the role of sleep apnea in clinical cardiology is also increasing in Japan. Although sleep apnea has been strongly linked to obesity in Western populations, in Japanese and other Asian populations there is evidence to indicate that sleep apnea may be prevalent even at lower levels of obesity. In this review we address the epidemiology of sleep apnea. Since sleep apnea includes the combined stresses of hypoxemia, apnea, and disrupted sleep, we also review briefly the potential disease mechanisms that may be activated as a consequence of sleep apnea. We further examine the role of sleep apnea in the pathophysiology and management of specific cardiovascular conditions. Overall, while the evidence of sleep apnea as a causal mechanism in cardiovascular disease is strong and increasing, definitive evidence of the etiologic role of sleep apnea has yet to be obtained. The evidence is most clear in patients with hypertension. Also remaining to be established is whether the treatment of sleep apnea prevents cardiac and vascular events. With regard to this question, although the available data strongly suggest that continuous positive airway pressure treatment is beneficial, randomized control trials are needed in order to confirm this.

Prevalence and risk factors associated with reversed Robin Hood syndrome in acute ischemic stroke

BACKGROUND AND PURPOSE

Early deterioration can occur after acute stroke for a variety of reasons. We describe a hemodynamic steal and associated neurological deterioration, the reversed Robin Hood syndrome (RRHS). We aimed to investigate the frequency and factors associated with RRHS.

METHODS

Consecutive patients with acute cerebral ischemia underwent serial National Institutes of Health Stroke Scale and bilateral transcranial Doppler monitoring with breathholding. Steal magnitude (%) was calculated from transient mean flow velocity reduction in the affected arteries at the time of velocity increase in normal vessels. Excessive sleepiness and likelihood of sleep apnea were evaluated by the Epworth Sleepiness Scale and Berlin Questionnaire.

RESULTS

Among 153 patients (age, 61+/-14 years; 48% women; 21% transient ischemic attack) admitted within 48 hours from symptom onset, 21 (14%) had steal phenomenon (median steal magnitude, 20%; interquartile range, 11%; range, 6% to 45%), and 11 (7%) had RRHS. RRHS was most frequent in patients with proximal arterial occlusions (17% versus 1%; P<0.001). The following factors were independently (P<0.05) associated with RRHS (multivariate logistic regression model): male gender, younger age, persisting arterial occlusions, and excessive sleepiness (P<0.001). A 1-point increase in the Epworth Sleepiness Scale was independently related to an increased likelihood of RRHS of 36% (95% CI, 7% to 73%).

CONCLUSIONS

RRHS and hemodynamic steal can be found in 7% and 14%, respectively, of consecutive patients with stroke without other known causes for deterioration. Patients with persisting arterial occlusions and excessive sleepiness can be particularly vulnerable to the steal.

Central periodic breathing during sleep in 74 patients with acute ischemic stroke - neurogenic and cardiogenic factors

OBJECTIVES

The aims of our study were 1) to better characterize central periodic breathing during sleep (CPBS) and its clinical relevance in acute stroke, 2) to better define the role of brain damage in its pathogenesis.

METHODS

We included 74 consecutive patients admitted within 96 hours after stroke onset. Stroke severity at admission, stroke outcome at discharge and stroke topography were assessed. ECG and transesophageal echocardiography were performed. Nocturnal breathing was assessed with an ambulatory device the first night after admission. CPBS severity was represented as absolute time and percentage of recording time.

RESULTS

Age was 63 +/- 13 (25-82), 49 (66 %) were male. Thirty (41 %) patients showed CPBS during >or= 10 % and 7 (9 %) during >or= 50 % of recording time. CPBS severity was associated with age (p = 0.017), stroke severity (p = 0.008), ECG abnormalities (p = 0.005) and lower left ventricular ejection fraction (p < 0.0001). CPBS severity was higher in patients with extensive hemispheric strokes (n = 6, p < 0.0001), and lower in patients with partial strokes involving the left insula (n = 5, p < 0.0001) and the mesencephalon (n = 5, p = 0.002).

CONCLUSIONS

CPBS is frequent in acute ischemic stroke and is associated with older age, stroke severity/extension, and lower left ventricular function. The lower occurrence of CPBS in left insular and mesencephalic stroke suggests a major role of distinct brain areas in the modulation of respiratory phenomena accompanying acute stroke.

Obstructive sleep apnea in ischemic stroke patients

OBJECTIVE

To investigate the prevalence of obstructive sleep apnea in patients with ischemic stroke and to evaluate the effectiveness of nasal continuous positive airway pressure treatment.

METHODS

Overnight polysomnography was performed by a computerized system in 19 subjects with ischemic stroke. Patients with an apnea-hypopnea index > or = 5 were considered to have obstructive sleep apnea. The appropriate level of continuous positive airway pressure for each patient was determined during an all-night continuous positive airway pressure determination study. Attended continuous positive airway pressure titration was performed with a continuous positive airway pressure auto-titrating device.

RESULTS

Obstructive sleep apnea prevalence among patients with ischemic stroke was 73.7%. The minimum SaO(2) was significantly lower, and the percent of total sleep time in the wake stage and stage 1 sleep was significantly longer in patients with obstructive sleep apnea. In two patients with severe obstructive sleep apnea, we observed a decrease in the apnea-hypopnea index, an increase in mean wake time, mean SaO(2), and minimum SaO(2), and alterations in sleep structures with continuous positive airway pressure treatment.

CONCLUSION

As the diagnosis and treatment of obstructive sleep apnea is of particular importance in secondary stroke prevention, we suggest that the clinical assessment of obstructive sleep apnea be part of the evaluation of stroke patients in rehabilitation units, and early treatment should be started.

Central sleep apnea in patients with congestive heart failure

Central apnea during sleep represents a manifestation of breathing instability in many clinical conditions of varied etiologies. Central apnea is the result of transient cessation of ventilatory motor output, which represents that inhibitory influences favoring instability predominate over excitatory influence favoring stable breathing. This article will review the determinants of central apnea, the specific features of CHF-related central apnea, and outline a management approach

A 1H magnetic resonance spectroscopy study in patients with obstructive sleep apnea

BACKGROUND AND PURPOSE

Repeated episodes of hypoxia, hypercapnia and transient blood pressure elevation in obstructive sleep apnea syndrome (OSAS) may damage neutral structures and induce cerebral metabolic impairment. This study aimed to determine the impact of OSAS on cerebral metabolites measured by (1)H magnetic resonance spectroscopy ((1)H -MRS).

METHODS

Twenty OSAS patients underwent standard overnight polysomnography and (1)H-MRS separately. Proton volumes of interest (VOIs) were placed in frontal and midtemporal regions bilaterally.

RESULTS

Significantly lower values of the N-acetylaspartate (NAA)/creatine (Cr) ratio were found in frontal regions (P < 0.004) compared with 20 age-matched control subjects. A significant increase in the myo-inositol (Ins)/Cr ratio was evident bilaterally in temporal and frontal regions (P < 0.00002 and P < 0.04). Choline (Cho)/Cr ratio values were also significantly greater in temporal regions (P < 0.00001). A significant negative correlation (r = -0.51, P < 0.03) was found between the apnea-hypopnea index (AHI) and NAA/Cr ratio in the frontal regions of OSAS patients.

CONCLUSIONS

Reduction in the NAA/Cr ratio in frontal regions of OSAS patients could be related to neural loss. Increase in the Cho/Cr ratio in temporal regions and Ins/Cr ratio in both frontal and temporal regions could be interpreted as evidence of membrane breakdown and reactive gliosis, respectively, consequent to repeated episodes of hypoxia in OSAS.

Correlation between sleep and cognitive functions after hemispheric ischaemic stroke

BACKGROUND

The aim of this study was to test the hypothesis of a link between sleep and cognitive functions, particularly memory and attention, after stroke.

METHODS

We studied 11 consecutive patients with first-ever hemispheric ischaemic stroke within eight days after symptoms onset and nine of them at least three months after stroke. Sleep EEG was recorded with a portable system. Cognitive functions were assessed using a standardized battery of tests allowing the estimation of the most relevant domains of cognition. Five age-matched healthy subjects served as controls.

RESULTS

The patients were aged 43 +/- 12 years (18-59). In five patients stroke was right-sided and in six patients left-sided. In the acute stroke phase a correlation between attention and amounts of slow wave sleep (SWS), Rapid eye movement (REM) sleep and sleep efficiency was found. In the recovery phase verbal/figural memory and attention significantly improved in most patients. Furthermore, an association between (i) verbal/figural (non-verbal) memory and amounts of SWS, REM sleep and sleep efficiency, and between (ii) attention and sleep efficiency was observed.

CONCLUSIONS

The results point to a link between sleep and cognitive functions and their recovery after hemispheric stroke. Further studies are needed to determine the specific nature of this link.

C-reactive protein and fibrinogen in acute stroke patients with and without sleep apnea

BACKGROUND AND PURPOSE

Although sleep apnea (SA) is a risk factor for ischemic stroke and an important prognosticator in affected patients, the exact pathophysiological link between SA and stroke remains to be established. We investigated whether levels of C-reactive protein (CRP) and fibrinogen are increased in patients with acute stroke and SA compared with stroke patients without SA.

PATIENTS AND METHODS

117 consecutive patients with ischemic stroke admitted to our stroke unit within 12 h after stroke onset were included in this study. On admission, CRP and fibrinogen levels were determined. All patients received cardiorespiratory polygraphy during the first 72 h of their hospital stay. In all patients, demographic data, National Institutes of Health Stroke Scale score and cerebrovascular risk factors were assessed.

RESULTS

SA defined by an apnea-hypopnea index (AHI) of > or =10/h was found in 64 (55%) patients. Elevated CRP and fibrinogen levels were seen twice as often in patients with SA than in patients without (CRP: 52 vs. 26%; fibrinogen: 72 vs. 37%). After multivariate logistic regression analysis, an AHI of > or =10/h was independently correlated with raised levels of both of these parameters.

CONCLUSION

SA is independently associated with raised levels of CRP and fibrinogen in patients with acute ischemic stroke. We assume that both proteins are part of the pathophysiological pathway linking SA to stroke.

Mortality risk factors in sleep apnoea: a matched case?control study

Sleep apnoea syndrome was reported to be associated with increased mortality but it is not known if this association is independent of obesity and co-morbidities. The present study investigated predictors of mortality in a large cohort of men with sleep apnoea using a case-control design. The study population consisted of 10,981 men diagnosed during 1991-2000 by whole-night polysomnography with sleep apnoea; 331 men died prior to 1 September 2001, of whom 277 were matched by age, gender, site and time of study to patients who were alive in September 2001. Multivariate analysis revealed that all-cause mortality was associated with chronic obstructive pulmonary disease (COPD) (odds ratio, OR: 7.07, 95% CI 2.75-18.16), chronic heart failure (CHF) (OR: 5.47, 95% CI 1.06-28.31), diabetes mellitus (DM) (OR: 3.30, 95% CI 1.51-7.20) and body mass index (BMI) (increase of 5 kg m(-2), OR: 1.44, 95% CI: 1.04-1.99). Chronic upper airway problems were associated with survival (OR: 0.45, 95% CI 0.23-0.90). There were significant interactions between respiratory disturbance index and BMI and COPD. Mortality of patients younger than the median age (62 years) was associated with COPD, DM and an interaction between BMI and apnoea severity. Predictors of mortality for the older patients were COPD, CHF and DM. We conclude that all-cause mortality in sleep apnoea is associated with co-morbidities and obesity. Severity of sleep apnoea affects mortality by interacting with obesity and lung disease.

Sleep-disordered breathing after stroke: a randomised controlled trial of continuous positive airway pressure

BACKGROUND

Sleep-disordered breathing (SDB) is common after stroke, but it is unclear whether it should be treated.

OBJECTIVE

To conduct a randomised controlled trial of continuous positive airway pressure (CPAP) after stroke.

METHODS

Patients with stroke with > or = 30 apnoeas and hypopnoeas per hour ((A+H)/h) with predominant obstructive sleep apnoea or hypopnoea were randomised to either CPAP treatment or conservative treatment for 8 weeks. Outcomes were measured blind to treatment allocation at 8 weeks and 6 months after the stroke. The primary outcome was physical function on the Nottingham Extended Activities of Daily Living Scale.

RESULTS

Of 658 patients with stroke screened, only 71 (10.7%) were eligible and consented to a sleep study 14-19 days after stroke. 66 patients completed the sleep study (21 women; mean age 72 years), 33 (50%) had > or = 30 (A+H)/h that were predominantly obstructive. 15 were randomised to CPAP treatment and 15 to conventional treatment. Despite intensive efforts, objective use of CPAP was poor, averaging 1.4 h a night. CPAP treatment resulted in no significant improvements (p>0.1) in the primary outcome or in neurological function or sleepiness, and in poorer health status on some measures.

CONCLUSIONS

This trial showed no benefit from CPAP treatment, the relevance of the observed detrimental effects is questionable. Even in our highly selected patients with stroke, use of CPAP was poor. At present, CPAP treatment should be advocated for patients with stroke only if they have symptoms of SDB.

Obstructive sleep apnea: what does the cardiovascular physician need to know?

Obstructive sleep apnea (OSA) is a common disorder in adults. It is becoming increasingly recognized as a risk factor for cardiovascular diseases such as hypertension, pulmonary hypertension, myocardial infarction, and stroke. Knowing the pathophysiologic effects that occur during obstructive apnea assists in understanding how chronic complications and sequelae develop. OSA is also being recognized as associated with glucose intolerance and motor vehicle accidents. Polysomnography in a sleep laboratory remains the diagnostic method of choice. Treatment options are somewhat limited in scope, but nasal continuous positive airway pressure is the first line and has been shown to clearly improve many of the symptoms and sequelae of the syndrome. Cardiovascular physicians require a working knowledge of OSA and its complications, as many of the diseases they manage have shown links to this sleep disorder.

Sleep-disordered breathing and acute ischemic stroke: diagnosis, risk factors, treatment, evolution, and long-term clinical outcome

BACKGROUND AND PURPOSE

Sleep-disordered breathing (SDB) is frequent in stroke patients. Risk factors, treatment response, short-term and long-term outcome of SDB in stroke patients are poorly known.

METHODS

We prospectively studied 152 patients (mean age 56+/-13 years) with acute ischemic stroke. Cardiovascular risk factors, Epworth sleepiness score (ESS), stroke severity/etiology, and time of stroke onset were assessed. The apnea-hypopnea index (AHI) was determined 3+/-2 days after stroke onset and 6 months later (subacute phase). Continuous positive airway pressure (CPAP) treatment was started acutely in patients with SDB (AHI > or =15 or AHI > or =10+ESS >10). CPAP compliance, incidence of vascular events, and stroke outcome were assessed 60+/-16 months later (chronic phase).

RESULTS

Initial AHI was 18+/-16 (> or =10 in 58%, > or =30 in 17% of patients) and decreased in the subacute phase (P<0.001). Age, diabetes, and nighttime stroke onset were independent predictors of AHI (r2=0.34). In patients with AHI > or =30, age, male gender, body mass index, diabetes, hypertension, coronary heart disease, ESS, and macroangiopathic etiology of stroke were significantly higher/more common than in patients with AHI <10. Long-term incidence of vascular events and stroke outcome were similar in both groups. CPAP was started in 51% and continued chronically in 15% of SDB pts. Long-term stroke mortality was associated with initial AHI, age, hypertension, diabetes, and coronary heart disease.

CONCLUSIONS

SDB is common particularly in elderly stroke male patients with diabetes, nighttime stroke onset, and macroangiopathy as cause of stroke; it improves after the acute phase, is associated with an increased poststroke mortality, and can be treated with CPAP in a small percentage of patients.

Association of sleep-disordered breathing and the occurrence of stroke

RATIONALE

Sleep-disordered breathing has been linked to stroke in previous studies. However, these studies either used surrogate markers of sleep-disordered breathing or could not, due to cross-sectional design, address the temporal relationship between sleep-disordered breathing and stroke.

OBJECTIVES

To determine whether sleep-disordered breathing increases the risk for stroke.

METHODS

We performed cross-sectional and longitudinal analyses on 1,475 and 1,189 subjects, respectively, from the general population. Sleep-disordered breathing was defined by the apnea-hypopnea index (frequency of apneas and hypopneas per hour of sleep) obtained by attended polysomnography. The protocol, including polysomnography, risk factors for stroke, and a history of physician-diagnosed stroke, was repeated at 4-yr intervals.

MEASUREMENTS AND MAIN RESULTS

In the cross-sectional analysis, subjects with an apnea-hypopnea index of 20 or greater had increased odds for stroke (odds ratio, 4.33; 95% confidence interval, 1.32-14.24; p = 0.02) compared with those without sleep-disordered breathing (apnea-hypopnea index, <5) after adjustment for known confounding factors. In the prospective analysis, sleep-disordered breathing with an apnea-hypopnea index of 20 or greater was associated with an increased risk of suffering a first-ever stroke over the next 4 yr (unadjusted odds ratio, 4.31; 95% confidence interval, 1.31-14.15; p = 0.02). However, after adjustment for age, sex, and body mass index, the odds ratio was still elevated, but was no longer significant (3.08; 95% confidence interval, 0.74-12.81; p = 0.12).

CONCLUSIONS

These data demonstrate a strong association between moderate to severe sleep-disordered breathing and prevalent stroke, independent of confounding factors. They also provide the first prospective evidence that sleep-disordered breathing precedes stroke and may contribute to the development of stroke.

Blood Pressure Evolution After Acute Ischemic Stroke in Patients With and Without Sleep Apnea

Background and Purpose— Sleep apnea (SA) is an independent risk factor for arterial hypertension and is present in 50% to 70% of patients with ischemic stroke. The effects of SA on blood pressure (BP) and stroke outcome in the acute stroke phase are essentially unknown.

Methods— We studied 41 consecutive patients admitted within 96 hours after stroke onset. Stroke severity on admission (National Institutes of Health Stroke Scale [NIHSS]) and stroke outcome at discharge (modified Rankin Disability Scale [mRS]) were assessed. Nocturnal breathing was assessed with an ambulatory device the first night after admission. SA was defined by an apnea-hypopnea-index (AHI) ≥10/hour, and moderate-severe SA (MSSA) was defined by an AHI >30/hour. BP monitoring was performed during the first 36 hours after admission. A nondipping status (NDS) was defined by a ratio >0.9 of mean systolic BP during nights 1 to 2/mean systolic BP during day 2.

Results— SA was found in 28 (68%) and MSSA in 11 (27%) of 41 patients. A correlation was found between AHI and both NIHSS ( r =0.331; P =0.035) and mRS ( r =0.341; P =0.031). Patients with MSSA had higher systolic and diastolic BP values during night 1 ( P =0.003), day 2 ( P =0.004), and night 2 ( P =0.03). NDS was found in 26 (63%) patients. Nondippers had a similar AHI but higher NIHSS ( P =0.004) and mRS ( P =0.005) than dippers. AHI and NDS were confirmed to be independent predictors for both stroke severity and stroke outcome in a multiple stepwise linear regression model.

Conclusions— SA severity is associated with high 24-hour BP values but only weakly with stroke severity and outcome. Conversely, NDS is linked with a more severe stroke and a poorer evolution but not with SA severity. These data suggest different, although overlapping, pathophysiological and clinical implications of circadian and nocturnal BP values in acute stroke.

Central sleep apnea

Central sleep apnea (CSA) is characterized by the periodic occurrence of apnea caused by loss of ventilatory motor output. CSA is often discussed as a minor variant of obstructive sleep apnea.However, this view obscures the critical contribution of CSA as an important manifestation of breathing instability in a variety of conditions with diverse causes. Central apnea can also be a physiologic phenomenon in healthy people during sleep onset. Conversely, patients who have obstructive apnea may also develop episodes of apparent central apnea, and apneas that begin as central may become obstructive as respiratory effort is restored ("mixed apneas"). Thus, there is a significant overlap between obstructive and central apnea. This article addresses the pathophysiology, clinical features, and management of normocapnic and hypercapnic CSA.

Obstructive sleep apnea: Plasma endothelin-1 precursor but not endothelin-1 levels are elevated and decline with nasal continuous positive airway pressure

Assessment of plasma endothelin-1 (ET-1) reveals conflicting results in cerebral and noncerebral conditions. Obstructive sleep apnea (OSA) syndrome has been used as a definite challenge for the investigation of endothelin measurements. Despite marked sleep-related breathing disturbances in untreated patients peripherally measurable ET-1 concentrations remained within the normal range and did not change after an appropriate therapy with continuous positive airway pressure (CPAP). In contrast, its precursor, big ET-1, was considerably elevated in untreated patients and dropped to normal values after long-term CPAP depending on compliance. Relatively stable big ET-1 elevations in untreated patients, during sleep and wakefulness, suggest that a general endothelial alteration beyond that explained by a direct impact of nocturnal breathing disturbances on the vascular system occurs. CPAP-therapy effectively lowered plasma big ET-1 in compliant patients and thus possibly their related risk for vascular diseases. Big ET-1 has been demonstrated to be a more appropriate marker of endothelial alteration than ET-1 because of its longer half-life. Simultaneous measurements are to be recommended.

Increased prevalence of sleep apnea in patients with recurring ischemic stroke compared with first stroke victims

Since sleep apnea (SA) and stroke have many shared risk factors an independent contribution of SA to the overall risk of stroke is not easily proven and has been questioned recently. To contribute to this controversy, we analysed the frequency of SA in groups of patients with first and recurring ischemic stroke. We prospectively studied 102 patients admitted to our stroke unit. The prevalence of vascular risk factors and a history of previous stroke were recorded. All patients received cardio-respiratory polygraphy during the first 72 hours after admission. CT and MRI scans were evaluated for the location of the acute stroke and the presence of older vascular lesions. Thirty-four women and 68 men with a mean age of 64.5 +/- 13.7 years were included in the study. Cerebral lesions attributable to a previous stroke were identified in 25 patients, of whom 19 reported to have suffered a stroke before. Patients with stroke recurrence had a higher mean apnea-hypopnea index (AHI) (26.6/h vs. 15.1/h, p<0.05) and more often presented with a sleep apnea syndrome (SA) defined by an AHI >or=10/h (80 vs. 52%, p < 0.05) than patients with first ever stroke. Logistic regression analysis including the variables "age", "gender", "cumulative risk factors", "AHI >or=10/h", and "diabetes" identified diabetes (Odd's ratio [OR]=4.5) and AHI >or=10/h (OR=3.5) as independent risk-factors for stroke recurrence. According to our results SA is an independent risk factor for stroke recurrence. We therefore advocate routine sleep-apnea screening in all patients having suffered an ischemic stroke.

Screening for Obstructive Sleep Apnea in Stroke Patients

Background and Purpose— Obstructive sleep apnea (OSA) is common after acute ischemic stroke and predicts poor stroke recovery, but whether screening for OSA and treatment by continuous positive airway pressure (CPAP) improves neurological outcome is unknown. We used a cost-effectiveness model to estimate the magnitude of benefit that would be necessary to make polysomnography (PSG) and OSA treatment cost-effective in stroke patients.

Methods— A decision tree modeled 2 alternative strategies: PSG followed by 3 months of CPAP for those found to have OSA versus no screening. The primary outcome was the utility gained through OSA screening and treatment in relation to 2 common willingness-to-pay thresholds of $50 000 and $100 000 per quality-adjusted life year (QALY).

Results— Screening resulted in an incremental cost-effectiveness ratio of $49 421 per QALY. Screening is cost-effective as long as the treatment of stroke patients with OSA by CPAP improves patient utilities by >0.2 for a willingness-to-pay of $50 000 per QALY and 0.1 for a willingness-to-pay of $100 000 per QALY.

Conclusions— A clinical trial assessing the effectiveness of CPAP in improving stroke outcome is warranted from a cost-effectiveness standpoint.

Long-term cardiovascular outcomes in men with obstructive sleep apnoea-hypopnoea with or without treatment with continuous positive airway pressure: an observational study

BACKGROUND

The effect of obstructive sleep apnoea-hypopnoea as a cardiovascular risk factor and the potential protective effect of its treatment with continuous positive airway pressure (CPAP) is unclear. We did an observational study to compare incidence of fatal and non-fatal cardiovascular events in simple snorers, patients with untreated obstructive sleep apnoea-hypopnoea, patients treated with CPAP, and healthy men recruited from the general population.

METHODS

We recruited men with obstructive sleep apnoea-hypopnoea or simple snorers from a sleep clinic, and a population-based sample of healthy men, matched for age and body-mass index with the patients with untreated severe obstructive sleep apnoea-hypopnoea. The presence and severity of the disorder was determined with full polysomnography, and the apnoea-hypopnoea index (AHI) was calculated as the average number of apnoeas and hypopnoeas per hour of sleep. Participants were followed-up at least once per year for a mean of 10.1 years (SD 1.6) and CPAP compliance was checked with the built-in meter. Endpoints were fatal cardiovascular events (death from myocardial infarction or stroke) and non-fatal cardiovascular events (non-fatal myocardial infarction, non-fatal stroke, coronary artery bypass surgery, and percutaneous transluminal coronary angiography).

FINDINGS

264 healthy men, 377 simple snorers, 403 with untreated mild-moderate obstructive sleep apnoea-hypopnoea, 235 with untreated severe disease, and 372 with the disease and treated with CPAP were included in the analysis. Patients with untreated severe disease had a higher incidence of fatal cardiovascular events (1.06 per 100 person-years) and non-fatal cardiovascular events (2.13 per 100 person-years) than did untreated patients with mild-moderate disease (0.55, p=0.02 and 0.89, p<0.0001), simple snorers (0.34, p=0.0006 and 0.58, p<0.0001), patients treated with CPAP (0.35, p=0.0008 and 0.64, p<0.0001), and healthy participants (0.3, p=0.0012 and 0.45, p<0.0001). Multivariate analysis, adjusted for potential confounders, showed that untreated severe obstructive sleep apnoea-hypopnoea significantly increased the risk of fatal (odds ratio 2.87, 95%CI 1.17-7.51) and non-fatal (3.17, 1.12-7.51) cardiovascular events compared with healthy participants.

INTERPRETATION

In men, severe obstructive sleep apnoea-hypopnoea significantly increases the risk of fatal and non-fatal cardiovascular events. CPAP treatment reduces this risk.

Disorders of Sleep and Wake in Patients After Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

To determine the frequency and severity of disorders of sleep and wake and their relation to the quality of life (QoL) in patients who have survived an episode of subarachnoid hemorrhage (SAH).

METHODS

In a prospectively collected, consecutive series of 89 patients, 83 patients completed validated and frequently used questionnaires for the assessment of disorders of sleep and wake (SDL and Epworth Sleepiness Score) at least 1 year (range, 1 to 3.4 years) after the SAH. We used the modified Rankin scale for functional outcome and Short Form 36 (SF-36) to assess QoL. We related the occurrence of severe problems with sleep (insomnia or excessive daytime sleepiness score or both > or =3 on SDL) to functional outcome and to the QoL scores and compared the latter scores with data from a Dutch reference population. In a subset of 20 patients with severe problems with sleep, we performed polysomnographic and actigraphic studies at home during 48 hours.

RESULTS

Twenty eight (34%) patients had severe problems with sleep. Frequently reported problems are initiating (25%) or maintaining (31%) sleep, difficulty returning (28%) asleep, tiredness (31%), and excessive sleepiness during the day (6%). QoL was considerably reduced in patients with severe problems with sleep. During the sleep monitoring studies, severe sleep fragmentation, sleep apnea, restless legs syndrome/periodic limb movement disorder, or a combination of these disorders of sleep and wake occurred in 19 of 20 patients.

CONCLUSIONS

Many patients who have survived an episode of SAH have disorders of sleep and wake, which are related to the QoL.

Evaluation of carotid artery wall thickness with high-resolution sonography in obstructive sleep apnea syndrome

PURPOSE

An increased intima-media thickness (IMT) in the carotid arteries is a marker of generalized atherosclerosis, and it has been associated with a high risk of stroke. The aim of this study was to investigate whether patients with obstructive sleep apnea syndrome (OSAS) have an increase in atherosclerotic indicators in the carotid arteries.

METHODS

We studied 30 men with severe OSAS who had an apnea-hypopnea index (AHI) of at least 20. IMT measurement and the presence of stenotic occlusive lesions in the carotid arteries (right common carotid artery [RCCA], right bulb [Rbulb], right internal carotid artery [RICA], left common carotid artery [LCCA], left bulb [Lbulb], and left internal carotid artery [LICA]) were investigated by high-resolution sonography. Results of the sonographic examinations were compared with those for a group of 20 subjects with mild OSAS (AHI <20) and 20 healthy subjects.

RESULTS

The mean IMT of the carotid arteries of patients with severe OSAS was significantly higher than those of patients with mild OSAS and control subjects (RCCA 0.81 versus 0.63 versus 0.58, p <0.01; Rbulb 0.96 versus 0.87 versus 0.65, p <0.001; RICA 0.77 versus 0.69 versus 0.61, p <0.05; LCCA 0.97 versus 0.78 versus 0.67, p <0.01; Lbulb 1.01 versus 0.89 versus 0.72, p <0.01; LICA 0.91 versus 0.75 versus 0.65, p <0.001).

CONCLUSIONS

This study shows that the carotid arteries' IMT is increased in patients with severe OSAS. This increase may predispose the patients to cerebrovascular disease. Additionally, the findings support the hypothesis that patients with OSAS are at risk of developing cerebrovascular disease regardless of the presence or absence of other vascular risk factors (eg, hypercholesterolemia, diabetus mellitus, and hypertension).

Cheyne-Stokes respiration in stroke: relationship to hypocapnia and occult cardiac dysfunction

BACKGROUND

Central sleep apnea (CSA) and Cheyne-Stokes respiration have been reported in association with stroke, but their pathophysiologic correlates have not been well described.

OBJECTIVE

To test the hypotheses that (1) CSA in patients with stroke is associated with nocturnal hypocapnia and (2) in those stroke patients with CSA and with left ventricular (LV) systolic dysfunction, periodic breathing (PB) will have a Cheyne-Stokes respiration pattern in which cycle duration is greater than in those without LV systolic dysfunction.

METHODS

We prospectively performed polysomnography and echocardiography in 93 patients with stroke. CSA was defined as central apneas and hypopneas occurring at a rate of 10 or more per hour of sleep. In patients with CSA, we compared PB cycle duration between those with normal and impaired LV systolic function (LV ejection fraction [LVEF] > 40% and < or = 40%, respectively).

RESULTS

CSA was found in 19% of subjects who had lower nocturnal transcutaneous PCO2 (39.3 +/- 0.9 vs. 42.8 +/- 0.8 mmHg, p = 0.015) and a higher prevalence of LVEF of 40% or less (22 vs. 5%, p = 0.043) than stroke patients without CSA. There was no significant difference in stroke location or type between the two groups. In patients with CSA, those with LVEF of 40% or less had a longer PB cycle than those with an LVEF of more than 40% (66.6 +/- 5.6 vs. 46.6 +/- 2.9 seconds, p = 0.006), but had no symptoms of heart failure.

CONCLUSION

In patients with stroke, CSA is associated with hypocapnia and occult LV systolic dysfunction but is not related to the location or type of stroke. The presence of LV systolic dysfunction is associated with a Cheyne-Stokes pattern of hyperpnea.

Obstructive sleep apnoea and stroke

Many patients with stroke have concomitant sleep apnoea, which can affect recovery potential. Although stroke can lead to the development of sleep-disordered breathing, the current evidence suggests that sleep-disordered breathing may function as a risk factor for stroke. In this review, we focus on the association between obstructive sleep apnoea and stroke reviewing both the epidemiological data with respect to causation and the biological data, which explores pathogenesis. There is convincing evidence to believe that sleep apnoea is a modifiable risk factor for stroke; however, prospective studies are needed to establish the cause-and-effect relationship.

Polysomnography in patients with intracranial tumors before and after operation

OBJECTIVE

To evaluate the breathing and sleep patterns in patients with brain tumors before and after operation, and assess their relation to the location and size of the tumor, as well as to the post-operative outcome.

METHODS

Polysomnographic studies were performed in 11 patients with intracranial tumors (nine supra- and two infratentorial) before and after surgery.

RESULTS

Pre-operatively, the mean apnea-hypopnea index (AHI) was 23.3. Six patients demonstrated signs of obstructive sleep apnea (SA) and one had mixed obstructive and central type SA. After operation, the mean AHI decreased to 8.1(P < 0.05). The duration of random eye movement sleep stage increased after tumor removal (P < 0.04). No relation was found between the characteristics of the tumor, nor the post-operative outcome and SA.

CONCLUSIONS

Patients with brain tumors often suffer from SA and this can further worsen their symptoms related to increased intracranial pressure. Removal of the tumor results in a substantial decrease in sleep-related disturbances and may thus play a role in clinical recovery.