Efficacy of continuous positive airway pressure treatment on 5-year survival in patients with ischaemic stroke and obstructive sleep apnea: a randomized controlled trial

Assessment and management of continuous positive airway pressure therapy in patient with obstructive sleep apnea

Obstructive sleep apnea (OSA) causes excessive daytime sleepiness, impaired daytime functioning, and an increased risk of cardiovascular diseases. Continuous positive airway pressure (CPAP) is a highly effective therapy for moderate to severe OSA. Although CPAP adherence is commonly assessed using a 4-hthreshold, determining the optimal usage time based on clinical outcomes is crucial. While subjective sleepiness often improves with ≥4 h of CPAP usage, an extended duration (≥6 h) may be necessary to impact objective sleepiness. CPAP demonstrated a modest yet clinically meaningful dose-dependent effect on lowering blood pressure. For patients seeking antihypertensive benefits from CPAP therapy, the goal should extend beyond 4 h of use to maximize the therapeutic impact. Recognizing individual variations in sleep duration and responses to CPAP therapy is essential. The adoption of 'individualized goals for CPAP use,' outlining target times for specific outcomes, should also consider an individual's total sleep duration, including periods without CPAP. The impact of CPAP on clinical outcomes may vary, even with the same duration of CPAP use, depending on the period without CPAP use, particularly during the first or second half of sleep. Patients who remove or initiate CPAP midway or have a low CPAP usage frequency may require different forms of guidance. Tailoring patient education to address CPAP usage patterns may be necessary to enhanced satisfaction, self-efficacy, and adherence to therapy. Management of CPAP treatment should be personalized to meet individual needs and adapted based on specific response patterns for achieving treatment efficacy.

Obstructive Sleep Apnea and Stroke: Determining the Mechanisms Behind their Association and Treatment Options

Sleep-disordered breathing (SDB) can be a sequela of stroke caused by vascular injury to vital respiratory centers, cerebral edema, and increased intracranial pressure of space-occupying lesions. Likewise, obstructive sleep apnea (OSA) contributes to increased stroke risk through local mechanisms such as impaired ischemic cerebrovascular response and systemic effects such as promoting atherosclerosis, hypercoagulability, cardiac arrhythmias, vascular-endothelial dysfunction, and metabolic syndrome. The impact of OSA on stroke outcomes has been established, yet it receives less attention in national guidelines on stroke management than hyperglycemia and blood pressure dysregulation. Furthermore, whether untreated OSA worsens stroke outcomes is not well-described in the literature. This scoping review provides an updated investigation of the correlation between OSA and stroke, including inter-relational pathophysiology. This review also highlights the importance of OSA treatment and its role in stroke outcomes. Knowledge of pathophysiology, the inter-relationship between these common disorders, and the impact of OSA therapy on outcomes affect the clinical management of patients with acute ischemic stroke. In addition, understanding the relationship between stroke outcomes and pre-existing OSA will allow clinicians to predict outcomes while treating acute stroke.

Up-to-date advance in the relationship between OSA and stroke: a narrative review

PURPOSE

Obstructive sleep apnea (OSA) and stroke affect each other. In this review, we summarized the effect of OSA on the onset and recurrence of stroke, the prognosis, and the treatment of poststroke patients with OSA.

METHODS

Pubmed/MEDLINE were searched through May 2023 to explore the relationship between OSA and stroke. The relevant papers included OSA and stroke, OSA and recurrent stroke, and the prognosis and treatment of poststroke patients with OSA.

RESULTS

The results showed that OSA can promote the onset and recurrence of stroke and that OSA may adversely affect the prognosis of poststroke patients. The application of continuous positive airway pressure (CPAP) and other treatments may benefit poststroke patients with OSA, though the long term effects of treatment are not well documented.

CONCLUSION

Both the onset and recurrence of stroke closely correlated with OSA, but the specific mechanisms remain unclear. Further studies should be carried out to explore effective treatments in patients with stroke and OSA.

Effect of ventilation modalities on the early prognosis of patients with poststroke sleep apnea

OBJECTIVE

Continuous positive airway pressure (CPAP) is the primary modality for treating sleep apnea after acute ischemic stroke (AIS). However, not all patients are well adherent to CPAP. Finding an alternative modality of ventilation to CPAP is essential.

METHODS

This prospective randomized clinical trial was conducted from 1 May 2022 to 8 January 2023 at the Department of Neurology, Wuhan Union Hospital. Participants diagnosed with sleep apnea after AIS were grouped according to block randomization principles into the usual care group (nasal cannula and facemask), nasal continuous positive airway pressure (nCPAP) group, and high-flow nasal cannula (HFNC) group. Rates of pulmonary infection and endotracheal intubation within 1 week of hospitalization and 28-day mortality (poststroke) were the primary outcomes (early prognosis).

RESULTS

In the trial, 178 patients (119 males [66.85%]; mean [SD] age, 61.04 [11.78] years) were eventually enrolled in the usual care group (n = 63), the nCPAP group (n = 55), and the HFNC group (n = 60). After ventilation, the nCPAP and HFNC groups were more effective than the usual care group in reducing the rate of pulmonary infection, endotracheal intubation, and improving neurological function and sleep apnea severity. However, there was no difference in 28-day mortality. Additionally, the improvement in prognosis was consistent between nCPAP and HFNC. In the comparison of comfort, the HFNC group was superior to nCPAP.

INTERPRETATION

nCPAP and HFNC reduced early pulmonary infection rates and endotracheal intubation rates. For patients with poor compliance with nCPAP, HFNC may be the best alternative.

From Snoring to Soaring: Unveiling the Positive Effects of Continuous Positive Airway Pressure Ventilation on Cardiovascular Health in Patients With Obstructive Sleep Apnoea Through a Systematic Review

Increased cardiovascular (CV) morbidity and death are linked to obstructive sleep apnoea (OSA). The primary method of treating OSA is continuous positive airway pressure (CPAP). CPAP has some debatable outcomes on CV events in people suffering from OSA. The current study investigates how CPAP affects CV outcomes. The goal is to evaluate CPAP's effectiveness in lowering CV outcomes in OSA patients. We used a computer to search the PubMed, PubMed Central Library, Science Direct, and Google Scholar databases for studies comparing the effects of CPAP and a control group on CV outcomes in OSA patients. These included randomised control trials (RCT), narrative reviews, systematic reviews, case-control studies, observational studies and meta-analyses. A total of 52,937 patients were included in the final analysis of six RCTs, four observational studies, 10 meta-analyses, one case-control study, two systematic reviews and one narrative review. The weighted mean follow-up lasted for a period of between three months and nine years. The risk of major cardiovascular adverse events (MACE) was the same for both the CPAP and control groups. According to subgroup analysis, patients with lower MACE adherence rates (four hours per night) were more likely to use CPAP. The risk of all-cause mortality, CV-related complications causing mortality, acute myocardial infarction acute stroke, or hospitalisations for angina was the same in the CPAP and control groups. The primary outcome was that in patients with therapy with CPAP in addition to usual care and usual care alone did not prevent CV events in patients with moderate-to-severe OSA and existing CV illness. Patients with OSA who utilise CPAP may not experience fewer CV events. Patients who use CPAP consistently (four hours per night) could benefit from improved CV results. Future research must assess how well-adherent patients with severe OSA and low CV event rates respond to CPAP therapy. In patients who use CPAP for more than four hours each night, CPAP therapy may minimise the risk of MACE and stroke. Additional randomised trials requiring adequate CPAP time adherence are needed to support this perception. Despite the fact that there is no evidence to support the claim that CPAP therapy improves CV outcomes, bias difficulties, CPAP adherence problems, and the patient groups included in each RCT may have made it more difficult to generalise the findings to all patients. Future research is therefore needed to look at these relevant results.

Obstructive sleep apnoea heterogeneity and cardiovascular disease

Obstructive sleep apnoea (OSA), characterized by recurrent periods of upper airway obstruction and intermittent hypoxaemia, is prevalent in patients with cardiovascular disease (CVD), and is therefore important to consider in the prevention and management of CVD. Observational studies indicate that OSA is a risk factor for incident hypertension, poorly controlled blood pressure, stroke, myocardial infarction, heart failure, cardiac arrhythmias, sudden cardiac death and all-cause death. However, clinical trials have not provided consistent evidence that treatment with continuous positive airway pressure (CPAP) improves cardiovascular outcomes. These overall null findings might be explained by limitations in trial design and low levels of adherence to CPAP. Studies have also been limited by the failure to consider OSA as a heterogeneous disorder that consists of multiple subtypes resulting from variable contributions from anatomical, physiological, inflammatory and obesity-related risk factors, and resulting in different physiological disturbances. Novel markers of sleep apnoea-associated hypoxic burden and cardiac autonomic response have emerged as predictors of OSA-related susceptibility to adverse health outcomes and treatment response. In this Review, we summarize our understanding of the shared risk factors and causal links between OSA and CVD and emerging knowledge on the heterogeneity of OSA. We discuss the varied mechanistic pathways that result in CVD that also vary across subgroups of OSA, as well as the potential role of new biomarkers for CVD risk stratification.

Sleep Disorders in Patients with Neurologic Disease

OBJECTIVE

This article provides an overview of the growing body of evidence showing bidirectional relationships between sleep and various neurologic disorders.

LATEST DEVELOPMENTS

Mounting evidence demonstrates that disrupted sleep can negatively impact various neurologic disease processes, including stroke, multiple sclerosis, epilepsy, neuromuscular disorders including amyotrophic lateral sclerosis, and headache syndromes. Abnormal sleep can also be a precursor to Alzheimer disease and neurodegenerative disease states such as Parkinson disease and dementia with Lewy bodies. Interventions to improve sleep and treat obstructive sleep apnea may play a vital role in preventing neurologic disease development and progression.

ESSENTIAL POINTS

Sleep disorders are common among patients with neurologic disorders. To provide comprehensive care to patients with neurologic conditions, neurologists must ask patients about sleep issues that may warrant further diagnostic testing, treatment, and sleep medicine referral when indicated.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Post-stroke sleep disturbance and recurrent cardiovascular and cerebrovascular events: A systematic review and meta-analysis

Despite improvements in survival rates, risk of recurrent events following stroke remains high. Identifying intervention targets to reduce secondary cardiovascular risk in stroke survivors is a priority. The relationship between sleep and stroke is complex: sleep disturbances are likely both a contributor to, and consequence of, stroke. The current aim was to examine the association between sleep disturbance and recurrent major acute coronary events or all-cause mortality in the post-stroke population. Thirty-two studies were identified, including 22 observational studies and 10 randomized clinical trials (RCTs). Identified studies included the following as predictors of post-stroke recurrent events: obstructive sleep apnea (OSA, n = 15 studies), treatment of OSA with positive airway pressure (PAP, n = 13 studies), sleep quality and/or insomnia (n = 3 studies), sleep duration (n = 1 study), polysomnographic sleep/sleep architecture metrics (n = 1 study), and restless legs syndrome (n = 1 study). A positive relationship of OSA and/or OSA severity with recurrent events/mortality was seen. Findings on PAP treatment for OSA were mixed. Positive findings indicating a benefit of PAP for post-stroke risk came largely from observational studies (pooled RR [95% CI] for association between PAP and recurrent cardiovascular event: 0.37 [0.17-0.79], I2 = 0%). Negative findings came largely from RCTs (RR [95% CI] for association between PAP and recurrent cardiovascular event + death: 0.70 [0.43-1.13], I2 = 30%). From the limited number of studies conducted to date, insomnia symptoms/poor sleep quality and long sleep duration were associated with increased risk. Sleep, a modifiable behavior, may be a secondary prevention target to reduce the risk of recurrent event and death following stroke. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42021266558.

Positive airway pressure therapy for post-stroke sleep disordered breathing: a systematic review, meta-analysis and meta-regression

BACKGROUND

Sleep disordered breathing (SDB) is an under-recognised independent risk factor and a potential consequence of stroke. We systematically reviewed and meta-analysed the effectiveness of positive airway pressure (PAP) therapy in improving post-stroke outcomes.

METHODS

We searched CENTRAL, Embase, PubMed, CINAHL, PsycINFO, Scopus, ProQuest, Web of Science and CNKI (China National Knowledge Infrastructure) for randomised controlled trials comparing PAP therapy against a control or placebo group. We evaluated the pooled effects of PAP therapy on recurrent vascular events, neurological deficit, cognition, functional independence, daytime sleepiness and depression using random effects meta-analyses.

RESULTS

We identified 24 studies. Our meta-analyses showed that PAP therapy reduced recurrent vascular events (risk ratio 0.47, 95% CI 0.28-0.78), and showed significant beneficial effects on neurological deficit (Hedges' g= -0.79, 95% CI -1.19- -0.39), cognition (g=0.85, 95% CI 0.04-1.65), functional independence (g=0.45, 95% CI 0.01-0.88) and daytime sleepiness (g= -0.96, 95% CI -1.56- -0.37). However, there was insignificant reduction in depression (g= -0.56, 95% CI -2.15-1.02). No publication bias was detected.

CONCLUSIONS

Post-stroke patients with SDB benefited from PAP therapy. Prospective trials are needed to determine the ideal initiation period and the minimum effective therapeutic dose.

Bidirectional relationships of comorbidity with obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is frequently associated with comorbidities that include metabolic, cardiovascular, renal, pulmonary and neuropsychiatric. There is considerable evidence that OSA is an independent risk factor for many of these comorbidities but, more recently, there is evidence that some of these comorbidities may predispose to the development of OSA. Thus, there is growing evidence of a bidirectional relationship between OSA and comorbidity, especially for heart failure, metabolic syndrome and stroke. Potential mechanisms of bidirectional relationships differ in individual comorbidities with fluid retention and redistribution being especially important in heart failure and end-stage renal disease, whereas neural mechanisms may be more important in diabetes mellitus and stroke. The evidence for other comorbidities, such as hypertension and atrial fibrillation, support these being more a consequence of OSA with limited evidence to support a bidirectional relationship. The present review explores the evidence for such bidirectional relationships with a particular perspective on comorbidities that may predispose to OSA. The impact of therapy in bidirectional relationships is also reviewed, which highlights the clinical importance of accurate diagnosis. This aspect is especially true of COPD, where the identification of co-existing OSA has important implications for optimum therapy.

Obstructive sleep apnoea (OSA) is an independent risk factor for comorbidity, especially cardiometabolic. However, some comorbidities may be risk factors for OSA, supporting a bidirectional relationship that may have important implications for treatment.https://bit.ly/3BbJy6V

Obstructive sleep apnea: transition from pathophysiology to an integrative disease model

Obstructive sleep apnea (OSA) is characterised by recurring episodes of upper airway obstruction during sleep and the fundamental abnormality reflects the inability of the upper airway dilating muscles to withstand the negative forces generated within the upper airway during inspiration. Factors that result in narrowing of the oropharynx such as abnormal craniofacial anatomy, soft tissue accumulation in the neck, and rostral fluid shift in the recumbent position increase the collapsing forces within the airway. The counteracting forces of upper airway dilating muscles, especially the genioglossus, are negatively influenced by sleep onset, inadequacy of the genioglossus responsiveness, ventilatory instability, especially post arousal, and loop gain. OSA is frequently associated with comorbidities that include metabolic, cardiovascular, renal, pulmonary, and neuropsychiatric, and there is growing evidence of bidirectional relationships between OSA and comorbidity, especially for heart failure, metabolic syndrome, and stroke. A detailed understanding of the complex pathophysiology of OSA encourages the development of therapies targeted at pathophysiological endotypes and facilitates a move towards precision medicine as a potential alternative to continuous positive airway pressure therapy in selected patients.

Breathing Exercises for Improving Cognitive Function in Patients with Stroke

Patients with stroke may experience a certain degree of cognitive decline during the period of recovery, and a considerable number of such patients have been reported to show permanent cognitive damage. Therefore, the period of recovery and rehabilitation following stroke is critical for rapid cognitive functional improvements. As dysfunctional breathing has been reported as one of the factors affecting the quality of life post stroke, a number of studies have focused on the need for improving the breathing function in these patients. Numerous breathing exercises have been reported to enhance the respiratory, pulmonary, cognitive, and psychological functions. However, scientific evidence on the underlying mechanisms by which these exercises improve cognitive function is scattered at best. Therefore, it has been difficult to establish a protocol of breathing exercises for patients with stroke. In this review, we summarize the psychological, vascular, sleep-related, and biochemical factors influencing cognition in patients and highlight the need for breathing exercises based on existing studies. Breathing exercises are expected to contribute to improvements in cognitive function in stroke based on a diverse array of supporting evidence. With relevant follow-up studies, a protocol of breathing exercises can be developed for improving the cognitive function in patients with stroke.

Obstructive Sleep apnea and cardiovascular events in Elderly Patients

INTRODUCTION

In recent decades, life expectancy has increased considerably. The cardiovascular effects of Obstructive Sleep Apnea (OSA) in the elderly lead to patient disability and high resource consumption. Intermittent nocturnal hypoxia leads to hemodynamic stress and adrenergic activation, which promotes cardiovascular disease. However, chronic intermittent hypoxia may protect elderly patients from cardiovascular events (CVE) due to biological adaptation.

AREAS COVERED

OSA patients are at increased risk of cardiovascular events. The severity of OSA increases cardiovascular risk, and this association also exists in the elderly. This article reviews the association between OSA, CPAP treatment, and CVE, particularly stroke and coronary heart disease (CHD), in the elderly. MEDLINE and the Cochrane Collaboration databases were searched from inception to July 2021.

EXPERT COMMENTARY

Although a positive association between OSA and the incidence of cardiovascular disease in the elderly has been established, the role of sleep apnea in certain cardiovascular events remains controversial. Most authors agree that untreated OSA is a risk factor for stroke or worse stroke prognosis. However, the association between OSA and CHD is usually less pronounced than between OSA and stroke, especially in the elderly.

Obstructive sleep apnea and stroke: The mechanisms, the randomized trials, and the road ahead

When considered separately from cardiovascular disease, stroke is the third leading cause of death in the U.S. and is the leading cause of long-term disability in adults. New approaches that can be offered to the majority of ischemic stroke patients, can be continued throughout post-stroke care, can limit stroke severity, and can complement or even enhance rehabilitation, would transform ischemic stroke recovery. The treatment of obstructive sleep apnea (OSA) in patients with acute ischemic stroke may represent one such approach. This manuscript reviews the epidemiologic studies of the bidirectional association between OSA and stroke, and the mechanisms and molecular signatures of OSA leading to transient ischemic attack and stroke as well as the randomized controlled trials and observational cohort studies examining continuous positive airway treatment efficacy on the impact of stroke outcomes. Finally, the insights these studies provide on future research are also discussed.

Continuous positive airway pressure and adverse cardiovascular events in obstructive sleep apnea: are participants of randomized trials representative of sleep clinic patients?

STUDY OBJECTIVES

Randomized controlled trials (RCTs) have shown no reduction in adverse cardiovascular (CV) events in patients randomized to continuous positive airway pressure (CPAP) therapy for obstructive sleep apnea (OSA). This study examined whether randomized study populations were representative of OSA patients attending a sleep clinic.

METHODS

Sleep clinic patients were 3,965 consecutive adults diagnosed with OSA by in-laboratory polysomnography from 2006 to 2010 at a tertiary hospital sleep clinic. Characteristics of these patients were compared with participants of five recent RCTs examining the effect of CPAP on adverse CV events in OSA. The percentage of patients with severe (apnea-hypopnea index, [AHI] ≥ 30 events/h) or any OSA (AHI ≥ 5 events/h) who met the eligibility criteria of each RCT was determined, and those criteria that excluded the most patients identified.

RESULTS

Compared to RCT participants, sleep clinic OSA patients were younger, sleepier, more likely to be female and less likely to have established CV disease. The percentage of patients with severe or any OSA who met the RCT eligibility criteria ranged from 1.2% to 20.9% and 0.8% to 21.9%, respectively. The eligibility criteria that excluded most patients were preexisting CV disease, symptoms of excessive sleepiness, nocturnal hypoxemia and co-morbidities.

CONCLUSIONS

A minority of sleep clinic patients diagnosed with OSA meet the eligibility criteria of RCTs of CPAP on adverse CV events in OSA. OSA populations in these RCTs differ considerably from typical sleep clinic OSA patients. This suggests that the findings of such OSA treatment-related RCTs are not generalizable to sleep clinic OSA patients.Randomized Intervention with Continuous Positive Airway Pressure in CAD and OSA (RICCADSA) trial, https://clinicaltrials.gov/ct2/show/NCT00519597, ClinicalTrials.gov number, NCT00519597.Usefulness of Nasal Continuous Positive Airway Pressure (CPAP) Treatment in Patients with a First Ever Stroke and Sleep Apnea Syndrome, https://clinicaltrials.gov/ct2/show/NCT00202501, ClinicalTrials.gov number, NCT00202501.Effect of Continuous Positive Airway Pressure (CPAP) on Hypertension and Cardiovascular Morbidity-Mortality in Patients with Sleep Apnea and no Daytime Sleepiness, https://clinicaltrials.gov/ct2/show/NCT00127348, ClinicalTrials.gov number, NCT00127348.Continuous Positive Airway Pressure (CPAP) in Patients with Acute Coronary Syndrome and Obstructive Sleep Apnea (OSA) (ISAACC), https://clinicaltrials.gov/ct2/show/NCT01335087, ClinicalTrials.gov number, NCT01335087.

Impact of continuous positive airway pressure ventilation on cardiovascular outcomes among patients with obstructive sleep apnea: A meta-analysis of randomized trials

Background

The impact of continuous positive airway pressure (CPAP) on cardiovascular outcomes among patients with obstructive sleep apnea (OSA) is controversial.

Objective

To evaluate the impact of CPAP on reducing cardiovascular outcomes in patients with OSA.

Methods

We performed a computerized search of MEDLINE, EMBASE and COCHRANE databases through April 2021 for randomized trials evaluating the impact of CPAP versus control on cardiovascular outcomes in patients with OSA. Summary estimates were reported using both fixed and random effects model. The main study outcome was major adverse cardiac events (MACE).

Results

The final analysis included 8 randomized trials with total of 5684 patients. The weighted mean follow-up was 42.6 months. There was no difference between the CPAP and control groups in the risk of MACE (14.4% versus 14.8%, risk ratio [RR]: 0.97; 95% confidence interval [CI]: 0.85 to 1.10; p = 0.60; I2 = 21%). Subgroup analysis suggested that CPAP was associated with lower MACE (by 36%) in CPAP-adherent patients (≥4 h/night) (Pinteraction = 0.08). There was no difference between the CPAP and control groups in the risk of all-cause mortality, cardiovascular mortality, acute stroke, acute myocardium infarction or hospitalizations for angina.

Conclusions and relevance

CPAP use might not be associated with lower cardiovascular events among patients with OSA. However, patients adherent to CPAP (≥4 h/night) might derive a benefit on cardiovascular outcomes. Future studies are warranted to evaluate the impact of CPAP in reducing cardiovascular events among patients with severe OSA and with optimal adherence rates to CPAP therapy.

Metrics of sleep apnea severity: beyond the apnea-hypopnea index

Obstructive sleep apnea (OSA) is thought to affect almost 1 billion people worldwide. OSA has well established cardiovascular and neurocognitive sequelae, although the optimal metric to assess its severity and/or potential response to therapy remains unclear. The apnea-hypopnea index (AHI) is well established; thus, we review its history and predictive value in various different clinical contexts. Although the AHI is often criticized for its limitations, it remains the best studied metric of OSA severity, albeit imperfect. We further review the potential value of alternative metrics including hypoxic burden, arousal intensity, odds ratio product, and cardiopulmonary coupling. We conclude with possible future directions to capture clinically meaningful OSA endophenotypes including the use of genetics, blood biomarkers, machine/deep learning and wearable technologies. Further research in OSA should be directed towards providing diagnostic and prognostic information to make the OSA diagnosis more accessible and to improving prognostic information regarding OSA consequences, in order to guide patient care and to help in the design of future clinical trials.

CPAP adherence is associated with reduced risk for stroke among older adult Medicare beneficiaries with obstructive sleep apnea

STUDY OBJECTIVES

To examine the impact of adherence to continuous positive airway pressure (CPAP) therapy on risk of stroke among a nationally representative sample of older adults with obstructive sleep apnea.

METHODS

We performed a retrospective cohort study among Medicare beneficiaries aged ≥ 65 years who were newly diagnosed with obstructive sleep apnea and had initiated CPAP (2009-2013). Monthly indicators of CPAP adherence included charges for machines, masks, or supplies and were summed over a 25-month follow-up to create a CPAP adherence variable. Stroke was modeled as a function of CPAP adherence using generalized estimating equations.

RESULTS

We found that 5,757 beneficiaries met the inclusion criteria and were included in the final sample. Of these, 407 (7%) experienced stroke. After adjusting for demographic and clinical characteristics, CPAP adherence was associated with a reduced risk of stroke (hazard ratio, 0.98; 95% confidence interval, 0.96-0.99) over 25 months, indicating a 2% reduction in risk of stroke for each month of CPAP adherence. When sensitivity analyses were performed to stratify results by time since the first CPAP charge, the protective effect remained significant for the 12- and 6-month but not the 3-month outcome models.

CONCLUSIONS

In this national analysis of older adult Medicare beneficiaries with obstructive sleep apnea, CPAP adherence was associated with significantly reduced risk of stroke.

Sleep disordered breathing as a cause and consequence of stroke: A review of pathophysiological and clinical relationships

Stroke is the leading cause of death and disability globally. Sleep disordered breathing (SDB), a potentially modifiable risk factor of stroke, is highly prevalent in stroke survivors. Evidence supports a causal, bidirectional relationship between SDB and stroke. SDB may increase the risk of stroke occurrence and recurrence, and worsen stroke outcome. While SDB is associated with an increased incidence of hypertension and cardiac arrhythmias, both of which are traditional stroke risk factors, SDB is also an independent risk factor for stroke. A number of characteristics of SDB may increase stroke risk, including intermittent hypoxemia, sympathetic activation, changes in cerebral autoregulation, oxidative stress, systemic inflammation, hypercoagulability, and endothelial dysfunction. On the other hand, stroke may also cause new SDB or aggravate preexisting SDB. Continuous positive airway pressure treatment of SDB may have a beneficial role in reducing stroke risk and improving neurological outcome after stroke. The treatment should be considered as early as possible, particularly when SDB is present post-stroke. The goal of this review is to highlight the strong link between SDB and stroke and to raise awareness for practitioners to consider the possibility of SDB being present in all stroke survivors.

[Cellex in the therapy of patients with complex and central apnea in the early recovery period of ischemic stroke]

A variety of structural and functional post-stroke disturbances demands an integrated clinical/diagnostic approach. Persistent hypoxemia due to disturbance of a saturation of blood oxygen in sleep can decrease the effectiveness of neurorehabilitation. In some cases of sleep apnea, the efficiency of continuous positive airway pressure therapy is insufficient and it should be combined with course neuroprotective therapy. Modern approaches to neuroprotective and neuroreparative therapy are considered as the independent direction for treatment of the central sleep apnea syndromes in patients with stroke consequences that is obviously important aspect of secondary prevention of a stroke.

Sleep Disorders in Stroke: An Update on Management

Stroke is a leading cause of disability and mortality all over the world. Due to an aging population, the incidence of stroke is rising significantly, which has led to devastating consequences for patients. In addition to traditional risk factors such as age, hypertension, hyperlipidemia, diabetes and atrial fibrillation, sleep disorders, as independent modifiable risk factors for stroke, have been highlighted increasingly. In this review, we provide an overview of common types of current sleep disturbances in cerebrovascular diseases, including insomnia, hypersomnia, breathing-related sleep disorders, and parasomnias. Moreover, evidence-based clinical therapeutic strategies and pitfalls of specific sleep disorders after stroke are discussed. We also review the neurobiological mechanisms of these treatments as well as their effects on stroke. Since depression after stroke is so prevalent and closely related to sleep disorders, treatments of post-stroke depression are also briefly mentioned in this review article.

High Plasma Cystine Levels Are Associated with Blood Pressure and Reversed by CPAP in Patients with Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) independent of obesity (OBS) imposes severe cardiovascular risk. To what extent plasma cystine concentration (CySS), a novel pro-oxidative vascular risk factor, is increased in OSA with or without OBS is presently unknown. We therefore studied CySS together with the redox state and precursor amino acids of glutathione (GSH) in peripheral blood mononuclear cells (PBMC) in untreated male patients with OSA (apnea-hypopnea-index (AHI) > 15 h^-1, n = 28) compared to healthy male controls (n = 25) stratifying for BMI ≥ or < 30 kg m^-2. Fifteen OSA patients were reassessed after 3-5-months CPAP. CySS correlated with cumulative time at an O₂-saturation <90% (Tu90%) (r = 0.34, p < 0.05) beside BMI (r = 0.58, p < 0.001) and was higher in subjects with "hypoxic stress" (59.4 ± 2.0 vs. 50.1 ± 2.7 µM, p < 0.01) defined as Tu90% ≥ 15.2 min (corresponding to AHI ≥ 15 h^-1). Moreover, CySS significantly correlated with systolic (r = 0.32, p < 0.05) and diastolic (r = 0.31, p < 0.05) blood pressure. CPAP significantly lowered CySS along with blood pressure at unchanged BMI. Unexpectedly, GSH antioxidant capacity in PBMC was increased with OSA and reversed with CPAP. Plasma CySS levels are increased with OSA-related hypoxic stress and associated with higher blood pressure. CPAP decreases both CySS and blood pressure. The role of CySS in OSA-related vascular endpoints and their prevention by CPAP warrants further studies.

Trials in Sleep Apnea and Stroke: Learning From the Past to Direct Future Approaches

Few randomized controlled trials have evaluated the effectiveness of continuous positive airway pressure (CPAP) in reducing recurrent vascular events and mortality in poststroke obstructive sleep apnea (OSA). To date, results have been mixed, most studies were underpowered and definitive conclusions are not available. Using lessons learned from prior negative trials in stroke, we reappraise prior randomized controlled trials that examined the use of CPAP in treating poststroke OSA and propose the following considerations: (1) Intervention-based changes, such as ensuring that patients are using CPAP for at least 4 hours per night (eg, through use of improvements in CPAP technology that make it easier for patients to use), as well as considering alternative treatment strategies for poststroke OSA; (2) Population-based changes (ie, including stroke patients with severe and symptomatic OSA and CPAP noncompliers); and (3) Changes to timing of intervention and follow-up (ie, early initiation of CPAP therapy within the first 48 hours of stroke and long-term follow-up calculated in accordance with sample size to ensure adequate power). Given the burden of vascular morbidity and mortality in stroke patients with OSA, there is a strong need to learn from past negative trials and explore innovative stroke prevention strategies to improve stroke-free survival.

Impact of Early Nutrition, Physical Activity and Sleep on the Fetal Programming of Disease in the Pregnancy: A Narrative Review

Early programming is the adaptation process by which nutrition and environmental factors alter development pathways during prenatal growth, inducing changes in postnatal metabolism and diseases. The aim of this narrative review, is evaluating the current knowledge in the scientific literature on the effects of nutrition, environmental factors, physical activity and sleep on development pathways. If in utero adaptations were incorrect, this would cause a mismatch between prenatal programming and adulthood. Adequate caloric intake, protein, mineral, vitamin, and long-chain fatty acids, have been noted for their relevance in the offspring brain functions and behavior. Fetus undernutrition/malnutrition causes a delay in growth and have detrimental effects on the development and subsequent functioning of the organs. Pregnancy is a particularly vulnerable period for the development of food preferences and for modifications in the emotional response. Maternal obesity increases the risk of developing perinatal complications and delivery by cesarean section and has long-term implications in the development of metabolic diseases. Physical exercise during pregnancy contributes to overall improved health post-partum. It is also interesting to highlight the relevance of sleep problems during pregnancy, which influence adequate growth and fetal development. Taking into account these considerations, we conclude that nutrition and metabolic factors during early life play a key role of health promotion and public health nutrition programs worldwide to improve the health of the offspring and the health costs of hospitalization.

Obstructive Sleep Apnoea Syndrome: Continuous Positive Airway Pressure Therapy for Prevention of Cardiovascular Risk

Obstructive sleep apnoea (OSA) syndrome is characterised by the presence of apnoea or obstructive hypopnoea during sleep, accompanied by hypoxia. It is estimated that the syndrome affects approximately 10% of men and 15% of women. Diagnosis and treatment rates have increased in recent years, but the condition remains undiagnosed in a high percentage of patients. Recent evidence suggests that OSA may increase the risk of cardiovascular disease. The relationship between OSA and cardiovascular disease can be explained, at least in part, by the coexistence of cardiovascular risk factors in the two pathologies, such as age, overweight, smoking and sedentary lifestyle. However, OSA has been independently associated with the risk of developing hypertension, cerebrovascular disease, ischaemic heart disease, heart failure and arrhythmias. Clinical trials that have evaluated the efficacy of continuous positive airway pressure (CPAP) treatment in primary and secondary cardiovascular prevention have not demonstrated a significant reduction in the incidence or recurrence of cardiovascular events. This article analyses the relationship between OSA and cardiovascular risk and discusses recent clinical trials on the efficacy of CPAP in primary and secondary cardiovascular prevention.

Obstructive Sleep Apnea, a Risk Factor for Cardiovascular and Microvascular Disease in Patients With Type 2 Diabetes: Findings From a Population-Based Cohort Study

OBJECTIVE

To determine the risk of cardiovascular disease (CVD), microvascular complications, and mortality in patients with type 2 diabetes who subsequently develop obstructive sleep apnea (OSA) compared with patients with type 2 diabetes without a diagnosis of OSA.

RESEARCH DESIGN AND METHODS

This age-, sex-, BMI-, and diabetes duration-matched cohort study used data from a U.K. primary care database from 1 January 2005 to 17 January 2018. Participants aged ≥16 years with type 2 diabetes were included. Exposed participants were those who developed OSA after their diabetes diagnosis; unexposed participants were those without diagnosed OSA. Outcomes were composite CVD (ischemic heart disease [IHD], stroke/transient ischemic attack [TIA], heart failure [HF]), peripheral vascular disease (PVD), atrial fibrillation (AF), peripheral neuropathy (PN), diabetes-related foot disease (DFD), referable retinopathy, chronic kidney disease (CKD), and all-cause mortality. The same outcomes were explored in patients with preexisting OSA before a diagnosis of type 2 diabetes versus diabetes without diagnosed OSA.

RESULTS

A total of 3,667 exposed participants and 10,450 matched control participants were included. Adjusted hazard ratios for the outcomes were as follows: composite CVD 1.54 (95% CI 1.32, 1.79), IHD 1.55 (1.26, 1.90), HF 1.67 (1.35, 2.06), stroke/TIA 1.57 (1.27, 1.94), PVD 1.10 (0.91, 1.32), AF 1.53 (1.28, 1.83), PN 1.32 (1.14, 1.51), DFD 1.42 (1.16, 1.74), referable retinopathy 0.99 (0.82, 1.21), CKD (stage 3-5) 1.18 (1.02, 1.36), albuminuria 1.11 (1.01, 1.22), and all-cause mortality 1.24 (1.10, 1.40). In the prevalent OSA cohort, the results were similar, but some associations were not observed.

CONCLUSIONS

Patients with type 2 diabetes who develop OSA are at increased risk of CVD, AF, PN, DFD, CKD, and all-cause mortality compared with patients without diagnosed OSA. Patients with type 2 diabetes who develop OSA are a high-risk population, and strategies to detect OSA and prevent cardiovascular and microvascular complications should be implemented.

Short-term results of upper airway stimulation in obstructive sleep apnoea patients: the Amsterdam experience

OBJECTIVES

This paper aimed to: retrospectively analyse single-centre results in terms of surgical success, respiratory outcomes and adverse events after short-term follow up in obstructive sleep apnoea patients treated with upper airway stimulation; and evaluate the correlation between pre-operative drug-induced sleep endoscopy findings and surgical success.

METHODS

A retrospective descriptive cohort study was conducted, including a consecutive series of obstructive sleep apnoea patients undergoing implantation of an upper airway stimulation system.

RESULTS

Forty-four patients were included. The total median Apnoea-Hypopnea Index and oxygen desaturation index significantly decreased from 37.6 to 8.3 events per hour (p < 0.001) and from 37.1 to 15.9 events per hour (p < 0.001), respectively. The surgical success rate was 88.6 per cent, and did not significantly differ between patients with or without complete collapse at the retropalatal level (p = 0.784). The most common therapy-related adverse event reported was (temporary) stimulation-related discomfort.

CONCLUSION

Upper airway stimulation is an effective and safe treatment in obstructive sleep apnoea patients with continuous positive airway pressure intolerance or failure. There was no significant difference in surgical outcome between patients with tongue base collapse with or without complete anteroposterior collapse at the level of the palate.

EAN/ERS/ESO/ESRS statement on the impact of sleep disorders on risk and outcome of stroke

Sleep disorders are highly prevalent in the general population and may be linked in a bidirectional fashion to stroke, which is one of the leading causes of morbidity and mortality.Four major scientific societies established a task force of experts in neurology, stroke, respiratory medicine, sleep medicine and methodology, to critically evaluate the evidence regarding potential links and the impact of therapy. 13 research questions were evaluated in a systematic literature search using a stepwise hierarchical approach: first, systematic reviews and meta-analyses; second, primary studies post-dating the systematic reviews/meta-analyses. A total of 445 studies were evaluated and 88 included. Statements were generated regarding current evidence and clinical practice.Severe obstructive sleep apnoea (OSA) doubles the risk for incident stroke, especially in young to middle-aged patients. Continuous positive airway pressure (CPAP) may reduce stroke risk, especially in treatment-compliant patients. The prevalence of OSA is high in stroke patients and can be assessed by polygraphy. Severe OSA is a risk factor for recurrence of stroke and may be associated with stroke mortality, while CPAP may improve stroke outcome. It is not clear if insomnia increases stroke risk, while pharmacotherapy of insomnia may increase it. Periodic limb movements in sleep (PLMS), but not restless limb syndrome (RLS), may be associated with an increased risk of stroke. Preliminary data suggest a high frequency of post-stroke insomnia and RLS and their association with a less favourable stroke outcome, while treatment data are scarce.Overall, the evidence base is best for OSA relationship with stroke and supports active diagnosis and therapy. Research gaps remain especially regarding insomnia and RLS/PLMS relationships with stroke.

Long-term Effect of CPAP Treatment on Cardiovascular Events in Patients With Resistant Hypertension and Sleep Apnea. Data From the HIPARCO-2 Study

BACKGROUND

There is some controversy about the effect of continuous positive airway pressure (CPAP) on the incidence of cardiovascular events (CVE). However, the incidence of CVE among patients with both obstructive sleep apnea (OSA) ans resistant hypertension (HR) has not been evaluated. Our objective was to analyze the long-term effect of CPAP treatment in patients with RH and OSA on the incidence of CVE.

METHODS

Multi-center, observational and prospective study of patients with moderate-severe OSA and RH. All the patients were followed up every 3-6 months and the CVE incidence was measured. Patients adherent to CPAP (at least 4h/day) were compared with those with not adherent or those who had not been prescribed CPAP.

RESULTS

Valid data were obtained from 163 patients with 64 CVE incidents. Treatment with CPAP was offered to 82%. After 58 months of follow-up, 58.3% of patients were adherent to CPAP. Patients not adherent to CPAP presented a non-significant increase in the total CVE incidence (HR:1.6; 95%CI: 0.96-2.7; p=0.07). A sensitivity analysis showed that patients not adherent to CPAP had a significant increase in the incidence of cerebrovascular events (HR: 3.1; CI95%: 1.07-15.1; p=0.041) and hypertensive crises (HR: 5.1; CI95%: 2.2-11.6; p=0.006), but the trend went in the opposite direction with respect to coronary events (HR: 0.22; CI95%: 0.05-1.02; p=0.053).

CONCLUSIONS

In patients with RH and moderate-severe OSA, an uneffective treatment with CPAP showed a trend toward an increase in the incidence of CVE (particularly neurovascular events and hypertensive crises) without any changes with respect to coronary events.

A meta-analysis of continuous positive airway pressure therapy in prevention of cardiovascular events in patients with obstructive sleep apnoea

Aims

To assess whether continuous positive airway pressure (CPAP) therapy reduces major adverse cardiovascular events (MACE) in patients with moderate-to-severe obstructive sleep apnoea (OSA).

Methods and results

A total of 235 articles were recovered using MEDLINE, EMBASE and Cochrane library (inception-December 2016) and references contained in the identified articles. Seven randomized controlled trials (RCTs) were selected for final analysis. Analysis of 4268 patients demonstrated non-significant 26% relative risk reduction in MACE with CPAP [risk ratio (RR) 0.74; 95% confidence interval (CI) 0.47-1.17; P = 0.19, I2 = 48%]. A series of sensitivity analyses suggested that increased CPAP usage time yielded significant risk reduction in MACE. and stroke. Subgroup analysis revealed that CPAP adherence time ≥4 hours (h)/night reduced the risk of MACE by 57% (RR 0.43; 95% CI 0.23-0.80; P = 0.01, I2 = 0%). CPAP therapy showed no beneficial effect on myocardial infarction (MI), all-cause mortality, atrial fibrillation/flutter (AF), or heart failure (HF) (P > 0.05). CPAP had positive effect on mood and reduced the daytime sleepiness [Epworth Sleepiness Scale (ESS): mean difference (MD) -2.50, 95% CI - 3.62, -1.39; P < 0.001, I2 = 81%].

Conclusion

CPAP therapy might reduce MACE and stroke among subjects with CPAP time exceeding 4 h/night. Additional randomized trials mandating adequate CPAP time adherence are required to confirm this impression.

Sleep Apnea and Early Neurological Deterioration in Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Evidence of an association between sleep apnea (SA) and early neurological deterioration (END) in acute phase ischemic stroke is scant. We investigated the prevalence of SA and the impact of SA severity on END in acute ischemic stroke (AIS) patients.

METHODS

We prospectively enrolled consecutive AIS patients admitted to our stroke unit within 72 hours of symptom onset. SA severity was assessed with ApneaLink-a validated portable respiratory monitor. SA was defined as an apnea-hypopnea index (AHI) of greater than or equal to 5 per hour. END was defined as an incremental increase in the National Institutes of Health Stroke Scale (NIHSS) score by greater than or equal to 1 point in motor power, or greater than or equal to 2 points in the total score within the first week after admission.

RESULTS

Of the 305 patients studied, 254 (83.3%) patients had SA (AHI ≥ 5 per hour), and of these, 114 (37.4%) had mild SA (AHI 5-14 per hour), 59 (19.3%) had moderate SA (AHI 15-29 per hour), and 81 (26.6%) had severe SA (AHI ≥ 30 per hour). Thirty-six (11.8%) patients experienced END: 2 of the 51 (3.9%) patients without SA and 34 of the 254 (14.4%) patients with SA. Multivariable regression analysis showed AHI independently predicted END (odds ratio 1.024; 95% confidence interval 1.006 to 1.042; P = .008).

CONCLUSIONS

SA is common in the acute phase of ischemic stroke, and SA severity is associated with the risk of END.

Severely Disturbed Sleep in Patients With Acute Ischemic Stroke on Stroke Units: A Pilot Study

Introduction: Previous studies revealed a high prevalence of sleep-wake disturbances in subacute and chronic stroke. We analyzed sleep quantity and quality in patients with hyperacute ischemic stroke on stroke units.

Methods: We categorized sleep stages as N1, N2, N3, and REM according to the 2017 criteria of the American Academy of Sleep Medicine in 23 continuous, overnight EEG registrations from 18 patients, starting within 48 h since the onset of cortical ischemic stroke. Associations between presence and duration of sleep stages, and secondary deterioration or functional outcome were analyzed.

Results: Physiological sleep cycles were seen in none of the patients. Otherwise, sleep stages alternated chaotically, both during day- and during nighttime, with a sleep efficiency of 30% and 10.5 ± 4.4 (mean ± SD) awakenings per hour of sleep. We cannot differentiate between stroke related and external factors. Only few interruptions could be related to planned nightly wake up calls, but turbulence on stroke units may have played a role. Six patients (seven nights) did not reach deep sleep (N3), 10 patients (13 nights) did not reach REM sleep. If reached, the mean durations of deep and REM sleep were short, with 37 (standard deviation (SD) 25) and 18 (SD15) minutes, respectively. Patients with secondary deterioration more often lacked deep sleep (N3) than patients without secondary deterioration [4 (57%) vs. 2 (25%)], but without statistical significance (p = 0.12).

Conclusion: We show that sleep is severely disturbed in patients with acute ischemic stroke admitted to stroke units. Larger studies are needed to clarify associations between deprivation of deep sleep and secondary deterioration.

Obstructive Sleep Apnea: Emerging Treatments Targeting the Genioglossus Muscle

Obstructive sleep apnea (OSA) is characterized by repetitive episodes of upper airway obstruction caused by a loss of upper airway dilator muscle tone during sleep and an inadequate compensatory response by these muscles in the context of an anatomically compromised airway. The genioglossus (GG) is the main upper airway dilator muscle. Currently, continuous positive airway pressure is the first-line treatment for OSA. Nevertheless, problems related to poor adherence have been described in some groups of patients. In recent years, new OSA treatment strategies have been developed to improve GG function. (A) Hypoglossal nerve electrical stimulation leads to significant improvements in objective (apnea-hypopnea index, or AHI) and subjective measurements of OSA severity, but its invasive nature limits its application. (B) A recently introduced combination of drugs administered orally before bedtime reduces AHI and improves the responsiveness of the GG. (C) Finally, myofunctional therapy also decreases AHI, and it might be considered in combination with other treatments. Our objective is to review these therapies in order to advance current understanding of the prospects for alternative OSA treatments.

Redesigning Care for OSA

Constrained by a limited supply of specialized personnel, health systems face a challenge in caring for the large number of patients with OSA. The complexity of this challenge is heightened by the varied clinical presentations of OSA and the diversity of treatment approaches. Innovations such as simplified home-based care models and the incorporation of nonspecialist providers have shown promise in the management of uncomplicated patients, producing comparable outcomes to the resource-intensive traditional approach. However, it is unclear if these innovations can meet the needs of all patients with OSA, including those with mild disease, atypical presentations, and certain comorbid medical and mental health conditions. This review discusses the diversity of needs in OSA care, the evidence base behind recent care innovations, and the potential limitations of each innovation in meeting the diversity of care needs. We propose how these innovations can fit within the stepped care and hub and spoke models in a way that addresses the full spectrum of OSA, and we discuss future research directions to assess the deployment of these innovations.

Improvement of Cognitive Function after Continuous Positive Airway Pressure Treatment for Subacute Stroke Patients with Obstructive Sleep Apnea: A Randomized Controlled Trial

Background: Obstructive sleep apnea (OSA) is common after stroke. Various studies on continuous positive airway pressure (CPAP) therapy for OSA after stroke have been published. However, there have been no studies from Korea and Asia. The present Korean study aimed to determine whether CPAP treatment during inpatient rehabilitation of stroke patients with sleep disorders, especially OSA, improves function, cognition, sleep quality, and daytime sleepiness. Methods: This single-blind randomized controlled study included 40 stroke patients with OSA between November 2017 and November 2018. The patients were divided into the CPAP treatment group (CPAP and rehabilitation; n = 20) and control group (only rehabilitation; n = 20). The intervention period was 3 weeks. The primary outcomes were function and cognition improvements, and the secondary outcomes were sleep-related improvements. Results: CPAP treatment started at an average of 4.6 ± 2.8 days after admission. Both groups showed improvements in stroke severity, function, and cognition after the 3-week intervention. However, after the intervention, the degree of change in attention and calculation was significantly higher in the CPAP treatment group than in the control group. Additionally, the improvements in sleep quality and daytime sleepiness were greater in the CPAP treatment group than in the control group. Conclusion: CPAP treatment can improve cognitive function, sleep quality, and daytime sleepiness, and it should be considered as part of the rehabilitation program for patients with stroke. Our findings might help in the treatment of stroke patients with OSA in Korea.

Sleep Apnea and Cardiovascular Disease: An Enigmatic Risk Factor

Synchronization of molecular, metabolic, and cardiovascular circadian oscillations is fundamental to human health. Sleep-disordered breathing, which disrupts such temporal congruence, elicits hemodynamic, autonomic, chemical, and inflammatory disturbances with acute and long-term consequences for heart, brain, and circulatory and metabolic function. Sleep apnea afflicts a substantial proportion of adult men and women but is more prevalent in those with established cardiovascular diseases and especially fluid-retaining states. Despite the experimental, epidemiological, observational, and interventional evidence assembled in support of these concepts, this substantial body of work has had relatively modest pragmatic impact, thus far, on the discipline of cardiology. Contemporary estimates of cardiovascular risk still are derived typically from data acquired during wakefulness. The impact of sleep-related breathing disorders rarely is entered into such calculations or integrated into diagnostic disease-specific algorithms or therapeutic recommendations. Reasons for this include absence of apnea-related symptoms in most with cardiovascular disease, impediments to efficient diagnosis at the population level, debate as to target, suboptimal therapies, difficulties mounting large randomized trials of sleep-specific interventions, and the challenging results of those few prospective cardiovascular outcome trials that have been completed and reported. The objectives of this review are to delineate the bidirectional interrelationship between sleep-disordered breathing and cardiovascular disease, consider the findings and implications of observational and randomized trials of treatment, frame the current state of clinical equipoise, identify principal current controversies and potential paths to their resolution, and anticipate future directions.

Evaluation of an OSA risk stratifying and treatment protocol during inpatient rehabilitation of post-stroke patients

PURPOSE

To evaluate outcomes, outside of a clinical trial setting, of a protocol utilizing overnight oximetry (NOx) to risk stratify post-stroke patients for obstructive sleep apnea (OSA) followed by autoadjusting continuous positive airway pressure (APAP) treatment in patients considered high risk for OSA.

METHODS

Retrospective observational study of post-stroke patients at an academic inpatient stroke rehabilitation facility. Patients underwent NOx, and those at high risk for OSA (oxygen desaturation index 3% > 10 per hour) were attempted on a trial of APAP, and further stratified into high risk adherent with treatment (HRAT) or high-risk failed treatment (HRFT). Change in functional independence measure (FIM) was used to assess recovery.

RESULTS

Two hundred twenty-four post-stroke patients underwent NOx, with 120 (53%) considered high risk for OSA. Twelve (10%) were compliant with APAP treatment (> 4 h/night on > 70% of nights). No difference in change in FIM scores was observed for HRAT versus HRFT [total FIM change - 5.8, 95% CI (- 13.9, 2.2); motor FIM change - 4.5, 95% CI (- 11.5, 2.4); cognitive FIM change - 1.3, 95% CI (-3.8, 1.2)]. A subgroup analysis matched 14 HRAT patients (using adherence criterion of APAP usage > 50% of nights) to 35 HRFT patients. A statistically significant, but clinically irrelevant, difference in total FIM change was observed (HRAT vs HRFT, difference between means - 5.2, p = 0.03).

CONCLUSIONS

The use of APAP in high-risk patients was poorly tolerated and did not improve post-stroke recovery. Further studies with larger sample sizes are needed to determine the effect of APAP treatment on short-term recovery.

Sleep Disorders and Stroke: Does Treatment of Obstructive Sleep Apnea Decrease Risk of Ischemic Stroke?

PURPOSE OF REVIEW

This review aims to support obstructive sleep apnea (OSA) as a risk factor for ischemic stroke, review treatment strategies for OSA, provide a comprehensive review of clinical data on OSA treatment and ischemic stroke risk, and to critically assess if treatment of OSA decreases the risk of ischemic stroke and if treatment improves outcomes and subsequent ischemic stroke risk in post-stroke patients.

RECENT FINDINGS

Several observational studies, randomized controlled trials (RCTs), and meta-analyses have examined the risk of ischemic stroke and cardiovascular events in patients with OSA and have also examined continuous positive airway pressure (CPAP) treatment in these patients. Observational studies have shown an increased risk of ischemic stroke in patients with untreated OSA when compared with patients treated with CPAP; however, results are not statistically significant. RCTs and meta-analyses have shown no significant ischemic stroke risk reduction in CPAP treated patients with OSA. Several studies have shown improved outcomes in post-stroke patients with OSA treated with CPAP; however, few data is available for subsequent ischemic stroke risk reduction. Further research is needed for surgical treatment of OSA and assessment of ischemic stroke risk. OSA is associated with increased risk of ischemic stroke, and OSA should be treated with the appropriate therapy. While the current data is promising, more studies are necessary to state whether treatment of OSA reduces ischemic stroke risk and subsequent ischemic stroke risk. A practical approach to the sleep disorder evaluation and treatment of patients with cerebrovascular disease is outlined.