Continuous positive airway pressure reduces postprandial lipidemia in obstructive sleep apnea: a randomized, placebo-controlled crossover trial

Clinical review of non-invasive ventilation

Non-invasive ventilation (NIV) is the mainstay to treat patients who need augmentation of ventilation for acute and chronic forms of respiratory failure. The last several decades have witnessed an extension of the indications for NIV to a variety of acute and chronic lung diseases. Evolving advancements in technology and personalised approaches to patient care make it feasible to prioritise patient-centred care models that deliver home-based management using telemonitoring and telemedicine systems support. These trends may improve patient outcomes, reduce healthcare costs and improve the quality of life for patients who suffer from chronic diseases that precipitate respiratory failure.

Prognostic implications of obstructive sleep apnea in patients with unstable angina stratified by remnant cholesterol and triglyceride: a prospective cohort study

BACKGROUND

The prognostic significance of obstructive sleep apnea (OSA) in patients with unstable angina (UA) based on remnant cholesterol (RC) or triglyceride (TG) levels remains unclear. This study aims to evaluate the effects of the interaction between RC, TG, and OSA on cardiovascular outcomes in UA patients.

METHODS

In this prospective cohort study, OSA was diagnosed when apnea-hypopnea index of ≥ 15 events/h. Patients with high RC (HRC, n = 370) or high TG (HTG, n = 362) included RC or TG in the highest tertile, and those in the middle and lowest tertiles were defined as normal RC (NRC, n = 736) or normal TG (NTG, n = 744). The primary endpoint was major adverse cardiovascular and cerebrovascular events (MACCE), including cardiovascular death, myocardial infarction, ischemia stroke, ischemia-driven revascularization, or hospitalization for UA.

RESULTS

A total of 1,106 eligible UA patients were enrolled, among which 560 (50.6%) had OSA. RC and TG levels were increased in OSA patients, but there was no difference in the prevalence of OSA between the NRC and HRC or NTG and HTG groups. During a median follow-up of 1.9 (1.1, 3.0) years, OSA was associated with an increased risk of MACCE occurrence compared to non-OSA in UA patients with HRC (adjusted HR 2.06; 95% CI 1.20-3.51, P = 0.008), but not in those with NRC (adjusted HR 1.21; 95% CI 0.84-1.75, P = 0.297). The incremental risk in HRC was attributable to higher rates of hospitalization for UA and ischemia-driven revascularization. Results for HTG and NTG were similar.

CONCLUSION

OSA was associated with a worse prognosis in UA patients with HRC or HTG, emphasizing the necessity of identifying OSA presence in this population.

TRIAL REGISTRATION

Clinicaltrials.gov; No: NCT03362385.

Obstructive sleep apnea hypopnea syndrome and vascular lesions: An update on what we currently know

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is the most prevalent sleep and respiratory disorder. This syndrome can induce severe cardiovascular and cerebrovascular complications, and intermittent hypoxia is a pivotal contributor to this damage. Vascular pathology is closely associated with the impairment of target organs, marking a focal point in current research. Vascular lesions are the fundamental pathophysiological basis of multiorgan ailments and indicate a shared pathogenic mechanism among common cardiovascular and cerebrovascular conditions, suggesting their importance as a public health concern. Increasing evidence shows a strong correlation between OSAHS and vascular lesions. Previous studies predominantly focused on the pathophysiological alterations in OSAHS itself, such as intermittent hypoxia and fragmented sleep, leading to vascular disruptions. This review aims to delve deeper into the vascular lesions affected by OSAHS by examining the microscopic pathophysiological mechanisms involved. Emphasis has been placed on examining how OSAHS induces vascular lesions through disruptions in the endothelial barrier, metabolic dysregulation, cellular phenotype alterations, neuroendocrine irregularities, programmed cell death, vascular inflammation, oxidative stress and epigenetic modifications. This review examines the epidemiology and associated risk factors for OSAHS and vascular diseases and subsequently describes the existing evidence on vascular lesions induced by OSAHS in the cardiovascular, cerebrovascular, retinal, renal and reproductive systems. A detailed account of the current research on the pathophysiological mechanisms mediating vascular lesions caused by OSAHS is provided, culminating in a discussion of research advancements in therapeutic modalities to mitigate OSAHS-related vascular lesions and the implications of these treatment strategies.

Assessing causality between obstructive sleep apnea with the dyslipidemia and osteoporosis: a Mendelian randomization study

Purpose

This study aims to assess the causal relationship between Obstructive Sleep Apnea (OSA), dyslipidemia, and osteoporosis using Mendelian Randomization (MR) techniques.

Methods

Utilizing a two-sample MR approach, the study examines the causal relationship between dyslipidemia and osteoporosis. Multivariable MR analyses were used to test the independence of the causal association of dyslipidemia with OSA. Single nucleotide polymorphisms (SNPs) were selected as instrumental variables based on genome-wide significance, independence, and linkage disequilibrium criteria. The data were sourced from publicly available Genome-Wide Association Studies (GWAS) of OSA (n = 375,657) from the FinnGen Consortium, the Global Lipids Genetics Consortium of dyslipidemia (n = 188,577) and the UK Biobank for osteoporosis (n = 456,348).

Results

The MR analysis identified a significant positive association between genetically predicted OSA and triglyceride levels (OR: 1.15, 95% CI: 1.04-1.26, p = 0.006) and a negative correlation with high-density lipoprotein cholesterol (HDL-C) (OR: 0.84, 95% CI: 0.77-0.93, p = 0.0003). Conversely, no causal relationship was found between dyslipidemia (total cholesterol, triglycerides, HDL-C, and low-density lipoprotein cholesterol) and OSA or the relationship between OSA and osteoporosis.

Conclusion

The study provides evidence of a causal relationship between OSA and dyslipidemia, highlighting the need for targeted prevention and management strategies for OSA to address lipid abnormalities. The absence of a causal link with osteoporosis and in the reverse direction emphasizes the need for further research in this area.

Cardio-metabolic health effects of CPAP treatment for sleep apnoea during weight loss: A randomised controlled pilot trial

BACKGROUND AND AIMS

This study assessed whether the addition of continuous positive airway pressure (CPAP) during weight loss would enhance cardiometabolic health improvements in patients with obesity and Obstructive Sleep Apnoea (OSA).

METHODS AND RESULTS

Patients with overweight or obesity, pre-diabetes and moderatesevere OSA were randomised to receive CPAP therapy with a weight loss programme (CPAP+WL) or a weight loss programme alone (WL alone).

PRIMARY OUTCOME

2-hour glucose assessed by an oral glucose tolerance test.

SECONDARY OUTCOMES

24 hr blood pressure, body composition (DEXA) and fasting blood markers. 17 patients completed 3-month follow-up assessments (8 CPAP+WL and 9 WL alone). Overall, participants in both groups lost ∼12 kg which reduced polysomnography determined OSA severity by ∼45 %. In the CPAP+WL group, CPAP use (compliance 5.29 hrs/night) did not improve any outcome above WL alone. There was no improvement in 2-hour glucose in either group. However, in the pooled (n = 17) analysis there were overall improvements in most outcomes including insulin sensitivity (.000965 units, p = .008), sleep systolic BP (- 16.2 mmHg, p = .0003), sleep diastolic BP (-9.8 mmHg, p = 0.02), wake diastolic BP (- 4.3 mmHg, p = .03) and sleepiness (Epworth Sleepiness Score -3.2, p = .0003). In addition, there were reductions in glucose area under the curve (-230 units, p = .009), total (-0.86 mmol/L, p = 0.006) and LDL cholesterol (-0.58 mmol/L, p = 0.007), triglycerides (-0.75 mmol/L, p = 0.004), fat mass (-7.6 kg, p < .0001) and abdominal fat (-310 cm3, p < .0001).

CONCLUSION

Weight loss reduced OSA and improved sleepiness and cardiometabolic health. These improvements were not further enhanced by using CPAP. Results suggest weight loss should be the primary focus of treatment for patients with OSA and obesity.

The role of microRNAs in pathophysiology and diagnostics of metabolic complications in obstructive sleep apnea patients

Obstructive sleep apnea (OSA) is one of the most common sleep disorders, which is characterized by recurrent apneas and/or hypopneas occurring during sleep due to upper airway obstruction. Among a variety of health consequences, OSA patients are particularly susceptible to developing metabolic complications, such as metabolic syndrome and diabetes mellitus type 2. MicroRNAs (miRNAs) as epigenetic modulators are promising particles in both understanding the pathophysiology of OSA and the prediction of OSA complications. This review describes the role of miRNAs in the development of OSA-associated metabolic complications. Moreover, it summarizes the usefulness of miRNAs as biomarkers in predicting the aforementioned OSA complications.

Placebo response in objective and subjective measures of hypersomnia in randomized clinical trials on obstructive sleep apnea. A systematic review and meta-analysis

Sleepiness is one of the outcomes most used in randomized clinical trials (RCT) on the effect of treatments for obstructive sleep apnea (OSA). Furthermore, it is known that there is a placebo effect, especially in subjective measures. Therefore, given that sleepiness is a subjective measure, the objective of this systematic review with meta-analysis and three-level meta-regression was to assess the response to different placebos (pills and sham-CPAP) used in RCTs in OSA, both on subjective (Epworth Sleepiness Scale [ESS]) and objective (Multiple Sleep Latency Test [MSLT], Maintenance Wake Test [MWT], the Osler test and the Psychomotor Vigilance Task [PVT]). We observed a statistically significant placebo effect in both subjective and objective measures of hypersomnia, and in both sham-CPAP and pills. This placebo effect was greater, even clinically significant, in subjective measures (ESS: -2.84 points) and in those RCTs that used pills as a placebo. In the meta-regression, only a higher baseline value of the ESS and Osler test was related to the placebo effect.

Screening for Obstructive Sleep Apnea in Adults: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force

IMPORTANCE

Obstructive sleep apnea (OSA) is associated with adverse health outcomes.

OBJECTIVE

To review the evidence on screening for OSA in asymptomatic adults or those with unrecognized OSA symptoms to inform the US Preventive Services Task Force.

DATA SOURCES

PubMed/MEDLINE, Cochrane Library, Embase, and trial registries through August 23, 2021; surveillance through September 23, 2022.

STUDY SELECTION

English-language studies of screening test accuracy, randomized clinical trials (RCTs) of screening or treatment of OSA reporting health outcomes or harms, and systematic reviews of treatment reporting changes in blood pressure and apnea-hypopnea index (AHI) scores.

DATA EXTRACTION AND SYNTHESIS

Dual review of abstracts, full-text articles, and study quality. Meta-analysis of intervention trials.

MAIN OUTCOMES AND MEASURES

Test accuracy, excessive daytime sleepiness, sleep-related and general health-related quality of life (QOL), and harms.

RESULTS

Eighty-six studies were included (N = 11 051). No study directly compared screening with no screening. Screening accuracy of the Multivariable Apnea Prediction score followed by unattended home sleep testing for detecting severe OSA syndrome (AHI ≥30 and Epworth Sleepiness Scale [ESS] score &gt;10) measured as the area under the curve in 2 studies (n = 702) was 0.80 (95% CI, 0.78 to 0.82) and 0.83 (95% CI, 0.77 to 0.90). Five studies assessing the accuracy of other screening tools were heterogeneous and results were inconsistent. Compared with inactive control, positive airway pressure was associated with a significant improvement in ESS score from baseline (pooled mean difference, -2.33 [95% CI, -2.75 to -1.90]; 47 trials; n = 7024), sleep-related QOL (standardized mean difference, 0.30 [95% CI, 0.19 to 0.42]; 17 trials; n = 3083), and general health-related QOL measured by the 36-Item Short Form Health Survey (SF-36) mental health component summary score change (pooled mean difference, 2.20 [95% CI, 0.95 to 3.44]; 15 trials; n = 2345) and SF-36 physical health component summary score change (pooled mean difference, 1.53 [95% CI, 0.29 to 2.77]; 13 trials; n = 2031). Use of mandibular advancement devices was also associated with a significantly larger ESS score change compared with controls (pooled mean difference, -1.67 [95% CI, 2.09 to -1.25]; 10 trials; n = 1540). Reporting of other health outcomes was sparse; no included trial found significant benefit associated with treatment on mortality, cardiovascular events, or motor vehicle crashes. In 3 systematic reviews, positive airway pressure was significantly associated with reduced blood pressure; however, the difference was relatively small (2-3 mm Hg).

CONCLUSIONS AND RELEVANCE

The accuracy and clinical utility of OSA screening tools that could be used in primary care settings were uncertain. Positive airway pressure and mandibular advancement devices reduced ESS score. Trials of positive airway pressure found modest improvement in sleep-related and general health-related QOL but have not established whether treatment reduces mortality or improves most other health outcomes.

Obstructive Sleep Apnoea and Lipid Metabolism: The Summary of Evidence and Future Perspectives in the Pathophysiology of OSA-Associated Dyslipidaemia

Obstructive sleep apnoea (OSA) is associated with cardiovascular and metabolic comorbidities, including hypertension, dyslipidaemia, insulin resistance and atherosclerosis. Strong evidence suggests that OSA is associated with an altered lipid profile including elevated levels of triglyceride-rich lipoproteins and decreased levels of high-density lipoprotein (HDL). Intermittent hypoxia; sleep fragmentation; and consequential surges in the sympathetic activity, enhanced oxidative stress and systemic inflammation are the postulated mechanisms leading to metabolic alterations in OSA. Although the exact mechanisms of OSA-associated dyslipidaemia have not been fully elucidated, three main points have been found to be impaired: activated lipolysis in the adipose tissue, decreased lipid clearance from the circulation and accelerated de novo lipid synthesis. This is further complicated by the oxidisation of atherogenic lipoproteins, adipose tissue dysfunction, hormonal changes, and the reduced function of HDL particles in OSA. In this comprehensive review, we summarise and critically evaluate the current evidence about the possible mechanisms involved in OSA-associated dyslipidaemia.

The mobile sleep medicine model in neurologic practice: Rationale and application

Background

Undiagnosed obstructive sleep apnea (OSA) is prevalent in neurological practice and significantly contributes to morbidity and mortality. OSA is prevalent in US adults and causes poor quality sleep and significant neurocognitive, cardiovascular, and cerebrovascular impairments. Timely treatment of OSA reduces cardio-cerebrovascular risks and improves quality of life. However, most of the US population has limited systematic access to sleep medicine care despite its clinical significance.

Focus

We discuss the importance of systematic screening, testing, and best-practice management of OSA and hypoventilation/hypoxemia syndromes (HHS) in patients with stroke, neurocognitive impairment, and neuromuscular conditions. This review aims to introduce and describe a novel integrated Mobile Sleep Medicine (iMSM) care model and provide the rationale for using an iMSM in general neurological practice to assist with systematic screening, testing and best-practice management of OSA, HHS, and potentially other sleep conditions.

Key points

The iMSM is an innovative, patient-centered, clinical outcome-based program that uses a Mobile Sleep Medicine Unit—a “sleep lab on wheels”—designed to improve access to OSA management and sleep care at all levels of health care system. The protocol for the iMSM care model includes three levels of operations to provide effective and efficient OSA screening, timely testing/treatment plans, and coordination of further sleep medicine care follow-up. The iMSM care model prioritizes effective, efficient, and patient-centered sleep medicine care; therefore, all parties and segments of care that receive and provide clinical sleep medicine services may benefit from adopting this innovative approach.

CPAP Influence on Readily Available Inflammatory Markers in OSA-A Pilot Study

Obstructive sleep apnea (OSA) is characterized by repetitive upper airway collapse, chronic hypoxia and a proinflammatory phenotype. The purpose of our study was to evaluate readily available inflammatory biomarkers (C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), white blood cell count (WBC), red cell distribution width (RDW), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), mean platelet volume (MPV), WBC-to-MPV ratio (WMR) and lymphocyte-to-C-reactive protein ratio (LCR)) before and after CPAP in patients with moderate-severe OSA. We performed a prospective study that included patients with newly-diagnosed moderate-severe OSA. The control groups (patients without OSA and with mild OSA) were selected from the hospital polygraphy database. All subjects underwent routine blood panel, which was repeated in moderate-severe OSA patients after 8 weeks of CPAP. Our final study group included 31 controls, 33 patients with mild, 22 patients with moderate and 37 patients with severe OSA. CRP, ESR, NLR and WMR were correlated with OSA severity. After 8-week CPAP therapy, we documented a decrease in weight status, which remained statistically significant in both CPAP-adherent and non-adherent subgroups. Readily available, inexpensive inflammatory parameters can predict the presence of moderate-severe OSA, but are not influenced by short-term CPAP.

ANGPTL3 and Cardiovascular Outcomes in Patients With Acute Coronary Syndrome and Obstructive Sleep Apnea

Background The aim of this prospective study was to determine the impact of elevated ANGPTL3 (angiopoietin-like protein 3) on cardiovascular events (CVEs) following acute coronary syndrome (ACS) in patients with or without obstructive sleep apnea (OSA). Methods and Results A total of 1174 patients with ACS underwent successful percutaneous coronary intervention were included in this prospective cohort study (NCT03362385). Patients were categorized according to the apnea-hypopnea index (≥15 events/h, OSA) and further classified by ANGPTL3 levels. We analyzed the incidence of CVEs in patients with ACS according to the status of OSA and ANGPTL3. During a median of 3.1 years of follow-up, 217 (18.48%) CVEs occurred. The patients with ACS with OSA had higher ANGPTL3 levels than those without OSA (30.4 [20.9-43.2] versus 27.80 [19.1-41.5] ng/mL; P<0.001). In all patients with ACS, 29≤ANGPTL3<42 mg/dL and ANGPTL3≥42 mg/dL were associated with an increased risk of CVEs with hazard ratios (HRs) of 1.555 (95% CI, 1.010-2.498) and 2.489 (95% CI 1.613-3.840), respectively. When the status of OSA or not was incorporated in stratifying factors, 29≤ANGPTL3<42 mg/dL and ANGPTL3≥42 mg/dL were associated with a significantly higher risk of CVEs in patients with ACS with OSA (HR, 1.916 [95% CI, 1.019-3.601] and HR, 2.692 [95% CI, 1.379-4.503]) but not without OSA. Moreover, adding ANGPTL3 to the Cox model increased C-statistic values by 0.035 and 0.029 in the OSA group and all patients with ACS, respectively, but was not statistically improved in patients with ACS without OSA. Conclusions In conclusion, our study demonstrates a predictive impact of plasma ANGPTL3 on cardiovascular risk in patients with ACS, especially in patients with ACS with OSA. It might be of clinical value in refining risk stratification and tailoring treatment of patients with ACS and OSA. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03362385.

Predictors of the Efficacy for Daytime Sleepiness in Patients With Obstructive Sleep Apnea With Continual Positive Airway Pressure Therapy: A Meta-Analysis of Randomized Controlled Trials

Objective

The main aim of this meta-analysis was to evaluate the predictors of the efficacy of continuous positive airway pressure (CPAP) in ameliorating excessive daytime sleepiness (EDS) in patients with obstructive sleep apnea (OSA).

Methods

Randomized controlled trials (RCTs) published between January 1994 and October 2021 were searched in the PubMed, EMBASE, and Cochrane Library databases. The weighted mean differences (WMDs) for the Epworth Sleepiness Scale (ESS) scores, the Multiple Sleep Latency Test (MSLT), and the Maintenance of Wakefulness Test (MWT) were pooled in STATA.

Results

A total of 41 RCTs involving 7,332 patients were included. CPAP therapy was found to be significantly associated with changes in ESS (WMD = −2.14, P < 0.001), MSLT (WMD = 1.23, P < 0.001), and MWT (WMD = 1.6, P < 0.001). Meta-regression analysis and subgroup analysis indicated that in mild OSA, the efficacy of CPAP therapy for subjective EDS was limited to patients <50 years of age, with a baseline body mass index (BMI) of ≥30 kg/m², baseline ESS score of ≥11, therapy adherence for ≥3 h/night, and treatment duration of ≥2 months. In moderate OSA, significant differences were observed in the changes in ESS among groups stratified by baseline ESS score (P = 0.005), adherence (P < 0.001), treatment duration (P = 0.009), and trial design type (P = 0.001). In severe OSA, this difference was observed among groups stratified by baseline BMI (P = 0.028), baseline ESS score (P = 0.001), and adherence (P = 0.047). Patients with moderate-severe OSA but not mild OSA showed significant improvements in MSLT. Patients with the age <50 years or BMI ≥33 kg/m² had a more significant increase in MWT.

Conclusion

Continuous positive airway pressure therapy improved subjective and objective sleepiness in patients with OSA. Age, baseline BMI, baseline ESS score, adherence, and duration of treatment may predict the effects of CPAP on EDS in patients with OSA. Notably, the baseline ESS scores and adherence were stable predictors regardless of OSA severity.

Obstructive Sleep Apnoea Severity Is Negatively Associated with Depressive Symptoms: A Cross-Sectional Survey of Outpatients with Suspected Obstructive Sleep Apnoea in Japan

Background: Multiple clinical departments are involved in the provision of obstructive sleep apnoea (OSA) therapy in Japan. Inconsistent results regarding the association between depression and OSA have been reported. Methods: This cross-sectional survey compared newly diagnosed OSA patients at two outpatient sleep apnoea units in Shiga Prefecture, Japan: one associated with the psychiatry department (n = 583), and the other with the otolaryngology department (n = 450). Results: The unit associated with the psychiatry department had more patients referred by psychiatrists than that with the otolaryngology department (11% vs. 3% p < 0.05). Sleepiness, insomnia, and depression were assessed using the Epworth Sleepiness Scale (ESS), Athens Insomnia Scale (AIS), and Patient Health Questionnaire-9 (PHQ-9), respectively. The ESS, AIS, and PHQ-9 scores were higher in the sleep unit in the psychiatry department (p < 0.001 each). Snoring and moderate to severe OSA were more prevalent in the unit attached to the otolaryngology department (p < 0.001 each). Patients with moderate to severe OSA had lower PHQ-9 scores than those with no to mild OSA (OR: 0.96, 95% CI: 0.92−1.00, p = 0.042). Conclusion: Patients with sleepiness, insomnia, and depressive symptoms were more likely to attend a sleep outpatient unit associated with a psychiatry department, whereas those with snoring and sleep apnoea attended that associated with an otolaryngology department. OSA severity was negatively associated with depressive symptoms.

Effect of Continuous Positive Airway Pressure on Lipid Profiles in Obstructive Sleep Apnea: A Meta-Analysis

BACKGROUND

Obstructive sleep apnea (OSA) is associated with dyslipidemia. However, the effects of continuous positive airway pressure (CPAP) treatment on lipid profiles are unclear.

METHODS

PubMed/Medline, Embase and Cochrane were searched up to July 2021. Randomized controlled trials (RCTs) of CPAP versus controls with ≥4 weeks treatment and reported pre- and post-intervention lipid profiles were included. Weighted mean difference (WMD) was used to assess the effect size. Meta-regression was used to explore the potential moderators of post-CPAP treatment changes in lipid profiles.

RESULTS

A total of 14 RCTs with 1792 subjects were included. CPAP treatment was associated with a significant decrease in total cholesterol compared to controls (WMD = -0.098 mmol/L, 95% CI = -0.169 to -0.027, p = 0.007, I² = 0.0%). No significant changes in triglyceride, high-density lipoprotein nor low-density lipoprotein were observed after CPAP treatment (all p > 0.2). Furthermore, meta-regression models showed that age, gender, body mass index, daytime sleepiness, OSA severity, follow-up study duration, CPAP compliance nor patients with cardiometabolic disease did not moderate the effects of CPAP treatment on lipid profiles (all p > 0.05).

CONCLUSIONS

CPAP treatment decreases total cholesterol at a small magnitude but has no effect on other markers of dyslipidemia in OSA patients. Future studies of CPAP therapy should target combined treatment strategies with lifestyle modifications and/or anti-hyperlipidemic medications in the primary as well as secondary cardiovascular prevention models.

CPAP Intervention as an Add-On Treatment to Lipid-Lowering Medication in Coronary Artery Disease Patients with Obstructive Sleep Apnea in the RICCADSA Trial

Dyslipidaemia is a well-known risk factor for coronary artery disease (CAD), and reducing lipid levels is essential for secondary prevention in management of these high-risk individuals. Dyslipidaemia is common also in patients with obstructive sleep apnea (OSA). Continuous positive airway pressure (CPAP) is the first line treatment of OSA. However, evidence of a possible lipid-lowering effect of CPAP in CAD patients with OSA is scarce. We addressed the effect of CPAP as an add-on treatment to lipid-lowering medication in a CAD cohort with concomitant OSA. This study was a secondary analysis of the RICCADSA trial (Trial Registry: ClinicalTrials.gov; No: NCT00519597), that was conducted in Sweden between 2005 and 2013. In total, 244 revascularized CAD patients with nonsleepy OSA (apnea-hypopnea index ≥ 15/h, Epworth Sleepiness Scale score < 10) were randomly assigned to CPAP or no-CPAP. Circulating triglycerides (TG), total cholesterol (TC), high-density lipoprotein (HDL) and low-density lipoprotein (LDL) levels (all in mg/dL) were measured at baseline and 12 months after randomization. The desired TG levels were defined as circulating TG < 150 mg/dL, and LDL levels were targeted as <70 mg/dL according to the recent guidelines of the European Cardiology Society and the European Atherosclerosis Society. A total of 196 patients with available blood samples at baseline and 12-month follow-up were included (94 randomized to CPAP, 102 to no-CPAP). We found no significant between-group differences in circulating levels of TG, TC, HDL and LDL at baseline and after 12 months as well as in the amount of change from baseline. However, there was a significant decline regarding the proportion of patients with the desired TG levels from 87.2% to 77.2% in the CPAP group (p = 0.022), whereas there was an increase from 84.3% to 88.2% in the no-CPAP group (n.s.). The desired LDL levels remained low after 12 months in both groups (15.1% vs. 17.2% in CPAP group, and 20.8% vs. 18.8% in no-CPAP group; n.s.). In a multiple linear regression model, the increase in the TG levels was predicted by the increase in body-mass-index (β = 4.1; 95% confidence interval (1.0-7.1); p = 0.009) adjusted for age, sex and CPAP usage (hours/night). CPAP had no lipid-lowering effect in this revascularized cohort with OSA. An increase in body-mass-index predicted the increase in TG levels after 12 months, suggesting that lifestyle modifications should be given priority in adults with CAD and OSA, regardless of CPAP treatment.

Sleep Apnea Syndrome (SAS) Clinical Practice Guidelines 2020

The prevalence of sleep disordered breathing (SDB) is reportedly very high. Among SDBs, the incidence of obstructive sleep apnea (OSA) is higher than previously believed, with patients having moderate-to-severe OSA accounting for approximately 20% of adult males and 10% of postmenopausal women not only in Western countries but also in Eastern countries, including Japan. Since 1998, when health insurance coverage became available, the number of patients using continuous positive airway pressure (CPAP) therapy for sleep apnea has increased sharply, with the number of patients about to exceed 500,000 in Japan. Although the "Guidelines for Diagnosis and Treatment of Sleep Apnea Syndrome (SAS) in Adults" was published in 2005, a new guideline was prepared in order to indicate the standard medical care based on the latest trends, as supervised by and in cooperation with the Japanese Respiratory Society and the "Survey and Research on Refractory Respiratory Diseases and Pulmonary Hypertension" Group, of Ministry of Health, Labor and Welfare and other related academic societies, including the Japanese Society of Sleep Research, in addition to referring to the previous guidelines. Because sleep apnea is an interdisciplinary field covering many areas, this guideline was prepared including 36 clinical questions (CQs). In the English version, therapies and managements for SAS, which were written from CQ16 to 36, were shown. The Japanese version was published in July 2020 and permitted as well as published as one of the Medical Information Network Distribution Service (Minds) clinical practice guidelines in Japan in July 2021.

Sleep Apnea Syndrome (SAS) Clinical Practice Guidelines 2020

The prevalence of sleep-disordered breathing (SDB) is reportedly very high. Among SDBs, the incidence of obstructive sleep apnea (OSA) is higher than previously believed, with patients having moderate-to-severe OSA accounting for approximately 20% of adult males and 10% of postmenopausal women not only in Western countries but also in Eastern countries, including Japan. Since 1998, when health insurance coverage became available, the number of patients using continuous positive airway pressure (CPAP) therapy for sleep apnea has increased sharply, with the number of patients about to exceed 500,000 in Japan. Although the "Guidelines for Diagnosis and Treatment of Sleep Apnea Syndrome (SAS) in Adults" was published in 2005, a new guideline was prepared to indicate the standard medical care based on the latest trends, as supervised by and in cooperation with the Japanese Respiratory Society and the "Survey and Research on Refractory Respiratory Diseases and Pulmonary Hypertension" Group, of Ministry of Health, Labor and Welfare and other related academic societies, including the Japanese Society of Sleep Research, in addition to referring to the previous guidelines. Since sleep apnea is an interdisciplinary field covering many areas, this guideline was prepared including 36 clinical questions (CQs). In the English version, therapies and managements for SAS, which were written from CQ16 to 36, were shown. The Japanese version was published in July 2020 and permitted as well as published as one of the Medical Information Network Distribution Service (Minds) clinical practice guidelines in Japan in July 2021.

A Prospective Study of CPAP Therapy in Relation to Cardiovascular Outcome in a Cohort of Romanian Obstructive Sleep Apnea Patients

Background: Despite efforts at treatment, obstructive sleep apnea (OSA) remains a major health problem, especially with increasing evidence showing an association with cardiovascular morbidity and mortality. The treatment of choice for OSA patients is Continuous Positive Airway Pressure (CPAP), which has been proven in randomized controlled trials to be an effective therapy for this condition. The impact of CPAP on the cardiovascular pathology associated with OSA remains, however, unclear. Although the effect of CPAP has been previously studied in relation to cardiovascular outcome, follow-up of the treatment impact on cardiovascular risk factors at one year of therapy is lacking in a Romanian population. Thus, we aimed to evaluate the one-year effect of CPAP therapy on lipid profile, inflammatory state, blood pressure and cardiac function, assessed by echocardiography, on a cohort of Romanian OSA patients. Methods: We enrolled 163 participants and recorded their baseline demographic and clinical characteristics with a follow-up after 12 months. Inflammatory and cardiovascular risk factors were assessed at baseline and follow up. Results: Our results show that CPAP therapy leads to attenuation of cardiovascular risk factors including echocardiographic parameters, while having no effect on inflammatory markers. Conclusion: Treatment of OSA with CPAP proved to have beneficial effects on some of the cardiovascular risk factors while others remained unchanged, raising new questions for research into the treatment and management of OSA patients.

The effect of acute intermittent hypoxia on postprandial triglyceride levels in humans: a randomized crossover trial

Background

Obstructive sleep apnea (OSA), a sleep disorder frequently observed in individuals living with obesity, consists of repeated involuntary breathing obstructions during sleep, leading to intermittent hypoxia (IH). In humans, acute continuous hypoxia slightly increases plasma triglycerides (TG). However, no study yet compared the postprandial TG response of individuals with or without OSA under intermittent hypoxia.

Methods

Using a randomized crossover design, seven individuals diagnosed with moderate OSA and eight healthy individuals without OSA were given a meal after which they were exposed for 6 h to normoxia or intermittent hypoxia (e.g., 15 hypoxic events per hour). Blood lipid levels were measured hourly during each session.

Results

Peak postprandial TG concentrations tended to be 22% higher under IH irrespective of group (IH × time interaction, p = 0.068). This trend toward higher total plasma TG was attributable to increased levels of denser TG-rich lipoproteins such as very low-density lipoproteins (VLDL) and chylomicrons (CM) remnants. Irrespective of group, the postprandial TG concentrations in denser TG-rich lipoproteins was 20% higher under IH (IH × time interaction, p = 0.036), although IH had virtually no impact on denser TG-rich lipoprotein concentrations in the OSA group.

Conclusion

Acute intermittent hypoxia tends to negatively affect postprandial TG levels in healthy individuals, which is attributable to an increase in denser TG-carrying lipoprotein levels such as VLDL and CM remnants. This altered postprandial TG response to acute intermittent hypoxia was not observed in individuals with OSA.

Mirabegron Ameliorated Atherosclerosis of ApoE-/- Mice in Chronic Intermittent Hypoxia but Not in Normoxia

PURPOSE

It has been established that obstructive sleep apnea (OSA) is an independent risk factor for atherosclerosis. Chronic intermittent hypoxia (CIH) activates sympathoadrenal system and upregulates β3 adrenergic receptor (β3 AR). However, the effect of selective β3 AR agonist mirabegron in CIH-induced atherosclerosis remains unknown.

METHODS

We generated a CIH-induced atherosclerosis model through exposing ApoE^-/- mice to CIH (8 h per day, cyclic inspiratory oxygen fraction 5-21%, 60-s cycle) for 6 weeks after 4-week high-fat dieting and investigated the effects of mirabegron, a selective β3 AR agonist, on CIH-induced atherosclerosis. The coronary endarterectomy (CE) specimens from coronary artery disease patients with OSA and without OSA were collected.

RESULTS

The expression of β3 AR was significantly elevated in CIH-induced atherosclerosis model. Furthermore, treatment with mirabegron (10mg/kg per day by oral administration for 6 weeks) ameliorated atherosclerosis in ApoE^-/- mice in CIH but not in normoxia. Mechanistically, mirabegron activated β3 AR and ameliorated intraplaque oxidative stress by suppressing p22phox expression and reactive oxygen species (ROS) level. In addition, in human CE specimens, β3 AR was also upregulated associated with increased p22phox expression and ROS level both in the lumen and in the plaque of coronary artery in OSA subjects.

CONCLUSION

This study first demonstrated that mirabegron impeded the progression of CIH-induced atherosclerosis, at least in part, via β3 AR-mediated oxidative stress, suggesting a promising therapeutic strategy for protecting against atherosclerosis induced by CIH.

International Consensus Document on Obstructive Sleep Apnea

The main aim of this international consensus document on obstructive sleep apnea is to provide guidelines based on a critical analysis of the latest literature to help health professionals make the best decisions in the care of adult patients with this disease. The expert working group was formed primarily of 17 scientific societies and 56 specialists from a wide geographical area (including the participation of 4 international societies), an expert in methodology, and a documentalist from the Iberoamerican Cochrane Center. The document consists of a main section containing the most significant innovations and a series of online manuscripts that report the systematic literature searches performed for each section of the international consensus document. This document does not discuss pediatric patients or the management of patients receiving chronic non-invasive mechanical ventilation (these topics will be addressed in separate consensus documents).

Metabolomics in Sleep, Insomnia and Sleep Apnea

Sleep-wake disorders are highly prevalent disorders, which can lead to negative effects on cognitive, emotional and interpersonal functioning, and can cause maladaptive metabolic changes. Recent studies support the notion that metabolic processes correlate with sleep. The study of metabolite biomarkers (metabolomics) in a large-scale manner offers unique opportunities to provide insights into the pathology of diseases by revealing alterations in metabolic pathways. This review aims to summarize the status of metabolomic analyses-based knowledge on sleep disorders and to present knowledge in understanding the metabolic role of sleep in psychiatric disorders. Overall, findings suggest that sleep-wake disorders lead to pronounced alterations in specific metabolic pathways, which might contribute to the association of sleep disorders with other psychiatric disorders and medical conditions. These alterations are mainly related to changes in the metabolism of branched-chain amino acids, as well as glucose and lipid metabolism. In insomnia, alterations in branched-chain amino acid and glucose metabolism were shown among studies. In obstructive sleep apnea, biomarkers related to lipid metabolism seem to be of special importance. Future studies are needed to examine severity, subtypes and treatment of sleep-wake disorders in the context of metabolite levels.

Meta-analysis of changes in the levels of catecholamines and blood pressure with continuous positive airway pressure therapy in obstructive sleep apnea

Stress from obstructive sleep apnea (OSA) stimulates catecholamine release consequently exacerbating hypertension. However, different studies have shown a conflicting impact of continuous positive airway pressure (CPAP) treatment in patients with OSA on catecholamine levels and blood pressure. We aimed to examine changes to catecholamine levels and blood pressure in response to CPAP treatment. We conducted a meta‐analysis of data published up to May 2020. The quality of the studies was evaluated using standard tools for assessing the risk of bias. Meta‐analysis was conducted using RevMan (v5.3) and expressed in standardized mean difference (SMD) for catecholamines and mean difference (MD) for systolic (SBP) and diastolic blood pressure (DBP). A total of 38 studies met our search criteria; they consisted of 14 randomized control trials (RCT) totaling 576 participants and 24 prospective cohort studies (PCS) of 547 participants. Mean age ranged between 41 and 62 year and body mass index between 27.2 and 35.1 kg/m². CPAP treatment reduced 24‐hour urinary noradrenaline levels both in RCT (SMD = −1.1; 95% confidence interval (CI): −1.63 to − 0.56) and in PCS (SMD = 0.38 (CI: 0.24 to 0.53). SBP was also reduced by CPAP treatment in RCT (4.8 mmHg; CI: 2.0‐7.7) and in PCS (7.5 mmHg; CI: 3.3‐11.7). DBP was similarly reduced (3.0 mmHg; CI: 1.4‐4.6) and in PCS (5.1 mmHg; CI: 2.3‐8.0). In conclusion, CPAP treatment in patients with OSA reduces catecholamine levels and blood pressure. This suggests that sympathetic activity plays an intermediary role in hypertension associated with OSA‐related stress.

Danlou Tablet () Improves Chronic Intermittent Hypoxia-induced Dyslipidemia and Arteriosclerosis by HIF-1 α-Angptl4 mRNA Signaling Pathway

OBJECTIVE

To detect whether Danlou Tablet (, DLT) regulates the hypoxia-induced factor (HIF)-1 α-angiopoietin-like 4 (Angptl4) mRNA signaling pathway and explore the role of DLT in treating chronic intermittent hypoxia (CIH)-induced dyslipidemia and arteriosclerosis.

METHODS

The mature adipocytes were obtained from 3T3-L1 cell culturation and allocated into 8 groups including control groups (Groups 1 and 5, 0.1 mL of cell culture grade water); DLT groups (Groups 2 and 6, 0.1 mL of 1,000 µg/mL DLT submicron powder solution); dimethyloxalylglycine (DMOG) groups (Groups 3 and 7, DMOG and 0.1 mL of cell culture grade water); DMOG plus DLT groups (Groups 4 and 8, DMOG and 0.1 mL of 1,000 µg/mL DLT submicron powder solution). Groups 1-4 used mature adipocytes and groups 5-8 used HIF-1 α-siRNA lentivirus-transfected mature adipocytes. After 24-h treatment, real-time polymerase chain reaction and Western blot were employed to determine the mRNA and protein expression levels of HIF-1 α and Angptl4. In animal experiments, the CIH model in ApoE^-/- mice was established. Sixteen mice were complete randomly divided into 4 groups including sham group, CIH model group [intermittent hypoxia and normal saline (2 mL/time) gavage once a day]; Angptl4 Ab group [intermittent hypoxia and Angptl4 antibody (30 mg/kg) intraperitoneally injected every week]; DLT group [intermittent hypoxia and DLT (250 mg/kg) once a day], 4 mice in each group. After 4-week treatment, enzyme linked immunosorbent assay was used to detect the expression levels of serum total cholesterol (TC) and triglyceride (TG). Hematoxylin-eosin and CD68 staining were used to observe the morphological properties of arterial plaques.

RESULTS

Angptl4 expression was dependent on HIF-1 α, with a reduction in mRNA expression and no response in protein level to DMOG or DLT treatment in relation to siHIF-1 α -transfected cells. DLT inhibited HIF-1 α and Angptl4 mRNA expression (P<0.05 or P<0.01) and reduced HIF-1 α and Angptl4 protein expressions with DMOG in mature adipocytes (all P<0.01), as the effect on HIF-1 α protein also existed in the presence of siHIF-1 α (P<0.01). ApoE^-/- mice treated with CIH had increased TG and TC levels (all P<0.01) and atherosclerotic plaque. Angptl4 antibody and DLT both reduce TG and TC levels (all P<0.01), as well as reducing atherosclerotic plaque areas, narrowing arterial wall thickness and alleviating atherosclerotic lesion symptoms to some extent.

CONCLUSION

DLT had positive effects in improving dyslipidemia and arteriosclerosis by inhibiting Angptl4 protein level through HIF-1 α-Angptl4 mRNA signaling pathway.

Sleep disordered breathing and metabolic comorbidities across sex and menopausal status in East Asians: the Nagahama Study

It is well known that the prevalence of sleep disordered breathing (SDB) is increased in patients with obesity or metabolic comorbidities. However, the way in which the prevalence of SDB increases in relation to comorbidities according to the severity of obesity remains unclear.

This cross-sectional study evaluated 7713 community participants using nocturnal oximetry ≥2 nights. SDB was assessed by the 3% oxygen desaturation index corrected for sleep duration obtained by wrist actigraphy (acti-ODI3%). SDB severity was defined by acti-ODI3%. Obesity was defined as body mass index ≥25 kg·m−2.

The prevalence of SDB was 41.0% (95% CI 39.9–42.1%), 46.9% (45.8–48.0%), 10.1% (9.5–10.8%) and 2.0% (1.7–2.3%) in normal, mild, moderate and severe SDB, respectively, with notable sex differences evident (males>post-menopausal females>premenopausal females). Comorbidities such as hypertension, diabetes and metabolic syndrome were independently associated with the prevalence of moderate-to-severe SDB, and coincidence of any one of these with obesity was associated with a higher probability of moderate-to-severe SDB (hypertension OR 8.2, 95% CI 6.6–10.2; diabetes OR 7.8, 95% CI 5.6–10.9; metabolic syndrome OR 6.7, 95% CI 5.2–8.6). Dyslipidaemia in addition to obesity was not additively associated with the prevalence of moderate-to-severe SDB. The number of antihypertensive drugs was associated with SDB (p for trend <0.001). Proportion of a high cumulative percentage of sleep time with oxygen saturation measured by pulse oximetry <90% increased, even among moderate-to-severe SDB with increases in obesity.

Metabolic comorbidities contribute to SDB regardless of the degree of obesity. We should recognise the extremely high prevalence of moderate-to-severe SDB in patients with obesity and metabolic comorbidities.

The role of sham continuous positive airway pressure as a placebo in controlled trials: Best Apnea Interventions for Research Trial

STUDY OBJECTIVES

The main objective of this study was to evaluate the role of sham continuous positive airway pressure (CPAP) compared to conservative medical therapy (CMT) as a control arm in the Best Apnea Interventions for Research (BestAIR) study by assessing differences in subjectively and objectively measured outcomes, adverse events, adherence, and retention rates.

METHODS

BestAIR is a clinical trial aimed to identify important design features for future randomized controlled trials of CPAP. Participants with obstructive sleep apnea were randomized to one of four groups; two control arms (CMT, sham-CPAP) and two active CPAP arms (with and without behavioral interventions). Blood pressure and health-related quality of life outcomes were assessed at baseline, 6 and 12 months. Study outcomes, retention, and adverse event rates were compared between the two control arms. Sham-CPAP adherence and self-efficacy were also compared to active-CPAP adherence (without behavioral intervention).

RESULTS

Our sample included 86 individuals in the control arms and 42 participants in the active-CPAP arm. There were no differences in longitudinal profiles in blood pressure, health-related quality of life outcomes, dropout rates, or adverse events in sham-CPAP group compared to CMT-only group (all ps > 0.05); standardized differences were generally small and with inconsistent directionality across measurements. When compared to active-CPAP, sham-CPAP was associated with 93 fewer minutes/night of usage over 12 months (p = 0.007) and lower outcome expectations (p < 0.05).

CONCLUSION

We observed no evidence of differences in objectively or subjectively measured outcomes with the use of sham-CPAP compared to CMT group. The lower adherence on sham-CPAP and poorer self-efficacy compared to active-CPAP may suggest differences in perceived benefit.

REGISTRATION

NCT01261390 Best Apnea Interventions for Research (BestAIR) www.clinicaltrials.gov.

Obstructive sleep apnea and dyslipidemia: from animal models to clinical evidence

Lipid metabolism deregulation constitutes the pathogenic basis for the development of atherosclerosis and justifies a high incidence of cardiovascular-related morbidity and mortality. Some data suggest that dyslipidemia may be associated with sleep-disordered breathing, mainly obstructive sleep apnea (OSA), due to alterations in fundamental biochemical processes, such as intermittent hypoxia (IH). The aim of this systematic review was to identify and critically evaluate the current evidence supporting the existence of a possible relationship between OSA and alterations in lipid metabolism. Much evidence shows that, during the fasting state, OSA and IH increase lipid delivery from the adipose tissue to the liver through an up-regulation of the sterol regulatory element-binding protein-1 and stearoyl-CoA desaturase-1, increasing the synthesis of cholesterol esters and triglycerides. In the postprandial state, lipoprotein clearance is delayed due to lower lipoprotein lipase activity, probably secondary to IH-up-regulation of angiopoietin-like protein 4 and decreased activity of the peroxisome proliferator-activated receptor alpha. Moreover, oxidative stress can generate dysfunctional oxidized lipids and reduce the capacity of high-density lipoproteins (HDL) to prevent low-density lipoprotein (LDL) oxidation. In the clinical field, several observational studies and a meta-regression analysis support the existence of a link between OSA and dyslipidemia. Although there is evidence of improved lipid profile after apnea-hypopnea suppression with continuous positive airway pressure (CPAP), the majority of the data come from observational studies. In contrast, randomized controlled trials evaluating the effects of CPAP on lipid metabolism present inconclusive results and two meta-analyses provide contradictory evidence.

Cardiometabolic comorbidities in obstructive sleep apnea patients are related to disease severity, nocturnal hypoxemia, and decreased sleep quality

BACKGROUND

Obstructive sleep apnea syndrome (OSA) is currently recognized as an independent risk factor for hypertension, arrhythmia, coronary heart disease, stroke, and metabolic disorders (e.g. diabetes, dyslipidemia). In clinical practice, apnea-hypopnea index (AHI) is the marker used to classify disease severity and guide treatment. However, AHI alone does not sufficiently identify OSA patients at risk for cardiometabolic comorbidities. With this in mind, the aim of this retrospective study was to determine whether some polysomnographic parameters (e.g. apnea-hypopnea duration, sleep structure, nocturnal hypoxemia) are specifically associated with cardiometabolic comorbidities in OSA.

METHODS

In this retrospective study, 1717 patients suffering from moderate/severe OSA were included between 2013 and 2017. Data on demographics, comorbidities, and polysomnographic characteristics were collected and analyzed to identify factors associated with cardiometabolic complications.

RESULTS

The medical files of 1717 patients (68% male) were reviewed. The mean AHI was 43.1 +/- 27.7 with 57.3% of patients suffering from severe OSA, and 52% from at least one cardiovascular comorbidity (CVCo). Diabetes affected 22% of the patients and 27% exhibited dyslipidemia. Patients affected by CVCos were older, and more often women and non-smokers. These patients also had worse sleep quality, and a more marked intermittent/global nocturnal hypoxemia. With regard to diabetes, diabetics were older, more often non-smoker, non-drinker women, and were more obese. These patients also exhibited more severe OSA, especially in non-REM (NREM) sleep, worse sleep quality, and a more marked intermittent/global nocturnal hypoxemia. Dyslipidemia was more frequent in the absence of alcohol consumption, and was associated with OSA severity, decreased sleep quality, and longer AH in REM sleep.

CONCLUSIONS

This study identifies demographic and polysomnographic factors associated with cardiometabolic comorbidities. Patients (especially women) suffering from more severe OSA, longer sleep apneas and hypopneas, worse sleep quality, and marked intermittent/global nocturnal hypoxemia are more likely to develop cardiometabolic comorbidities. This should stimulate clinicians to obtain adequate treatment in this population.

Obstructive Sleep Apnea, Hypoxia, and Nonalcoholic Fatty Liver Disease

Recent studies have demonstrated that obstructive sleep apnea (OSA) is associated with the development and evolution of nonalcoholic fatty liver disease (NAFLD), independent of obesity or other shared risk factors. Like OSA, NAFLD is a prevalent disorder associated with major adverse health outcomes: Patients with NAFLD may develop cirrhosis, liver failure, and hepatocellular carcinoma. One major finding that has emerged from these studies is that the OSA-NAFLD association is related to the degree of nocturnal hypoxemia in OSA. Animal models have therefore largely focused on intermittent hypoxia, a key manifestation of OSA, to shed light on the mechanisms by which OSA may give rise to the complex metabolic disturbances that are seen in NAFLD. Intermittent hypoxia leads to tissue hypoxia and can result in oxidative stress, mitochondrial dysfunction, inflammation, and overactivation of the sympathetic nervous system, among many other maladaptive effects. In such models, intermittent hypoxia has been shown to cause insulin resistance, dysfunction of key steps in hepatic lipid metabolism, atherosclerosis, and hepatic steatosis and fibrosis, each of which is pertinent to the development and/or progression of NAFLD. However, many intriguing questions remain unanswered: Principally, how aggressively should the clinician screen for NAFLD in patients with OSA, and vice versa? In this review, we attempt to apply the best evidence from animal and human studies to highlight the relationship between these two disorders and to advocate for further trials aimed at defining these relationships more precisely.

Bidirectional relationship between sleep and Alzheimer's disease: role of amyloid, tau, and other factors

As we age, we experience changes in our nighttime sleep and daytime wakefulness. Individuals afflicted with Alzheimer's disease (AD) can develop sleep problems even before memory and other cognitive deficits are reported. As the disease progresses and cognitive changes ensue, sleep disturbances become even more debilitating. Thus, it is imperative to gain a better understanding of the relationship between sleep and AD pathogenesis. We postulate a bidirectional relationship between sleep and the neuropathological hallmarks of AD; in particular, the accumulation of amyloid-β (Aβ) and tau. Our research group has shown that extracellular levels of both Aβ and tau fluctuate during the normal sleep-wake cycle. Disturbed sleep and increased wakefulness acutely lead to increased Aβ production and decreased Aβ clearance, whereas Aβ aggregation and deposition is enhanced by chronic increased wakefulness in animal models. Once Aβ accumulates, there is evidence in both mice and humans that this results in disturbed sleep. New findings from our group reveal that acute sleep deprivation increases levels of tau in mouse brain interstitial fluid (ISF) and human cerebrospinal fluid (CSF) and chronic sleep deprivation accelerates the spread of tau protein aggregates in neural networks. Finally, recent evidence also suggests that accumulation of tau aggregates in the brain correlates with decreased nonrapid eye movement (NREM) sleep slow wave activity. In this review, we first provide a brief overview of the AD and sleep literature and then highlight recent advances in the understanding of the relationship between sleep and AD pathogenesis. Importantly, the effects of the bidirectional relationship between the sleep-wake cycle and tau have not been previously discussed in other reviews on this topic. Lastly, we provide possible directions for future studies on the role of sleep in AD.

Metabolism of sleep and aging: Bridging the gap using metabolomics

Sleep is a conserved behavior across the evolutionary timescale. Almost all known animal species demonstrate sleep or sleep like states. Despite extensive study, the mechanistic aspects of sleep need are not very well characterized. Sleep appears to be needed to generate resources that are utilized during the active stage/wakefulness as well as clearance of waste products that accumulate during wakefulness. From a metabolic perspective, this means sleep is crucial for anabolic activities. Decrease in anabolism and build-up of harmful catabolic waste products is also a hallmark of aging processes. Through this lens, sleep and aging processes are remarkably parallel- for example behavioral studies demonstrate an interaction between sleep and aging. Changes in sleep behavior affect neurocognitive phenotypes important in aging such as learning and memory, although the underlying connections are largely unknown. Here we draw inspiration from the similar metabolic effects of sleep and aging and posit that large scale metabolic phenotyping, commonly known as metabolomics, can shed light to interleaving effects of sleep, aging and progression of diseases related to aging. In this review, data from recent sleep and aging literature using metabolomics as principal molecular phenotyping methods is collated and compared. The present data suggests that metabolic effects of aging and sleep also demonstrate similarities, particularly in lipid metabolism and amino acid metabolism. Some of these changes also overlap with metabolomic data available from clinical studies of Alzheimer's disease. Together, metabolomic technologies show promise in elucidating interleaving effects of sleep, aging and progression of aging disorders at a molecular level.

The Relationship between Obstructive Sleep Apnea and Alzheimer's Disease

Obstructive sleep apnea (OSA) and Alzheimer's disease (AD) are highly prevalent conditions with growing impact on our aging society. While the causes of OSA are now better characterized, the mechanisms underlying AD are still largely unknown, challenging the development of effective treatments. Cognitive impairment, especially affecting attention and executive functions, is a recognized clinical consequence of OSA. A deeper contribution of OSA to AD pathogenesis is now gaining support from several lines of research. OSA is intrinsically associated with disruptions of sleep architecture, intermittent hypoxia and oxidative stress, intrathoracic and hemodynamic changes as well as cardiovascular comorbidities. All of these could increase the risk for AD, rendering OSA as a potential modifiable target for AD prevention. Evidence supporting the relevance of each of these mechanisms for AD risk, as well as a possible effect of AD in OSA expression, will be explored in this review.

Treatment of Adult Obstructive Sleep Apnea With Positive Airway Pressure: An American Academy of Sleep Medicine Systematic Review, Meta-Analysis, and GRADE Assessment

INTRODUCTION

The purpose of this systematic review is to provide supporting evidence for the clinical practice guideline for the treatment of obstructive sleep apnea (OSA) in adults using positive airway pressure (PAP).

METHODS

The American Academy of Sleep Medicine commissioned a task force of experts in sleep medicine. A systematic review was conducted to identify studies that compared the use of PAP with no treatment as well as studies that compared different PAP modalities. Meta-analyses were performed to determine the clinical significance of using PAP in several modalities (ie, continuous PAP, auto-adjusting PAP, and bilevel PAP), to treat OSA in adults. In addition, meta-analyses were performed to determine the clinical significance of using an in-laboratory versus ambulatory strategy for the initiation of PAP, educational and behavioral interventions, telemonitoring, humidification, different mask interfaces, and flexible or modified pressure profile PAP in conjunction with PAP to treat OSA in adults. Finally, the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) process was used to assess the evidence for making recommendations.

RESULTS

The literature search resulted in 336 studies that met inclusion criteria; 184 studies provided data suitable for meta-analyses. The data demonstrated that PAP compared to no treatment results in a clinically significant reduction in disease severity, sleepiness, blood pressure, and motor vehicle accidents, and improvement in sleep-related quality of life in adults with OSA. In addition, the initiation of PAP in the home demonstrated equivalent effects on patient outcomes when compared to an in-laboratory titration approach. The data also demonstrated that the use of auto-adjusting or bilevel PAP did not result in clinically significant differences in patient outcomes compared with standard continuous PAP. Furthermore, data demonstrated a clinically significant improvement in PAP adherence with the use of educational, behavioral, troubleshooting, and telemonitoring interventions. Systematic reviews for specific PAP delivery method were also performed and suggested that nasal interfaces compared to oronasal interfaces have improved adherence and slightly greater reductions in OSA severity, heated humidification compared to no humidification reduces some continuous PAP-related side effects, and pressure profile PAP did not result in clinically significant differences in patient outcomes compared with standard continuous PAP.

Associations Between Obstructive Sleep Apnea and Measures of Arterial Stiffness

STUDY OBJECTIVES

The aim of this study was to determine whether severity measures of obstructive sleep apnea (OSA) are associated with arterial stiffness and central blood pressure (two important cardiovascular risk factors) in a large group of patients with OSA.

METHODS

Baseline data from six studies on OSA in which arterial stiffness and central aortic blood pressure measures were determined using applanation tonometry were pooled. Associations between measures of arterial stiffness (heart rate corrected augmentation index [AI75]), central aortic blood pressure (central systolic pressure [CSP] and heart rate corrected central augmentation pressure [CAP75]) and measures of OSA severity were explored using stepwise regression modelling.

RESULTS

Data from 362 participants (M:F ratio 13:1) with mean (standard deviation) age 49.2 (11.0) years, body mass index 31.9 (5.3) kg/m², apnea-hypopnea index (AHI) 35.7 (20.7) events/h were included in the analyses. The AHI, oxygen desaturation index (ODI3%), and sleep time with SpO₂ < 90% (T90) were all associated with arterial stiffness (AI75), (AHI: adj. β = .069; P = .01; ODI3%: adj. β = .072; P = .01; T90: adj. β = .18; P < .0001) and CAP75 (AHI: adj. β = .030; P = .01; ODI3%: adj. β = .027; P = .02; T90: adj. β = .080; P < .0001). AHI was also associated with CSP (AHI: adj. β = .11; P = .002).

CONCLUSIONS

OSA severity was significantly associated with augmentation index and CAP75 although the relationships were not strong.

Cardiovascular outcomes of continuous positive airway pressure therapy for obstructive sleep apnea

Obstructive sleep apnea is a common disorder with increased risk for cardiovascular morbidity and mortality. The first choice of treatment of obstructive sleep apnea is continuous positive airway pressure, which reduces excessive daytime sleepiness and improves quality of life in sleep clinic cohorts. Nevertheless, the majority of patients with cardiovascular disease and concomitant obstructive sleep apnea do not report daytime sleepiness, and adherence to treatment is insufficient particularly in this group. The current article aims to give an updated overview of the impact of continuous positive airway pressure therapy on cardiovascular outcomes mainly based on the observational studies and the recent randomized controlled trials.

Dose-dependent effects of continuous positive airway pressure for sleep apnea on weight or metabolic function: Individual patient-level clinical trial meta-analysis

Therapeutic-continuous positive airway pressure seems to increase weight compared with placebo-continuous positive airway pressure. It is not known whether weight gain with therapeutic-continuous positive airway pressure dose is dependent or whether it causes metabolic dysfunction. Data synthesis of three randomised placebo-continuous positive airway pressure-controlled trials (2-3 months) was performed to test whether there is a dose-dependent effect of continuous positive airway pressure on weight. Fasting glucose, insulin, insulin resistance (homeostatic model assessment), lipids and visceral abdominal fat were also tested to determine any effect on metabolic function. Mixed-model analysis of variance was used to quantify these effects. One-hundred and twenty-eight patients were analysed. Overall there was a small increase in weight with therapeutic-continuous positive airway pressure use compared with placebo-continuous positive airway pressure (difference: 1.17 kg; 0.37-1.97, p = 0.005), which was greater with high-use therapeutic-continuous positive airway pressure compared with high-use placebo-continuous positive airway pressure (1.45 kg; 0.10-2.80, p = 0.04). Continuous positive airway pressure use as a continuous variable was also significantly associated with weight change in continuous positive airway pressure users (0.30 kg hr^-1  night^-1 ; 0.04-0.56, p = 0.001), but not in placebo users (0.04 kg hr^-1  night^-1 ; -0.22 to 0.26, p = 0.76). Neither therapeutic-continuous positive airway pressure nor the dose of therapeutic-continuous positive airway pressure caused any changes to metabolic outcomes. The weight gain effects of medium-term therapeutic-continuous positive airway pressure appear modest and are not accompanied by any adverse metabolic effects.

Obstructive sleep apnoea independently predicts lipid levels: Data from the European Sleep Apnea Database

BACKGROUND AND OBJECTIVE

Obstructive sleep apnoea (OSA) and dyslipidaemia are independent risk factors for cardiovascular disease. This study investigates the association between OSA and plasma lipid concentrations in patients enrolled in the European Sleep Apnea Database (ESADA) cohort.

METHODS

The cross-sectional analysis included 8592 patients without physician-diagnosed hyperlipidaemia or reported intake of a lipid-lowering drug (age 50.1 ± 12.7 years, 69.1% male, BMI: 30.8 ± 6.6 kg/m² , mean apnoea-hypopnoea index (AHI): 25.7 ± 25.9 events/h). The independent relationship between measures of OSA (AHI, oxygen desaturation index (ODI), mean and lowest oxygen saturation) and lipid profile (total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and fasting triglycerides (TG)) was determined by means of general linear model analysis.

RESULTS

There was a dose response relationship between TC and ODI (mean ± SE (mg/dL): 180.33 ± 2.46, 184.59 ± 2.42, 185.44 ± 2.42 and 185.73 ± 2.44; P < 0.001 across ODI quartiles I-IV). TG and LDL concentrations were better predicted by AHI than by ODI. HDL-C was significantly reduced in the highest AHI quartile (mean ± SE (mg/dL): 48.8 ± 1.49 vs 46.50 ± 1.48; P = 0.002, AHI quartile I vs IV). Morbid obesity was associated with lower TC and higher HDL-C values. Lipid status was influenced by geographical location with the highest TC concentration recorded in Northern Europe.

CONCLUSION

OSA severity was independently associated with cholesterol and TG concentrations.

Sleep: important considerations for the prevention of cardiovascular disease

PURPOSE OF REVIEW

Sleep plays many roles in maintenance of cardiovascular health. This review summarizes the literature across several areas of sleep and sleep disorders in relation to cardiometabolic disease risk factors.

RECENT FINDINGS

Insufficient sleep duration is prevalent in the population and is associated with weight gain and obesity, inflammation, cardiovascular disease, diabetes, and mortality. Insomnia is also highly present and represents an important risk factor for cardiovascular disease, especially when accompanied by short sleep duration. Sleep apnea is a well-characterized risk factor for cardiometabolic disease and cardiovascular mortality. Other issues are relevant as well. For example, sleep disorders in pediatric populations may convey cardiovascular risks. Also, sleep may play an important role in cardiovascular health disparities.

SUMMARY

Sleep and sleep disorders are implicated in cardiometabolic disease risk. This review addresses these and other issues, concluding with recommendations for research and clinical practice.

Obstructive sleep apnea and effects of continuous positive airway pressure on triglyceride-rich lipoprotein metabolism

This study aimed to explore lipoprotein metabolism in obstructive sleep apnea (OSA) and the effects of continuous positive airway pressure (CPAP). We studied 15 men with severe OSA [apnea-hypopnea index (AHI) ≥30 events/hour] and 12 age-, BMI-, and waist circumference-matched volunteers without OSA (AHI <5 events/hour). Carotid intima-media thickness (CIMT) was determined by a blind examiner. After 12 h fasting, a triglyceride-rich chylomicron-like emulsion, labeled with [¹⁴C]cholesteryl oleate and [³H]triolein, was injected intravenously followed by blood sample collection at preestablished times. Fractional clearance rate (FCR) of the radiolabeled lipids was estimated by compartmental analysis of radioisotope decay curves. Compared with controls, patients with OSA showed a significant delay in both cholesteryl ester FCR (0.0126 ± 0.0187 vs. 0.0015 ± 0.0025 min^-1; P = 0.0313) and triglycerides FCR (0.0334 ± 0.0390 vs. 0.0051 ± 0.0074 min^-1; P = 0.0001). CIMT was higher in the OSA group: 620 ± 17 vs. 725 ± 29 µm; P = 0.004. Cholesteryl ester FCRs were inversely related to total sleep time <90% (r = -0.463; P = 0.029) and CIMT (r = -0.601; P = 0.022). The triglyceride FCR was inversely correlated with AHI (r = -0.537; P = 0.04). In a subgroup of patients treated with CPAP for 3 months (n = 7), triglyceride FCR increased 5-fold (P = 0.025), but the cholesteryl ester FCR was unchanged. In conclusion, severe OSA decreased lipolysis of triglyceride-rich lipoproteins and delayed removal of remnants. CPAP treatment may be effective to restore the lipolysis rates.

Changes of vitamin D levels and bone turnover markers after CPAP therapy: a randomized sham-controlled trial

The aim was to investigate whether continuous positive airway pressure treatment could modulate serum vitamin D (25-hydroxyvitamin D) and bone turnover markers (collagen-type 1 cross-linked C-telopeptide, osteocalcin and N-terminal propeptide of type 1 collagen) in secondary analysis from a randomized controlled trial. Sixty-five continuous positive airway pressure-naïve male patients with obstructive sleep apnea (age = 49 ± 12 years, apnea-hypopnea index = 39.9 ± 17.7 events h^-1 , body mass index = 31.3 ± 5.2 kg m^-2 ) were randomized to receive either real (n = 34) or sham (n = 31) continuous positive airway pressure for 12 weeks. At 12 weeks, all participants received real continuous positive airway pressure for an additional 12 weeks. After 12 weeks of continuous positive airway pressure (real versus sham), there were no between-group differences for any of the main outcomes [Δ25-hydroxyvitamin D: -0.80 ± 5.28 ng mL^-1 (mean ± SE) versus 3.08 ± 3.66 ng mL^-1 , P = 0.42; Δcollagen-type 1 cross-linked C-telopeptide: 0.011 ± 0.014 ng mL^-1 versus -0.004 ± 0.009 ng mL^-1 , P = 0.48; Δosteocalcin: 1.13 ± 1.12 ng mL^-1 versus 0.46 ± 0.75 ng mL^-1 , P = 0.80; ΔN-terminal propeptide of type 1 collagen: 2.07 ± 3.05 μg L^-1 versus -1.05 ± 2.13 μg L^-1 , P = 0.48]. There were no further differences in subgroup analyses (continuous positive airway pressure-compliant patients, patients with severe obstructive sleep apnea or sleepy patients). However, after 24 weeks irrespective of initial randomization, vitamin D increased in patients with severe obstructive sleep apnea (9.56 ± 5.51 ng mL^-1 , P = 0.045) and in sleepy patients (14.0 ± 4.69 ng mL^-1 , P = 0.007). Also, there was a significant increase in osteocalcin at 24 weeks (3.27 ± 1.06 ng mL^-1 , P = 0.01) in compliant patients. We conclude that 12 weeks of continuous positive airway pressure did not modulate vitamin D or modulate any of the bone turnover markers compared with sham. However, it is plausible that continuous positive airway pressure may have late beneficial effects on vitamin D levels and bone turnover markers in selected groups of patients with obstructive sleep apnea.

Tratamiento del síndrome de apnea-hipopnea obstructiva del sueño (SAHOS) con presión positiva en la vía aérea (PAP)

Para el tratamiento de cualquier enfermedad es necesario un adecuado manejo multidisciplinar e involucrar al paciente en la mejor opción que se requiera a largo plazo; la falta de tratamiento de los pacientes implica una enorme carga para el sistema sanitario y la sociedad. En la actualidad, existen diferentes tratamientos para los pacientes con síndrome de apnea-hipopnea obstructiva del sueño (SAHOS); el de mayor elección, después de descartar anomalías anatómicas susceptibles de cirugía, es el PAP (presión positiva en vía aérea). Las indicaciones para terapia con PAP incluyen pacientes con índice de apnea-hipopnea (IAH) ≥15 eventos/hora o ≥5 y ≤14 eventos/hora y quejas de somnolencia diurna excesiva, deterioro cognitivo, trastorno del afecto o insomnio, hipertensión arterial documentada, enfermedad arterial coronaria o historia de evento cerebrovascular. Es importante recordar que el IAH debe basarse en sueño ≥2 horas de registro polisomnográfico. Hay diferentes modalidades de tratamiento con PAP y se debe intervenir para buscar mejorar la adherencia al dispositivo, principal limitante para alcanzar la eficacia en el tratamiento. El impacto del tratamiento del SAHOS ha sido investigado, pero la mayoría de los estudios reportados son de carácter observacional.

Verifying the Relative Efficacy between Continuous Positive Airway Pressure Therapy and Its Alternatives for Obstructive Sleep Apnea: A Network Meta-analysis

Obstructive sleep apnea (OSA) is a common breathing disorder, and continuous positive airway pressure (CPAP) therapy together with its alternatives has been developed to treat this disease. This network meta-analysis (NMA) was aimed to compare the efficacy of treatments for OSA. Cochrane Library, MEDLINE, and Embase were searched for eligible studies. A conventional and NMA was carried out to compare all therapies. Sleeping characteristics, including Apnea–Hypopnea Index (AHI), Epworth Sleepiness Scale (ESS), arterial oxygen saturation, and arousal index (AI), and changes of blood pressure were selected as outcomes. A total of 84 studies were finally included after rigorous screenings. For the primary outcomes of AHI and ESS, the value of auto-adjusting positive airway pressure (APAP), CPAP, and oral appliance (OA) all showed statistically reduction compared with inactive control (IC). Similar observation was obtained in AI, with treatments of the three active interventions. A lower effect of IC in SaO₂ was exhibited when compared with APAP, CPAP, and OA. Similar statistically significant results were presented in 24 h systolic blood pressure and 24 h DBP when comparing with CPAP. Our NMA identified CPAP as the most efficacious treatment for OSA patients after the evaluation of sleeping characteristics and blood pressures. In addition, more clinical trials are needed for further investigation due to the existence of inconsistency observed in this study.