Effect of CPAP therapy on endothelial function in obstructive sleep apnoea: A systematic review and meta-analysis

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.

Hypoxic and Autonomic Mechanisms from Sleep-Disordered Breathing Leading to Cardiopulmonary Dysfunction

Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder. Its prevalence has increased due to increasing obesity and improved screening and diagnostic strategies. OSA overlaps with cardiopulmonary diseases to promote intermittent hypoxia and autonomic dysfunction. Intermittent hypoxia increases the risk for oxidative stress and inflammation, which promotes endothelial dysfunction and predisposes to atherosclerosis and other cardiovascular complications. OSA is associated with an increased sympathetic nervous system drive resulting in autonomic dysfunction leading to worsening of cardiopulmonary diseases. Cardiovascular diseases are observed in 40% to 80% of OSA patients. Therefore, it is essential to screen and treat cardiovascular diseases.

The Curious Role of PAI-1 in Severe Obstructive Sleep Apnea

Plasminogen activator inhibitor-1 (PAI-1) has a significant role in fibrinolysis, atherogenesis, cellular senescence, and chronic inflammation. OSA (obstructive sleep apnea) leads to increased PAI-1 levels and the development of cardiovascular disease (CVD). The aim of this study was to determine the effects of CPAP therapy on coagulation parameters and PAI-1 in patients with severe OSA. This prospective, controlled study enrolled 57 patients who were newly diagnosed with severe OSA, 37 of whom had had good CPAP adherence after 6 months of therapy (usage of the device for at least 4 h per night), and their data were analyzed. The analysis showed a statistically significant increase in D-dimer values before CPAP therapy (415 (316.5-537.5)) vs. after therapy (499 (327-652)), p = 0.0282, and a decrease in fibrinogen values (3.665 ± 0.752 before CPAP therapy vs. 3.365 ± 0.771 after therapy, p = 0.0075)). PAI-1 concentration values before and after CPAP therapy did not differ significantly (17.35 ± 7.01 ng/mL before CPAP therapy vs. 17.42 ± 6.99 ng/mL after therapy, p = 0.9367). This study shows a tendency for fibrinolytic capacity to improve in patients with OSA after CPAP therapy, although PAI-1 levels did not differ significantly.

A Cross-Sectional Study Evaluating the Association of Brachial Artery Flow Mediated Vasodilation with Physical Activity Measured by Accelerometry in Patients with the Overlap of Obstructive Sleep Apnea and Chronic Obstructive Pulmonary Disease

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in Overlap Syndrome (OS), the co-occurrence of Obstructive Sleep Apnea and Chronic Obstructive Pulmonary Disease. Clustering of patients in subgroups with similar pre-clinical manifestations (ie, endothelial dysfunction) may identify relevant therapeutic phenotype categories for patients with OS who are at high risk of CVD. We therefore conducted a cross-sectional pilot study of endothelial function in 7 patients with OS (Forced Expiratory Volume in 1 second/Forced Vital Capacity < 0.7) on continuous positive airway pressure therapy (n = 7) to assess the relationship between FMD and physical activity. We found a strong association between FMD and step counts (rho = 0.77, p = 0.04); and FMD and moderate physical activity (rho = 0.9, p = 0.005). Further, larger studies are needed to confirm that FMD may identify patients with OS at high risk of CVD who benefit from increased physical activity.

Continuous Positive Airway Pressure but Not GLP1-mediated Weight Loss Improves Early Cardiovascular Disease in Obstructive Sleep Apnea: A Randomized Proof-of-Concept Study

Rationale: Obstructive sleep apnea (OSA) is an independent risk factor for cardiovascular (CV) morbidity and mortality, but the benefit of continuous positive airway pressure (CPAP) is uncertain. However, most randomized controlled trials have focused on the role of CPAP in secondary prevention, although there is growing evidence of a potential benefit on early CV disease. Weight loss in combination with CPAP may be superior but is difficult to achieve and maintain with conventional measures alone. Objectives: The aim of this study was to gain insights into the effect of CPAP on early atherosclerotic processes and to compare it with a glucagon-like peptide (GLP)-1-mediated weight loss regimen in patients with OSA. Methods: We performed a randomized proof-of-concept study comparing CPAP, a GLP1-mediated weight-loss regimen (liraglutide [Lir]), and both in combination for 24 weeks in 30 consecutive patients with OSA (apnea-hypopnea index >15 events/h; body mass index 30-40 kg/m2; and no history of diabetes, heart failure, or unstable CV disease). In addition to extensive evaluation for CV risk factors and endothelial function at baseline and end of study, subjects underwent 18F-fluoro-2-deoxy-D-glucose positron emission tomography-computed tomography (18F-FDG PET-CT) for the measurement of aortic wall inflammation (target-to-background ratio) and coronary computed tomography angiography for semiautomated coronary plaque analysis. Results: Baseline characteristics were similar between groups. CPAP alone and in combination resulted in greater reduction in apnea-hypopnea index than Lir alone (mean difference, -45 and -43 events/h, respectively, vs. -12 events/h; P < 0.05). Both Lir and combination treatment led to significant weight loss, but only CPAP alone resulted in significant decrease in vascular inflammation (aortic wall target-to-background ratio from 2.03 ± 0.34 to 1.84 ± 0.43; P = 0.010), associated with an improvement in endothelial function and a decrease in C-reactive protein. Low-attenuation coronary artery plaque volume as a marker of unstable plaque also decreased with CPAP (from 571 ± 490 to 334 ± 185 mm3) and with combination therapy (from 401 ± 145 to 278 ± 126 mm3) but not with Lir. Conclusions: These data suggest that CPAP therapy, but not GLP1-mediated weight loss, improves vascular inflammation and reduces unstable plaque volume in patients with OSA. Further large randomized controlled studies are warranted to assess the benefit of CPAP therapy in modifying early CV disease. Clinical trial registered with www.clinicaltrials.gov (NCT04186494).

Relationship between obstructive sleep apnea and pulmonary hypertension: past, present and future

INTRODUCTION

Obstructive sleep apnea (OSA) is a widely prevalent condition with consequent multiple organ systems complications. There is consensus that OSA is associated with negative effects on pulmonary hemodynamics but whether it contributes to development of clinical pulmonary hypertension (PH) is unclear.

AREAS COVERED

In this review, we (1) highlight previous studies looking into the possible bidirectional association of OSA and PH, focusing on those that explore clinical prognostic implications, (2) explore potential pathophysiology, (3) discuss the new metrics in OSA, (4) describe endo-phenotyping of OSA, (5) recommend possible risk assessment and screening pathways.

EXPERT OPINION

Relying only on symptoms to consider a sleep study in PH patients is a missed opportunity to detect OSA, which, if present and not treated, can worsen outcomes. The potential prognostic role of sleep study metrics such as oxygen desaturation index (ODI), hypoxic burden (HB) and ventilatory burden (VB) in OSA should be studied in prospective trials to identify patients at risk for PH. AHI alone has not provided clarity. In those with PH, we should consider replacing ambulatory overnight pulse oximetry (OPO) with home sleep studies (HST). In PH patients, mild OSA should be sufficient to consider PAP therapy.

Continuous Positive Airway Pressure Effect on Progression of Retinal Disease in Patients with Sleep Apnea and Nonproliferative Diabetic Retinopathy: A Randomized Clinical Trial

Rationale: Obstructive sleep apnea (OSA) is associated with impaired glycemic control and a higher risk of vascular complications, such as diabetic retinopathy. However, the effect of apnea-hypopnea suppression on retinal disease progression is unclear. Objectives: To evaluate the efficacy and safety of continuous positive airway pressure (CPAP) for the reduction of retinal lesions in patients with non-proliferative diabetic retinopathy (NPDR) and OSA. Methods: This open-label, parallel-group, randomized controlled trial was conducted between October 2016 and February 2020 at a university hospital in Spain. The date of final follow-up was March 2, 2021. Eighty-three patients with OSA and mild to moderate NPDR receiving stable treatment were randomized to receive CPAP and usual care (43 patients with 79 available eyes) or usual care alone (40 patients with 67 available eyes) for 52 weeks. The primary outcomes were the change in the percentage of eyes with retinal exudates and the number of retinal microhemorrhages from baseline to week 52. We also assessed the effects of both interventions on retinal thickness by means of optical coherence tomography, serum concentrations of glycated hemoglobin, blood pressure, lipid concentrations, sleepiness, and quality of life. Results: Fifty-two weeks of CPAP treatment was associated with reductions from baseline in the percentage of eyes with hard exudates (overall difference, -21.7%; P = 0.035) and in optical coherence tomography indices of retinal edema, including central subfield thickness and cube volume. However, in patients who met prespecified criteria for CPAP adherence, treatment was also associated with a higher number of retinal microhemorrhages at 52 weeks (intergroup adjusted difference, 6.0 [95% confidence interval, 0.6-11.5]; P = 0.029), which was directly related to prescribed pressure levels. CPAP treatment also improved glycemic control, sleepiness, and general health-related quality of life. Conclusions: In patients with OSA and NPDR, long-term CPAP treatment in addition to usual care may result in slower progression of retinal disease, although it could also induce an increase in retinal microhemorrhages. Clinical trial registered with www.clinicaltrials.gov (NCT02874313).

Hypoxic burden to guide CPAP treatment allocation in patients with obstructive sleep apnoea: a post hoc study of the ISAACC trial

BACKGROUND

Hypoxic burden (HB) has emerged as a strong predictor of cardiovascular risk in obstructive sleep apnoea (OSA). We aimed to assess the potential of HB to predict the cardiovascular benefit of treating OSA with continuous positive airway pressure (CPAP).

METHODS

This was a post hoc analysis of the ISAACC trial (ClinicalTrials.gov: NCT01335087) including non-sleepy patients with acute coronary syndrome (ACS) diagnosed with OSA (apnoea-hypopnoea index ≥15 events·h-1) by respiratory polygraphy. Patients were randomised to CPAP or usual care and followed for a minimum of 1 year. HB was calculated as the total area under all automatically identified desaturations divided by total sleep time. Patients were categorised as having high or low baseline HB according to the median value (73.1%min·h-1). Multivariable Cox regression models were used to assess whether the effect of CPAP on the incidence of cardiovascular outcomes was dependent on the baseline HB level.

RESULTS

The population (362 patients assigned to CPAP and 365 patients assigned to usual care) was middle-aged (mean age 59.7 years), overweight/obese and mostly male (84.5%). A significant interaction was found between the treatment arm and the HB categories. In the high HB group, CPAP treatment was associated with a significant reduction in the incidence of cardiovascular events (HR 0.57, 95% CI 0.34-0.96). In the low HB group, CPAP-treated patients exhibited a trend toward a higher risk of cardiovascular outcomes than those receiving usual care (HR 1.33, 95% CI 0.79-2.25). The differential effect of the treatment depending on the baseline HB level followed a dose-response relationship.

CONCLUSION

In non-sleepy ACS patients with OSA, high HB levels were associated with a long-term protective effect of CPAP on cardiovascular prognosis.

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.

Cognitive Impairments, Neuroinflammation and Blood-Brain Barrier Permeability in Mice Exposed to Chronic Sleep Fragmentation during the Daylight Period

Obstructive sleep apnea (OSA) is a chronic condition characterized by intermittent hypoxia (IH) and sleep fragmentation (SF). In murine models, chronic SF can impair endothelial function and induce cognitive declines. These deficits are likely mediated, at least in part, by alterations in Blood-brain barrier (BBB) integrity. Male C57Bl/6J mice were randomly assigned to SF or sleep control (SC) conditions for 4 or 9 weeks and in a subset 2 or 6 weeks of normal sleep recovery. The presence of inflammation and microglia activation were evaluated. Explicit memory function was assessed with the novel object recognition (NOR) test, while BBB permeability was determined by systemic dextran-4kDA-FITC injection and Claudin 5 expression. SF exposures resulted in decreased NOR performance and in increased inflammatory markers and microglial activation, as well as enhanced BBB permeability. Explicit memory and BBB permeability were significantly associated. BBB permeability remained elevated after 2 weeks of sleep recovery (p < 0.01) and returned to baseline values only after 6 weeks. Chronic SF exposures mimicking the fragmentation of sleep that characterizes patients with OSA elicits evidence of inflammation in brain regions and explicit memory impairments in mice. Similarly, SF is also associated with increased BBB permeability, the magnitude of which is closely associated with cognitive functional losses. Despite the normalization of sleep patterns, BBB functional recovery is a protracted process that merits further investigation.

New perspective on exploring the predictive factors of blood pressure reduction during CPAP treatment in people with severe OSA and hypertension: a prospective observational study

BACKGROUND

The predictive factors of blood pressure (BP) response to continuous positive airway pressure (CPAP) in obstructive sleep apnoea (OSA) are still being explored. We aimed to assess the antihypertensive effect of CPAP considering the obstructive respiratory event-triggered BP surge profiles in 130 subjects with severe OSA and untreated hypertension.

METHODS

Nocturnal BP was monitored continuously and synchronised with polysomnography. Event-triggered BP surge profiles were studied: BP surge as the value of event-related systolic BP (SBP) elevation; BP index as the number of BP surge events of ≥10 mm Hg per hour. Patients were then divided into two groups according to the median BP index (high and low BP surge groups) and assigned to 4 weeks of CPAP. Changes in BPs and plasma biomarkers were compared. After the initial evaluation, patients with a better BP response in the high BP surge group were then followed up for the second evaluation at 24 months.

RESULTS

Overall, a modest decrease was observed in both office and asleep BPs at the 4-week follow-up; however, BPs dropped more markedly in patients in the high BP surge group than those in the low BP surge group, in both office SBP (5.3 mm Hg vs 2.2 mm Hg, p=0.003) and diastolic BP (4.0 mm Hg vs 1.2 mm Hg, p<0.001), especially the asleep SBP (9.0 mm Hg vs 2.1 mm Hg, p<0.001). For 30 cases in the high BP surge group, optimal BP control was achieved in 60.0% of patients and BP<140/90 mm Hg reached up to 83.3% after 24 months of CPAP. Linear regression revealed that BP index was significantly associated with BP decrease during CPAP treatment.

CONCLUSIONS

Our results suggested that high event-triggered BP surge was a sensitive predictor of BP response to CPAP in patients with severe OSA and untreated hypertension.

TRIAL REGISTRATION NUMBER

Clinical Trials.gov Identifier: NCT03246022; https://clinicaltrials.gov/ct2/show/NCT03246022?term=NCT+03246022&draw=2&rank=1.

A State-of-the-Art Review on Sleep Apnea Syndrome and Heart Failure

Heart failure (HF) affects many patients worldwide every year. It represents a leading cause of hospitalization and still, today, mortality remains high, albeit the progress in treatment strategies. Several factors contribute to the development and progression of HF. Among these, sleep apnea syndrome represents a common but still underestimated factor because its prevalence is substantially higher in patients with HF than in the general population and is related to a worse prognosis. This review summarizes the current knowledge about sleep apnea syndrome coexisting with HF in terms of morbidity and mortality to provide actual and future perspectives about the diagnosis, evaluation, and treatment of this association.

Continuous Positive Airway Pressure Effect on Albuminuria Progression in Patients with Obstructive Sleep Apnea and Diabetic Kidney Disease: A Randomized Clinical Trial

Rationale: Obstructive sleep apnea (OSA) is associated with impaired glycemic control and a higher risk of vascular complications, such as diabetic kidney disease (DKD). However, the effect of apnea-hypopnea suppression on DKD progression is unclear. Objectives: To assess the effect of continuous positive airway pressure (CPAP) on the urinary albumin-to-creatinine ratio (UACR) in patients with DKD and OSA. Methods: In a 52-week, multicentric, open-label, parallel, and randomized clinical trial, 185 patients with OSA and DKD were randomized to CPAP and usual care (n = 93) or usual care alone (n = 92). Measurements and Main Results: UACR, estimated glomerular filtration rate, serum concentrations of creatinine and glycated hemoglobin, insulin resistance, lipid concentrations, sleepiness, and quality of life. A 52-week change in UACR from baseline did not differ significantly between the CPAP group and the usual-care group. However, in per-protocol analyses that included 125 participants who met prespecified criteria for adherence, CPAP treatment was associated with a great reduction in UACR (mean difference, -10.56% [95% confidence interval, -19.06 to -2.06]; P = 0.015). CPAP effect on UACR was higher in nonsleepy patients with more severe OSA, worse renal function, and a more recent diagnosis of DKD. CPAP treatment also improved glycemic control and insulin resistance, as well as sleepiness and health-related quality of life. Conclusions: In patients with OSA and DKD, the prescription of CPAP did not result in a statistically significant reduction in albuminuria. However, good adherence to CPAP treatment in addition to usual care may result in long-term albuminuria reduction compared with usual care alone. Clinical trial registered with www.clinicaltrials.gov (NCT02816762).

Ischemia with Nonobstructive Coronary Artery Disease and Atrial Cardiomyopathy-Two Sides of the Same Story?

Ischemia with nonobstructive coronary artery disease (INOCA) is increasingly recognized as a significant cause of angina, myocardial remodeling, and eventually heart failure (HF). Coronary microvascular dysfunction (CMD) is a major endotype of INOCA, and it is caused by structural and functional alterations of the coronary microcirculation. At the same time, atrial cardiomyopathy (ACM) defined by structural, functional, and electrical atrial remodeling has a major clinical impact due to its manifestations: atrial fibrillation (AF), atrial thrombosis, stroke, and HF symptoms. Both these pathologies share similar risk factors and have a high comorbidity burden. CMD causing INOCA and ACM frequently coexist. Thus, questions arise whether there is a potential link between these pathologies. Does CMD promote AF or the reverse? Which are the mechanisms that ultimately lead to CMD and ACM? Are both part of a systemic disease characterized by endothelial dysfunction? Lastly, which are the therapeutic strategies that can target endothelial dysfunction and improve the prognosis of patients with CMD and ACM? This review aims to address these questions by analyzing the existing body of evidence, offering further insight into the mechanisms of CMD and ACM, and discussing potential therapeutic strategies.

The relationship between adherence to continuous positive airway pressure and nasal resistance measured by rhinomanometry in patients with obstructive sleep apnea syndrome

Nasal breathing disorders are associated with obstructive sleep apnea (OSA) syndrome and influence the availability of continuous positive airway pressure (CPAP) therapy. However, information is scarce about the impact of nasal resistance assessed by rhinomanometry on CPAP therapy. This study aimed to examine the relationship between CPAP adherence and nasal resistance evaluated by rhinomanometry, and to identify clinical findings that can affect adherence to CPAP therapy for patients with OSA. This study included 260 patients (199 men, 61 women; age 58 [interquartile ranges (IQR) 50-66] years) with a new diagnosis of OSA who underwent rhinomanometry (before, and 1 and 3 months after CPAP introduction) between January 2011 and December 2018. CPAP use was recorded, and the good and poor CPAP adherence groups at the time of patient registration were compared. Furthermore, those with improved and unimproved pre-CPAP high rhinomanometry values were also compared. Their apnea-hypopnea index (AHI) by polysomnography at diagnosis was 45.6 (IQR 33.7-61.6)/hour, but the residual respiratory event (estimated AHI) at enrollment was 2.5 (IQR 1.4-3.9)/hour and the usage time was 318 (IQR 226-397) minutes, indicating that CPAP was effective and adherence was good. CPAP adherence was negatively correlated with nasal resistance (r = -0.188, p = 0.002). The participants were divided into good (n = 153) and poor (n = 107) CPAP adherence groups. In the poor adherence group, rhinomanometry values before CPAP introduction were worse (inspiration, p = 0.003; expiration, p = 0.006). There was no significant difference in patient background when comparing those with improved (n = 16) and unimproved (n = 12) pre-CPAP high rhinomanometry values. However, CPAP usage time was significantly longer in the improved group 1 month (p = 0.002) and 3 months (p = 0.026) after CPAP introduction. The results suggest that nasal resistance evaluated by rhinomanometry is a useful predictor of CPAP adherence, and that improved rhinomanometry values may contribute to extending the duration of CPAP use.

Should we treat with continuous positive airway pressure severe non-sleepy obstructive sleep apnea individuals without underlying cardiovascular disease?

The majority of the current international obstructive sleep apnea (OSA) guidelines base the recommendation to treat OSA with continuous positive airway pressure (CPAP) on the presence of symptoms (principally, albeit not exclusively on daytime hypersomnolence). In nonsleepy patients, even with severe OSA, controversies remain, as clear evidence supporting CPAP treatment of this subgroup of OSA patients is lacking. However, given the nonnegligible proportion of non-sleepy OSA patients, clinicians often face a serious dilemma since CPAP treatment in these patients may prove to be not cost-effective. Here, we propose a simple three-step-based algorithm that attempts to better phenotype non-sleepy OSA patients prior to reaching a CPAP treatment decision while also considering a series of clinically relevant elements in the process that may improve with CPAP therapy. Such algorithm focuses on the presence of several OSA symptoms that are susceptible to benefit from treatment and also relies on OSA phenotypes that need to be considered in an effort to achieve optimal cardiovascular prevention. Here, we attempt to establish a framework for clinicians who are evaluating severe nonsleepy OSA patients in their practices. However, the algorithm proposal needs to be extensively validated before being systematically implemented in clinical settings.

Symptoms Underestimate the Presence of Obstructive Sleep Apnea in Patients with Spontaneous Cerebrospinal Fluid Leaks of the Temporal Bone

OBJECTIVE

To determine the severity of symptoms and degree of obstructive sleep apnea (OSA) in patients with spontaneous cerebrospinal fluid (sCSF) leaks of the temporal bone given the known association between sCSF leaks and OSA.

STUDY DESIGN

Retrospective case review.

SETTING

Ambulatory clinics in tertiary referral centers.

PATIENTS

Polysomnogram testing in 34 consecutive patients who had been diagnosed with sCSF leaks of the temporal bone was examined. Diagnosis of sCSF leak was defined as biochemically confirmed CSF from middle ear fluid with no other obvious source.

INTERVENTION

Diagnostic.

MAIN OUTCOMES MEASURES

Patient characteristics (age, sex, body mass index, Epworth Sleepiness Scale score, presence of hypoxia, overnight change in blood pressure, and apnea hypopnea index [AHI]) were recorded. Diagnosis of OSA was defined as mild when AHI ≥5 and <15/h, moderate when AHI ≥15 and <30/h, and severe when AHI ≥30/h.

RESULTS

Of the 34 patients, 28 (82%) had a confirmed diagnosis of OSA. There was a male predisposition in those with OSA, and 17 of 28 (61%) were male. A majority were overweight, and the mean body mass index was 30.1 (SD, 4.8; range, 23.2-40) kg/m2. The mean severity of OSA was moderate, and the mean AHI was 28.7 (SD, 21.9; range, 5.4-92.8). Of the 28 patients, 13 with OSA (46%) had Epworth Sleepiness Scale scores higher than 8, suggesting that many were asymptomatic for excessive daytime sleepiness at the time of presentation.

CONCLUSION

OSA is highly prevalent among patients with sCSF leaks of the temporal bone. Patients with sCSF leaks irrespective of symptoms of OSA should undergo formal polysomnogram testing.

Positive Airway Pressure Adherence, Mortality, and Cardiovascular Events in Patients with Sleep Apnea

Rationale: Randomized controlled trials showed no effect of positive airway pressure (PAP) therapy for obstructive sleep apnea (OSA) on cardiovascular (CV) risk. However, patient selection and low PAP adherence preclude the generalization of their data to clinical samples. Objectives: To evaluate the association between hours of PAP use, mortality, and CV morbidity in real-life conditions. Methods: Data from the Pays de la Loire Cohort were linked to health administrative data to identify incident major adverse cardiovascular events (MACEs; a composite outcome of mortality, stroke, and cardiac diseases) in patients with OSA who were prescribed PAP. Cox proportional hazards analyses were conducted to evaluate the association between MACEs and quartiles of average daily PAP use over the study period. Measurements and Main Results: After a median follow-up of 6.6 years, 961 of 5,138 patients experienced MACEs. Considering nonadherent patients (0-4 h/night) as the reference group, adjusted hazard ratios (95% confidence intervals) for MACEs were 0.87 (0.73-1.04) for the 4-6 h/night group, 0.75 (0.62-0.92) for the 6-7 h/night group, and 0.78 (0.65-0.93) for the ⩾7 h/night group (P = 0.0130). Sensitivity analyses using causal inference approaches confirmed the association of PAP use with MACEs. The association was stronger in male patients (P value for interaction = 0.0004), patients without overt CV disease at diagnosis (P < 0.0001), and those belonging to the excessively sleepy symptom subtype (P = 0.060). Conclusions: These real-life clinical data demonstrate a dose-response relationship between PAP adherence and incident MACEs in OSA. Patient support programs may help improve PAP adherence and CV outcomes in patients with OSA.

Temporal changes in coronary artery function and flow velocity reserve in mice exposed to chronic intermittent hypoxia

Study Objectives

Obstructive sleep apnea (OSA) is a chronic condition characterized by intermittent hypoxia (IH) that is implicated in an increased risk of cardiovascular disease (i.e., coronary heart disease, CHD) and associated with increased overall and cardiac-specific mortality. Accordingly, we tested the hypothesis that experimental IH progressively impairs coronary vascular function and in vivo coronary flow reserve.

Methods

Male C57BL/6J mice (8-week-old) were exposed to IH (FiO2 21% 90 s–6% 90 s) or room air (RA; 21%) 12 h/day during the light cycle for 2, 6, 16, and 28 weeks. Coronary artery flow velocity reserve (CFVR) was measured at each time point using a Doppler system. After euthanasia, coronary arteries were micro-dissected and mounted on wire myograph to assess reactivity to acetylcholine (ACh) and sodium nitroprusside (SNP).

Results

Endothelium-dependent coronary relaxation to ACh was preserved after 2 weeks of IH (80.6 ± 7.8%) compared to RA (87.8 ± 7.8%, p = 0.23), but was significantly impaired after 6 weeks of IH (58.7 ± 16.2%, p = 0.02). Compared to ACh responses at 6 weeks, endothelial dysfunction was more pronounced in mice exposed to 16 weeks (48.2 ± 5.3%) but did not worsen following 28 weeks of IH (44.8 ± 11.6%). A 2-week normoxic recovery after a 6-week IH exposure reversed the ACh abnormalities. CFVR was significantly reduced after 6 (p = 0.0006) and 28 weeks (p &lt; 0.0001) of IH when compared to controls.

Conclusion

Chronic IH emulating the hypoxia-re-oxygenation cycles of moderate-to-severe OSA promotes coronary artery endothelial dysfunction and CFVR reductions in mice, which progressively worsen until reaching asymptote between 16 and 28 weeks. Normoxic recovery after 6 weeks exposure reverses the vascular abnormalities.

The multisystemic effects of oral appliance therapy for obstructive sleep apnea: A narrative review

Obstructive sleep apnea (OSA) is a chronic condition accompanied by repeated obstruction of the upper airway during sleep despite respiratory efforts, resulting in intermittent hypoxemia, altered sleep structure, and sympathetic activation. Previous studies have shown a significant association between OSA and general health issues such as cardiovascular diseases, endocrine disorders, neurocognitive function decline, and poor quality of life. Continuous positive airway pressure (CPAP) has been considered as the first line treatment for OSA. However, accumulating evidence supports the role of oral appliance (OA) therapy, including mandibular advancement devices, as an alternative option for snoring and OSA patients who do not comply with or refuse CPAP usage. Despite a generally favorable outcome of OA therapy for OSA related respiratory indices, studies focusing on the impact of systemic effects of OA therapy in OSA patients are relatively scarce compared with the extensive literature focusing on the systemic effects of CPAP. Therefore, this article aimed to provide an overview of the current evidence regarding the multisystemic effects of OA therapy for OSA.

Effect of obstructive sleep apnoea on retinal microvascular function: a randomised controlled trial

PURPOSE

Retinal microvascular endothelial dysfunction is thought to be of importance in the development of ocular vascular diseases. Obstructive sleep apnoea (OSA) causes macrovascular endothelial dysfunction, but the effect of OSA on retinal microvascular endothelial function is not known. We aimed to determine the effect of OSA on retinal microvascular function.

METHODS

We conducted a multi-centre, double-blind, randomised, parallel, controlled trial in patients with known moderate-to-severe OSA, established on continuous positive airway pressure (CPAP). Participants were randomised to 14 nights of either continued CPAP or sham CPAP to generate a return of OSA. Retinal vascular responses to flickering light were measured using dynamic vessel analysis both at baseline and after 14 nights of intervention. The primary outcome was the change from baseline to follow-up in the area under the curve of the arteriolar response to flickering light, sham CPAP versus continued CPAP.

RESULTS

Nineteen patients were randomised to sham CPAP, and 18 patients were randomised to continued CPAP. There was no significant effect of CPAP withdrawal and return of OSA on retinal responses, with a change in the area under the curve of the arteriole response to flickering light of + 3.8 arbitrary units (95% CI - 10.6 to + 18.2, p = 0.59), sham CPAP versus continued CPAP.

CONCLUSIONS

CPAP withdrawal and a return of OSA had no significant effect on retinal microvascular responses. This contrasts with the effect of CPAP withdrawal on macrovascular endothelial function and suggests that OSA has different effects on macrovascular and microvascular endothelial function. ISRCTN 78082983, 23/10/2014, Prospectively registered.

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.

Association between obstructive sleep apnea and venous thromboembolism recurrence: results from a French cohort

Background

Growing evidence suggests the relationship between obstructive sleep apnea (OSA) and venous thromboembolism (VTE). Few studies focused on VTE recurrence risk associated with OSA after anticoagulation cessation.

Methods

In a prospective cohort study, patients with documented VTE, were followed for an indefinite length of time and VTE recurrence were documented and adjudicated. The primary outcome was recurrent VTE after anticoagulation discontinuation. Secondary outcomes included all-cause mortality and the clinical presentation of VTE. Univariable and multivariable analyses were performed to identify risk factors for recurrence and mortality.

Results

Among the 2109 patients with documented VTE included, 74 patients had moderate to severe OSA diagnosis confirmed by home sleep test or polysomnography. During a median follow-up of 4.8 (interquartile range 2.5–8.0) years recurrent VTE occurred in 252 patients (9 with OSA and 243 without OSA). The recurrence risk in the univariable and multivariable analysis was not increased in patients with OSA, regardless of the time of diagnosis (before or after index VTE or pooled). VTE phenotype was significantly more often PE with or without associated deep vein thrombosis in the first event and recurrence for OSA patients compared to non-OSA patients. The risk of death was not increased in the OSA population compared to non-OSA patients in multivariable analysis.

Conclusions

In patients with OSA and VTE, the risk of all-cause mortality and VTE recurrence after anticoagulation discontinuation was not increased compared to non-OSA patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12959-021-00358-8.

Relationships Between Obstructive Sleep Apnea and Cardiovascular Disease: A Bibliometric Analysis (2010-2021)

Background

Obstructive sleep apnea (OSA) is a common disease that can lead to intermittent hypoxia, increased sympathetic overdrive, and excessive oxidative stress, and eventually lead to cardiovascular/cerebrovascular diseases and metabolic disorders. The prevalence of OSA is reported to be higher in people with certain cardiovascular diseases (CVD). Therefore, the relationship between OSA and CVD has been gradually favored by researchers.

Material/Methods

Data were downloaded from the Web of Science Core Collection database. Citespace was used to remove duplicated data and construct knowledge visual maps.

Results

A total of 7047 publications were obtained. The USA was the largest contributor as well as an important player in the cooperation network between nations. The leading institution was the Mayo Clinic. Our study ultimately identified the top 5 hotspots and 4 research frontiers in this field. Top 5 hotspots were: the specific types of obstructive sleep apnea-related cardiovascular and metabolic co-morbidities, the curative effects of CPAP on these co-morbidities, the specific mechanisms of co-morbidities, the importance of polysomnography on OSA and its co-morbidities with CVD, and the prevalence of OSA and its co-morbidities with CVD in particular populations. The top 4 frontiers were: the relationship between OSA and resistant hypertension, the molecular mechanisms of OSA and its co-morbidities with CVD, specific medications and treatment guidelines for the co-morbidities, and the mainstream research methods in this field.

Conclusions

This study provides insight and valuable information for researchers and helps to identify new perspectives concerning potential collaborators and cooperative institutions, hot topics, and research frontiers in this field.

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.

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.

Non-invasive positive airway pressure therapy for improving erectile dysfunction in men with obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea syndrome (OSAS) is associated with several chronic diseases, including erectile dysfunction (ED). The association of OSAS and ED is far more common than might be found by chance; the treatment of OSAS with non-invasive positive airway pressure therapy is associated with improvement of respiratory symptoms, and may contribute to the improvement of associated conditions, such as ED.

OBJECTIVES

To assess the effectiveness and acceptability of non-invasive positive airway pressure therapy for improving erectile dysfunction in OSAS.

SEARCH METHODS

We identified studies from the Cochrane Airways Trials Register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, AMED EBSCO, and LILACS, the US National Institutes of Health ongoing trials register ClinicalTrials.gov, and the World Health Organisation international clinical trials registry platform to 14 June 2021, with no restriction on date, language, or status of publication. We checked the reference lists of all primary studies, and review articles for additional references, and relevant manufacturers' websites for study information. We also searched specific conference proceedings for the British Association of Urological Surgeons; the European Association of Urology; and the American Urological Association to 14 June 2021.

SELECTION CRITERIA

We considered randomised controlled trials (RCTs) with a parallel or cross-over design, or cluster-RCTs, which included men aged 18 years or older, with OSAS and ED. We considered RCTs comparing any non-invasive positive airway pressure therapy (such as continuous positive airways pressure (CPAP), bilevel positive airway pressure (BiPAP), variable positive airway pressure (VPAP), or similar devices) versus sham, no treatment, waiting list, or pharmacological treatment for ED. The primary outcomes were remission of ED and serious adverse events; secondary outcome were sex-related quality of life, health-related quality of life, and minor adverse events.

DATA COLLECTION AND ANALYSIS

Two review authors independently conducted study selection, data extraction, and risk of bias assessment. A third review author solved any disagreement. We used the Cochrane RoB 1 tool to assess the risk of bias of the included RCTs. We used the GRADE approach to assess the certainty of the body of evidence. To measure the treatment effect on dichotomous outcomes, we used the risk ratio (RR); for continuous outcomes, we used the mean difference (MD). We calculated 95% confidence intervals (CI) for these measures. When possible (data availability and homogeneous studies), we used a random-effect model to pool data with a meta-analysis.

MAIN RESULTS

We included six RCTs (all assessing CPAP as the non-invasive positive airway pressure therapy device), with a total of 315 men with OSAS and ED. All RCTs presented some important risk of bias related to selection, performance, assessment, or reporting bias. None of included RCTs assessed the ED remission rate, and we used the provided ED mean scores as a proxy. CPAP versus no CPAP There is uncertainty about the effect of CPAP on mean ED scores after 4 weeks, using the International index of erectile function (IIEF-5, higher = better; MD 7.50, 95% CI 4.05 to 10.95; 1 RCT; 27 participants; very low-certainty evidence), and after 12 weeks (IIEF-ED, ED domain; MD 2.50, 95% CI -1.10 to 6.10; 1 RCT; 57 participants; very low-certainty evidence, downgraded due to methodological limitations and imprecision). There is uncertainty about the effect of CPAP on sex-related quality of life after 12 weeks, using the Self-esteem and relationship test (SEAR, higher = better; MD 1.00, 95% CI -8.09 to 10.09; 1 RCT; 57 participants; very low-certainty evidence, downgraded due to methodological limitations and imprecision); no serious adverse events were reported after 4 weeks (1 RCT; 27 participants; very low-certainty evidence, downgraded due to methodological limitations and imprecision). CPAP versus sham CPAP One RCT assessed this comparison (61 participants), but we were unable to extract outcomes for this comparison due to the factorial design and reporting of this trial. CPAP versus sildenafil (phosphodiesterase type 5 inhibitors) Sildenafil may slightly improve erectile function at 12 weeks when compared to CPAP, measured with the IIEF-ED (MD -4.78, 95% CI -6.98 to -2.58; 3 RCTs; 152 participants; I² = 59%; low-certainty evidence, downgraded due to methodological limitations). There is uncertainty about the effect of CPAP on sex-related quality of life after 12 weeks, measured with the Erectile Dysfunction Inventory of Treatment Satisfaction questionnaire (EDITS, higher = better; MD -1.24, 95% CI -1.80 to -0.67; 2 RCTs; 122 participants; I² = 0%; very low-certainty evidence, downgraded due to methodological limitations). No serious adverse events were reported for either group (2 RCTs; 70 participants; very low-certainty evidence, downgraded due to methodological limitations and imprecision). There is uncertainty about the effects of CPAP when compared to sildenafil for the incidence of minor adverse events (RR 1.33, 95% CI 0.34 to 5.21; 1 RCT; 40 participants; very low-certainty evidence, downgraded due to methodological limitations and imprecision). The confidence interval was wide and neither a significant increase nor reduction in the risk of minor adverse events can be ruled out with the use of CPAP (4/20 men complained of nasal dryness in the CPAP group, and 3/20 men complained of transient flushing and mild headache in the sildenafil group).

AUTHORS' CONCLUSIONS

When compared with no CPAP, we are uncertain about the effectiveness and acceptability of CPAP for improving erectile dysfunction in men with obstructive sleep apnoea. When compared with sildenafil, there is some evidence that sildenafil may slightly improve erectile function at 12 weeks.

Novel non-invasive assessment of upper airway inflammation in obstructive sleep apnea using positron emission tomography/magnetic resonance imaging

PURPOSE

To develop a novel non-invasive technique to quantify upper airway inflammation using positron emission tomography/magnetic resonance imaging (PET/MRI) in patients with obstructive sleep apnea (OSA).

METHODS

Patients with treatment naïve moderate-to-severe OSA underwent [18F]-fluoro-2-deoxy-D-glucose (FDG) PET/MRI. Three readers independently performed tracings of the pharyngeal soft tissue on MRI. Standardized uptake values (SUV) were generated from region of interest (ROI) tracings on corresponding PET images. Background SUV was measured from the sternocleidomastoid muscle. SUV and target-to-background (TBR) were compared across readers using intraclass correlation coefficient (ICC) analyses. SUV from individual image slices were compared between each reader using Bland-Altman plots and Pearson correlation coefficients. All tracings were repeated by one reader for assessment of intra-reader reliability.

RESULTS

Five participants completed our imaging protocol and analysis. Median age, body mass index, and apnea-hypopnea index were 41 years (IQR 40.5-68.5), 32.7 kg/m² (IQR 28.1-38.1), and 30.7 event per hour (IQR 19.5-48.1), respectively. The highest metabolic activity regions were consistently localized to palatine or lingual tonsil adjacent mucosa. Twenty-five ICC met criteria for excellent agreement. The remaining three were TBR measurements which met criteria for good agreement. Head-to-head comparisons revealed strong correlation between each reader.

CONCLUSIONS

Our novel imaging technique demonstrated reliable quantification of upper airway FDG avidity. This technology has implications for future work exploring local airway inflammation in individuals with OSA and exposure to pollutants. It may also serve as an assessment tool for response to OSA therapies.

The treatment of mild OSA with CPAP or mandibular advancement device and the effect on blood pressure and endothelial function after one year of treatment

STUDY OBJECTIVES

To evaluate and compare the effects of continuous positive airway pressure (CPAP), use of a mandibular advancement device (MAD), and no treatment on 24-hour ambulatory blood pressure monitoring and peripheral arterial tonometry at 6 and 12 months follow-up in individuals with mild obstructive sleep apnea (OSA), and in a subgroup who had an apnea-hypopnea index of < 5 events/h and adherence of ≥ 4 hours per night (effective-treatment subgroups).

METHODS

The inclusion criteria were individuals with mild obstructive sleep apnea, any sex, age between 18 and 65 years, and a body mass index of ≤ 35 kg/m². Patients were randomized into CPAP, MAD, and no-treatment groups. The evaluations included physical examination, full polysomnography, 24-hour ambulatory blood pressure monitoring, and peripheral arterial tonometry at baseline and after 6 and 12 months. A generalized linear mixed model was used for comparisons.

RESULTS

The CPAP and MAD groups had lower apnea-hypopnea indexes than the control group at 6 and 12 months, and the CPAP group had higher blood oxygen levels (SpO₂) than the MAD group. The MAD group had more hours of treatment per night and better adaptation to treatment than the CPAP group (MAD: 5.7 ± 2.7 h/night; CPAP: 3.8 ± 3.4 h/night; MAD: 16% did not adapt; CPAP: 42% did not adapt). No differences were found in the total sample and effective treatment in relation to peripheral arterial tonometry or 24-hour ambulatory blood pressure monitoring outcomes.

CONCLUSIONS

Treatment of mild obstructive sleep apnea with CPAP or MAD did not improve blood pressure or endothelial function after 1 year, even in patients with effective treatment.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Continuous Positive Airway Pressure and Oral Appliances Treatments in Mild Obstructive Sleep Apnea; URL: https://clinicaltrials.gov/ct2/show/NCT01461486; Identifier: NCT01461486.

Cardiovascular Disorders Triggered by Obstructive Sleep Apnea-A Focus on Endothelium and Blood Components

Obstructive sleep apnea (OSA) is known to be an independent cardiovascular risk factor. Among arousal from sleep, increased thoracic pressure and enhanced sympathetic activation, intermittent hypoxia is now considered as one of the most important pathophysiological mechanisms contributing to the development of endothelial dysfunction. Nevertheless, not much is known about blood components, which justifies the current review. This review focuses on molecular mechanisms triggered by sleep apnea. The recurrent periods of hypoxemia followed by reoxygenation promote reactive oxygen species (ROS) overproduction and increase inflammatory response. In this review paper we also intend to summarize the effect of treatment with continuous positive airway pressure (CPAP) on changes in the profile of the endothelial function and its subsequent potential clinical advantage in lowering cardiovascular risk in other comorbidities such as diabetes, atherosclerosis, hypertension, atrial fibrillation. Moreover, this paper is aimed at explaining how the presence of OSA may affect platelet function and exert effects on rheological activity of erythrocytes, which could also be the key to explaining an increased risk of stroke.

Longitudinal changes in regional cerebral blood flow in late middle-aged and older adults with treated and untreated obstructive sleep apnea

Obstructive sleep apnea (OSA) is associated with abnormal cerebral perfusion at wakefulness, but whether these anomalies evolve over time is unknown. Here, we examined longitudinal changes in regional cerebral blood flow (rCBF) distribution in late middle‐aged and older adults with treated or untreated OSA. Twelve controls (64.8 ± 8.0 years) and 23 participants with newly diagnosed OSA (67.8 ± 6.2 years) were evaluated with polysomnography and cerebral ^99mTc‐HMPAO single‐photon emission computed tomography during wakeful rest. OSA participants were referred to a sleep apnea clinic and 13 of them decided to start continuous positive airway pressure (CPAP). Participants were tested again after 18 months. Voxel‐based analysis and extracted relative rCBF values were used to assess longitudinal changes. Untreated OSA participants showed decreased relative rCBF in the left hippocampus and the right parahippocampal gyrus over time, while treated participants showed trends for increased relative rCBF in the left hippocampus and the right parahippocampal gyrus. No changes were found over time in controls. Untreated OSA is associated with worsening relative rCBF in specific brain areas over time, while treated OSA shows the opposite. Considering that OSA possibly accelerates cognitive decline in older adults, CPAP treatment could help reduce risk for cognitive impairment.

Coagulation and Fibrinolysis in Obstructive Sleep Apnoea

Obstructive sleep apnoea (OSA) is a common disease which is characterised by repetitive collapse of the upper airways during sleep resulting in chronic intermittent hypoxaemia and frequent microarousals, consequently leading to sympathetic overflow, enhanced oxidative stress, systemic inflammation, and metabolic disturbances. OSA is associated with increased risk for cardiovascular morbidity and mortality, and accelerated coagulation, platelet activation, and impaired fibrinolysis serve the link between OSA and cardiovascular disease. In this article we briefly describe physiological coagulation and fibrinolysis focusing on processes which could be altered in OSA. Then, we discuss how OSA-associated disturbances, such as hypoxaemia, sympathetic system activation, and systemic inflammation, affect these processes. Finally, we critically review the literature on OSA-related changes in markers of coagulation and fibrinolysis, discuss potential reasons for discrepancies, and comment on the clinical implications and future research needs.

Intermittent hypoxia-induced autophagy via AMPK/mTOR signaling pathway attenuates endothelial apoptosis and dysfunction in vitro

PURPOSE

The aim of this study was to examine whether or not intermittent hypoxia (IH) upregulated autophagy and the contributions of autophagy to endothelial apoptosis and dysfunction in human umbilical vein endothelial cells (HUVECs).

METHOD

HUVECs were incubated under normoxia and IH conditions. After 3-, 6-, 12-, and 24-h exposure, the autophagic vacuoles and autophagosomes were observed by transmission electron microscopy and monodansylcadaverine staining. The protein levels of autophagy-related biomarkers and AMPK/mTOR pathway were measured by Western blot. The apoptosis-related proteins and the percentage of apoptotic cells were evaluated by Western blot and flow cytometry, respectively, while the levels of endothelial function biomarkers were assessed by ELISA.

RESULTS

IH induced autophagy, as determined by the increased numbers of the autophagic vacuoles, autophagosomes, and by the elevated levels of Beclin-1 protein, the LC3II/LC3I ratio, and p62 degradation. IH-induced autophagic flux peaked at 12-h duration and weakened at 24 h. IH increased the ratio of p-AMPK/AMPK and decreased the ratio of p-mTOR/mTOR, while compound C restored the alteration. A significant decrease in the Bcl-2 level and the Bcl-2/Bax ratio and a significant increase in the protein expression levels of Bax and cleaved caspase 3 and in the percentage of apoptosis were observed under IH exposure. Moreover, the NO level was reduced, while the ET-1 and VEGF levels were raised under IH condition. These alterations were suppressed by the pretreatment of 3-methyladenine.

CONCLUSIONS

IH upregulates autophagy through AMPK/mTOR pathway in HUVECs in vitro, which might be protective against endothelial apoptosis and dysfunction caused by IH.

Obstructive sleep apnoea and cardiovascular disease: a literature review

As obesity becomes more common worldwide, the prevalence of obstructive sleep apnoea (OSA) continues to rise. Obstructive sleep apnoea is a well-known disorder that causes chronic intermittent hypoxia (CIH), which is considered a risk factor for atherosclerosis directly and indirectly. Ischaemic heart disease remains the leading cause of death. Most risk factors for atherosclerosis are well understood. However, other factors such as CIH are less well understood. Several studies have investigated the pathophysiology of CIH, attempting to uncover its link to atherosclerosis and to determine whether OSA treatment can be a therapeutic modality to modify the risk for atherosclerosis. In this article, we will review the pathophysiology of OSA as an independent risk factor for cardiovascular disease and discuss the most common markers that have been studied. We will also examine the potential impact of OSA management as a risk factor modifier on the reversibility of atherosclerosis.

Understanding the pathophysiological mechanisms of cardiometabolic complications in obstructive sleep apnoea: towards personalised treatment approaches

In January 2019, a European Respiratory Society research seminar entitled "Targeting the detrimental effects of sleep disturbances and disorders" was held in Dublin, Ireland. It provided the opportunity to critically review the current evidence of pathophysiological responses of sleep disturbances, such as sleep deprivation, sleep fragmentation or circadian misalignment and of abnormalities in physiological gases such as oxygen and carbon dioxide, which occur frequently in respiratory conditions during sleep. A specific emphasis of the seminar was placed on the evaluation of the current state of knowledge of the pathophysiology of cardiovascular and metabolic diseases in obstructive sleep apnoea (OSA). Identification of the detailed mechanisms of these processes is of major importance to the field and this seminar offered an ideal platform to exchange knowledge, and to discuss pitfalls of current models and the design of future collaborative studies. In addition, we debated the limitations of current treatment strategies for cardiometabolic complications in OSA and discussed potentially valuable alternative approaches.

Circulating plasma exosomes in obstructive sleep apnoea and reverse dipping blood pressure

BACKGROUND

Obstructive sleep apnoea (OSA) increases the risk of an abnormal nondipping 24 h blood pressure profile, an independent risk factor for cardiovascular disease (CVD). We examined differential exosomal microRNA (miRNA) expression in untreated OSA patients with normal dipping blood pressure (NDBP) and reverse dipping blood pressure (RDBP), an extreme form of nondipping, to understand the mechanisms underlying nondipping blood pressure in OSA.

METHODS

46 patients (15 RDBP versus 31 NDBP) matched for OSA severity (respiratory event index 32.6±22.5 versus 32.2±18.1 events·h^-1; p=0.9), age (54.8±12.9 versus 49±9.9 years; p=0.09) and body mass index (36.2±6.6 versus 34.4±6.8 kg·m^-2; p=0.4) were included. Plasma exosomes were characterised by flow cytometry and functional in vitro reporter assays were conducted on cultured endothelial cells. Exosome miRNA cargo was profiled with microarrays followed by bioinformatics analyses.

RESULTS

Exosomes from RDBP patients increased the permeability of endothelial cell tight junctions and adhesion molecule expression. Principal component analyses of miRNA array data showed strict separation and identification of the two groups. A restricted and validated signature of exosomal miRNAs was identified in the RDBP versus NDBP group. Their predicted target genes involved phosphatidylinositol 3-kinase-Akt (p=0.004), Ras (p=3.42E-05), Wnt (p=0.003) and hypoxia inducible factor-1 signalling (p=0.04), inflammatory mediator regulation of transient receptor potential channels (p=0.01), and several cancer-related pathways.

CONCLUSIONS

Patients with RDBP have altered miRNA cargoes in circulating exosomes that invoke in vitro endothelial dysfunction. A selected number of circulating exosomal miRNAs play an important role in abnormal circadian regulation of blood pressure and may provide prognostic biomarkers of CVD risk in OSA.

Inhibition of miR-193a-3p protects human umbilical vein endothelial cells against intermittent hypoxia-induced endothelial injury by targeting FAIM2

OBJECTIVE

The functions and molecular regulatory mechanisms of miR-193a-3p in cardiac injury induced by obstructive sleep apnea (OSA) are poorly understood. This study aimed to explore the role of miR-193a-3p in intermittent hypoxia(IH)-induced human umbilical vein endothelial cells (HUVECs) injury.

RESULTS

In this study, we found that IH significantly decreased viability but enhanced cell apoptosis. Concurrently, the miR-193a-3p expression level was increased in HUVECs after IH. Subsequent experiments showed that IH-induced injury was ameliorated through miR-193a-3p silence. Fas apoptotic inhibitory molecule 2 (FAIM2) was predicted by bioinformatics analysis and further identified as a direct target gene of miR-193a-3p. Interestingly, the effect of miR-193a-3p inhibition under IH could be reversed by down-regulating FAIM2 expression.

CONCLUSION

In conclusion, our study first revealed that miR-193a-3p inhibition could protect HUVECs against intermittent hypoxia-induced damage by negatively regulating FAIM2. These findings could advance our understanding of the underlying mechanisms for OSA-related cardiac injury.

METHODS

We exposed HUVECs to IH condition; the expression levels of miR-193a-3p were detected by RT-qPCR. Cell viability, and the expressions of apoptosis-associated proteins were examined via CCK-8, and western blotting, respectively. Target genes of miR-193a-3p were confirmed by dual-luciferase reporter assay.

Non-sleepy obstructive sleep apnoea: to treat or not to treat?

Non-sleepy obstructive sleep apnoea (OSA) is thought to have a prevalence of around 20-25% in industrialised countries. However, the question of whether it should be routinely treated or not is controversial. This review collates the results from recent randomised controlled trials addressing OSA and examines whether treating the condition leads to improvements in quality of life and reduced cardiometabolic dysfunction, comorbidities generally attributed to untreated obstructive sleep apnoea/hypopnoea syndrome.

Plasma Extracellular Vesicles in Children with OSA Disrupt Blood-Brain Barrier Integrity and Endothelial Cell Wound Healing in Vitro

Pediatric obstructive sleep apnea (P-OSA) is associated with neurocognitive deficits and endothelial dysfunction, suggesting the possibility that disruption of the blood-brain barrier (BBB) may underlie these morbidities. Extracellular vesicles (EVs), which include exosomes, are small particles involved in cell-cell communications via different mechanisms and could play a role in OSA-associated end-organ injury. To examine the roles of EVs in BBB dysfunction, we recruited three groups of children: (a) absence of OSA or cognitive deficits (CL, n = 6), (b) OSA but no evidence of cognitive deficits (OSA-NC(-), n = 12), and (c) OSA with evidence of neurocognitive deficits (OSA-NC(+), n = 12). All children were age-, gender-, ethnicity-, and BMI-z-score-matched, and those with OSA were also apnea-hypopnea index (AHI)-matched. Plasma EVs were characterized, quantified, and applied on multiple endothelial cell types (HCAEC, HIAEC, human HMVEC-D, HMVEC-C, HMVEC-L, and hCMEC/D3) while measuring monolayer barrier integrity and wound-healing responses. EVs from OSA children induced significant declines in hCMEC/D3 transendothelial impedance compared to CL (p < 0.001), and such changes were greater in NC(+) compared to NC(-) (p < 0.01). The effects of EVs from each group on wound healing for HCAEC, HIAEC, HMVED-d, and hCMEC/D3 cells were similar, but exhibited significant differences across the three groups, with evidence of disrupted wound healing in P-OSA. However, wound healing in HMVEC-C was only affected by NC(+) (p < 0.01 vs. NC(-) or controls (CO). Furthermore, no significant differences emerged in HMVEC-L cell wound healing across all three groups. We conclude that circulating plasma EVs in P-OSA disrupt the integrity of the BBB and exert adverse effects on endothelial wound healing, particularly among OSA-NC(+) children, while also exhibiting endothelial cell type selectivity. Thus, circulating EVs cargo may play important roles in the emergence of end-organ morbidity in pediatric OSA.

Relationship between the endothelial dysfunction and the expression of the β1-subunit of BK channels in a non-hypertensive sleep apnea group

STUDY OBJECTIVES

Vascular damage must be diagnosed early in patients with hypertension. In this regard, endothelial dysfunction (ED) is an early sign of vascular disease and a predictor of cardiovascular diseases. In obstructive sleep apnea (OSA), intermittent hypoxia triggers ED, but mechanisms are not clear. In this context, it has been described that BK channels regulates arterial tone and that chronic and intermittent hypoxia downregulates the expression of the BK channel β1-subunit facilitating vasoconstriction. Thus, we investigated the relationship among hypoxemia, ED, and mRNA expression of the β1-subunit in patients with severe OSA. We aimed to assess (1) ED in non-hypertensive patients with OSA using laser-Doppler flowmetry, (2) BK β1-subunit mRNA expression, and (3) the impact of continuous positive airway pressure (CPAP) treatment on ED and β1-subunit regulation.

METHODS

OSA patients underwent 24-hour blood pressure monitoring to exclude hypertension. Laser-Doppler flowmetry was performed to assess ED, and β1-subunit mRNA expression was evaluated using a blood test of peripheral blood leukocytes at baseline and after 3 months of CPAP treatment.

RESULTS

In normotensive patients with OSA, endothelial function correlated with the severity of OSA. CPAP improved endothelial function in normotensive OSA patients and the speed of the arterial response was significantly correlated with β1-subunit mRNA expression. β1-subunit mRNA expression at baseline correlated inversely with its change after CPAP.

CONCLUSIONS

Sleep apnea is related to ED in normotensive patients with OSA. CPAP therapy improves endothelial function and regulates β1-subunit mRNA expression.

Obstructive sleep apnoea syndrome and endothelial function: potential impact of different treatment strategies-meta-analysis of prospective studies

PURPOSE

Previous studies have shown an association between obstructive sleep apnoea syndrome (OSAS) and cardiovascular events. Whether this association is mediated by an impairment of endothelial function, which is itself a driver of elevated cardiovascular risk, has yet to be clarified, as it is the eventual protective role of several OSAS treatments. The aim of our meta-analysis is to evaluate the effect of various OSAS treatments on endothelial function calculated by means of flow-mediated dilatation (FMD).

METHODS

We conducted a meta-analysis of prospective studies including patients affected by mild to severe OSAS treated with continuous positive airway pressure (CPAP), surgery, oral appliance and medical treatments. FMD was measured before and after treatment RESULTS: After pooling results from different treatment strategies, OSAS treatment showed a positive impact on endothelial function (Mean Difference [MD] = 2.58; 95% CI 1.95-3.20; p < 0.00001).

CONCLUSIONS

Our study supports the hypothesis that several modalities of treatment for OSAS positively impact endothelial function. Whether this effect also associates with an improvement of clinical outcomes remains to be ascertained.

Effects of CPAP on the transcriptional signatures in patients with obstructive sleep apnea via coexpression network analysis

A growing number of studies provide epidemiological evidence linking obstructive sleep apnea (OSA) with a number of chronic disorders. Transcriptional analyses have been conducted to analyze the gene expression data. However, the weighted gene coexpression network analysis (WGCNA) method has not been applied to determine the transcriptional consequence of continuous positive airway pressure (CPAP) therapy in patients with severe OSA. The aim of this study was to identify key pathways and genes in patients with OSA that are influenced by CPAP treatment and uncover/unveil potential molecular mechanisms using WGCNA. We analyzed the microarray data of OSA (GSE 49800) listed in the Gene Expression Omnibus database. Coexpression modules were constructed using WGCNA. In addition, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis were also conducted. After the initial data processing, 5101 expressed gene profiles were identified. Next, a weighted gene coexpression network was established and 16 modules of coexpressed genes were identified. The interaction analysis demonstrated a relative independence of gene expression in these modules. The black module, tan module, midnightblue module, pink module, and greenyellow module were significantly associated with the alterations in circulating leukocyte gene expression at baseline and after exposure to CPAP. The five hub genes were considered to be candidate OSA-related genes after CPAP treatment. Functional enrichment analysis revealed that steroid biosynthesis, amino sugar and nucleotide sugar metabolism, protein processing in the endoplasmic reticulum, and the insulin signaling pathway play critical roles in the development of OSA in circulating leukocyte gene expression at baseline and after exposure to CPAP. Using this new systems biology approach, we identified several genes and pathways that appear to be critical to OSA after CPAP treatment, and these findings provide a better understanding of OSA pathogenesis.

Coexistence of obstructive sleep apnea and telomerase activity, concentration of selected adipose tissue hormones and vascular endothelial function in patients with arterial hypertension

AIM

The aim of the present study was to determine the effect of obstructive sleep apnea (OSA) with hypertension on telomerase activity, visfatin and adipsine concentration in the blood and vascular endothelial function assessed by ultrasound measured flow-mediated dilatation of the brachial artery (FMD).

MATERIAL AND METHODS

The study involved a group of 106 people (average age: 54.79 years). The determination of telomerase activity and blood visfatin and adipsine concentrations, brachial artery ultrasound examination with endothelium-dependent dilatation evaluation (FMD) and polysomnography were carried out.

RESULTS

Patients with hypertension without OSA were characterized by significantly greater FMD in comparison to patients with arterial hypertension and OSA (8.13 ± 5.12 %vs. 6.82 ± 5.36%; p < 0.05). Negative linear relationship between apnea-hypopnea index (AHI) and FMD (r = -0.22, p < 0.05) has been demonstrated. Negative linear relationship between adipsine concentration in the blood and length of REM (Rapid Eye Movement) sleep (r = -0.21, p < 0.05) was found. Positive linear relationship between the concentration of visfatin in the blood and the length of REM sleep (r = 0.22, p < 0.05) was also observed. Higher body mass index, higher total cholesterol, triglyceride and glucose levels have been shown to be independent predictors of higher AHI values, while greater telomerase activity, greater FMD and use of angiotensin converting enzyme inhibitors are independent predicators for lower AHI values.

CONCLUSION

Higher values of AHI index in polysomnography in hypertensive patients can be related to lower telomerase activity in the blood and impaired function of vascular endothelial function assessed using ultrasound.

Alpha Lipoic Acid Improves Endothelial Function and Oxidative Stress in Mice Exposed to Chronic Intermittent Hypoxia

Objective

Obstructive sleep apnea (OSA) is characterized by recurrent airway collapse that causes chronic intermittent hypoxia (CIH). OSA is associated with systemic inflammation and oxidative stress resulting in endothelial dysfunction and cardiovascular disease (CVD). Alpha lipoic acid (ALA) is a potent antioxidant with anti-inflammatory properties. We hypothesized that dietary ALA can improve endothelial function of mice exposed to CIH.

Methods

Mice were exposed to either CIH or intermittent air (IA) and treated with dietary ALA (0.2% w/w) or a regular chow diet for 8 weeks. Endothelial function, endothelial nitric oxide (eNOS) uncoupling, systemic oxidative stress, systemic inflammation, aortic expression of inflammatory cytokines, and antioxidant enzymes were measured after 8 weeks.

Results

Mice exposed to CIH exhibited endothelial dysfunction accompanied by systemic oxidative stress and inflammation as well as increased aortic expression of inflammatory cytokines. Furthermore, CIH led to eNOS uncoupling. Treatment with dietary ALA reversed endothelial dysfunction in mice exposed to CIH, lowered systemic oxidative stress and inflammation, prevented the increases of inflammatory cytokine gene expression, increased the expression of antioxidant enzymes, and preserved eNOS in a coupled state.

Conclusion

ALA attenuates endothelial dysfunction by preventing oxidative stress and inflammation and restoring nitric oxide bioavailability in mice exposed to CIH. Our data suggests the potential beneficial use of ALA as adjunctive therapy in OSA.

Crossover comparison between CPAP and mandibular advancement device with adherence monitor about the effects on endothelial function, blood pressure and symptoms in patients with obstructive sleep apnea

Mandibular advancement device (MAD) is an alternative therapeutic option for CPAP to treat obstructive sleep apnea (OSA). While MAD showed the better adherence, patients with over moderate OSA have been treated more frequently with CPAP despite increasing positive evidence on the cardiovascular outcome with MAD, even in severe patients. Thus, more information is needed regarding the cardiovascular and symptomatic outcome of MAD treatment objectively compared to CPAP. Forty-five supine-dependent OSA patients (apnea-hypopnea index 20-40/h) were randomized to either CPAP or MAD and treated for 8 weeks and switched to another for 8 weeks. The primary endpoint was improvement in the endothelial function, indexed by the flow-mediated dilatation (FMD), and the secondary endpoint was the sleep-time blood pressure (BP). The duration of MAD use was evaluated objectively by an implanted adherence monitor. Treatment efficacy was also evaluated by home sleep monitor and a questionnaire about the symptoms. The adherence was not significantly different (CPAP vs. MAD: 274.5 ± 108.9 min/night vs. 314.8 ± 127.0 min/night, p = 0.095). FMD and sleep-time mean BP were not markedly changed from the baseline with either approach (CPAP vs. MAD: FMD, + 0.47% ± 3.1% vs. + 0.85% ± 2.6%, p = 0.64; BP, - 1.5 ± 5.7 mmHg vs. - 1.2 ± 7.5 mmHg, p = 0.48), although sleepiness, nocturia, and sleep-related parameters were similarly improved and more patients preferred MAD. As MAD and CPAP showed similar effects on cardiovascular outcome and symptomatic relief even with a comparable length of usage, we might expect MAD as an alternative treatment option for CPAP in this range of OSA group.