Hypertension in obstructive sleep apnea: risk and therapy

Screening of plasma exosomal lncRNAs to identify potential biomarkers for obstructive sleep apnea

Background

Obstructive sleep apnea (OSA) is highly prevalent, but frequently undiagnosed. The existing biomarkers of OSA are relatively insensitive and inaccurate. Long non-coding RNAs (lncRNAs) have no protein-coding ability but have a role in regulating gene expression. They are stably expressed in exosomes, easily and rapidly measurable. Changes in expression of exosomal lncRNAs can be useful for disease diagnoses. However, there are few reports on the association of exosomal lncRNAs with OSA. We aimed to investigate the exosomal lncRNA profiles to establish the differences between non-OSA, OSA with or without hypertension (HTN) and serve as a potential diagnostic biomarker.

Methods

This diagnostic test included 63 participants: [normal control (NC) =25], (OSA =23), and (HTN-OSA =15). Expression profiling of lncRNAs in isolated exosomes was performed through high-throughput sequencing in 9 participants. Subsequently, OSA/HTN-OSA related lncRNAs were selected for validation by droplet digital polymerase chain reaction (ddPCR), receiver operating characteristic (ROC) curves were used to determine the diagnostic value. The reliabilities of the screened gene were further validated in another independent cohort: (NC =10), (OSA mild =10), (OSA moderate =11), and (OSA severe =10), the correlation between clinical features and its expression was analyzed. The MiRanda software was used to predict the binding sites of interaction between microRNA (miRNA) and target genes regulated by screened lncRNA.

Results

We identified the differentially expressed lncRNAs and mRNAs in plasma exosomes of the NC, OSA, HTN-OSA groups. Most pathways enriched in differentially expressed lncRNAs and mRNAs had previously been linked to OSA. Among them, ENST00000592016 enables discrimination between NC and OSA individuals [area under curve (AUC) =0.846, 95% confidence interval (CI): 0.72–0.97]. The severity of OSA was associated with changes in the ENST00000592016 expression. Furthermore, ENST00000592016 affected the PI3K-Akt, MAPK, and TNF pathways by regulating miRNA expressions.

Conclusions

This is the first report about differential expression of lncRNA in OSA and HTN-OSA exosomes. ENST00000592016 enables discrimination between NC and OSA individuals. This work enabled characterization of OSA and provided the preliminary work for the study of biomarker of OSA.

Role of dynamic sleep MRI in obstructive sleep apnea syndrome

PURPOSE

To identify obstruction sites of the upper airway during sleep in patients with obstructive sleep apnea syndrome (OSAS) under dynamic conditions and improve knowledge to guide surgical treatment and advancements.

MATERIALS AND METHODS

The study included 15 patients (5 females and 10 males) who were diagnosed as having OSAS. Overall mean age was 40.2 years (± 7.01 years). All the patients underwent drug-induced sleep endoscopy (DISE) and dynamic sleep MRI. The presence, location, and direction of airway collapse were assessed. Dynamic MRI findings were correlated to DISE. Data of the site and direction of airway collapse were correlated with those of endoscopic findings and interobserver agreement was done.

RESULTS

The dynamic images in sagittal section showed collapse of the upper airway at retropalatal level in 14 patients (93.33%) and at retroglossal level in seven patients (46.7%) and of these 14 patients; seven had combined retropalatal and retroglossal collapse. These findings were highly correlated with DISE findings with an excellent interobserver agreement for retropalatal and retroglossal levels (Kappa = 1 and 0.867, P value = 0.000), respectively. Objective measurements of the direction of collapse in axial dynamic sleep MRI images showed significant statistical correlation with endoscopic findings regarding retropalatal anteroposterior and circumferential collapse (Kappa = 0.58 and 0.52, P value = 0.02 and 0.03, respectively).

CONCLUSION

Dynamic sleep MRI can reliably characterize the actual site of dynamic airway obstruction and has the potential of improving predictions of successful surgical outcomes in OSAS patients.

Comparison of prevalence rates of restless legs syndrome, self-assessed risks of obstructive sleep apnea, and daytime sleepiness among patients with multiple sclerosis (MS), clinically isolated syndrome (CIS) and Neuromyelitis Optica Spectrum Disorder (NMOSD)

BACKGROUND

Prevalence rates for restless legs syndrome (RLS) and risk of Obstructive Sleep Apnea (OSA) in individuals with Neuromyelitis Optica Spectrum Disorder (NMOSD) and Clinically Isolated Syndrome (CIS) are unknown. The aims of the present study were to assess symptoms of RLS and self-assessed risks of OSA in individuals with NMOSD and CIS, to compare these prevalence rates with those of persons with multiple sclerosis (MS), and to associate RLS and OSA with expanded disability status scale (EDSS) scores, daytime sleepiness, fatigue, paresthesia, and medication.

METHODS

A total of 495 individuals (mean age = 34.92 years, 84.9% females) were assessed. Of these, 24 had NMOSD, 112 had CIS and 359 had MS. Trained neurologists ascertained individuals' neurological diagnoses, assessed their EDSS scores, and conducted a clinical interview to assess RLS. Additionally, participants completed questionnaires covering sociodemographic information, risks of snoring and OSA, daytime sleepiness, fatigue, paresthesia and medication.

RESULTS

Prevalence rates of RLS were 45.8% in NMOSD, 41.1% in CIS, and 28.7% in MS. Prevalence rates of self-assessed risks of OSA were 8.3% in NMOSD, 7.7% in CIS, and 7.8% in MS; these rates were not significantly different. Across the entire sample and within the diagnostic groups, RLS and OSA scores were unrelated to EDSS, daytime sleepiness, fatigue or medication.

CONCLUSIONS

Individuals with NMOSD, CIS and MS have high prevalence rates for RLS and self-assessed risks of obstructive sleep apnea syndrome (OSAS), which are unrelated to EDSS, daytime sleepiness, fatigue, paresthesia, or medication. Sleep issues should be monitored during routine check-ups for individuals with NMOSD and CIS.

The Relationship Between Obstructive Sleep Apnea and Ruptured Intracranial Aneurysms

STUDY OBJECTIVES

The role of obstructive sleep apnea (OSA) in the overall outcome of ruptured intracranial aneurysms (RIAs) is unknown. We have investigated the role of OSA in overall outcome of RIAs.

METHODS

Data from 159 consecutive patients were retrospectively reviewed. A chi-square test and regression analysis were performed to determine the significant difference. A value of P < .05 was considered significant.

RESULTS

The prevalence of OSA in RIAs was fivefold higher in the nonaneurysm patient group, P = .002. The number of patients with hypertension (P < .0001), body mass index ≥ 30 (P < .0001), hyperlipidemia (P = .018), chronic heart disease (P = .002) or prior ischemic stroke (P = .001) was significantly higher in the OSA group. Similarly, the number of wide-neck aneurysms (P < .0001) and aneurysm > 7 mm (P = .004), poor Hunt and Hess grade IV-V (P = .005), vasospasms, (P = .03), and patients with poor Modified Rankin Scale scores (3-6) was significantly higher in the OSA group (P < .0001). Interestingly, for the first time in univariate (P = .01) and multivariate (P = .003) regression analysis, OSA was identified as an individual predictor of unfavorable outcome of RIAs. In addition, hypertension (P = .04), smoking (P = .049), chronic heart disease (P = .01), and Hunt and Hess grade IV-V (P = .04) were revealed as predictors of poor outcome of RIAs.

CONCLUSIONS

This is a novel study to determine the association between OSA and ruptured cerebral aneurysm in terms of comorbidities, size of aneurysm, severity of symptoms, and outcomes after treatment. In addition, for the first time, OSA is identified as a positive predictor of unfavorable outcome of RIAs.

Arterial blood pressure feature estimation using photoplethysmography

Continuous and noninvasive monitoring of blood pressure has numerous clinical and fitness applications. Current methods of continuous measurement of blood pressure are either invasive and/or require expensive equipment. Therefore, we investigated a new method for the continuous estimation of two main features of blood pressure waveform: systolic and diastolic pressures. The estimates were obtained from a photoplethysmography signal as input to the fifth order autoregressive moving average models. The performance of the method was evaluated using beat-to-beat full-wave blood pressure measurements from 15 young subjects, with no known cardiovascular disorder, in supine position as they breathed normally and also while they performed a breath-hold maneuver. The level of error in the modeling and prediction estimates during normal breathing and breath-hold maneuvers, as measured by the root mean square of the residuals, were less than 5 mmHg and 11 mm Hg, respectively. The mean of model residuals both during normal breathing and breath-hold maneuvers was considered to be less than 3.2 mmHg. The dependency of the accuracy of the estimates on the subject data was assessed by comparing the modeling errors for the 15 subjects. Less than 1% of the models showed significant differences (p < 0.05) from the other models, which indicates a high level of consistency among the models.

Improving OSA screening and diagnosis in patients with hypertension in an academic safety net primary care clinic: quality improvement project

Obstructive sleep apnoea (OSA) is more prevalent in patients with hypertension (HTN), and associated morbidities include stroke, heart failure and premature death. In the Internal Medicine Clinic (IMC), over 70% of the patients had a diagnosis of HTN and obesity. We identified a lack of OSA screening in patients with HTN. The aim of this quality improvement (QI) was to increase OSA diagnosis to 5% from the baseline rate of less than 1% in patients with HTN between the ages of 18 and 75 years over 6 months at IMC. We used the Plan-Do-Study-Act (PDSA) method. The QI team performed root cause analysis to identify materials/methods, provider and patient-related barriers. PDSA cycle included: (1) integration of customised workflow of loud Snoring, Tiredness, Observed apnea, high blood Pressure (STOP)-Body mass index (BMI), Age, Neck circumference, and Gender (BANG) OSA screening tool in the electronic health record (EHR); (2) physician education of OSA and EHR workflow; and (3) completion of STOP survey by patients, which was facilitated by nursing staff. The outcome measure was the percentage of OSA diagnosis in patients with HTN. The process measures included the percentage of patients with HTN screened for OSA and the increase in sleep study referrals in hypertensive patients with STOP-BANG score of ≥3. Increase in patient wait time and cost of sleep study were the balance measures. Data analysis was performed using weekly statistical process control chart. The average increase in OSA screening rate using the STOP-BANG tool was 3.88%. The significant variation seen in relation to PDSA cycles was not sustainable. 32% of patients scored ≥3 on the STOP-BANG tool, and 10.4% had a confirmed diagnosis of OSA. STOP-BANG tool integration in the EHR and a team approach did not result in a sustainable increase in OSA screening. OSA diagnosis was increased to 3.3% in IMC patient population within the 6-month period. The team identified multiple barriers to screening and diagnosis of OSA in the IMC.

Inflammatory and oxidative stress‑associated factors in chronic intermittent hypoxia in Chinese patients, rats, lymphocytes and endotheliocytes

In order to investigate the association between inflammatory and oxidative stress (OS)-associated factors in chronic intermittent hypoxia (CIH), 238 CIH patients and 156 healthy volunteers were included. CIH rat and lymphocytes were used as experimental models. Interleukin (IL)-6, tumor necrosis factor-α (TNF-α), C-reactive protein (CRP), nitric oxide (NO) and nitric oxide synthase (NOS) were analyzed. Patients with CIH were older, with hypertension, increased heart rate (HR) and body mass index (BMI), and there were more males than females. Those with a history of smoking or type 2 diabetes (T2DM) history exhibited an increased risk of CIH. Serum IL-6, TNF-α and CRP in patients with CIH were increased, while NO and NOS were decreased. Hakka patients exhibited increased BMI measurements and NO expression, and decreased systolic arterial pressure, IL-6 and TNF-α compared with non-Hakka patients. Rats with CIH exhibited hypertension and stable weight, less activity and decreased appetite, increased HR and serum IL-6, TNF-α and CRP, and decreased NO and NOS. IL-6, TNF-α, CRP, NO and induced-NOS (iNOS) were increased in the lymphocytes of CIH rats compared with healthy ones. In rat endotheliocytes induced by CIH, IL-6, TNF-α, CRP and iNOS increased, while NO and endothelial-NOS (eNOS) decreased. In the supernatant of co-cultured lymphocytes and endotheliocytes, IL-6, TNF-α and CRP increased, although NO and NOS decreased. In conclusion, age, male gender, BMI, smoking and T2DM history, serum IL-6, TNF-α and CRP were positively correlated with CIH combined with hypertension, while NO and NOS were negatively correlated with CIH. Serum NO was predominantly synthesized and released by eNOS. Hakka patients exhibited decreased inflammation and OS with CIH. Increasing IL-6, TNF-α and CRP, and decreasing NO and NOS are biomarkers of CIH, which could be targets in diagnosis, treatment and prevention of CIH.

Coexistence of obstructive sleep apnea worsens the overall outcome of intracranial aneurysm: a pioneer study

OBJECTIVE Obstructive sleep apnea (OSA) is associated with the progression of abdominal and thoracic aortic aneurysms. However, the role of OSA in the overall outcome of intracranial aneurysms (IAs) has not yet been established. Authors of this report investigated the role of OSA in the overall outcome of IAs. METHODS Radiological and clinical data on patients (from 2010 through 2015) with confirmed IA were retrospectively reviewed. Significant differences between the OSA and non-OSA groups were determined using a chi-square test. Logistic regression analysis was performed to identify the predictors of an unfavorable IA outcome. RESULTS Among the 283 patients with confirmed IAs, 45 patients (16%) were positively screened for OSA, a proportion that was significantly higher than the prevalence of OSA in nonaneurysmal neurosurgical patients (4%, p = 0.008). The percentage of patients with hypertension (p = 0.018), a body mass index ≥ 30 kg/m² (p < 0.0001), hyperlipidemia (p = 0.034), diabetes mellitus (p = 0.005), chronic heart disease (CHD; p = 0.024), or prior stroke (p = 0.03) was significantly higher in the OSA group than in the non-OSA group. Similarly, the percentage of wide-necked aneurysms (p = 0.00001) and patients with a poor Hunt and Hess Grade IV-V (p = 0.01) was significantly higher in the OSA group than in the non-OSA group. In addition, the percentage of ruptured aneurysms (p = 0.03) and vasospasms (p = 0.03) was significantly higher in the OSA group. The percentage of patients with poor modified Rankin Scale (mRS) scores (3-6) was significantly higher in the OSA group (p = 0.03). A separate cohort of patients with ruptured IAs showed similar results. In both univariate (p = 0.01) and multivariate (p = 0.04) regression analyses, OSA was identified as an individual predictor of an unfavorable outcome. In addition, hypertension and prior stroke were revealed as predictors of a poor IA outcome. CONCLUSIONS Complications of IA such as rupture and vasospasm are often the consequence of uncontrolled OSA. Overall outcome (mRS) of IAs is also affected by the co-occurrence of OSA. Therefore, the coexistence of OSA with IA affects the outcome of IAs. Obstructive sleep apnea is a risk factor for a poor outcome in IA patients.

Sex differences of continuous positive airway pressure treatment on flow-mediated dilation in patients with obstructive sleep apnea syndrome

INTRODUCTION

There is growing research evidence suggesting the presence of endothelial dysfunction and systemic inflammation in patients with obstructive sleep apnea syndrome (OSAS). Continuous positive airway pressure (CPAP) is the most effective method for treating OSAS; nonetheless, the effects of CPAP on the aforementioned pathophysiologic pathways as well as on the systemic disease that result or coexist with the OSAS remain elusive.

AIM

To assess the effect of 3-month CPAP therapy on endothelial-dependent dilation, plasma levels of inflammatory markers, blood pressure (BP), and glucose control on male and female patients with OSAS.

METHODS

Our study group consisted of 40 (24 males and 16 females) patients with no prior history of cardiovascular disease, with an apnea-hypopnea index ≥15, who were assigned to receive CPAP treatment. Measurements of flow-mediated dilation (FMD), 24-hour ambulatory BP, and blood analysis were performed at baseline and 3 months after CPAP therapy.

RESULTS

Baseline FMD values were negatively correlated with the apnea-hypopnea index (r=-0.55, P=0.001). After 3 months of CPAP, there was an increase in the FMD values (5.40%±2.91% vs 3.13%±3.15%, P<0.05) and a significant reduction in the patients' 24-hour systolic BP (122.82±11.88 mmHg vs 130.24±16.75 mmHg, P<0.05), diastolic BP (75.44±9.14 mmHg vs 79.68±11.09 mmHg, P<0.05), and pulse pressure (47.38±9.77 mmHg vs 52.72±11.38 mmHg, P<0.05); daytime systolic BP (125.76±12.69 mmHg vs 132.55±17.00 mmHg, P<0.05) and diastolic BP (77.88±10.39 mmHg vs 82.25±11.01 mmHg, P<0.05); nighttime systolic BP (118.17±13.16 mmHg vs 126.22±17.42 mmHg, P<0.05) and pulse pressure (46.61±10.76 mmHg vs 52.66±11.86 mmHg, P<0.05); and C-reactive protein and HbA1c levels (0.40 [0.40-0.70] mg/L vs 0.60 [0.40-0.84] mg/L and 5.45%±0.70% vs 5.95%±1.08%, respectively; P<0.05). When divided by sex, only male patients produced similar statistically significant results, while female patients failed to show such associations.

CONCLUSION

Our results suggest that CPAP therapy improves the endothelial function, the BP, and the glucose control in male patients with OSAS. Further research is warranted in order to verify these results and to further elucidate the impact of CPAP on the cardiovascular risk of male and female patients with OSAS.

Cardiovascular and psychiatric morbidity in obstructive sleep apnea (OSA) with insomnia (sleep apnea plus) versus obstructive sleep apnea without insomnia: a case-control study from a Nationally Representative US sample

PURPOSE

To evaluate cardiovascular and psychiatric morbidity in patient visits with obstructive sleep apnea (OSA) with insomnia (OSA+Insomnia) versus OSA without insomnia (OSA-Insomnia) in a nationally representative US sample.

METHODS

A retrospective case-control study of epidemiologic databases (National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey) representing an estimated ± standard error (SE) 62,253,910 ± 5,274,747 (unweighted count=7234) patient visits with diagnosis of OSA from 1995-2010, was conducted. An estimated 3,994,104 ± 791,386 (unweighted count=658) were classified as OSA+Insomnia and an estimated 58,259,806 ± 4,849,800 (unweighted count=6576) as OSA-Insomnia. Logistic regression analysis was carried out using OSA+Insomnia versus OSA-Insomnia as the dependent variable, and age (>50 years versus ≤ 50 years), sex, race ('White' versus 'non-White'), essential hypertension, heart failure, ischemic heart disease, cardiac dysrhythmia, cerebrovascular disease, diabetes, obesity, hyperlipidemia, depressive, anxiety, and adjustment disorders (includes PTSD), hypersomnia and all medications used as independent variables. All comorbidities were physician diagnosed using the ICD9-CM.

RESULTS

Among patient visits with OSA, an estimated 6.4%± 0.9% also had insomnia. Logistic regression analysis revealed that the OSA+Insomnia group was significantly more likely to have essential hypertension (all ICD9-CM codes 401) (OR=1.83, 95% CI 1.27-2.65) and provisionally more likely to have cerebrovascular disease (ICD9-CM codes 430-438) (OR=6.58, 95% CI 1.66-26.08). The significant OR for cerebrovascular disease was considered provisional because the unweighted count was <30.

CONCLUSIONS

In a nationally representative sample, OSA+Insomnia was associated significantly more frequently with essential hypertension than OSA-Insomnia, a finding that has not been previously reported. In contrast to studies that have considered patient self-reports of psychological morbidity, the absence of a significant association with psychiatric disorders in our study may be indicative of the fact that we considered only physician-rated psychiatric syndromes meeting ICD9-CM criteria. Our findings among the OSA+Insomnia group are therefore most likely conservative.

Obstructive sleep apnoea and cardiovascular complications: perception versus knowledge

Epidemiological evidence has confirmed that obstructive sleep apnoea (OSA) significantly promotes cardiovascular risk, independent of age, sex, race and other common risk factors for cardiovascular diseases, such as smoking, drinking, obesity, diabetes mellitus, dyslipidaemia and hypertension. Patients with severe OSA exhibit a higher prevalence of coronary artery disease, heart failure and stroke. Despite the tight correlation between sleep apnoea and these comorbidities, the mechanisms behind increased cardiovascular risk in OSA remain elusive. Several theories have been postulated, including sympathetic activation, endothelial dysfunction, oxidative stress and inflammation. The association between OSA and cardiovascular diseases may be rather complicated and compounded by the presence of components of metabolic syndrome, such as obesity, hypertension, diabetes mellitus and dyslipidaemia. The present minireview updates current knowledge with regard to the cardiovascular sequelae of OSA and the mechanisms involved.

Cardiac response to chronic intermittent hypoxia with a transition from adaptation to maladaptation: the role of hydrogen peroxide

Obstructive sleep apnea (OSA) is a highly prevalent respiratory disorder of sleep, and associated with chronic intermittent hypoxia (CIH). Experimental evidence indicates that CIH is a unique physiological state with potentially “adaptive” and “maladaptive” consequences for cardio-respiratory homeostasis. CIH is also a critical element accounting for most of cardiovascular complications of OSA. Cardiac response to CIH is time-dependent, showing a transition from cardiac compensative (such as hypertrophy) to decompensating changes (such as failure). CIH-provoked mild and transient oxidative stress can induce adaptation, but severe and persistent oxidative stress may provoke maladaptation. Hydrogen peroxide as one of major reactive oxygen species plays an important role in the transition of adaptive to maladaptive response to OSA-associated CIH. This may account for the fact that although oxidative stress has been recognized as a driver of cardiac disease progression, clinical interventions with antioxidants have had little or no impact on heart disease and progression. Here we focus on the role of hydrogen peroxide in CIH and OSA, trying to outline the potential of antioxidative therapy in preventing CIH-induced cardiac damage.

The relative impact of obstructive sleep apnea and hypertension on the structural and functional changes of the thoracic aorta

BACKGROUND

Recent studies suggest that obstructive sleep apnea (OSA) causes thoracic aortic dilatation; but it is well accepted that hypertension can cause aortic dilatation, and hypertension is a common finding in patients with OSA. We aimed to investigate the relative impact of OSA and hypertension on the structural and functional changes of the thoracic aorta.

METHODS

This was an echocardiography substudy of our prospective OSA study in patients with acute myocardial infarction (AMI). Ninety-four male patients who completed both echocardiography and polysomnography were recruited. OSA was defined as an apnea-hypopnea index (AHI) > or = 15/hour.

RESULTS

The patients' mean age was 53 +/- 10 years, and mean body mass index (BMI) was 24.6 +/- 3 kg/m2. Sixty-four (68.1%) patients had OSA; of these, 39 (41.5%) had severe OSA. Thirty-three (52.6%) of the OSA cohort had hypertension. There was no correlation between any of the echocardiographic parameters and thoracic aortic size. Stepwise multivariate regression showed that BMI (P = 0.024), older age (P = 0.044), and hypertension (P = 0.025) were the only determinants. There was no significant independent relationship between OSA/AHI and thoracic aortic size. Systolic blood pressure but notAHI correlated significantly with aortic distensibility and compliance (r = -0.40 and -0.26, P < 0.001 and 0.022, respectively).

CONCLUSIONS

Hypertension is a common finding in male AMI patients with OSA. In these patients, increased afterload from systemic hypertension rather than mechanical stress on the aortic wall determines the thoracic aortic size and abnormalities in aortic functional indices. BMI and age were also independent predictors of thoracic aortic dilatation.