Obstructive sleep apnoea syndrome as a risk factor for hypertension: population study

Relationship Between OSA and Hypertension

There is a bidirectional association between OSA and systemic hypertension. The strengths of this relationship appear to be modulated by factors such as age, sex, and somnolence. The 24-h BP circadian pattern also appears to be influenced by OSA. Patients with this syndrome exhibit a high prevalence of nondipping or riser circadian patterns, which are related to clinical and subclinical organ damage in the heart and brain. However, the influence of OSA on nocturnal hypertension development has not yet been clarified. A special area of interest is the recognized relationship between OSA and resistant hypertension. The majority of patients with resistant hypertension suffer OSA. CPAP treatment significantly reduces BP in such patients and could play a clinical role in the management of BP in these patients. Several meta-analyses have demonstrated a concordant mild effect of CPAP on systemic hypertension. This effect is related to CPAP compliance, somnolence status, and baseline BP. The effects of oral appliances on BP in patients with OSA must be evaluated in randomized controlled trials. In the absence of additional data reported by clinical studies on other antihypertensive drug treatments, diuretics, particularly antialdosteronic diuretic agents, should be considered the first-line antihypertensive drug treatment in patients with OSA. By reducing parapharyngeal edema and secondary upper airway obstruction, these drugs appear to improve OSA severity and also to reduce BP.

Sleep medicine in Taiwan

The sleep medicine is a young medical science in Taiwan. It began from less than 10 sleep beds 20 years ago in four hospitals all over Taiwan. By the organization of sleep team in Chang Gung Memorial Hospital and the initiation of Taiwan Society of Sleep Medicine, sleep medicine becomes a popular medicine in the past decades. The setting of Sleep Society in 2002 is the milestone to promote the sleep medicine, educate the public and professionals, and control of the quality of clinical practice. Epidemiologic study in Taiwan shows many Taiwanese suffer from sleep disorders and hence more sleep institutes are needed. Accreditation has become a mission of the Taiwan Society of Sleep Medicine. Technicians, sleep centers, sleep specialists and sleep phycologists are gradually certified by the society. 215 sleep technicians, 307 sleep physicians, 31 iCBT therapists and 21 sleep centers are certified by the society till 2015. The first sleep related medical courses are initiated in the Department of Respiratory Therapy in Chang Gung University from 2003. For the following years, eight medical courses are set in six Universities now. Given the fact that the Asian accounts for the largest proportion of population in the world, investigation on the OSA in Asian population is essential. In this article, we aimed to demonstrate the outcomes of OSA-related research in Asia. In particular, the progress driven by the studies in Taiwan will be discussed. Data were obtained online from the Science Citation Index Expanded database of the Thomson Reuters' Web of Science Core Collection. Keywords including "apnea" and "hyponea" were used to search by applying the filters of the title and the publication years between 1991 and 2014. In total, 2623 articles were hit, subject to the criteria for data search. Among the 2623 articles, sleep and breathing related articles (128, 4.95 %) were the most frequently reported. Japan is the country that published the highest amount of OSA-related articles. The Asian institutions that ranked the first two in the number of OSA-related articles were Technion-Israel Institute of Technology and Tel Aviv University in Israel. In Taiwan, Chang Gung Memorial Hospital and Chang Gung University ranked fourth and fifth. Both institutes reported 63 articles. In Asia, Japan leads in the quantity of publication and the Japanese research institutes performed evenly. China had rapid growth in the number of articles since 2011. Although sleep medicine developed smoothly in the past decades in Taiwan, there were problems that the sleep society and specialists had to encounter. Insurance limits the expansion of sleep labs and the reimbursement is very low for sleep medicine to survive. The affiliations of sleep specialist and the sleep education are also important issue that the sleep specialists in the society have to discuss.The previous achievements do not guarantee future success. We have to face these problems seriously and take action for the following years to maintain the development of sleep medicine in Taiwan.

Precision Medicine in Patients With Resistant Hypertension and Obstructive Sleep Apnea: Blood Pressure Response to Continuous Positive Airway Pressure Treatment

BACKGROUND

In patients with resistant hypertension (RH) and obstructive sleep apnea (OSA), the blood pressure response to continuous positive airway pressure (CPAP) treatment is highly variable and could be associated with differential micro-ribonucleic acid (miRNA) profiles. Currently, no available methods exist to identify patients who will respond favorably to CPAP treatment.

OBJECTIVES

The aim of this study was to identify plasma miRNA profiles that predict blood pressure responses to CPAP treatment.

METHODS

Cardiovascular system-focused circulating miRNA expression was evaluated in plasma samples using an 84-miRNA array among patients with RH and OSA at baseline and after 3 months of adherent CPAP use. Pathway analysis and miRNA target gene enrichment were performed in silico. Plasma levels of peptides and hormones related to cardiovascular function were also measured.

RESULTS

The OSA responder group exhibited blood pressure decreases exceeding the observed median (>4.5 mm Hg) after CPAP, which were not present in the nonresponder group (≤4.5 mm Hg) (p < 0.01). Three miRNAs provided a discriminatory predictive model for such a favorable blood pressure response to CPAP (area under the curve: 0.92; p = 0.01). Additionally, CPAP treatment significantly altered a total of 47 plasma miRNAs and decreased aldosterone-to-renin ratios in the responder group (p = 0.016) but not in the nonresponder group.

CONCLUSIONS

A singular pre-CPAP treatment cluster of 3 plasma miRNAs predicts blood pressure responses to CPAP treatment in patients with RH and OSA. CPAP treatment is accompanied by changes in cardiovascular system-related miRNAs that may potentially influence the risk for cardiovascular disease among patients with OSA and RH. (Effect of Continuous Positive Airway Pressure [CPAP] Treatment in the Control of Refractory Hypertension; NCT00616265).

Cardiovascular comorbidities in obstructive sleep apnoea according to age: a sleep clinic population study

PURPOSE

To describe the features of obstructive sleep apnoea (OSA) and its association with arterial hypertension (HT), coronary artery disease (CAD), and arrhythmias in elderly (≥65 years) versus younger patients.

METHODS

All adult patients referred to our Sleep Research Unit for suspected OSA were included and underwent a thorough medical examination and an in-laboratory polysomnography. The severity of OSA was defined by the apnoea-hypopnoea index (AHI) as mild [5-15/h), moderate [15-30/h), and severe (≥30/h).

RESULTS

Elderly patients (n = 136) and really old patients (>75 years) had higher prevalence of OSA (89 %) and severe OSA (36.8 %) as compared to younger patients (n = 439; 79.5 and 27.6 %, respectively, p < 0.05). In patients with OSA, the elderly group had a poorer sleep quality and more severe nocturnal oxygen desaturation than the younger group. Elderly patients presented higher percentages of HT (47.8 %), CAD (19.8 %), and arrhythmias (16.2 %) as compared to younger patients (p < 0.01). The odds ratio (OR) for HT increased with OSA severity from 1.0 to 1.65 (95 % confidence interval 0.83-3.27), 1.0 to 2.5 (95 % CI 1.25-5.00), and 1.0 to 3.77 (1.95-7.29) in younger patients, but not in elderly ones where the OR increased from 1.0 to 0.6 (0.17-2.04), 1.0 to 1.14 (0.34-3.82), and 1.0 to 1.46 (0.46-4.63), respectively.

CONCLUSION

Stronger relation of HT and OSA severity in younger patients should encourage us to screen OSA in these patients at very young age. Increased OSA severity without obesity in very old patients needs to be confirmed and further studied.

Numerical simulations of airflow in the human pharynx of OSAHS patients

Abstract: Computational Fluid Dynamic simulations are performed in real patient individual pharynx geometries of an Obstructive Sleep Apnea patient. The Navier-Stokes equations as well as the Reynolds Averaged Navier-Stokes equations and k − ∊ and k −ω turbulence models are used. The velocity profile and pressure distribution of the patient without any treatment and the patient wearing a mandibular advancement appliance are compared to each other. The simulation results for the different model conditions all lead to similar results showing the robustness of the numerical solutions. The pressure loss along the pharynx is lower in the presence of a mandibular appliance, which can indicate the reduction of OSAHS severity.

Chronic widespread musculoskeletal pain in patients with obstructive sleep apnea syndrome and the relationship between sleep disorder and pain level, quality of life, and disability

[Purpose] The aim of this study was to ascertain the prevalence of chronic widespread musculoskeletal pain in patients with obstructive sleep apnea syndrome and to assess the relationship between sleep disorder and pain, quality of life, and disability. [Subjects and Methods] Seventy-four patients were included in the study and classified as having mild, moderate, or severe obstructive sleep apnea. Chronic widespread pain, quality of life, and disability were evaluated. [Results] Forty-one patients (55.4%) had chronic widespread pain. Female patients had a higher incidence of chronic pain, and female patients with chronic pain had higher body mass indexes, pain levels, and disability scores than did male patients. Physical component scores of female patients with chronic pain were lower than those of male patients. No correlation was observed between the degree of sleep disorder and severity of pain, pain duration, disability, or quality of life in obstructive sleep apnea patients with pain. [Conclusion] This study showed a 55.4% prevalence of chronic widespread pain in patients with obstructive sleep apnea and a greater risk of chronic pain in female than in male patients. Female patients with obstructive sleep apnea and chronic pain have higher pain and disability levels and a lower quality of life.

Sleep-disordered breathing and resistant hypertension

Hypertension is a highly prevalent problem worldwide, affecting at least one third of the adult general population. Although the exact prevalence is uncertain, it is estimated that at least 15% to 20% of individuals with hypertension have resistant hypertension. Resistant hypertension has been shown to predict more adverse cardiovascular and renal outcomes. In 2003, the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure recognized obstructive sleep apnea (OSA) as an important cause of secondary hypertension. A large body of epidemiologic evidence has linked OSA to resistant hypertension, nondipping nocturnal blood pressure, as well as target organ damage, including left ventricular hypertrophy, arterial stiffness, and microalbuminuria. The importance of OSA as a risk factor for the development of hypertension independent of other confounding factors also was observed in a prospective longitudinal study. More importantly, OSA predicts an increased risk of adverse cardiovascular outcomes, mortality, and sudden cardiac death. This article discusses the associations between OSA and resistant hypertension and reviews the latest understanding on the pathophysiologic mechanisms of hypertension in OSA. Nocturnal continuous positive airway pressure therapy is regarded as the standard treatment for OSA. Prospective randomized controlled trials and meta-analyses of prospective randomized controlled trials within the past 10 years that have examined the effects of continuous positive airway pressure therapy on blood pressure control in patients with OSA with or without hypertension are reviewed and summarized. The majority of the trials suggest a modest but significant benefit on blood pressure control with continuous positive airway pressure therapy. Whether continuous positive airway pressure therapy may improve hard outcomes of patients with OSA and resistant hypertension warrants further investigation.

Angiotensin II receptor blocker prevents upper gastrointestinal bleeding in hypertensive patients with chronic kidney disease not on dialysis

AIMS

Investigate if angiotensin II receptor blocker (ARB) decreases risk of upper gastrointestinal bleeding (UGIB) in hypertensive patients with chronic kidney disease (CKD) not on dialysis.

METHODS

All hypertensive patients with CKD not on dialysis in outpatient department of China Medical University Hospital from 2003 to May 2013 were enrolled. The risk of UGIB was analysed using Cox proportional hazard regression.

RESULTS

A total of 2744 hypertensive CKD patients including 1515 male and 1229 female, aged 64.9 ± 13.8 years old in a median of 1.9 (0.9-3.9) years were analysed. The incidence of UGIB was 4.5 per 100 patient-years. ARB was associated with a decreased risk of UGIB (p < 0.001) with an adjusted hazard ratio (HR) of 0.533 [95% confidence interval (CI) 0.404-0.703]. A history of UGIB, Helicobacter pylori infection, diabetes, lower estimated glomerular filtration rate, elevated blood urea nitrogen and decreased serum albumin were independently associated with an increased risk of UGIB.

CONCLUSIONS

Angiotensin II receptor blocker is associated with a decreased risk of UGIB in hypertensive CKD patients not on dialysis, independent of their renal function, history of gastrointestinal bleeding and nutrition status.

Obstructive sleep apnea and hypertension: a critical review

Obstructive sleep apnea (OSA) is a prevalent sleep disorder which is characterized by recurrent upper closure with oxygen desaturation and sleep disruption. OSA increases the risk of vascular disorders in the form of stroke, myocardial infarction, congestive heart failure, and hypertension. The mechanisms underlying the vascular disorders are several and include intermittent hypoxia with release of cytokines, angiogenic inhibitors, free radicals, and adhesion molecules. During apneas, arterial blood pressure gradually rises and surges abruptly after the termination of apnea. Two thirds of patients with OSA will ultimately have diurnal hypertension. This review discusses the literature supporting the significant role of OSA in hypertension and the effect of OSA treatment on blood pressure.

Nitric Oxide Bioavailability in Obstructive Sleep Apnea: Interplay of Asymmetric Dimethylarginine and Free Radicals

Obstructive sleep apnea (OSA) occurs in 2% of middle-aged women and 4% of middle-aged men and is considered an independent risk factor for cerebrovascular and cardiovascular diseases. Nitric oxide (NO) is an important endothelium derived vasodilating substance that plays a critical role in maintaining vascular homeostasis. Low levels of NO are associated with impaired endothelial function. Asymmetric dimethylarginine (ADMA), an analogue of L-arginine, is a naturally occurring product of metabolism found in the human circulation. Elevated levels of ADMA inhibit NO synthesis while oxidative stress decreases its bioavailability, so impairing endothelial function and promoting atherosclerosis. Several clinical trials report increased oxidative stress and ADMA levels in patients with OSA. This review discusses the role of oxidative stress and increased ADMA levels in cardiovascular disease resulting from OSA.

Use of continuous positive airway pressure for sleep apnea in the treatment of hypertension

PURPOSE OF REVIEW

Obstructive sleep apnea (OSA) and hypertension are highly prevalent and treatable conditions that often coexist and both contribute to an increased cardiovascular risk. The ability of continuous positive airway pressure (CPAP) to improve blood pressure in hypertensive patients with OSA is debated. This review highlights findings from recent studies that have investigated the impact of CPAP on blood pressure in patients with OSA.

RECENT FINDINGS

Comparing the results of various studies is complicated by important methodological differences among them. In hypertensive patients with OSA, treatment with CPAP improves blood pressure to a smaller degree than that derived from antihypertensive medication. Patients with more severe OSA and with greater adherence to CPAP are likely to gain the most benefit from the therapy.

SUMMARY

CPAP should be used in combination with antihypertensive medications in hypertensive patients with OSA. CPAP has the additional benefits of restoring nocturnal dipping and improving arterial stiffness, thus potentially influencing cardiovascular morbidity in these high-risk patients.

Intrarenal hemodynamic and oxidative stress in patients with obstructive sleep apnea syndrome

BACKGROUND

Oxygen desaturation and reoxygenation, related to intermittent hypoxia cycles due to upper airway obstruction, are major pathophysiologic features of obstructive sleep apnea syndrome (OSAS) and are thought to be responsible for an increased risk of cardiovascular diseases. Continuous positive airway pressure (CPAP) is therefore considered the gold standard in the management of OSAS. Further data demonstrated a high prevalence of OSAS in patients with altered renal function despite the underlying pathophysiological mechanisms that have not been clarified. This study aims to provide evidence on the reported high prevalence of endothelial dysfunction and alterations of the intrarenal hemodynamic in patients affected by OSAS. Furthermore, we evaluated the effect of a CPAP therapy on these endpoints.

METHODS

Twenty patients were enrolled in a prospective study and underwent ultrasound examination to assess endothelial dysfunction, by collecting brachial flow-mediated dilation (FMD) and intrarenal artery stiffness, pre- and post a 30-day treatment with CPAP.

RESULTS

Endothelial dysfunction and intrarenal artery stiffness significantly improved in all patients after a month of CPAP. In particular, we observed a significant reduction in the renal resistance index (RI) (p < 0.001) and systolic/diastolic ratio (S/D) ratio (p < 0.001) and a significant increase of FMD (p < 0.001). The apnea-hypopnea index (AHI) showed a negative correlation with Δ FMD (p < 0.05, r = -0.46). Conversely, a positive correlation exists between Δ RI and the oxygen desaturation index (ODI) (specificare la sigla) (p < 0.05, r = 0.46).

CONCLUSIONS

Our study firstly showed a significant effect of CPAP on renal perfusion and endothelial function in OSAS patients without concomitant cardiovascular comorbidities.

A practical algorithm for managing Alzheimer's disease: what, when, and why?

Alzheimer's disease (AD) is the most common form of dementia and its prevalence is increasing. Recent developments in AD management provide improved ways of supporting patients and their caregivers throughout the disease continuum. Managing cardiovascular risk factors, maintaining an active lifestyle (with regular physical, mental and social activity) and following a Mediterranean diet appear to reduce AD risk and may slow cognitive decline. Pharmacologic therapy for AD should be initiated upon diagnosis. All of the currently available cholinesterase inhibitors (ChEIs; donepezil, galantamine, and rivastigmine) are indicated for mild-to-moderate AD. Donepezil (10 and 23 mg/day) and rivastigmine transdermal patch (13.3 mg/24 h) are indicated for moderate-to-severe AD. Memantine, an N-methyl-d-aspartate receptor antagonist, is approved for moderate-to-severe AD. ChEIs have been shown to improve cognitive function, global clinical status and patients' ability to perform activities of daily living. There is also evidence for reduction in emergence of behavioral symptoms with ChEI therapy. Treatment choice (e.g., oral vs. transdermal) should be based on patient or caregiver preference, ease of use, tolerability, and cost. Treatment should be individualized; patients can be switched from one ChEI to another if the initial agent is poorly tolerated or ineffective. Memantine may be introduced in moderate-to-severe disease stages. Clinicians will regularly monitor symptoms and behaviors, manage comorbidities, assess function, educate and help caregivers access information and support, evaluate patients' fitness to drive or own firearms, and provide advice about the need for legal and financial planning. Review of caregiver well-being and prompt referral for support is vital.

Sleepiness, inflammation and oxidative stress markers in middle-aged males with obstructive sleep apnea without metabolic syndrome: a cross-sectional study

BACKGROUND

The simultaneous occurrence of metabolic syndrome and excessive daytime sleepiness are very common in obstructive sleep apnea (OSA) patients. Both conditions, if present in OSA, have been reported to be associated with inflammation and disruption of oxidative stress balance that impair the cardiovascular system. To verify the impact of daytime sleepiness on inflammatory and oxidative stress markers, we evaluated OSA patients without significant metabolic disturbance.

METHODS

Thirty-five male subjects without diagnostic criteria for metabolic syndrome (Adult Treatment Panel III) were distributed into a control group (n = 10) (43 ± 10.56 years, apnea-hypopnea index - AHI 2.71 ± 1.48/hour), a non-sleepy OSA group (n = 11) (42.36 ± 9.48 years, AHI 29.48 ± 22.83/hour) and a sleepy OSA group (n = 14) (45.43 ± 10.06 years, AHI 38.20 ± 25.54/hour). Excessive daytime sleepiness was considered when Epworth sleepiness scale score was ≥ 10. Levels of high-sensitivity C-reactive protein, homocysteine and cysteine, and paraoxonase-1 activity and arylesterase activity of paraoxonase-1 were evaluated.

RESULTS

Patients with OSA and excessive daytime sleepiness presented increased high-sensitivity C-reactive protein levels even after controlling for confounders. No significant differences were found among the groups in paraoxonase-1 activity nor arylesterase activity of paraoxonase-1. AHI was independently associated and excessive daytime sleepiness tended to have an association with high-sensitivity C-reactive protein.

CONCLUSIONS

In the absence of metabolic syndrome, increased inflammatory response was associated with AHI and daytime sleepiness, while OSA was not associated with abnormalities in oxidative stress markers.

Identifying Longitudinal Patterns for Individuals and Subgroups: An Example with Adherence to Treatment for Obstructive Sleep Apnea

To improve complex behaviors such as adherence to medical recommendations, a better understanding of behavior change over time is needed. The focus of this study was adherence to treatment for obstructive sleep apnea (OSA). Adherence to the most common treatment for OSA is poor. This study involved a sample of 161 participants, each with approximately 180 nights of data. First, a time series analysis was performed for each individual. Time series parameters included the mean (average hours of use per night), level, slope, variance, and autocorrelation. Second, a dynamic cluster analysis was performed to find homogenous subgroups of individuals with similar adherence patterns. A four-cluster solution was found, and the subgroups were labeled: Great Users (17.2%; high mean and level, no slope), Good Users (32.8%; moderate mean and level, no slope), Low Users (22.7%; low mean and level, negative slope), and Slow Decliners (moderate mean and level, negative slope, high variance). Third, participants in the identified subgroups were compared to establish external validity. These steps represent a Typology of Temporal Patterns (TTP) approach. Combining time series analysis and dynamic cluster analysis is a useful way to evaluate longitudinal patterns at both the individual level and subgroup level.

Cumulative association of obstructive sleep apnea severity and short sleep duration with the risk for hypertension

Obstructive sleep apnea (OSA) and short sleep duration are individually associated with an increased risk for hypertension (HTN). The aim of this multicenter cross-sectional study was to test the hypothesis of a cumulative association of OSA severity and short sleep duration with the risk for prevalent HTN. Among 1,499 patients undergoing polysomnography for suspected OSA, 410 (27.3%) previously diagnosed as hypertensive and taking antihypertensive medication were considered as having HTN. Patients with total sleep time (TST) <6 h were considered to be short sleepers. Logistic regression procedures were performed to determine the independent association of HTN with OSA and sleep duration. Considering normal sleepers (TST ≥6 h) without OSA as the reference group, the odds ratio (OR) (95% confidence intervals) for having HTN was 2.51 (1.35-4.68) in normal sleepers with OSA and 4.37 (2.18-8.78) in short sleepers with OSA after adjustment for age, gender, obesity, diabetes, depression, current smoking, use of thyroid hormones, daytime sleepiness, poor sleep complaint, time in bed, sleep architecture and fragmentation, and study site. The risk for HTN appeared to present a cumulative association with OSA severity and short sleep duration (p<0.0001 for linear trend). The higher risk for HTN was observed in short sleepers with severe OSA (AHI ≥30) (OR, 4.29 [2.03-9.07]). In patients investigated for suspected OSA, sleep-disordered breathing severity and short sleep duration have a cumulative association with the risk for prevalent HTN. Further studies are required to determine whether interventions to optimize sleep may contribute to lower BP in patients with OSA.

Guidelines for the primary prevention of stroke: a statement for healthcare professionals from the American Heart Association/American Stroke Association

The aim of this updated statement is to provide comprehensive and timely evidence-based recommendations on the prevention of stroke among individuals who have not previously experienced a stroke or transient ischemic attack. Evidence-based recommendations are included for the control of risk factors, interventional approaches to atherosclerotic disease of the cervicocephalic circulation, and antithrombotic treatments for preventing thrombotic and thromboembolic stroke. Further recommendations are provided for genetic and pharmacogenetic testing and for the prevention of stroke in a variety of other specific circumstances, including sickle cell disease and patent foramen ovale.

Cardiovascular risk in patients with sleep apnoea with or without continuous positive airway pressure therapy: follow-up of 4.5 million Danish adults

BACKGROUND

The prognostic significance of age and continuous positive airway pressure (CPAP) therapy on cardiovascular disease in patients with sleep apnoea has not been assessed previously.

METHODS

Using nationwide databases, the entire Danish population was followed from 2000 until 2011. First-time sleep apnoea diagnoses and use of CPAP therapy were determined. Incidence rate ratios (IRRs) of ischaemic stroke and myocardial infarction (MI) were analysed using Poisson regression models.

RESULTS

Amongst 4.5 million individuals included in the study, 33 274 developed sleep apnoea (mean age 53, 79% men) of whom 44% received persistent CPAP therapy. Median time to initiation of CPAP therapy was 88 days (interquartile range 34-346). Patients with sleep apnoea had more comorbidities compared to the general population. Crude rates of MI and ischaemic stroke were increased for sleep apnoea patients (5.4 and 3.6 events per 1000 person-years compared to 4.0 and 3.0 in the general population, respectively). Relative to the general population, risk of MI [IRR 1.71, 95% confidence interval (CI) 1.57-1.86] and ischaemic stroke (IRR 1.50, 95% CI 1.35-1.66) was significantly increased in patients with sleep apnoea, in particular in patients younger than 50 years (IRR 2.12, 95% CI 1.64-2.74 and IRR 2.34, 95% CI 1.77-3.10, respectively). Subsequent CPAP therapy was not associated with altered prognosis.

CONCLUSIONS

Sleep apnoea is associated with increased risk of ischaemic stroke and MI, particularly in patients younger than 50 years of age. CPAP therapy was not associated with a reduced rate of stroke or MI.

Distinct associations between hypertension and obstructive sleep apnea in male and female patients

Obstructive sleep apnea (OSA) is highly associated with hypertension. However, the correlation between hypertension and OSA at different levels of severity and the influence of gender on that correlation are unclear. A total of 996 patients (776 males and 190 females) with OSA were recruited. The influence of gender on the correlation between hypertension and OSA at different stratifications of severity, based on the apnea-hypopnea index (AHI), was fully evaluated together with the major health risk factors obesity, age, and diabetes. Females with OSA were significantly older on average than males with OSA. Moreover, females had milder degrees of OSA on average than the extent of severity seen in males. The proportion of females with diabetes or hypertension was higher than that of males. The proportion of males with hypertension and obesity increased significantly with OSA, and age also increased with OSA. The percentage of females with hypertension at different degrees of OSA severity was stable at about 26% in the mild, moderate, and severe OSA groups. Among females, age was increased significantly in the moderate relative to the mild OSA group. Moreover, the proportion of obese subjects was increased significantly in the severe compared with the moderate OSA group. The proportions of males and females with diabetes were not significantly different among all OSA severity groups. An ordinal multivariate logistic regression analysis confirmed that hypertension, age, and obesity were associated with OSA severity in males, whereas only age and obesity were associated with OSA severity in females. Although the proportion of subjects with hypertension was higher in females with OSA than in males with OSA, the proportion of subjects with hypertension increased as the severity of OSA increased in males but not in females.

Sleep-disordered breathing, type 2 diabetes and the metabolic syndrome

Sleep-disordered breathing (SDB) encompasses a spectrum of conditions that can lead to altered sleep homeostasis. In particular, obstructive sleep apnoea (OSA) is the most common form of SDB and is associated with adverse cardiometabolic manifestations including hypertension, metabolic syndrome and type 2 diabetes, ultimately increasing the risk of cardiovascular disease. The pathophysiological basis of these associations may relate to repeated intermittent hypoxia and fragmented sleep episodes that characterize OSA which drive further mechanisms with adverse metabolic and cardiovascular consequences. The associations of OSA with type 2 diabetes and the metabolic syndrome have been described in studies ranging from epidemiological and observational studies to controlled trials investigating the effects of OSA therapy with continuous positive airway pressure (CPAP). In recent years, there have been rising prevalence rates of diabetes and obesity worldwide. Given the established links between SDB (in particular OSA) with both conditions, understanding the potential influence of OSA on the components of the metabolic syndrome and diabetes and the underlying mechanisms by which such interactions may contribute to metabolic dysregulation are important in order to effectively and holistically manage patients with SDB, type 2 diabetes or the metabolic syndrome. In this article, we review the literature describing the associations, the possible underlying pathophysiological mechanisms linking these conditions and the effects of interventions including CPAP treatment and weight loss.

The efficacy of antihypertensive drugs in chronic intermittent hypoxia conditions

Sleep apnea/hypopnea disorders include centrally originated diseases and obstructive sleep apnea (OSA). This last condition is renowned as a frequent secondary cause of hypertension (HT). The mechanisms involved in the pathogenesis of HT can be summarized in relation to two main pathways: sympathetic nervous system stimulation mediated mainly by activation of carotid body (CB) chemoreflexes and/or asphyxia, and, by no means the least important, the systemic effects of chronic intermittent hypoxia (CIH). The use of animal models has revealed that CIH is the critical stimulus underlying sympathetic activity and hypertension, and that this effect requires the presence of functional arterial chemoreceptors, which are hyperactive in CIH. These models of CIH mimic the HT observed in humans and allow the study of CIH independently without the mechanical obstruction component. The effect of continuous positive airway pressure (CPAP), the gold standard treatment for OSA patients, to reduce blood pressure seems to be modest and concomitant antihypertensive therapy is still required. We focus this review on the efficacy of pharmacological interventions to revert HT associated with CIH conditions in both animal models and humans. First, we explore the experimental animal models, developed to mimic HT related to CIH, which have been used to investigate the effect of antihypertensive drugs (AHDs). Second, we review what is known about drug efficacy to reverse HT induced by CIH in animals. Moreover, findings in humans with OSA are cited to demonstrate the lack of strong evidence for the establishment of a first-line antihypertensive regimen for these patients. Indeed, specific therapeutic guidelines for the pharmacological treatment of HT in these patients are still lacking. Finally, we discuss the future perspectives concerning the non-pharmacological and pharmacological management of this particular type of HT.

Therapeutic potential of intermittent hypoxia: a matter of dose

Intermittent hypoxia (IH) has been the subject of considerable research in recent years, and triggers a bewildering array of both detrimental and beneficial effects in multiple physiological systems. Here, we review the extensive literature concerning IH and its impact on the respiratory, cardiovascular, immune, metabolic, bone, and nervous systems. One major goal is to define relevant IH characteristics leading to safe, protective, and/or therapeutic effects vs. pathogenesis. To understand the impact of IH, it is essential to define critical characteristics of the IH protocol under investigation, including potentially the severity of hypoxia within episodes, the duration of hypoxic episodes, the number of hypoxic episodes per day, the pattern of presentation across time (e.g., within vs. consecutive vs. alternating days), and the cumulative time of exposure. Not surprisingly, severe/chronic IH protocols tend to be pathogenic, whereas any beneficial effects are more likely to arise from modest/acute IH exposures. Features of the IH protocol most highly associated with beneficial vs. pathogenic outcomes include the level of hypoxemia within episodes and the number of episodes per day. Modest hypoxia (9-16% inspired O2) and low cycle numbers (3-15 episodes per day) most often lead to beneficial effects without pathology, whereas severe hypoxia (2-8% inspired O2) and more episodes per day (48-2,400 episodes/day) elicit progressively greater pathology. Accumulating evidence suggests that "low dose" IH (modest hypoxia, few episodes) may be a simple, safe, and effective treatment with considerable therapeutic potential for multiple clinical disorders.

Nocturnal intermittent hypoxia predicts prevalent hypertension in the European Sleep Apnoea Database cohort study

Systemic hypertension is associated with obstructive sleep apnoea syndrome (OSAS) but the pathophysiological mechanisms are incompletely understood. A collaborative European network of 24 sleep centres established a European Sleep Apnoea Database to evaluate cardiovascular morbidity associated with OSAS. 11 911 adults referred with suspected OSAS between March 2007 and September 2013 underwent overnight sleep studies, either cardiorespiratory polygraphy or polysomnography. We compared the predictive value of the apnoea-hypopnoea index (AHI) and 4% oxygen desaturation index (ODI) for prevalent hypertension, adjusting for relevant covariates including age, smoking, obesity, dyslipidaemia and diabetes. Among patients (70% male, mean±sd age 52±12 years), 78% had AHI>5 events·h(-1) and 41% systemic hypertension. Both AHI and ODI independently related to prevalent hypertension after adjustment for relevant covariates (p<0.0001 for linear trend across quartiles (Q) of severity for both variables). However, in multiple regression analysis with both ODI and AHI in the model, ODI was, whereas AHI was not, independently associated with prevalent hypertension: odds ratios (95% CI) for Q4 versus Q1 regarding ODI were 2.01 (1.61-2.51) and regarding AHI were 0.92 (0.74-1.15) (p<0.0001 and p=0.3054, respectively). This cross sectional study suggests that chronic intermittent hypoxia plays an important role in OSAS-related hypertension.

New frontiers in obstructive sleep apnoea

OSA (obstructive sleep apnoea), the most common respiratory disorder of sleep, is caused by the loss of upper airway dilating muscle activity during sleep superimposed on a narrow upper airway. This results in recurrent nocturnal asphyxia. Termination of these events usually requires arousal from sleep and results in sleep fragmentation and hypoxaemia, which leads to poor quality sleep, excessive daytime sleepiness, reduced quality of life and numerous other serious health consequences. Furthermore, patients with untreated sleep apnoea are at an increased risk of hypertension, stroke, heart failure and atrial fibrillation. Although there are many predisposing risk factors for OSA, including male gender, endocrine disorders, use of muscle relaxants, smoking, fluid retention and increased age, the strongest risk factor is obesity. The aim of the present review is to focus on three cutting-edge topics with respect to OSA. The section on animal models covers various strategies used to simulate the physiology or the effects of OSA in animals, and how these have helped to understand some of the underlying mechanisms of OSA. The section on diabetes discusses current evidence in both humans and animal models demonstrating that intermittent hypoxia and sleep fragmentation has a negative impact on glucose tolerance. Finally, the section on cardiovascular biomarkers reviews the evidence supporting the use of these biomarkers to both measure some of the negative consequences of OSA, as well as the potential benefits of OSA therapies.

Estimation of hypertension risk from lifestyle factors and health profile: a case study

Hypertension is a highly prevalent risk factor for cardiovascular disease and it can also lead to other diseases which seriously harm the human health. Screening the risks and finding a clinical model for estimating the risk of onset, maintenance, or the prognosis of hypertension are of great importance to the prevention or treatment of the disease, especially if the indicator can be derived from simple health profile. In this study, we investigate a chronic disease questionnaire data set of 6563 rural citizens in East China and find out a clinical signature that can assess the risk of hypertension easily and accurately. The signature achieves an accuracy of about 83% on the external test dataset, with an AUC of 0.91. Our study demonstrates that a combination of simple lifestyle features can sufficiently reflect the risk of hypertension onset. This finding provides potential guidance for disease prevention and control as well as development of home care and home-care technologies.

Obstructive Sleep Apnea and Multiple Anthropometric Indices of General Obesity and Abdominal Obesity among Young Adults

This study aimed to examine the association between obstructive sleep apnea (OSA) and obesity among young adults. A total of 2911 college students in Thailand participated in the study. Anthropometric measurements and blood pressure were taken by trained research staff. Overall, 6.3% of college students had OSA determined by the Berlin Questionnaire, 9.6% were overweight (BMI: 25-29 kg/m²), 4.5% were obese (BMI≥30 kg/m²); 12.4% had abdominal obesity (men: waist circumference≥90 cm; women: waist circumference≥80 cm). There were significant associations between OSA and overweight (odds ratio (OR)=1.72; 95% confidence interval (CI)=1.04-1.85) and obesity (OR=24.23; 95% CI=15.20-38.61), independent of demographic and lifestyle factors, blood pressure, and psychological distress. Students with OSA were more likely to have abdominal obesity than those without OSA (OR=2.09; 95% CI=1.19-3.67). OSA was significantly related to joint effects of general and abdominal obesity. The OSA-obesity associations were robust and evident for both genders, individuals with normal and elevated blood pressure, and those with and without psychological distress. This study shows independent associations of OSA with general and abdominal obesity among young adults. OSA could be a risk factor for obesity and consequent cardiovascular morbidities. OSA screening and treatment might be important for young adults.

Upper gastrointestinal bleeding in patients with CKD

BACKGROUND AND OBJECTIVES

Patients with CKD receiving maintenance dialysis are at risk for upper gastrointestinal bleeding. However, the risk of upper gastrointestinal bleeding in patients with early CKD who are not receiving dialysis is unknown. The hypothesis was that their risk of upper gastrointestinal bleeding is negatively linked to renal function. To test this hypothesis, the association between eGFR and risk of upper gastrointestinal bleeding in patients with stages 3-5 CKD who were not receiving dialysis was analyzed.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients with stages 3-5 CKD in the CKD program from 2003 to 2009 were enrolled and prospectively followed until December of 2012 to monitor the development of upper gastrointestinal bleeding. The risk of upper gastrointestinal bleeding was analyzed using competing-risks regression with time-varying covariates.

RESULTS

In total, 2968 patients with stages 3-5 CKD who were not receiving dialysis were followed for a median of 1.9 years. The incidence of upper gastrointestinal bleeding per 100 patient-years was 3.7 (95% confidence interval, 3.5 to 3.9) in patients with stage 3 CKD, 5.0 (95% confidence interval, 4.8 to 5.3) in patients with stage 4 CKD, and 13.9 (95% confidence interval, 13.1 to 14.8) in patients with stage 5 CKD. Higher eGFR was associated with a lower risk of upper gastrointestinal bleeding (P=0.03), with a subdistribution hazard ratio of 0.93 (95% confidence interval, 0.87 to 0.99) for every 5 ml/min per 1.73 m(2) higher eGFR. A history of upper gastrointestinal bleeding (P<0.001) and lower serum albumin (P=0.004) were independently associated with higher upper gastrointestinal bleeding risk.

CONCLUSIONS

In patients with CKD who are not receiving dialysis, lower renal function is associated with higher risk for upper gastrointestinal bleeding. The risk is higher in patients with previous upper gastrointestinal bleeding history and low serum albumin.

Associations of Alcohol Consumption and Chronic Diseases With Sleep Apnea Among US Adults

BACKGROUND

Sleep apnea (SA) is a common sleep disorder among US adults. Associations of SA with alcohol consumption and some chronic diseases have been inconsistent.

OBJECTIVES

This study aimed to estimate prevalence of SA and examine its associations with potential factors including alcohol consumption, asthma, diabetes, and hypertension.

PATIENTS AND METHODS

This was a cross-sectional study on 823 adults with SA and 38,638 controls from the 2011 National Survey on Drug Use and Health Data. Weighted univariate and multiple logistic regression analyses were used to examine the associations of SA with the potential factors.

RESULTS

The prevalence of SA was higher in males (4.01%) than in females (2.61%), while the prevalence increased with age (0.86%, 3.50%, and 4.47% for age groups of 18-25, 26-64, and ≥ 65, respectively). Univariate analysis revealed that all factors except for income and education were associated with SA (P < 0.05). In multivariable analyses, participants who were current and past alcohol consumers had significantly higher odds of having SA (OR = 1.52, 95% CI = 1.03-2.23; OR = 1.65, 95% CI = 1.09-2.49, respectively) than non-alcohol drinker. Furthermore, asthma (OR = 2.77, 95% CI = 2.04-3.75), diabetes (OR = 2.89, 95% CI = 2.19-3.83), and hypertension (OR = 2.42, 95% CI = 1.91-3.07) were significantly associated with SA.

CONCLUSIONS

Age, alcohol consumption, asthma, diabetes, and hypertension, were positively associated with SA. More efforts should be directed to promoting screening for SA and finding possible treatments for SA among these vulnerable groups.

Correlation between the severity of apnea and hypopnea sleep, hypertension and serum lipid and glycemic: a case control study

The purpose of this study was to evaluate the correlation between the severity of obstructive sleep apnea (OSA) and the levels of blood pressure (BP), lipids and glucose, as intermittent hypoxia increases BP, changes the oxidative balance, and can induce the formation of free radicals and atherogenesis. 32 patients were evaluated about BP during wakefulness and sleep, total cholesterol and lipids, LDL (low-density lipoprotein), HDL (high-density lipoprotein), triglycerides, glucose and polysomnography. They were divided into four groups according to the respiratory events per hour of sleep (RDI): control group (RDI < 5), Group I (RDI 5–15), Group II (RDI 15–30), Group III (RDI > 30). There was no increase in BP in groups’ cases, the verification of systolic (p = 0.429) and diastolic (p = 0.475) BP in 24 h, systolic (p = 0.277) and diastolic (p = 0.143) BP during wakefulness, and systolic (p = 0.394) and diastolic (p = 0.703) BP during sleep in the control group. When implementing the Spearman correlation test, a correlation directly proportional to the severity of the disease was not observed. Regarding the level of serum total cholesterol (p = 0.092), LDL (p = 0.242), HDL (p = 0.517), triglycerides (p = 0.947), total lipids (p = 0.602) and glucose (0.355), there was no statistically significant difference between groups (p > 0.05 for all parameters). There is no correlation between the severity of OSA and BP levels in 24 h, during daytime, during the sleep and serum levels of LDL and HDL cholesterol.

Analysis of the vertebrobasilar system in patients with obstructive sleep apnea

We conducted a prospective study to evaluate the vertebrobasilar system in adults with and without obstructive sleep apnea (OSA). Our study population was made up of 48 patients with OSA and 21 healthy volunteers who served as controls; the OSA patients were subdivided into one group with mild or moderate OSA (n = 22) and another with severe OSA (n = 26). Each participant underwent Doppler ultrasonography three times to measure the diameter of the vertebral artery, the peak systolic velocity (PSV), the resistive index (RI), and the vertebral artery flow volume; the mean of the three measurements was calculated for each patient, for the OSA and control groups, and for various subgroups. No significant differences in vessel diameter, PSV, or RI were seen among any of the subgroups. Overall, the vertebral artery flow volume was slightly, but not significantly, higher in all patients with OSA (206 ml/min) than in the control group (177 ml/min); this difference might reflect the body's daytime response to the chronic apneic events experienced during sleep. The only statistically significant difference we found was in vertebral artery flow volume between the controls and the subgroup with mild or moderate OSA (p = 0.026); no difference was seen between the controls and the patients with severe OSA (p = 0.318). Likewise, no significant difference in any of the four parameters was seen when patients were subclassified by body mass index and arterial oxygen saturation level.