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

[Cardiac dysfunction and the obstructive sleep apnoea syndrome]

INTRODUCTION

Cardiac insufficiency affects nearly 2% of the population with increased morbidity/mortality despite advances in therapeutic management. The sleep apnoea syndrome (SAS) is a risk factor for, and cause of aggravation of, myocardial dysfunction.

BACKGROUND

SAS is found in 70% of patients with chronic cardiac failure, 65% of patients with refractory hypertension, 60% of patients with cerebro-vascular accidents and 50% of patients with atrial fibrillation. The associated cardiovascular mortality is multiplied by a factor of 2 to 3. The pathophysiological mechanisms are intermittent nocturnal hypoxia, variations in CO₂ levels, variations in intrathoracic pressure and repeated arrousals from sleep, concurrent with sympathetic hyperactivity, endothelial dysfunction and systemic inflammation.

CONCLUSIONS

SAS and cardiological management in patients presenting with myocardial dysfunction should be combined. It is necessary to pursue the scientific investigations with the aim of determining a precise care pathway and the respective places of each of the cardiological and pulmonary measures.

[Sleep-related breathing disorders in adults: diagnosis, consequences and comorbidities]

Obstructive sleep apnea/hypopnea syndrome (OSAHS) is a collapse of the upper airways leading to a decrease (hypopneas) or interruption of air flow (apneas). Since its identification, only forty years ago, definitions, diagnostic techniques have evolved, the consequences of this syndrome have been widely studied but establishing it as an independent cardiovascular (CV) risk factor has come up against the existence of many confounding factors, such as obesity, high blood pressure (hypertension)… Paraclinical diagnosis is based on the results of poly(somno)graphy. Recommendations on measurement techniques and scoring are regularly published, evolving in parallel with technological progress, with the aim of standardizing and ensuring the reliability of the diagnosis. At the same time, large cohort studies were set up in the 1990s, allowing for transversal and longitudinal follow-up of thousands of patients. Finally, the pathophysiological mechanisms of the consequences of SAHOS were explored. OSA has been shown to be responsible for a particularly high accidental risk due to sleep fragmentation induced by abnormal respiratory events. It has been possible to establish an independent statistical relationship between SAHOS and CV diseases, metabolic disorders and more recently cancer, mainly explained by intermittent hypoxia. OSAHOS is a frequent disease, diagnosed on the basis of clinical signs and poly(somno)graphy, now established as an independent risk factor for morbidity and mortality (accidental and CV).

Hypertension and Acromegaly

Hypertension is one of the most frequent complications in acromegaly, with a median frequency of 33.6% (range, 11%-54.7%). Although the pathogenesis has not been fully elucidated, it probably results from concomitant factors leading to expansion of extracellular fluid volume, increase of peripheral vascular resistance, and development of sleep apnea syndrome. Because the effect of normalization of growth hormone and insulinlike growth factor 1 excess on blood pressure levels is unclear, an early diagnosis of hypertension and prompt antihypertensive treatment are eagerly recommended, regardless of the specific treatment of the acromegalic disease and the level of biochemical control attained.

Resistant/Refractory Hypertension and Sleep Apnoea: Current Knowledge and Future Challenges

Hypertension is one of the most frequent cardiovascular risk factors. The population of hypertensive patients includes some phenotypes whose blood pressure levels are particularly difficult to control, thus putting them at greater cardiovascular risk. This is especially true of so-called resistant hypertension (RH) and refractory hypertension (RfH). Recent findings suggest that the former may be due to an alteration in the renin-angiotensin-aldosterone axis, while the latter seems to be more closely related to sympathetic hyper-activation. Both these pathophysiological mechanisms are also activated in patients with obstructive sleep apnoea (OSA). It is not surprising, therefore, that the prevalence of OSA in RH and RfH patients is very high (as reflected in several studies) and that treatment with continuous positive airway pressure (CPAP) manages to reduce blood pressure levels in a clinically significant way in both these groups of hypertensive patients. It is therefore necessary to incorporate into the multidimensional treatment of patients with RH and RfH (changes in lifestyle, control of obesity and drug treatment) a study of the possible existence of OSA, as this is a potentially treatable disease. There are many questions that remain to be answered, especially regarding the ideal combination of treatment in patients with RH/RfH and OSA (drugs, renal denervation, CPAP treatment) and patients' varying response to CPAP treatment.

Arrhythmogenic mechanisms of obstructive sleep apnea in heart failure patients

Heart failure (HF) affects 23 million people worldwide and results in 300000 annual deaths. It is associated with many comorbidities, such as obstructive sleep apnea (OSA), and risk factors for both conditions overlap. Eleven percent of HF patients have OSA and 7.7% of OSA patients have left ventricular ejection fraction <50% with arrhythmias being a significant comorbidity in HF and OSA patients. Forty percent of HF patients develop atrial fibrillation (AF) and 30%-50% of deaths from cardiac causes in HF patients are from sudden cardiac death. OSA is prevalent in 32%-49% of patients with AF and there is a dose-dependent relationship between OSA severity and resistance to anti-arrhythmic therapies. HF and OSA lead to various downstream arrhythmogenic mechanisms, including metabolic derangement, remodeling, inflammation, and autonomic imbalance. (1) Metabolic derangement and production of reactive oxidative species increase late Na+ currents, decrease outward K+ currents and downregulate connexin-43 and cell-cell coupling. (2) remodeling also features downregulated K+ currents in addition to decreased Na+/K+ ATPase currents, altered Ca2+ homeostasis, and increased density of If current. (3) Chronic inflammation leads to downregulation of both Nav1.5 channels and K+ channels, altered Ca2+ homeostasis and reduced cellular coupling from alterations of connexin expression. (4) Autonomic imbalance causes arrhythmias by evoking triggered activity through increased Ca2+ transients and reduction of excitation wavefront wavelength. Thus, consideration of these multiple pathophysiological pathways (1-4) will enable the development of novel therapeutic strategies that can be targeted against arrhythmias in the context of complex disease, such as the comorbidities of HF and OSA.

[Preoperative risk and perioperative management of obese patients]

The obese patient is at an increased risk of perioperative complications. Most importantly, these include difficult access to the airways (intubation, difficult or impossible ventilation), and post-extubation respiratory distress secondary to the development of atelectasis or obstruction of the airways, sometimes associated with the use of morphine derivatives. The association of obstructive sleep apnea syndrome (OSA) with obesity is very common, and induces a high risk of peri- and postoperative complications. Preoperative OSA screening is crucial in the obese patient, as well as its specific management: use of continuous positive pre, per and postoperative pressure. For any obese patient, the implementation of protocols for mask ventilation and/or difficult intubation and the use of protective ventilation, morphine-sparing strategies and a semi-seated positioning throughout the care, is recommended, combined with close monitoring postoperatively. The dosage of anesthetic drugs should be based on the theoretical ideal weight and then titrated, rather than dosed to the total weight. Monitoring of neuromuscular blocking should be used where appropriate, as well as monitoring of the depth of anesthesia. The occurrence of intraoperative recall is indeed more frequent in the obese patient than in the non-obese patient. Appropriate prophylaxis against venous thromboembolic disease and early mobilization are recommended, as thromboembolic disease is increased in the obese patient. The use of non-invasive ventilation to prevent the occurrence of acute post-operative respiratory failure and for its treatment is particularly effective in obese patients. In case of admission to ICU, an individualized ventilatory management based on pathophysiology and careful monitoring should be initiated.

Chronic kidney disease in patients with obstructive sleep apnea. A narrative review

Prevalence of both chronic kidney disease (CKD) and obstructive sleep apnea (OSA) is continuously increasing. Moreover, the prevalence of OSA increases as kidney function declines and is higher among patients with end-stage renal disease (ESRD). In addition, OSA is recognized as a potential nontraditional risk factor for development and progression of CKD. Continuous positive airway pressure (CPAP) plays a pivotal role in the management of OSA, eliminating patients' symptoms and improving their quality of life. Recent studies suggested that CPAP treatment may have beneficial effects on kidney function among patients with OSA. This narrative review summarizes the existing knowledge on the association between CKD and OSA, with emphasis on the epidemiology, the pathophysiology of the development of CKD in OSA and vice versa, as well as the effect of CPAP on renal function.

The association of obstructive sleep apnea and left ventricular hypertrophy in obese and overweight children with history of elevated blood pressure

Obesity is a potent cardiovascular disease (CVD) risk factor and is associated with left ventricular hypertrophy (LVH). Obstructive sleep apnea (OSA) is common among individuals with obesity and is also associated with CVD risk. The authors sought to determine the association of OSA, a modifiable CVD risk factor, with LVH among overweight/obese youth with elevated blood pressure (EBP). This was a cross-sectional analysis of the baseline visit of 61 consecutive overweight/obese children with history of EBP who were evaluated in a pediatric obesity hypertension clinic. OSA was defined via sleep study or validated questionnaire. Children with and without OSA were compared using Fisher's exact tests, Student's t tests, and Wilcoxon rank sum test. Multivariable logistic regression evaluated the association between OSA and LVH. In this cohort, 71.7% of the children had LVH. Children with OSA were more likely to have LVH (85.7% vs 59.4%, P = 0.047). OSA was associated with 4.11 times greater odds of LVH (95% CI 1.15, 14.65; P = 0.030), remaining significant after adjustment for age, sex, race, and BMI z-score (after adjustment for hypertension, P = 0.051). A severe obstructive apnea-hypopnea index (AHI >10) was associated with 14 times greater odds of LVH (95% CI 1.14, 172.64, P = 0.039). OSA was significantly associated with LVH among overweight/obese youth with EBP, even after adjustment for age, sex, race, and BMI z-score. Those with the most severe OSA (AHI >10) had the greatest risk for LVH. Future studies exploring the impact of OSA treatment on CVD risk in children are needed.

The Additive Interaction between Body Mass Index and Hypertension Family History in Han and Yugur: The China National Health Survey (CNHS)

OBJECTIVE

To estimate the additive interaction of body mass index (BMI) and family history of hypertension (FHH) on hypertension and explore whether the interaction could be influenced by behavioural risk factors.

METHODS

The cross-sectional data on 5791 participants were from the China National Health Survey in Gansu province in 2016. We assessed the additive interaction by calculating the relative excess risk due to interaction (RERI), the attributable proportion due to interaction (AP), and the synergy index (SI).

RESULTS

ORs for hypertension were highest in Han (13.52, 95% CI: 9.45 to 19.34) and Yugur (13.85, 95% CI: 8.48 to 22.63) with the combination of obesity and FHH. The interaction of BMI and FHH was significant in Han people, with the RERI, AP, and SI and their 95% CIs being 2.48 (1.13 to 3.82), 0.33 (0.19 to 0.47), and 1.61 (1.26 to 2.07) for overweight and FHH and 6.32 (1.91 to 10.73), 0.47 (0.27 to 0.67), and 2.02 (1.33 to 3.07) for obesity and FHH, respectively. The interaction of BMI and FHH was not significant in Yugur people. Adjustment for behavioural risk factors had little influence on the interactions, and risks of hypertension remained increased.

CONCLUSIONS

BMI and FHH were associated with hypertension, and the interaction of BMI and FHH on hypertension was significant in Han but not in Yugur people. Behavioural risk factors had little influence on the associations and interactions. The exacerbation of hypertension risks by overweight or obesity in hypertension families deserves attention in weight control and community care.

Effect of age on the cardiovascular remodelling induced by chronic intermittent hypoxia as a murine model of sleep apnoea

BACKGROUND AND OBJECTIVE

Chronic intermittent hypoxia (CIH) is a major determinant of the cardiovascular morbidity associated with obstructive sleep apnoea (OSA), and the magnitude of CIH impact may be influenced by ageing. Here, we assessed the role of ageing in the early cardiovascular structural remodelling induced by severe CIH in a murine model of OSA.

METHODS

Cardiovascular remodelling was assessed in young (2 months old, n = 20) and aged (18 months old, n = 20) C57BL/6 female mice exposed to CIH (20% O₂ for 40 s, 5% O₂ for 20 s) or normoxia (room air) for 8 weeks (6 h/day).

RESULTS

Early vascular remodelling was observed in young mice exposed to CIH as illustrated by intima-media thickening (mean change: 4.6 ± 2.6 μm; P = 0.02), elastin fibre disorganization (mean change: 9.2 ± 4.5%; P = 0.02) and fragmentation (mean change: 2.5 ± 0.8%; P = 0.03), and collagen (mean change: 3.2 ± 0.6%; P = 0.001) and mucopolysaccharide accumulation (mean change: 2.4 ± 0.8%; P = 0.01). In contrast, vascular remodelling was not apparent in aged mice exposed to CIH. Furthermore, left ventricular perivascular fibrosis (mean change: 0.71 ± 0.1; P < 0.001) and hypertrophy (mean change: 0.17 ± 0.1; P = 0.038) were increased by CIH exposure in young mice, but not in aged mice. Principal component analysis identified similar cardiovascular alterations among the young mice exposed to CIH and both older mouse groups, suggesting that CIH induces premature cardiovascular senescence.

CONCLUSION

Cardiovascular remodelling induced by severe CIH is affected by the age at which CIH onset occurs, suggesting that the deleterious cardiovascular effects associated with CIH may be more pronounced in younger populations, and such changes resemble chronological age-related declines in cardiovascular structural integrity.

The Association of Obstructive Sleep Apnea and Hypertension

Obstructive sleep apnea (OSA) is a condition characterized by recurrent episodes of partial or complete upper airway obstruction during sleep. Hypertension (HTN) is defined by the presence of a chronic elevation of systemic arterial pressure above a certain threshold value (≥140 mm Hg systolic or ≥90 mm Hg diastolic). On the surface, OSA and HTN appear very different from one another. Despite this, they share several common risk factors including obesity, male gender, and advancing age. In 2003, the Seventh Joint National Committee (JNC VII) recognized OSA as a secondary cause of HTN. As physicians, our goal is to understand the OSA-HTN association better through academic study regarding its epidemiology, its pathophysiology, and its treatment. 

Diurnal changes in central blood pressure and pulse pressure amplification in patients with obstructive sleep apnoea

STUDY OBJECTIVES

Recent evidence suggests that compared to peripheral blood pressure (BP), central BP may be more strongly associated with target organ damage and cardiovascular morbidity and mortality. Technological advances now allow the ambulatory measurement of peripheral and central BP over 24 ​h. For the first time, we set out to characterise the diurnal profile of central BP and pulse pressure amplification (PPA) in patients with obstructive sleep apnoea (OSA).

METHODS

In this observational study, patients with moderate to severe OSA underwent 24 ​h central and peripheral BP testing before and after at least 4 weeks of CPAP therapy. Concurrent actigraphy was performed to confirm sleep and wake times.

RESULTS

36 patients were screened, 31 had successful testing (mean (SD) age 45 ​± ​10 years, AHI 58 ​± ​27 events/hr, Office BP 136/89 ​± ​10.7/9.5 ​mmHg, 32% on anti-hypertensives, 77% dippers), 21 completed testing post CPAP. Central systolic and diastolic BP followed the same nocturnal dipping profile as peripheral BP, however the peripheral pulse pressure (PP) narrowed in sleep (-3.2 ​mmHg, p ​< ​0.001), whereas the central PP remained unchanged (0.124 ​mmHg, NS), causing a significant reduction in PPA overnight (-10.7%, p ​< ​0.001). The magnitude of dip in central systolic pressure was less than peripheral systolic pressure (by 2.3 ​mmHg, p ​< ​0.001). After treatment with CPAP, the PPA reduction overnight was attenuated (by -3.3%, p ​= ​0.004).

CONCLUSIONS

In moderate to severe OSA, central BP and PPA reduce overnight during sleep. Further randomised controlled studies are needed to quantify the differential effects of CPAP and anti-hypertensives on central versus peripheral BP.

A Global Comparison of Anatomic Risk Factors and Their Relationship to Obstructive Sleep Apnea Severity in Clinical Samples

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is a global health issue and is associated with obesity and oropharyngeal crowding. Global data are limited on the effect of ethnicity and sex on these relationships. We compare associations between the apnea-hypopnea index (AHI) and these risk factors across ethnicities and sexes within sleep clinics.

METHODS

This is a cross-sectional, multicenter study of patients with OSA from eight sleep centers representing the Sleep Apnea Global Interdisciplinary Consortium (SAGIC). Four distinct ethnic groups were analyzed, using a structured questionnaire: Caucasians (Australia, Iceland, Germany, United States), African Americans (United States), Asians (Taiwan), and South Americans (Brazil). Regression analyses and interaction tests were used to assess ethnic and sex differences in relationships between AHI and anthropometric measures (body mass index [BMI], neck circumference, waist circumference) or Mallampati score.

RESULTS

Analyses included 1,585 individuals from four ethnic groups: Caucasian (60.6%), African American (17.5%), Asian (13.1%), and South American (8.9%). BMI was most strongly associated with AHI in South Americans (7.8% increase in AHI per 1 kg/m² increase in BMI; P < .0001) and most weakly in African Americans (1.9% increase in AHI per 1 kg/m² increase in BMI; P = .002). In Caucasians and South Americans, associations were stronger in males than females. Mallampati score differed between ethnicities but did not influence AHI differently across groups.

CONCLUSIONS

We demonstrate ethnic and sex variations in associations between obesity and OSA. For similar BMI increases, South American patients show greatest AHI increases compared to African Americans. Findings highlight the importance of considering ethnicity and sex in clinical assessments of OSA risk.

The association between cigarette smoking and obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea (OSA) is a serious sleep disorder characterized by repetitive episodes of paused or shallow breathing during sleep. Patients with OSA often have excessive daytime sleepiness. The role of cigarette smoking in OSA remains controversial. The aim of this study was to examine the relationship between cigarette smoking and OSA.

METHODS

In this retrospective chart review, we reviewed 18-month sleep laboratory charts in central Taiwan. We collected data regarding sleep, current cigarette smoking status, sex, age, body mass index (BMI), neck circumference, Epworth Sleepiness Scale score, and polysomnographic sleep parameters. In total, 733 subjects were recruited; among these, 151 were smokers and 582 were non-smokers.

RESULTS

Smokers had significantly higher apnea-hypopnea index (p<0.001) for non-rapid eye movement sleep stage, higher apnea-hypopnea index (p<0.001) for total sleep time, and higher snore frequency (p<0.001) in t-test analysis. They also demonstrated higher Epworth Sleepiness Scale scores, shorter sleep times, lower percentage of slow-wave (deep) sleep, and longer snore times. However, no significant association was found between cigarette smoking and OSA after adjusting for sex, age, and BMI (OR=1.02, 95% CI: 0.66-1.57).

CONCLUSIONS

We did not find any significant association between cigarette smoking and OSA after adjusting for age, sex, and BMI. Further well-designed prospective controlled cohort studies might clarify the relationship between cigarette smoking and OSA.

Self-Reported Sleep, Anxiety, and Cognitive Performance in a Sample of U.S. Military Active Duty and Veterans

Unhealthy sleep can interfere with U.S. military service members affective and cognitive functioning, and increase accident and injury risks. This study examined the relationship between U.S. active duty and veterans' (n = 233) self-reported sleep (Pittsburgh Sleep Quality Index), anxiety (Zung Self-Rating Anxiety Scale), and cognitive performance (Automated Neuropsychological Assessment Metric). Statistical analyses included Pearson product moment correlations and multivariate analysis of variance, with Tukey-b post-hoc tests, with a p < 0.05 significance level. Higher education, abstinence from sleep aids, longer time in active duty service, and being on active duty were correlated with better sleep and lower anxiety. Greater sleep disturbance, poor sleep quality, and sleepiness-related daytime dysfunction were associated with greater anxiety and slower response times, and lower response accuracy. Statistically controlling for anxiety diminished the magnitude and significance of the correlations between sleep and cognitive performance, suggesting that reducing anxiety will improve sleep and diminish cognitive performance effects. These findings suggest the need for addressing both sleep and anxiety for those with diagnosed sleep disorders, as well as using a procedural systems approach to decrease anxiety during missions that demand outstanding cognitive performance.

Idiopathic intracranial hypertension in the British population with obesity

PURPOSE

Idiopathic intracranial hypertension (IIH) is a syndrome that is characterized by persistently high intracranial pressure and associated with high rates of morbidity and visual loss. Its exact etiology and clinical picture is poorly understood, but it is known to be associated with obesity. The aim of this study was to investigate the prevalence and clinical manifestations of IIH using a large nationwide database of British subjects.

MATERIALS AND METHODS

The anonymized healthcare records of patients with a BMI of ≥ 30 kg/m² were extracted from the Clinical Practice Research Datalink (CPRD), and analyzed.

RESULTS

The patients with IIH were older and more likely to have peripheral vascular disease, ischemic heart disease, and anemia; to have had a previous myocardial infarction; and have used non-steroidal anti-inflammatory drugs (NSAIDs) and steroids. Multivariate analysis with adjustment for confounders showed that anemia (p = 0.033) and the use of NSAIDs (p = 0.011) were the only factors independently associated with IIH. Increases in BMI beyond the threshold of obesity did not independently increase risk of IIH.

CONCLUSIONS

IIH is a multifactorial disease; the risk of which is increased in patients with a background of anemia, and those who use NSAIDs. Across BMI categories beyond the threshold for obesity (BMI ≥ 30 kg/m²), there is no continuation of the previously described "dose-response" relationship between BMI and IIH.

ETHICAL APPROVAL

Scientific approval for the study was granted from the Regulatory Agency's Independent Scientific Advisory Committee and ethical approval by the Health Research Authority IRAS Project ID: 203143. ISAC approval registration number 16_140R2.

Effect of CPAP Therapy on Serum Lipids and Blood Pressure in Patients with Obstructive Sleep Apnea Syndrome

BACKGROUND

Most of patients with Obstructive Sleep Apnea (OSA) are at risk of metabolic syndrome. The treatment of choice for OSA patients is the Continuous Positive Airway Pressure (CPAP). Reports about the effect of CPAP on metabolic parameters are controversial. So, we aimed to evaluate the effect of CPAP therapy on blood pressure, Fasting Blood Sugar (FBS), and serum lipids including: Triglycerides (TG), total cholesterol (Chol), High Density Lipoproteins (HDL), and Low Density Lipoproteins (LDL).

MATERIALS AND METHODS

This study included 35 OSA patients. Initially, their baseline demographic and clinical characteristics were recorded. Then, the patients underwent CPAP therapy on average 4-7 hours for 8 weeks. The level of FBS, TG, Cholesterol, HDL, LDL, and blood pressure were measured and recorded before and after treatment. Finally, the collected data were analyzed with SPSS version 22.

RESULTS

This study included 35 OSA patients [24 men (68.6%)], with mean age of 45.58±8.02 years. Results indicated that CPAP therapy led to decrease of 9.76 and 3.49 mmHg in systolic and diastolic blood pressures, respectively. Also, LDL decreased to 6.27mg/dl and HDL increased to 0.75 mg/dl (P<0.001) with treatment. The changes of other variables were not significant (P>0.05).

CONCLUSION

Treatment of OSA with CPAP has beneficial effects on blood pressure and some items of lipid profile. Regarding the importance of metabolic disturbances in OSA complications, choosing an appropriate treatment for OSA patients can play an important role in improvement of patients status as well as prevention of these complications.

Comorbidities associated with obstructive sleep apnea: a retrospective Egyptian study on 244 patients

PURPOSE

The aim of the present study was to assess prevalence of associated comorbidities in a group of patients diagnosed with obstructive sleep apnea syndrome (OSAS).

METHODS

This retrospective study enrolled 244 consecutive patients diagnosed by polysomnogram with OSAS between October 2010 and January 2015 after being referred to our Sleep-Related Breathing Disorders Unit, Chest Diseases Department, in the Alexandria Main University Hospital.

RESULTS

Of 244 patients, 47% were men, mean age was 56.9 years, and mean apnea-hypopnea index was 43.6 events per hour. Patients were categorized into two groups: group 1 (38%), mild and moderate OSAS, and group 2 (62%), severe, very severe, and extreme OSAS. Comorbidities were present in 91% of patients. The most common comorbidities were obesity, hypertension (HTN), and diabetes mellitus (DM). Prevalence of obesity, HTN, DM, congestive heart failure, deep vein thrombosis, pulmonary embolism (PE), and hypothyroidism was significantly higher in severity group 2. PE, bronchial asthma, and chronic obstructive pulmonary disease were significantly higher among men, whereas hypothyroidism was significantly higher among women. During this period of over 4 years, mortality rate was 8%. The majority of deaths occurred at night. Most of the studied patients (60%) either received no treatment or were not adherent to positive airway pressure (PAP) therapy. None of the patients received surgicaltreatment. The majority (50%) gained access to PAP therapy through donations. Associated hypoventilation was the only significant predictor of PAP adherence. Quality of life was significantly better among PAP adherent patients.

CONCLUSIONS

Patients suffering from OSAS have very high prevalence of comorbidities indicating a great burden on the healthcare system. Despite this fact, over 50% of the patients studied did not receive any treatment. Charities were the main portal fortreatment.

Prevalence and Risk of Obstructive Sleep Apnea and Arterial Hypertension in the Adult Population in Poland: An Observational Subset of the International Prospective Urban Rural Epidemiology (PURE) Study

Obstructive sleep apnea (OSA) is a common breathing disorder affecting millions of people worldwide. The disorder is connected with serious consequences including hypertension, myocardial infarction, arrhythmias, coronary disease, cardiac insufficiency, stroke, transient ischemic attack, and cognitive decline. Epidemiological data assessing the prevalence of OSA in different countries vary in methodology, size, and characteristics of population chosen and thus are hardly comparable. There are very few reports on the prevalence of OSA and on the diagnostic accuracy of sleep questionnaires available in Poland. In this report we present the analysis of the prevalence of, and risk factors for OSA in the Polish adult population consisting of 613 community-based subjects (227 men and 386 women). The study was based on the STOP-BANG questionnaire, a validated Screening Tool for OSA in primary care. It is a part of Polish subset of the Prospective Urban Rural Epidemiology (PURE) study, an ongoing population cohort study of individuals from urban and rural communities from 21 countries. We took into account age, gender, body mass index (BMI), and antihypertensive treatment. The findings are that over one half of the Polish population investigated had a moderate to high risk of OSA (66.5% of men and 60.1% of women). After the adjustments for age, gender, and BMI we noticed a dose-response relationship between arterial blood pressure behavior and OSA. The association was significant among women, but not men. Based on previous studies we can assume that one half of this high risk group would be further diagnosed for OSA. This study, the first large scale screening for OSA in Poland, shows a substantial, much higher than previously appreciated, prevalence of risk for OSA in the population at large.

GUT Microbiome-GUT Dysbiosis-Arterial Hypertension: New Horizons

Arterial hypertension is a progressive cardiovascular syndrome arising from complex and interrelated etiologies. The human microbiome refers to the community of microorganisms that live in or on the human body. They influence human physiology by interfering in several processes such as providing nutrients and vitamins in Phase I and Phase II drug metabolism. The human gut microbiota is represented mainly by Firmicutes and Bacteroidetes and to a lesser degree by Actinobacteria and Proteobacteria, with each individual harbouring at least 160 such species. Gut microbiota contributes to blood pressure homeostasis and the pathogenesis of arterial hypertension through production, modification, and degradation of a variety of microbial-derived bioactive metabolites. Animal studies and to a lesser degree human research has unmasked relative mechanisms, mainly through the effect of certain microbiome metabolites and their receptors, outlining this relationship. Interventions to utilize these pathways, with probiotics, prebiotics, antibiotics and fecal microbiome transplantation have shown promising results. Personalized microbiome-based disease prediction and treatment responsiveness seem futuristic. Undoubtedly, a long way of experimental and clinical research should be pursued to elucidate this novel, intriguing and very promising horizon.

The epidemiology of obstructive sleep apnoea and cardiovascular disease

Obstructive sleep apnoea, the most common form of sleep-disordered breathing, is highly prevalent in patients with cardiovascular disease. The last 30 years has seen a plethora of large scale epidemiological studies investigating the relationship between sleep apnoea and cardiovascular outcomes. This review highlights the key epidemiological studies addressing the links between sleep apnoea and hypertension, cardiac arrhythmias, cerebrovascular disease, coronary artery disease, heart failure and pulmonary hypertension, with a particular focus on some of the most recent reports.

Abdominal aortic calcification score can predict future coronary artery disease in hemodialysis patients: a 5-year prospective cohort study

BACKGROUND

Abdominal aortic calcification (AAC) has been known to be associated with cardiovascular mortality in hemodialysis. However, the association between AAC and future coronary artery disease (CAD) occurrence is not clear. We aimed to clarify the association of AAC severity and the occurrence of future CAD events in hemodialysis patients.

METHODS

Hemodialysis (HD) patients were recruited in this prospective cohort study. AAC severity was quantified by AAC score, which was measured by lateral lumbar radiography. We used receiver operation curve (ROC) analysis to find the cutoff AAC value for CAD prediction. CAD-free survival was analyzed by Kaplan-Meier study.

RESULTS

There were 303 patients recruited for study with a median (interquartile range) follow-up of 95 (65-146) months. The AAC score in patients with occurrence of new CAD [9 (3-15.25), n = 114] was higher than in patients without new CAD occurrence [5 (1-9) n = 189], p < 0.001. Multivariate hazard ratio of AAC score for CAD was 1.039 (p = 0.016). ROC study showed that an AAC score of 5.5 had a sensitivity of 0.658 and a specificity of 0.587 in the prediction of new CAD occurrence. Patients with AAC score above 5.5 had significantly higher cumulative incidence of CAD than patients with AAC score below 5.5. Age, diabetes, prior history of CAD, and longer dialysis vintage were major factors associated with higher AAC score.

CONCLUSIONS

AAC score can predict the occurrence of future CAD events in HD patients. The best cut-off value of AAC score is 5.5. AAC score greater than 5.5 is a reliable abdominal aortic calcification marker, and can predict future CAD in ESRD patients. Major contributive factors for higher AAC score were age, presence of diabetes, prior history of CAD, and longer dialysis vintage.

Chronotherapy for Hypertension

PURPOSE OF REVIEW

Given the emerging knowledge that circadian rhythmicity exists in every cell and all organ systems, there is increasing interest in the possible benefits of chronotherapy for many diseases. There is a well-documented 24-h pattern of blood pressure with a morning surge that may contribute to the observed morning increase in adverse cardiovascular events. Historically, antihypertensive therapy involves morning doses, usually aimed at reducing daytime blood pressure surges, but an absence of nocturnal dipping blood pressure is also associated with increased cardiovascular risk.

RECENT FINDINGS

To more effectively reduce nocturnal blood pressure and still counteract the morning surge in blood pressure, a number of studies have examined moving one or more antihypertensives from morning to bedtime dosing. More recently, such studies of chronotherapy have studied comorbid populations including obstructive sleep apnea, chronic kidney disease, or diabetes. Here, we summarize major findings from recent research in this area (2013-2017). In general, nighttime administration of antihypertensives improved overall 24-h blood pressure profiles regardless of disease comorbidity. However, inconsistencies between studies suggest a need for more prospective randomized controlled trials with sufficient statistical power. In addition, experimental studies to ascertain mechanisms by which chronotherapy is beneficial could aid drug design and guidelines for timed administration.

Comparing REM- and NREM-Related Obstructive Sleep Apnea in Jordan: A Cross-Sectional Study

Obstructive sleep apnea (OSA) is a common disorder that includes an intermittent mechanical obstruction of the upper airway during sleep, which can occur either during rapid eye movement (REM) phase or non-REM (NREM) phase. In this study, we aim to evaluate the differences in demographic and polysomnographic features between REM- and NREM-related OSA in a Jordanian sample, using both the broad and the restricted definitions of REM-related OSA. All patients who were referred due to clinical suspicion of OSA and underwent sleep study were screened. We included patients with a diagnosis of OSA who had Apnea-Hypopnea Index (AHI) greater than or equal to five. We classified patients into REM-related OSA according to either the broad definition (AHI_REM/AHI_NREM ≥ 2) or the strict definition (AHI_REM > 5 and AHI_NREM < 5 with a total REM sleep duration of at least 30 minutes), and patients with AHI_REM/AHI_NREM less than two were classified as NREM-related OSA. A total of 478 patients were included in this study with a mean age of 55.3 years (±12.6). According to the broad definition of REM-related OSA, 86 (18%) of OSA patients were classified as having REM-related OSA compared to only 13 (2.7%) patients according to the strict definition. Significant differences were found between both NREM-related OSA and REM-related OSA according to the broad and to the strict definitions for arousal index (p < 0.001 and p < 0.032), respectively, duration of saturation below 90% (p < 0.001 for both), and saturation nadir (p < 0.036 and p < 0.013), respectively. No significant differences were found between this group and other OSA patients regarding age, BMI, ESS, and snoring. Our study showed that the stricter the definition for REM-related OSA, the milder the associated clinical changes.

DNA methylation in the central and efferent limbs of the chemoreflex requires carotid body neural activity

KEY POINTS

The mechanisms underlying long-term (30 days) intermittent hypoxia (LT-IH)-evoked DNA methylation of anti-oxidant enzyme (AOE) gene repression in the carotid body (CB) reflex pathway were examined. LT-IH-treated rats showed increased reactive oxygen species (ROS) levels in the CB reflex pathway. Administration of a ROS scavenger or CB ablation blocked LT-IH-evoked DNA methylation and AOE gene repression in the central and efferent limbs of the CB reflex. LT-IH increased DNA methyltransferase (Dnmt) activity through upregulation of Dnmt1 and 3b proteins by ROS-dependent inactivation of glycogen synthase kinase 3β (GSK3β) by Akt. A pan-Akt inhibitor prevented LT-IH-induced GSK3β inactivation, elevated Dnmt protein expression and activity, AOE gene methylation, sympathetic activation and hypertension.

ABSTRACT

Long-term exposure to intermittent hypoxia (LT-IH; 30 days), simulating blood O2 profiles during sleep apnoea, has been shown to repress anti-oxidant enzyme (AOE) gene expression by DNA methylation in the carotid body (CB) reflex pathway, resulting in persistent elevation of plasma catecholamine levels and blood pressure. The present study examined the mechanisms by which LT-IH induces DNA methylation. Adult rats exposed to LT-IH showed elevated reactive oxygen species (ROS) in the CB, nucleus tractus solitarius (nTS) and rostroventrolateral medulla (RVLM) and adrenal medulla (AM), which represent the central and efferent limbs of the CB reflex, respectively. ROS scavenger treatment during the first ten days of IH exposure prevented ROS accumulation, blocked DNA methylation, and normalized AOE gene expression, suggesting that ROS generated during the early stages of IH activate DNA methylation. CB ablation prevented the ROS accumulation, normalized AOE gene expression in the nTS, RVLM, and AM and blocked DNA methylation, suggesting that LT-IH-induced DNA methylation in the central and efferent limbs of the CB reflex is indirect and requires CB neural activity. LT-IH increased DNA methyl transferase (Dnmt) activity through upregulation of Dnmt1 and 3b protein expression due to ROS-dependent inactivation of glycogen synthase kinase 3β (GSK3β) by protein kinase B (Akt). Treating rats with the pan-Akt inhibitor GSK690693 blocked the induction of Dnmt activity, Dnmt protein expression, and DNA methylation, leading to normalization of AOE gene expression as well as plasma catecholamine levels and blood pressure.

Bioinformatics analysis to reveal the key genes related to obstructive sleep apnea

PURPOSE

Obstructive sleep apnea (OSA) is induced by obstruction of the upper airway, which can raise multiple health risks. This study is designed to reveal the key genes involved in OSA.

METHODS

GSE38792 was extracted from Gene Expression Omnibus database, including ten visceral adipose tissues from OSA patients and eight visceral adipose tissues from normal controls. Differential expression analysis was conducted using limma package, and then the functions of the differentially expressed genes (DEGs) were analyzed using DAVID database, followed by protein-protein interaction (PPI) network, and integrated regulatory network analysis was performed using Cytoscape software.

RESULTS

A total of 368 DEGs (176 upregulated and 192 downregulated) were identified in OSA samples. Epstein-Barr virus infection (involving IL10RB, MAPK9, and MAPK10) and olfactory transduction were the main pathways separately enriched for the upregulated genes and the downregulated genes. After the PPI network was built, the top ten network nodes (such as TXN) were selected according to node degrees. Two significant PPI network modules were identified. Moreover, the integrated regulatory network was constructed.

CONCLUSION

IL10RB, MAPK9, MAPK10, and TXN might function in the pathogenesis of OSA.

Comparison of success criteria based on long-term symptoms and new-onset hypertension in mandibular advancement device treatment for obstructive sleep apnoea: observational cohort study

OBJECTIVE

To identify adequate criteria to determine the success or failure of mandibular advancement device (MAD) treatment for obstructive sleep apnoea (OSA) based on long-term symptoms and new-onset hypertension.

DESIGN

Observational cohort study.

SETTING

A tertiary care hospital setting in South Korea.

PARTICIPANTS

Patients (age >18 years) who were diagnosed with OSA by a polysomnography (PSG) or Watch peripheral arterial tonometry (PAT), and who had been treated with MAD between January 2007 and December 2014 were enrolled.

PRIMARY AND SECONDARY OUTCOME MEASURES

Patients underwent PSG or Watch PAT twice; before and 3 months after the application of MAD. The patients were categorised into success and failure groups using seven different criteria. MAD compliance, witnessed apnoea and snoring, Epworth Sleepiness Scale score and occurrence of new-onset hypertension were surveyed via telephonic interview to determine the criteria that could identify success and failure of MAD.

RESULTS

A total of 97 patients were included. The mean follow-up duration was 60.5 months, and the mean apnoea-hypopnoea index (AHI) was 35.5/hour. Two of the seven criteria could significantly differentiate the success and failure groups based on long-term symptoms, including (1) AHI<10/hour with MAD and (2) AHI<10/hour and AHI reduction of >50% with MAD. Kaplan-Meier survival analysis showed that one criterion of AHI<15/hour with MAD could differentiate the success and failure groups based on new-onset hypertension (p=0.035). The receiver operating characteristic curve analysis indicated that the cut-off AHI for new-onset hypertension was 16.8/hour (71.4% sensitivity and 75.0% specificity).

CONCLUSION

Our long-term follow-up survey for symptoms and new-onset hypertension suggested that some of the polysomnographic success criteria, that is, AHI<10/hour with MAD, AHI<10/hour and AHI reduction of >50% with MAD and AHI<15/hour with MAD may be useful in distinguishing the success group from failure one. Further prospective longitudinal studies are warranted to validate these criteria.

The gut microbiome and hypertension

PURPOSE OF REVIEW

The mammalian mucosal surfaces are densely inhabited by a diverse microbial ecosystem termed the microbiota. Among these highly heterogeneous populations, the largest and richest is the gut microbiota, recently suggested to affect various physiological traits and susceptibility to disease. Novel metagenomic and metabolomic approaches, which have been developed in the past decade, have enabled the elucidation of the contribution of the microbiota to metabolic, immunologic, neurologic and endocrine homeostasis.

RECENT FINDINGS

Dysbiosis, the alteration in the gut microbiota composition and function, has been lately associated with the pathogenesis of multifactorial diseases such as obesity, diabetes and cardiovascular disorders. Recent studies have also suggested associations between dysbiosis and essential hypertension, a common chronic medical condition affecting 20% or more of the adult population worldwide, which is considered a major causative factor for heart disease, stroke, chronic renal failure, blindness and dementia.

SUMMARY

In this review, we discuss the accumulating research pointing to possible interplays between the gut microbiome and hypertension and highlight future prospects by which utilization of microbiome-related techniques may be incorporated into the diagnosis and therapeutic arsenal of hypertension management.

Reactive oxygen radicals and gaseous transmitters in carotid body activation by intermittent hypoxia

Sleep apnea is a prevalent respiratory disease characterized by periodic cessation of breathing during sleep causing intermittent hypoxia (IH). Sleep apnea patients and rodents exposed to IH exhibit elevated sympathetic nerve activity and hypertension. A heightened carotid body (CB) chemoreflex has been implicated in causing autonomic abnormalities in IH-treated rodents and in sleep apnea patients. The purpose of this article is to review the emerging evidence showing that interactions between reactive oxygen species (ROS) and gaseous transmitters as a mechanism cause hyperactive CB by IH. Rodents treated with IH exhibit markedly elevated ROS in the CB, which is due to transcriptional upregulation of pro-oxidant enzymes by hypoxia-inducible factor (HIF)-1 and insufficient transcriptional regulation of anti-oxidant enzymes by HIF-2. ROS, in turn, increases cystathionine γ-lyase (CSE)-dependent H₂S production in the CB. Blockade of H₂S synthesis prevents IH-evoked CB activation. However, the effects of ROS on H₂S production are not due to direct effects on CSE enzyme activity but rather due to inactivation of heme oxygenase-2 (HO-2), a carbon monoxide (CO) producing enzyme. CO inhibits H₂S production through inactivation of CSE by PKG-dependent phosphorylation. During IH, reduced CO production resulting from inactivation of HO-2 by ROS releases the inhibition of CO on CSE thereby increasing H₂S. Inhibiting H₂S synthesis prevented IH-evoked sympathetic activation and hypertension.

Erythropoietin, a putative neurotransmitter during hypoxia, is produced in RVLM neurons and activates them in neonatal Wistar rats

Recent studies indicate that erythropoietin (EPO) is present in many areas of the brain and is active in the restoration of impaired neurons. In this study, we examined the presence of EPO and its role in bulbospinal neurons in the rostral ventrolateral medulla (RVLM). Hypoxia is often accompanied by a high blood pressure (BP). We hypothesized that EPO is produced in response to hypoxia in RVLM neurons and then activates them. To investigate whether RVLM neurons are sensitive to EPO, we examined the changes in the membrane potentials (MPs) of bulbospinal RVLM neurons using the whole cell patch-clamp technique during superfusion with EPO. A brainstem-spinal cord preparation was used for the experiments. EPO depolarized the RVLM neurons, and soluble erythropoietin receptor (SEPOR), an antagonist of EPO, hyperpolarized them. Furthermore, hypoxia-depolarized RVLM neurons were significantly hyperpolarized by SEPOR. In histological examinations, the EPO-depolarized RVLM neurons showed the presence of EPO receptor (EPOR). The RVLM neurons that possessed EPORs showed the presence of EPO and hypoxia-inducible factor (HIF)-2α. We also examined the levels of HIF-2α and EPO messenger RNA (mRNA) in the ventral sites of the medullas (containing RVLM areas) in response to hypoxia. The levels of HIF-2α and EPO mRNA in the hypoxia group were significantly greater than those in the control group. These results suggest that EPO is produced in response to hypoxia in RVLM neurons and causes a high BP via the stimulation of those neurons. EPO may be one of the neurotransmitters produced by RVLM neurons during hypoxia.

Carotid body chemoreflex: a driver of autonomic abnormalities in sleep apnoea

What is the topic of this review? This article presents emerging evidence for heightened carotid body chemoreflex activity as a major driver of sympathetic activation and hypertension in sleep apnoea patients. What advances does it heighlight? This article discusses the recent advances on cellular, molecular and epigenetic mechanisms underlying the exaggerated chemoreflex in experimental models of sleep apnoea. The carotid bodies are the principal peripheral chemoreceptors for detecting changes in arterial blood oxygen concentration, and the resulting chemoreflex is a potent regulator of the sympathetic tone, blood pressure and breathing. Sleep apnoea is a disease of the respiratory system that affects several million adult humans. Apnoeas occur during sleep, often as a result of obstruction of the upper airway (obstructive sleep apnoea) or because of defective respiratory rhythm generation by the CNS (central sleep apnoea). Patients with sleep apnoea exhibit several co-morbidities, with the most notable among them being heightened sympathetic nerve activity and hypertension. Emerging evidence suggests that intermittent hypoxia resulting from periodic apnoea stimulates the carotid body, and the ensuing chemoreflex mediates the increased sympathetic tone and hypertension in sleep apnoea patients. Rodent models of intermittent hypoxia that simulate the O2 saturation profiles encountered during sleep apnoea have provided important insights into the cellular and molecular mechanisms underlying the heightened carotid body chemoreflex. This article describes how intermittent hypoxia affects the carotid body function and discusses the cellular, molecular and epigenetic mechanisms underlying the exaggerated chemoreflex.

[Sleep apneas, metabolic syndrome and cardiovascular risk: Data from the Pays de la Loire sleep cohort]

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is a prevalent disease characterized by recurrent episodes of partial or complete obstruction of upper airway during sleep. Untreated moderate to severe OSAHS is recognized as a cardiovascular (CV) risk factor. Data from the Pays de la Loire sleep cohort and other clinic- or population-based cohorts demonstrate a strong association between OSAHS and the different components of the metabolic syndrome including systemic hypertension, diabetes and impaired lipid metabolism. Beside sleep-disordered breathing severity, these factors contribute to increase the risk of CV events in OSAHS patients. Continuous positive airway pressure (CPAP) therapy of OSAHS is associated with a modest but clinically significant blood pressure reduction. Conversely, there is no clear evidence in support of a metabolic impact of CPAP in OSAHS patients. Considering the multifactorial pathophysiology of CV risk in OSAHS patients and the beneficial impact of various lifestyle and pharmacologic interventions on blood pressure and metabolic dysfunction, combined modality therapy is a promising strategy to improve CV outcomes in individuals with OSAHS.

The utility of home sleep apnea tests in patients with low versus high pre-test probability for moderate to severe OSA

PURPOSE

Home sleep apnea tests (HSATs) are an alternative to attended polysomnograms (PSGs) when the pre-test probability for moderate to severe OSA is high. However, insurers often mandate use anytime OSA is suspected regardless of the pre-test probability. Our objective was to determine the ability of HSATs to rule in OSA when the pre-test probability of an apnea hypopnea index (AHI) in the moderate to severe range is low.

METHODS

Patients who underwent HSATs were characterized as low or high pre-test probability based on the presence of two symptoms of the STOP instrument plus either BMI > 35 or male gender. The odds of HSAT diagnostic for OSA dependent on pre-test probability was calculated. Stepwise selection determined predictors of non-diagnostic HSAT. As PSG is performed after HSATs that do not confirm OSA, false negative results were assessed.

RESULTS

Among 196 individuals, pre-test probability was low in 74 (38%) and high in 122 (62%). A lower percentage of individuals with a low versus high pre-test probability for moderate to severe OSA had HSAT results that confirmed OSA (61 versus 84%, p = 0.0002) resulting in an odds ratio (OR) of 0.29 for confirmatory HSAT in the low pre-test probability group (95% CI [0.146, 0.563]). Multivariate logistic regression demonstrated that age ≤ 50 (OR 3.10 [1.24-7.73]), female gender (OR 3.58[1.50-8.66]), non-enlarged neck circumference (OR 11.50 [2.50-52.93]), and the absence of loud snoring (OR 3.47 [1.30-9.25]) best predicted non-diagnostic HSAT. OSA was diagnosed by PSG in 54% of individuals with negative HSAT which was similar in both pre-test probability groups.

CONCLUSION

HSATs should be reserved for individuals with high pre-test probability for moderate to severe disease as opposed to any individual with suspected OSA.

Diastolic Blood Pressure Rises with the Exacerbation of Obstructive Sleep Apnea in Males

OBJECTIVE

To characterize the association pattern between blood pressure (BP), metabolism changes, and obstructive sleep apnea (OSA) severity within male OSA patients.

METHODS

The association between systolic BP (SBP), diastolic BP (DBP), glucose, lipids, apnea-hypopnea index (AHI), oxygen desaturation index (ODI), and arousal index (ArI) was evaluated after adjustment for BMI and waist circumference/hip circumference ratio (WHR) in 1,370 male OSA patients.

RESULTS

In the multiple linear regression models using SBP as an independent variable, SBP did not associate with the increase of any OSA indexes. BMI and glucose positively associated with AHI, ODI, and ArI elevation. WHR was also positively associated with increasing AHI and ODI. Total cholesterol levels increased with ODI and ArI increases. Triglyceride was associated with ArI. In the multiple linear regression models using DBP as an independent variable, DBP associated universally with AHI, ODI, and ArI with stable coefficients ranging from 0.19 to 0.20. The remaining independent variables were associated with AHI, ODI, and ArI with a similar trend to the models including SBP as an independent variable.

CONCLUSIONS

Apnea-hypopnea, hypoxemia, and arousal changed glycometabolism, fat metabolism, and BP profoundly in a particular pattern.

Blood pressure response to CPAP treatment in subjects with obstructive sleep apnoea: the predictive value of 24-h ambulatory blood pressure monitoring

The reduction in blood pressure (BP) with continuous positive airway pressure (CPAP) is modest and highly variable. In this study, we identified the variables that predict BP response to CPAP.

24-h ambulatory BP monitoring (ABPM), C-reactive protein (CRP), leptin, adiponectin and 24-h urinary catecholamine were measured before and after 6 months of CPAP in obstructive sleep apnoea (OSA) patients.

Overall, 88 middle-aged, obese male patients with severe OSA (median apnoea–hypopnoea index 42 events·h−1) were included; 28.4% had hypertension. 62 patients finished the study, and 60 were analysed. The daytime diastolic BP (−2 mmHg) and norepinephrine (−109.5 nmol·day-1) were reduced after CPAP, but no changes in the 24-h BP, night-time BP, dopamine, epinephrine, CRP, leptin or adiponectin were detected. The nocturnal normotension was associated with an increased night-time-BP (+4 mmHg) after CPAP, whereas nocturnal hypertension was associated with a reduction of 24-h BP (−3 mmHg). A multivariate linear regression model showed differential night-time BP changes after CPAP. Specifically, low night-time heart rate (<68 bpm) and BP dipper profile were associated with increased night-time BP and new diagnosis of nocturnal hypertension.

Our results suggest that nocturnal hypertension, circadian BP pattern and night-time heart rate could be clinical predictors of BP response to CPAP and support the usefulness of 24-h ABPM for OSA patients before treatment initiation. These results need to be confirmed in further studies.

Review of and Updates on Hypertension in Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a prevalent sleep disorder as is hypertension (HTN) in the 21st century with the rising incidence of obesity. Numerous studies have shown a strong association of OSA with cardiovascular morbidity and mortality. There is overwhelming evidence supporting the relationship between OSA and hypertension (HTN). The pathophysiology of HTN in OSA is complex and dependent on various factors such as sympathetic tone, renin-angiotensin-aldosterone system, endothelial dysfunction, and altered baroreceptor reflexes. The treatment of OSA is multifactorial ranging from CPAP to oral appliances to lifestyle modifications to antihypertensive drugs. OSA and HTN both need prompt diagnosis and treatment to help address the growing cardiovascular morbidity and mortality due to these two entities.

Prevalence of sleep apnea and cardiovascular risk factors in patients with hypertension in a day hospital model

INTRODUCTION

To identify patients at risk for obstructive sleep apnea (OSA) syndrome at a specialized hypertension center, we administered questionnaires and used respiratory polygraphy (RP).

RESULTS

We studied 168 patients (64.8% men and 35.2% women). Patients' body mass index (BMI) was 34.7 ± 6.79 and Epworth Sleepiness Scale (ESS) scores were 8.01 for male and 8.92 for women (p = 0.69). RP recordings revealed AHI (Apnea-Hypopnea Index) of 18.03 ± 15.7, an ODI (Oxygen Desaturation Index) of 18.6 ± 15.2, and a time oxygen saturation <90% (%) of 20.8 ± 24.3. Around 44% of patients had an AHI of >15 events/h, and continuous positive airway pressure (CPAP) was recommended to 69 patients (41.07%). Pulse wave velocity (PWV) showed high values in AHI > 15/h (p = 0.050), and carotid intima-media thickness (IMT) did not correlate with AHI > 15; right IMT: 0.83 ± 1.3 versus 0.78 ± 0.13 mm (p = 0.41) and 0.82 ± 0.16 versus 0.78 ± 0.19 mm (p = 0.40). However, we find correlation with carotid plaque (p = 0.046). The ACC/AHA calculator revealed a gradual increase in the risk of cardiovascular events: 8.7% with AHI < 5/h, and 30.3% in severe OSA.

CONCLUSIONS

In hypertension (HT) patients, RP revealed a high prevalence of OSA associated with carotid artery disease, high PWV, and increased cardiovascular risk.

Twenty-four hour Blood Pressure in Obese Patients with Moderate-to-Severe Obstructive Sleep Apnea

BACKGROUND

Obesity, systemic arterial hypertension (SAH) and obstructive sleep apnea (OSA) are closely related. Up to 70% of patients with OSA may be asymptomatic, and there is evidence that these patients have cardiovascular disease, especially nocturnal SAH.

OBJECTIVES

The aim of this study was to evaluate 24-hour blood pressure circadian variation in asymptomatic, obese individuals with moderate-to-severe OSA and compare it with that in individuals with mild OSA or without OSA.

METHODS

Eighty-six obese subjects aged between 30 and 55 years (BMI 30-39 kg/m2), with casual blood pressure < 140/90 mmHg and without comorbidities were recruited. Eighty-one patients underwent clinical and anthropometric assessment, ambulatory blood pressure monitoring (ABPM), and Watch-PAT. Participants were divided into two groups, based on the apnea-hypopnea index (AHI): group 1, with AHI < 15 events/hour, and group 2 with AHI ≥ 15 events/hour.

RESULTS

Compared with group 1, group 2 had higher neck circumference and waist-hip circumference (40.5 ± 3.2 cm vs. 38.0 ± 3.7 cm, p = 0.002, and 0.94 ± 0.05 vs. 0.89 ± 0.05, p = 0.001, respectively), higher systolic and diastolic blood pressure measured by the 24-h ABPM (122 ± 6 vs 118 ± 8 mmHg, p = 0.014, and 78 ± 6 vs 73 ± 7 mmHg, p = 0.008, respectively), and higher nocturnal diastolic pressure load (44,6 ± 25,9% vs 31,3 ± 27,3%, p = 0,041). Moreover, there was a positive correlation between nocturnal diastolic blood pressure and AHI (r = 0.43, p < 0.05).

CONCLUSIONS

Asymptomatic obese subjects with moderate-to-severe OSA have higher systolic and diastolic blood pressure at 24 hours compared with those with absent / mild OSA, despite normal casual blood pressure between the groups. These results indicate that ABPM may be useful in the evaluation of asymptomatic obese patients with moderate-to-severe OSA.