Combined effects of sleep disordered breathing and metabolic syndrome on endothelial function: the Wisconsin Sleep Cohort study

Obstructive sleep apnoea heterogeneity and cardiovascular disease

Obstructive sleep apnoea (OSA), characterized by recurrent periods of upper airway obstruction and intermittent hypoxaemia, is prevalent in patients with cardiovascular disease (CVD), and is therefore important to consider in the prevention and management of CVD. Observational studies indicate that OSA is a risk factor for incident hypertension, poorly controlled blood pressure, stroke, myocardial infarction, heart failure, cardiac arrhythmias, sudden cardiac death and all-cause death. However, clinical trials have not provided consistent evidence that treatment with continuous positive airway pressure (CPAP) improves cardiovascular outcomes. These overall null findings might be explained by limitations in trial design and low levels of adherence to CPAP. Studies have also been limited by the failure to consider OSA as a heterogeneous disorder that consists of multiple subtypes resulting from variable contributions from anatomical, physiological, inflammatory and obesity-related risk factors, and resulting in different physiological disturbances. Novel markers of sleep apnoea-associated hypoxic burden and cardiac autonomic response have emerged as predictors of OSA-related susceptibility to adverse health outcomes and treatment response. In this Review, we summarize our understanding of the shared risk factors and causal links between OSA and CVD and emerging knowledge on the heterogeneity of OSA. We discuss the varied mechanistic pathways that result in CVD that also vary across subgroups of OSA, as well as the potential role of new biomarkers for CVD risk stratification.

Association between sleep-disordered breathing and self-reported sinusitis in adults in the United States: NHANES 2005-2006

OBJECTIVES

The association between sleep-disordered breathing (SDB) and sinusitis has been widely studied; however, research on SDB-related sleep problems and sinusitis are limited. This study aims to determine the relationship between SDB-related sleep problems, SDB symptom score, and sinusitis.

METHODS

After the screening, data were analyzed from 3414 individuals (≥20 years) from the 2005-2006 National Health and Nutrition Examination Survey questionnaire. Data on snoring, daytime sleepiness, obstructive sleep apnea (snorting, gasping, or cessation of breathing while sleeping), and sleep duration were analyzed. The SDB symptom score was determined based on a summary of the scores of the above four parameters. Pearson chi-square test and logistic regression analysis were used in statistical analyses.

RESULTS

After adjusting for confounders, self-reported sinusitis was strongly correlated with frequent apneas (OR: 1.950; 95% CI: 1.349-2.219), excessive daytime sleepiness (OR: 1.880; 95% CI: 1.504-2.349), and frequent snoring (OR: 1.481; 95% CI: 1.097-2.000). Compared to an SDB symptom score of 0, the higher the SDB symptom score, the higher the risk of self-reported sinusitis. For the subgroup analyses, this association was significant in females and across ethnic groups.

CONCLUSION

In the United States, SDB is significantly associated with self-reported sinusitis in adults. In addition, our study suggests that patients with SDB should be aware of the risk of developing sinusitis.

Vascular endothelium as a target for perfluroalkyl substances (PFAs)

INTRODUCTION

Perfluoroalkyl substances (PFAs) are ubiquitous, anthropogenic organic compounds that have been linked with cardiovascular disease and cardiovascular risk factors. Older, long-chain PFAs have been phased out due to adverse cardiometabolic health effect and replaced by newer short-chain PFAs. However, emerging research suggests that short-chain PFAs may also have adverse cardiovascular effects. Non-invasive measures of vascular function can detect preclinical cardiovascular disease and serve as a useful surrogate for early CVD risk. We hypothesized that serum concentrations of PFAs would be associated with noninvasive measures of vascular function, carotid-femoral pulse wave velocity (PWV) and brachial artery reactivity testing (BART), in adults with non-occupational exposure to PFAs.

METHODS

We measured serum concentrations of 14 PFAs with hybrid solid-phase extraction and ultrahigh-performance liquid chromatography-tandem mass spectrometry in 94 adult outpatients with no known cardiovascular disease. We collected clinical and demographic data; and measured vascular function, PWV and BART, using standard protocols. We assessed associations of individual PFAs with log-transformed BART and PWV using linear regression. We used weighted quantile sum regression to assess effects of correlated PFA mixtures on BART and PWV.

RESULTS

Ten PFAs were measured above the limit of detection in >50% of participants. Each standard deviation increase in concentration of perfluoroheptanoic acid (PFHpA) was associated with 15% decrease in BART (95% CI: -28.5, -0.17). The weighted index of a mixture of PFAs with correlated concentrations was inversely associated with BART: each tertile increase in the weighted PFA mixture was associated with 25% lower BART, with 73% of the effect driven by PFHpA. In contrast, no PFAs or mixtures were associated with PWV.

CONCLUSIONS

Serum concentration of PFHpA, a new, short-chain PFA, was associated with impaired vascular function among outpatients without CVD. Our findings support a potential adverse cardiovascular effect of newer, short-chain PFAs.

Cardiopulmonary coupling-derived sleep quality is associated with improvements in blood pressure in patients with obstructive sleep apnea at high-cardiovascular risk

OBJECTIVE

Investigate if changes in objective sleep quality index (SQI) assessed through cardiopulmonary-coupling analysis impacts blood pressure (BP) in patients with obstructive sleep apnea at high-cardiovascular risk.

METHODS

Secondary analysis of ECG and pulse-oximetry-[oxygen saturation (SpO2)] data from the Heart Biomarker Evaluation in Apnea Treatment study, multicenter, controlled trial in patients with cardiovascular disease and moderate-severe obstructive sleep apnea, randomly assigned to intervention of healthy lifestyle and sleep hygiene education (HLSE; control group), continuous positive airway pressure (CPAP) or nocturnal supplemental oxygen (NSO). Participants with good-quality ECG-signal and SpO2-signal (n = 241) were included.

RESULTS

CPAP-therapy significantly improved BP, with net average improvement in mean arterial blood pressure during sleep (MAP) when compared with nocturnal supplemental oxygen-therapy or healthy lifestyle and sleep education-therapy, -3.92 (P = 0.012) and -3.83 (P = 0.016), respectively. When stratified on the basis of baseline-SQI, CPAP-therapy improves 24-h MAP -3.02 (P = 0.030) and MAP -5.00 (P = 0.001), in patients with compromised baseline-SQI (SQI < 55). Stratifying the cohort based on changes in SQI during the study period (SQI-SQI), controlling for sex, age over 60, apnea-hypopnea index, SpO2 less than 80%, baseline BP and cardiovascular disease, significant differences are observed comparing the groups that Improved-SQI (SQI < 55, SQI ≥ 55) and Declined-SQI (SQI ≥ 55, SQI < 55) in MAP -4.87 (P = 0.046) and mean diastolic blood pressure (MDP) -4.42 (P = 0.026) as well as MAP -6.36 (P = 0.015), mean systolic blood pressure wake (MSP) -7.80 (P = 0.048) and MDP -5.64 (P = 0.009), respectively. Improved SQI reflects the magnitude of positive effect on BP which is reached mostly through initiation of CPAP-therapy.

CONCLUSION

Cardiopulmonary coupling-derived sleep quality impacted 24-h MAP and MDP, as well as BP during wake, in patients participating in the Heart Biomarker Evaluation in Apnea Treatment-study.

Sleep apnoea and endothelial dysfunction: An individual patient data meta-analysis

We performed an individual patient data meta-analysis to investigate the association between obstructive sleep apnoea (OSA) severity and the reactive hyperaemia index (RHI) measured by peripheral arterial tonometry (PAT), a validated measurement of endothelial function, and a strong predictor of late cardiovascular (CV) events. Patients from 12 studies underwent PAT and overnight polysomnography or respiratory polygraphy for suspected OSA. Endothelial dysfunction was defined by a log-transformed RHI<0.51. Subgroup analyses were performed to investigate this relationship in specific populations. Among 730 patients without overt CV disease, 387 (53.0%) had severe OSA (apnoea-hypopnea index ≥30) and 164 (22.5%) exhibited endothelial dysfunction. After adjustment for age, gender, diastolic blood pressure, obesity, diabetes and chronic obstructive pulmonary disease, endothelial dysfunction was associated with severe OSA (odds ratio, OR [95% confidence interval]: 2.27 [1.12-4.60]; p = 0.02), and nocturnal hypoxemia defined by >20 min with oxygen saturation <90% (OR: 1.83 [1.22-2.92]; p = 0.004) or mean oxygen saturation <92% (OR: 1.52 [1.17-1.96]; p = 0.002). On subgroup analyses, the association between severe OSA and endothelial dysfunction was not significant in patients with hypertension, obesity and/or diabetes. Among adults without overt CV disease, severe OSA is independently associated with an increased risk of endothelial dysfunction that may predispose to late CV events.

The Ventilatory and Diffusion Dysfunctions in Obese Patients with and without Obstructive Sleep Apnea-Hypopnea Syndrome

OBJECTIVE

To analyze the ventilatory and alveolar-capillary diffusion dysfunctions in case of obesity with or without an OSAS.

METHODS

It is a cross-sectional study of 48 obese adults (23 OSAS and 25 controls). Anthropometric data (height, weight, and body mass index (BMI)) were collected. All adults responded to a medical questionnaire and underwent polysomnography or sleep polygraphy for apnea-hypopnea index (AHI) and percentage of desaturation measurements. The following lung function data were collected: pulmonary flows and volumes, lung transfer factor for carbon monoxide (DLCO), and fraction of exhaled nitric oxide (F_eNO).

RESULTS

Obesity was confirmed for the two groups with a total sample mean value of BMI = 35.06 ± 4.68 kg/m². A significant decrease in lung function was noted in patients with OSAS compared with controls. Indeed, when compared with the control group, the OSAS one had a severe restrictive ventilatory defect (total lung capacity: 93 ± 14 vs. 79 ± 12%), an abnormal DLCO (112 ± 20 vs. 93 ± 22%), and higher bronchial inflammation (18.40 ± 9.20 vs. 31.30 ± 13.60 ppb) (p < 0.05).

CONCLUSION

Obesity when associated with OSAS increases the severity of pulmonary function and alveolar-capillary diffusion alteration. This can be explained in part by the alveolar inflammation.

Assessment of the relationship between metabolic syndrome and obstructive sleep apnea in male drivers of Shahroud city in 2018: a cross sectional study

BACKGROUND

Metabolic syndrome involves a set of metabolic risk factors that directly increases the risk of atherosclerotic cardiovascular disease. Physical inactivity due to driving can increase the risk of metabolic syndrome. It is also known that sleep disorders (sleep apnea) can result in MetS. Driving in Iran is considered a very popular but risky occupation, so paying attention to this profession is of special importance. Therefore, the researchers aimed to investigate the association between sleep disorders and metabolic syndrome in drivers in Shahroud city in 2018.

METHODS

This cross-sectional study was carried out on 948 drivers from Shahroud city in 2018. After obtaining consent from participants, 3 questionnaires including demographic, Epworth Sleepiness Scale and STOP-BANG were completed. Clinical and anthropometric measurements were assessed, including blood pressure, waist circumference, hip circumference, weight, height, and body mass index. In addition, blood was drawn to measure High Density Lipoprotein, Low Density Lipoprotein, Triglyceride, cholesterol, and Fasting Blood Sugar levels. The relationship between metabolic syndrome and sleep disorders was then studied. In this study, statistical analyses were performed using SPSS software version 23 at a significance level of 0.05.

RESULTS

Mean age of drivers was 44.15 ± 11.66 (years). The mean waist circumference and mean hip circumference in subjects with a Class 1 Driver's License (a certificate for trucks and buses) were higher than those with a Class 2 Driver's License (a certificate for motorcars, minibuses, vans, etc. (seating< 20)) (P = 0.01 and P = 0.003, respectively). Moreover, the BMI in subjects with a Class 1 Driver's License was higher compared to subjects with a Class 2 Driver's License. The correlation between metabolic syndrome with sleep apnea based on STOP-BANG questionnaire was significant (p < 0.001) irrespective of definition (ATP and IDF).

CONCLUSIONS

According to the results of this study, there was a bi-directional association between sleep disorders and Mets, so this group should pass periodic medical examinations and training courses. Moreover, their families should be informed of prevention and treatment of this syndrome.

Reported obstructive sleep apnea does not diminish the cardiometabolic health benefits from a comprehensive lifestyle intervention program

Obstructive sleep apnea (OSA) commonly coexists with the metabolic syndrome, a condition for which behavioral changes are often prescribed. Whether OSA diminishes the cardiometabolic health benefits from lifestyle interventions remains unclear. We evaluated 278 consecutive metabolic syndrome participants enrolled in a 12-week comprehensive lifestyle intervention program. The changes in blood pressure (BP), along with other metabolic health parameters, from baseline to follow-up were compared between those with and without OSA. Mean age was 52.4 ± 10.9 years and 37% were male. At enrollment, mean body mass index (BMI) was 38.2 ± 7.7 kg/m² . OSA was reported in 126 of 269 final participants (47%). At baseline, participants with reported OSA were more likely to be male, older, have a higher BMI, waist and neck size (all P < 0.05). At program completion, participants with (-5.8 ± 16.1/-3.0 ± 10.0 mm Hg) and without OSA (-4.7 ± 13.1/-3.3 ± 8.2 mm Hg) had significant reductions in systolic and diastolic BP as well as BMI, fasting glucose, and triglyceride levels. There were no significant differences in the absolute or percentage changes in BP or other metabolic parameters between groups. Our findings support that patients with the metabolic syndrome can derive substantial health benefits, including reductions in BP, by a lifestyle intervention program regardless of the presence of OSA.

Diet associated with exercise improves baroreflex control of sympathetic nerve activity in metabolic syndrome and sleep apnea patients

PURPOSE

We tested the hypothesis that (i) diet associated with exercise would improve arterial baroreflex (ABR) control in metabolic syndrome (MetS) patients with and without obstructive sleep apnea (OSA) and (ii) the effects of this intervention would be more pronounced in patients with OSA.

METHODS

Forty-six MetS patients without (noOSA) and with OSA (apnea-hypopnea index, AHI > 15 events/h) were allocated to no treatment (control, C) or hypocaloric diet (- 500 kcal/day) associated with exercise (40 min, bicycle exercise, 3 times/week) for 4 months (treatment, T), resulting in four groups: noOSA-C (n = 10), OSA-C (n = 12), noOSA-T (n = 13), and OSA-T (n = 11). Muscle sympathetic nerve activity (MSNA), beat-to-beat BP, and spontaneous arterial baroreflex function of MSNA (ABR_MSNA, gain and time delay) were assessed at study entry and end.

RESULTS

No significant changes occurred in C groups. In contrast, treatment in both patients with and without OSA led to a significant decrease in weight (P < 0.05) and the number of MetS factors (P = 0.03). AHI declined only in the OSA-T group (31 ± 5 to 17 ± 4 events/h, P < 0.05). Systolic BP decreased in both treatment groups, and diastolic BP decreased significantly only in the noOSA-T group. Treatment decreased MSNA in both groups. Compared with baseline, ABR_MSNA gain increased in both OSA-T (13 ± 1 vs. 24 ± 2 a.u./mmHg, P = 0.01) and noOSA-T (27 ± 3 vs. 37 ± 3 a.u./mmHg, P = 0.03) groups. The time delay of ABR_MSNA was reduced only in the OSA-T group (4.1 ± 0.2 s vs. 2.8 ± 0.3 s, P = 0.04).

CONCLUSIONS

Diet associated with exercise improves baroreflex control of sympathetic nerve activity and MetS components in patients with MetS regardless of OSA.

Self-reported nocturnal sleep duration and glycosylated hemoglobin A in the Study of Cardiovascular Risks in Adolescents (ERICA)

OBJECTIVE

At present, epidemiologic studies regarding the relationship between sleep duration and glucose metabolism in adolescents are scarce. The objective was to investigate the association between self-reported nocturnal sleep duration and glycosylated hemoglobin A in 12- to 17-year-old Brazilian adolescents.

PATIENTS/METHODS

A school-based multicenter cross-sectional study was carried out in private and public schools from 273 municipalities with more than 100,000 inhabitants. The final sample comprised 24,923 adolescents. A self-administered questionnaire was used. Blood tests included glucose, insulin, glycosylated hemoglobin A and serum lipids. Age, sex, skin color, school type, body mass index (BMI), physical activity, and Brazilian regions were studied as possible effect modifiers and/or confounders using linear regression.

RESULTS

A significant positive association was found between more than 12 h of nocturnal sleep and glycosylated hemoglobin A in two Brazilian regions: Southeast and South, even after adjustment for age, sex, skin color, and BMI (coefficients of 0.142 and 0.339, respectively). No association was found with nocturnal sleep duration <7 h.

CONCLUSION

Notably, a significant positive relationship was found between more than 12 h of nocturnal sleep duration and glycosylated hemoglobin A in two Brazilian regions. The specific pubertal sleep curtailment can be a compensatory mechanism for dealing with the insulin resistance during adolescence. Those that escape from this regulatory strategy and sleep longer than the adequate duration, break down this balance and tend to damage their glucose metabolism. To our knowledge, this is the first large scale study, of the association between sleep duration and glucose metabolism in adolescents.

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.

Metabolic Profile in Patients with Mild Obstructive Sleep Apnea

BACKGROUND

Mild obstructive sleep apnea (OSA) is a highly prevalent disorder in adults. However, it is not clear whether mild OSA has significant metabolic complications. This study examined the prevalence of metabolic syndrome (MS) in patients with mild OSA compared to control group.

METHODS

Adults (18-65 years of age) of both genders with a body mass index (BMI) ≤35 kg/m² were included. The mild OSA group comprised of patients with an apnea-hypopnea index (AHI) score of ≥5 but ≤15 events/hr of sleep, independent of other symptoms. The control group (CG) comprised individuals with an AHI of <5 events/hr of sleep and an Epworth Sleepiness Scale score of <10. The following were used for both groups: two questionnaires on sleepiness, the maintenance of wakefulness test, and full-night polysomnography. Anthropometric measurements and fasting blood samples were obtained, including fasting glucose and insulin, total cholesterol and its subfractions [low-density lipoprotein, very low-density lipoprotein, and low-density lipoprotein cholesterol (HDL-c)], triglycerides (TG), and the TG/HDL-c ratio. In addition, the quantitative insulin sensitivity check index and homeostasis model assessment indices were calculated.

RESULTS

Thirty-two percent of mild OSA patients had MS, 43.5% of mild OSA patients had hypertension, 14% showed dyslipidemia, and 56% had prediabetes. The OSA group showed increased TG (CG: 90.0 ± 51.9 vs. OSA: 140.3 ± 78.2 mg/dL, P = 0.004), and TG/HDL-c (CG: 1.9 ± 1.4 vs. OSA: 3.1 ± 2.0, P = 0.05), independent of adjustments. Independent of obesity (BMI <30 kg/m²), there was a negative correlation between total cholesterol and TG with mean oxygen saturation, independent of obesity (BMI <30 kg/m²).

CONCLUSIONS

Our findings showed dysregulation in lipid profiles after adjustments for confounders in the mild OSA group, and there was a correlation between these parameters and sleep hypoxemia. The TG/HDL-c ratio in particular was high, suggesting that it might be investigated as a marker of a detrimental metabolic profile in these patients.

Impact of Mandibular Advancement Therapy on Endothelial Function in Severe Obstructive Sleep Apnea

RATIONALE

Endothelial dysfunction, a major predictor of late cardiovascular events, is linked to the severity of obstructive sleep apnea (OSA).

OBJECTIVES

To determine whether treatment with mandibular advancement device, the main alternative to continuous positive airway pressure, improves endothelial function in patients with severe OSA.

METHODS

In this trial, we randomized patients with severe OSA and no overt cardiovascular disease to receive 2 months of treatment with either effective mandibular advancement device or a sham device. The primary outcome, change in reactive hyperemia index, a validated measurement of endothelial function, was assessed on an intention-to-treat basis. An embedded microsensor objectively measured treatment compliance.

MEASUREMENTS AND MAIN RESULTS

A total of 150 patients (86% males; mean [SD] age, 54 [10] yr; median [interquartile range] apnea-hypopnea index, 41 [35-53]; mean [SD] Epworth sleepiness scale, 9.3 [4.2]) were randomized to effective mandibular advancement device (n = 75) or sham device (n = 75). On intention-to-treat analysis, effective mandibular advancement device therapy was not associated with improvement of endothelial function compared with the sham device. Office and ambulatory blood pressure outcomes did not differ between the two groups. Effective mandibular advancement device therapy was associated with significant improvements in apnea-hypopnea index (P < 0.001); microarousal index (P = 0.008); and symptoms of snoring, fatigue, and sleepiness (P < 0.001). Mean (SD) objective compliance was 6.6 (1.4) h/night with the effective mandibular advancement device versus 5.6 (2.3) h/night with the sham device (P = 0.006).

CONCLUSIONS

In moderately sleepy patients with severe OSA, mandibular advancement therapy reduced OSA severity and related symptoms but had no effect on endothelial function and blood pressure despite high treatment compliance. Clinical trial registered with www.clinicaltrials.gov (NCT 01426607).

Sex, stress and sleep apnoea: Decreased susceptibility to upper airway muscle dysfunction following intermittent hypoxia in females

Obstructive sleep apnoea syndrome (OSAS) is a devastating respiratory control disorder more common in men than women. The reasons for the sex difference in prevalence are multifactorial, but are partly attributable to protective effects of oestrogen. Indeed, OSAS prevalence increases in post-menopausal women. OSAS is characterized by repeated occlusions of the pharyngeal airway during sleep. Dysfunction of the upper airway muscles controlling airway calibre and collapsibility is implicated in the pathophysiology of OSAS, and sex differences in the neuro-mechanical control of upper airway patency are described. It is widely recognized that chronic intermittent hypoxia (CIH), a cardinal feature of OSAS due to recurrent apnoea, drives many of the morbid consequences characteristic of the disorder. In rodents, exposure to CIH-related redox stress causes upper airway muscle weakness and fatigue, associated with mitochondrial dysfunction. Of interest, in adults, there is female resilience to CIH-induced muscle dysfunction. Conversely, exposure to CIH in early life, results in upper airway muscle weakness equivalent between the two sexes at 3 and 6 weeks of age. Ovariectomy exacerbates the deleterious effects of exposure to CIH in adult female upper airway muscle, an effect partially restored by oestrogen replacement therapy. Intriguingly, female advantage intrinsic to upper airway muscle exists with evidence of substantially greater loss of performance in male muscle during acute exposure to severe hypoxic stress. Sex differences in upper airway muscle physiology may have relevance to human OSAS. The oestrogen-oestrogen receptor α axis represents a potential therapeutic target in OSAS, particularly in post-menopausal women.

Treatment of Obstructive Sleep Apnea in Young and Middle-Aged Adults: Effects of Positive Airway Pressure and Compliance on Arterial Stiffness, Endothelial Function, and Cardiac Hemodynamics

Background

The cardiovascular effects of positive airway pressure (PAP) therapy in obstructive sleep apnea (OSA) patients are not clear because of confounding by comorbid conditions.

Methods and Results

Prospective interventional study of PAP therapy and withdrawal. Apnea Hypopnea Index (AHI; events/hour of sleep) was determined from polysomnography. Central aortic blood pressures (BPs), Aortic Augmentation Index (AAIx), and central (PWV_c‐f) and peripheral pulse wave (PWV_c‐r) velocities were determined by applanation tonometry. Echocardiography and brachial artery reactivity testing were performed at baseline, after 4 and 12 weeks of PAP therapy, and 1 week after PAP withdrawal. The 84 participants were mean (SD) 41.1 (7.6) years old and had 39.8 (24.5) AHI events/hour. After 4 weeks post‐PAP initiation and sustained after 12 weeks, subjects experienced decreases in central systolic BP (P=0.008), diastolic BP, mean BP, AAIx, and PWV_c‐r, and brachial artery dilation (all P<0.001), as well as improvements in left ventricular diastolic function and systemic and pulmonary vascular resistance. In adjusted models, PAP use (hours/night) predicted reductions in diastolic BP (β=−0.65 [SE, 0.32] mm Hg/hour; P=0.045), AAIx (β=−0.53 [0.27] %/hour; P=0.049) and PWV_c‐r (β=−0.13 [0.05] m·s⁻¹/hour; P=0.007), and improved brachial artery flow‐mediated dilation (β=0.31 [0.14] %/hour use; P=0.015). After 1 week of PAP withdrawal, brachial diameter, diastolic BP, mean BP, AAIx, and heart rate increased (P≤0.05).

Conclusions

PAP therapy reduces arterial tone and improves endothelial and diastolic function in young to middle‐aged adults. This positive effect is observed after 4 weeks and depends on hours of use, but reverts quickly with PAP withdrawal.

Clinical Trial Registration

URL: https://clinicaltrials.gov/. Unique identifier: NCT01317329.

Bisphenol-A and Sleep Adequacy among Adults in the National Health and Nutrition Examination Surveys

STUDY OBJECTIVES

To evaluate bisphenol-A (BPA) level and its relationship to sleep adequacy in a nationally representative sample of U.S. adults.

METHODS

A population-based cross-sectional study was conducted using 2005-2010 National Health and Nutrition Examination Survey whereby data were collected using in-person interviews, physical examination and laboratory testing. BPA level was measured in urine samples and analyzed as loge-transformed variable and in quartiles (< 0.9 ng/mL; 0.9 to < 1.9 ng/mL; 1.9 to < 3.7 ng/mL; 3.7+ ng/mL). Sleep adequacy was operationalized with three questions: "How much sleep do you usually get at night on weekdays or workdays?", "Have you ever told a doctor or other health professionals that you have trouble sleeping?" and "Have you ever been told by a doctor or other health professional that you have a sleep disorder?" Sleep duration was further categorized as (< 6 h, ≥ 6 h); (< 7 h, 7-8 h, > 8 h); (< 5 h, 5-6 h, 7-8 h, ≥ 9 h). Linear, binary, and ordinal logistic regression models were constructed.

RESULTS

Loge-transformed BPA level was inversely related to sleep duration defined, in hours, as a continuous variable, a dichotomous variable (≥ 6, < 6), or an ordinal variable (≥ 9, 7-8, 5-6, < 5), after adjustment for confounders. Help-seeking behavior for sleep problems and diagnosis with sleep disorders were not significantly associated with loge-transformed BPA level in fully adjusted models.

CONCLUSIONS

Loge-transformed BPA level may be associated with fewer hours of sleep among U.S. adults, with implications for prevention. Further research involving diverse populations are needed to confirm these study findings.

Obstructive sleep apnoea syndrome

Obstructive sleep apnoea syndrome (OSAS) is a common clinical condition in which the throat narrows or collapses repeatedly during sleep, causing obstructive sleep apnoea events. The syndrome is particularly prevalent in middle-aged and older adults. The mechanism by which the upper airway collapses is not fully understood but is multifactorial and includes obesity, craniofacial changes, alteration in upper airway muscle function, pharyngeal neuropathy and fluid shift towards the neck. The direct consequences of the collapse are intermittent hypoxia and hypercapnia, recurrent arousals and increase in respiratory efforts, leading to secondary sympathetic activation, oxidative stress and systemic inflammation. Excessive daytime sleepiness is a burden for the majority of patients. OSAS is also associated with cardiovascular co-morbidities, including hypertension, arrhythmias, stroke, coronary heart disease, atherosclerosis and overall increased cardiovascular mortality, as well as metabolic dysfunction. Whether treating sleep apnoea can fully reverse its chronic consequences remains to be established in adequately designed studies. Continuous positive airway pressure (CPAP) is the primary treatment modality in patients with severe OSAS, whereas oral appliances are also widely used in mild to moderate forms. Finally, combining different treatment modalities such as CPAP and weight control is beneficial, but need to be evaluated in randomized controlled trials. For an illustrated summary of this Primer, visit: http://go.nature.com/Lwc6te.

Relationships between sleep apnea, cardiovascular disease risk factors, and aortic pulse wave velocity over 18 years: the Wisconsin Sleep Cohort

PURPOSE

The purpose of this study is to determine if apnea-hypopnea index (AHI) severity predicts future aortic pulse wave velocity (PWV) in the Wisconsin Sleep Cohort.

METHODS

Applanation tonometry was used to derive carotid-to-femoral PWV a mean of 18 years (standard deviation 4) after overnight polysomnography. Multivariable regression models were created to describe prospective associations between baseline AHI and future PWV.

RESULTS

The 618 adults were mean 65 (7) years old (55 % male) with a mean body mass index of 31 (7) kg/m(2) at the tonometry visit. Mean baseline AHI was 4.6 (9.7) events/h. In multiple linear regression models adjusted for age (β = 0.13/year, standard error [SE] = 0.01, p < 0.001) and sex, higher log10AHI (β = 0.43/events/h, SE = 0.18, p = 0.02) was associated with PWV. After adjustment for waist circumference (β = 0.01/cm, SE = 0.01, p = 0.05) and height, the association between baseline log10AHI and future PWV was not statistically significant (p = 0.11), although the association with age persisted unchanged. Addition of covariates such as smoking status (current smoker β = 0.66, SE = 0.22, p = 0.002), diabetes mellitus status (β = 2.89, SE = 0.59, p < 0.001), and systolic blood pressure (BP, β = 0.03/mmHg, SE = 0.01, p < 0.001) did not change the association. AHI did not interact with age or smoking status to predict PWV. A secondary analysis of nocturnal oxygen saturation parameters in 517 participants, 9 (2) years prior also did not show any significant relationships with future PWV.

CONCLUSIONS

The prospective association between AHI and PWV is confounded by body size and influenced by smoking, diabetes mellitus, and BP. Weight management, BP control, and smoking cessation may help prevent arterial stiffening associated with obstructive sleep apnea.

Reduced systemic levels of IL-10 are associated with the severity of obstructive sleep apnea and insulin resistance in morbidly obese humans

Obstructive sleep apnea (OSA) has been related to elevation of inflammatory cytokines and development of insulin resistance in morbidly obese (MO) subjects. However, it is still unclear whether the systemic concentration of anti-inflammatory mediators is also affected in MO subjects directly related to the severity of OSA and level of insulin resistance. Normal weight and MO subjects were subjected to overnight polysomnography in order to establish the severity of OSA, according to the apnea-hypopnea index (AHI). Blood samples were obtained for estimation of total cholesterol and triglycerides, insulin, glucose, insulin resistance, tumor necrosis factor alpha (TNF-α), interleukin 12 (IL12), and interleukin 10 (IL-10). Serum levels of IL-10 were significantly lower in MO subjects with OSA than in MO and control individuals without OSA. Besides being inversely associated with serum TNF-α and IL-12, decreased IL-10 levels were significantly related to increased AHI, hyperinsulinemia, and insulin resistance. Serum IL-10 is significantly reduced in morbidly obese subjects with severe OSA while also showing a clear relationship with a state of hyperinsulinemia and insulin resistance probably regardless of obesity in the present sample. It may be of potential clinical interest to identify the stimulatory mechanisms of IL-10 in obese individuals with OSA.