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

Prolonged partial upper airway obstruction during sleep - an underdiagnosed phenotype of sleep-disordered breathing

Obstructive sleep apnea syndrome (OSAS) is a well-recognized disorder conventionally diagnosed with an elevated apnea-hypopnea index. Prolonged partial upper airway obstruction is a common phenotype of sleep-disordered breathing (SDB), which however is still largely underreported. The major reasons for this are that cyclic breathing pattern coupled with arousals and arterial oxyhemoglobin saturation are easy to detect and considered more important than prolonged episodes of increased respiratory effort with increased levels of carbon dioxide in the absence of cycling breathing pattern and repetitive arousals. There is also a growing body of evidence that prolonged partial obstruction is a clinically significant form of SDB, which is associated with symptoms and co-morbidities which may partially differ from those associated with OSAS. Partial upper airway obstruction is most prevalent in women, and it is treatable with the nasal continuous positive pressure device with good adherence to therapy. This review describes the characteristics of prolonged partial upper airway obstruction during sleep in terms of diagnostics, pathophysiology, clinical presentation, and comorbidity to improve recognition of this phenotype and its timely and appropriate treatment.

The Link Between Obstructive Sleep Apnea and Cardiovascular Disease

Obstructive sleep apnea (OSA) is common in the general population and highly prevalent in patients with cardiovascular disease. In this paper, we review (1) the pathophysiological mechanisms of OSA that may causally contribute to cardiovascular disease; (2) current evidence regarding the association between OSA and hypertension, stroke, ischemic heart disease, heart failure, atrial fibrillation, and cardiovascular mortality; and (3) the impact of continuous positive airway pressure (CPAP) treatment on cardiovascular risk factors and outcomes. We emphasize the importance of obesity as a comorbidity of OSA and a confounder in the association between OSA and cardiovascular disease. We also discuss the importance of addressing obesity in patients with OSA, as a strategy to reduce the burden of cardiovascular risk factors in this population. Implications for the approach of patients' OSA in clinical practice and future research directions are discussed.

Roles and Mechanisms of Obstructive Sleep Apnea-Hypopnea Syndrome and Chronic Intermittent Hypoxia in Atherosclerosis: Evidence and Prospective

The morbidity and mortality of obstructive sleep apnea-hypopnea syndrome (OSAHS) are regarded as consequences of its adverse effects on the cardiovascular system. Chronic intermittent hypoxia (CIH) induced by OSAHS can result in vascular endothelial injury, thus promoting development of atherosclerosis (AS). Studies have shown that CIH is an independent risk factor for the occurrence and development of AS, but the underlying mechanism remains unclear. Here, we review clinical and fundamental studies reported during the last 10 years on the occurrence and development of AS mediated by CIH, focusing on inflammation, oxidative stress, insulin resistance, cell apoptosis, vascular endothelial injury, platelet activation, and neuroendocrine disorders. This review will offer current evidence and perspective to researchers for the development of effective intervention strategies for OSAHS-related cardiocerebrovascular diseases.

Cumulative Hypoxemia During Sleep Predicts Vascular Endothelial Dysfunction in Patients With Sleep-Disordered Breathing

BACKGROUND

Sleep-disordered breathing (SDB) is associated with repeated intermittent hypoxemia, and it is known as one of the risk factors for cardiovascular diseases. Previous studies assessing the effects of frequency and depth of hypoxemia on cardiovascular diseases have shown conflicting results. The aim of the current study was to clarify what SDB-related parameters most predict endothelial dysfunction to better understand the pathogenesis of endothelial dysfunction in patients with SDB.

METHODS

We conducted polysomnography (PSG) and measured flow-mediated vasodilation response (%FMD) in 50 outpatients suspected of SDB. Evaluated indices included: apnea-hypopnea index (AHI), 3% oxygen desaturation index (3%ODI), averaged arterial oxygen saturation (averaged SpO2), lowest arterial oxygen saturation (lowest SpO2), ratio of arterial oxygen saturation <90% (

RESULTS

Significant differences were observed only in the TDS between the first and third (P = 0.03) and between the first and forth (P = 0.04) quartile groups, stratified by %FMD. The %FMD showed a significant relationship with TDS (β = -0.47, P = 0.001), even after adjusting for confounding factors (β = -0.33, P = 0.02). In contrast, AHI, 3%ODI, averaged SpO2, lowest SpO2, and

CONCLUSIONS

This study shows the validity of TDS in predicting endothelial damage in patients with SDB. Cumulative hypoxemia, rather than the frequency of hypoxemic events presented as AHI, may be a greater contributing factor in causing endothelial dysfunction. A simple index like TDS may be a useful and novel indicator of the influence of SDB on the vasculature.

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Key Words

• blood pressure
• cardiovascular diseases
• endothelial function
• hypertension
• hypoxemia
• sleep-disordered breathing.

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MESH Headings

• Adult
• Aged
• Biomarkers/blood
• Endothelium, Vascular/physiopathology
• Female
• Humans
• Hyperemia/physiopathology
• Hypoxia/blood
• Hypoxia/diagnosis
• Hypoxia/etiology
• Hypoxia/physiopathology
• Male
• Middle Aged
• Oximetry
• Oxygen/blood
• Polysomnography
• Predictive Value of Tests
• Respiration
• Risk Factors
• Sleep
• Sleep Apnea Syndromes/complications
• Sleep Apnea Syndromes/diagnosis
• Sleep Apnea Syndromes/physiopathology
• Vascular Diseases/diagnosis
• Vascular Diseases/etiology
• Vascular Diseases/physiopathology
• Vasodilation

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Affiliation(s)

Hiroyuki Sawatari Department of Health Sciences, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
Akiko Chishaki Department of Health Sciences, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
Mari Nishizaka Sleep Apnea Center, Kyushu University Hospital, Fukuoka, Japan; Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
Tomotake Tokunou Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
Sonomi Adachi Sleep Apnea Center, Kyushu University Hospital, Fukuoka, Japan; Center for Clinical and Translational Research, Kyushu University Hospital, Fukuoka, Japan
Chikara Yoshimura Sleep Apnea Center, Kyushu University Hospital, Fukuoka, Japan
Tomoko Ohkusa Kirameki Projects Career Support Center, Kyushu University Hospital, Fukuoka, Japan
Shin-ichi Ando Sleep Apnea Center, Kyushu University Hospital, Fukuoka, Japan;

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Age, Body Mass Index, and Daytime and Nocturnal Hypoxia as Predictors of Hypertension in Patients With Obstructive Sleep Apnea

A growing body of evidence links obstructive sleep apnea (OSA) with hypertension. The authors performed a retrospective cohort study using the University Hospital of Larissa Sleep Apnea Database (1501 patients) to determine predictors of in-laboratory diagnosed OSA for development of hypertension. Differences in continuous variables were assessed via independent samples t test, whereas discrete variables were compared by Pearson's chi-square test. Multivariate analysis was performed via discriminant function analysis. There were several significant differences between hypertensive and normotensive patients. Age, body mass index, comorbidity, daytime oxygen saturation, and indices of hypoxia during sleep were deemed the most accurate predictors of hypertension, whereas apnea-hypopnea index and desaturation index were not. The single derived discriminant function was statistically significant (Wilk's lambda=0.771, χ(2) =289.070, P<.0001). Daytime and nocturnal hypoxia as consequences of chronic intermittent hypoxia play a central role in OSA-related hypertension and should be further evaluated as possible severity markers in OSA.

Sleep, death, and the heart

Obstructive and central sleep apnea have been associated with increased risk of adverse cardiovascular events and mortality. Sympathetic dysregulation occurring as a result of the respiratory disturbance is thought to play a role in this increased risk. Sleep apnea increases the risk of arrhythmias, myocardial ischemia/infarction, stroke, and heart failure, all of which may increase mortality risk. A higher incidence of nocturnal arrhythmias, cardiac ischemia, and sudden death has been noted in subjects with sleep-disordered breathing (SDB). In this review, the association between SDB and each of these conditions is discussed, as well as the potential mechanisms underlying these risks and the effects of treatment of SDB. Particular emphasis is placed on the relationship between SDB and nocturnal atrial and ventricular arrhythmias, myocardial ischemia/infarction and sudden death.

Epidemiological aspects of obstructive sleep apnea

Obstructive sleep apnea (OSA) is probably the most common respiratory disorder, with recent data from the United States and Europe suggesting that between 14% and 49% of middle-aged men have clinically significant OSA. The intimate relationship between OSA and obesity means that its prevalence will only increase as the global obesity epidemic evolves. At an individual level, OSA leads to a significant decrease in quality of life (QOL) and functional capacity, alongside a markedly increased risk of cardiovascular disease and death. Emerging data also suggest that the presence and severity of OSA and associated nocturnal hypoxemia are associated with an increased risk of diabetes and cancer. At a societal level, OSA not only leads to reduced economic productivity, but also constitutes a major treatable risk factor for hypertension, coronary artery disease (CAD) and stroke. This article addresses OSA from an epidemiological perspective, from prevalence studies to economic aspects to co-morbidity.

Trauma and syncope-evidence for further sleep study? A case report

We report on an 83-year-old male with traumatic brain injury after syncope with a fall in the morning. He had a history of seizures, coronary artery disease and paroxysmal atrial fibrillation (AF). No medical cause for seizures and syncope was determined. During rehabilitation, the patient still complained of seizures, and also reported sleepiness and snoring. Sleep apnea diagnostics revealed obstructive sleep apnea (SA) with an apnea-hypopnoea index of 35/h, and sudden onset of tachycardia with variations of heart rate based on paroxysmal atrial fibrillation. Additional tests showed nocturnal AF which spontaneously converted to sinus rhythm mid-morning with an arrest of 5 s (sick sinus syndrome) and seizures. A DDD-pacer was implanted and no further seizures occurred. SA therapy with nasal continuous positive airway pressure was refused by the patient. Our findings suggests that screening for SA may offer the possibility to reveal causes of syncope and may introduce additional therapeutic options as arrhythmia and SA often occur together which in turn might be responsible for trauma due to syncope episodes.