Comorbidities and mortality in hypercapnic obese under domiciliary noninvasive ventilation.

Background: The higher mortality rate in untreated patients with obesity-associated hypoventilation is a strong rationale for long-term noninvasive ventilation (NIV). The impacts of comorbidities, medications and NIV compliance on survival of these patients remain largely unexplored.

Methods: Observational cohort of hypercapnic obese patients initiated on NIV between March 2003 and July 2008.

Characterizing sympathetic neurovascular transduction in humans.

Despite its critical role for cardiovascular homeostasis in humans, only a few studies have directly probed the transduction of sympathetic nerve activity to regional vascular responses--sympathetic neurovascular transduction. Those that have variably relied on either vascular resistance or vascular conductance to quantify the responses. However, it remains unclear which approach would better reflect the physiology.

Intermittent hypoxia-activated cyclooxygenase pathway: role in atherosclerosis.

Intermittent hypoxia, the main stimulus of obstructive sleep apnoea (OSA), induces inflammation, leading to early atherosclerosis. Whether the cyclooxygenase (COX) pathway contributes to intermittent hypoxia-induced atherosclerosis remains to be determined. We studied the effects of 8-weeks of intermittent hypoxia exposure on COX-pathway gene expression and atherosclerosis, and the influence of COX-1 inhibition by SC-560 on atherosclerosis progression in aortas of apolipoprotein E(-/-) mice.

Mechanisms of cardiac dysfunction in obstructive sleep apnea.

Obstructive sleep apnea (OSA) is associated with cardiovascular morbidity and mortality, largely as a result of myocardial anomalies. Numerous mechanisms cause OSA-related myocardial damage. The majority are initiated as a result of OSA-induced, chronic, intermittent hypoxia.

[Surviving sleep: when the heart and brain are damaged by apnea].

Sleep apnea generally results from pharyngeal collapse and leads to the so-called obstructive sleep apnea syndrome (OSAS). OSAS is associated with excessive daytime sleepiness and chronic fatigue and has cardiovascular consequences. Acute hemodynamic changes during obstructive apnea are mainly due to sympathetic activation.

Leukotriene B4 pathway activation and atherosclerosis in obstructive sleep apnea.

Leukotriene B(4) (LTB(4)) production increases in obstructive sleep apnea syndrome (OSA) and is linked to early vascular remodeling, the mechanism of which is unknown. The objective of this study was to to determine the molecular mechanisms of LTB(4) pathway activation in polymorphonuclear cells (PMNs) and early vascular remodeling in OSA and the specific contribution of intermittent hypoxia (IH). PMNs were isolated from 120 OSA patients and 33 healthy subjects and used for measurements of LTB(4) production, determination of mRNA and protein expression levels, or exposed for four cycles of in vitro IH.

Reduced six-minute walking distance, high fat-free-mass index and hypercapnia are associated with endothelial dysfunction in COPD.

This study investigated the determinants of endothelial function in patients with chronic obstructive pulmonary disease (COPD). Digital pulse amplitude augmentation was measured by post-ischemic reactive hyperemia (RH-PAT) in 44 COPD patients and analyzed with covariates: condition vs. exacerbation, fat-free mass index (FFMI), pulmonary function, blood pressure, inflammation, six-minute walking distance, muscle function, medications, diabetes and prevalent cardiovascular diseases.

At 68 years, unrecognised sleep apnoea is associated with elevated ambulatory blood pressure.

After the age of 65 yrs the specific impact of unrecognised sleep-related breathing disorders (SRBD) on 24-h blood pressure (BP) levels remains under debate. We tested the cross-sectional relationship between the severity of obstructive sleep apnoea/hypopnoea (OSAH) and the increase of BP using ambulatory BP monitoring (ABPM) in the PROOF (PROgnostic indicator OF cardiovascular and cerebrovascular events study)-SYNAPSE (Autonomic Nervous System Activity, Aging and Sleep Apnea/Hypopnea study) cohort. 470 subjects (aged 68 yrs) neither treated for hypertension nor diagnosed for SRBD were included.

Pulse transit time as a measure of respiratory effort under noninvasive ventilation.

Among the respiratory events that may occur during nocturnal noninvasive ventilation (NIV), differentiating between central and obstructive events requires appropriate indicators of respiratory effort. The aim of the present study was to assess pulse transit time (PTT) as an indicator of respiratory effort under NIV in comparison with oesophageal pressure (P(oes)). During wakefulness, PTT was compared to P(oes) during spontaneous breathing and under NIV with or without induced leaks in 11 healthy individuals.

The upper airway resistance syndrome.

Obstructive sleep apnea syndrome has been recognized as a major public health problem. Both its cardiovascular and metabolic comorbidities and symptoms motivate for an accurate diagnosis and appropriate treatment. The main stimulus associated with obstructive sleep apnea (OSA) and explaining deleterious consequences is intermittent hypoxia.

The impact of obstructive sleep apnea on homocysteine and carotid remodeling in metabolic syndrome.

Obstructive sleep apnea (OSA) and metabolic syndrome (MetS) are associated with increased cardiovascular morbidity and mortality. Increased homocysteine is suggested as an independent risk factor for atherosclerosis and cardiovascular disease but remains disputed in OSA. We assessed polysomnography, carotid intima-media thickness (CIMT) and biology in 35 MetS patients, according to the presence (OSA+MetS; n=26) or the absence of OSA (MetS; n=9).

Sleep deprivation, sleep apnea and cardiovascular diseases.

Sleep dramatically influences cardiovascular regulation. Changes in sleep duration or quality as seen in sleep disorders may prevent blood pressure to fall during sleep as expected in human physiology. This supports the increased prevalence of hypertension and drug-resistant hypertension in those with sleep loss.

Obesity hypoventilation syndrome: from sleep-disordered breathing to systemic comorbidities and the need to offer combined treatment strategies.

Obesity hypoventilation syndrome (OHS) is defined as a combination of obesity (body mass index ≥ 30 kg/m(2)), daytime hypercapnia (partial arterial carbon dioxide concentration ≥45 mm Hg) and sleep-disordered breathing after ruling out other disorders that may cause alveolar hypoventilation. Through the prism of the International Classification of Functioning, OHS is a chronic condition associated with respiratory, metabolic, hormonal and cardiovascular impairments, leading to a decrease in daily life activities, a lack of social participation and high risk of hospitalization and death. Despite its severity, OHS is largely underdiagnosed and the health-related costs are higher than those of apnoeic or obese eucapnic patients.

Increased aortic root size is associated with nocturnal hypoxia and diastolic blood pressure in obstructive sleep apnea.

Study Objectives: Obstructive sleep apnea (OSA) is known as a major cardiovascular risk factor, and high prevalence of OSA has been reported in patients with thoracic aortic dissection. The aim of our study was to assess the relationship between OSA, its vascular consequences, and aortic root size.

Design/patients: 156 newly diagnosed apneic patients free of cardiovascular disease and medication were included.

Effectiveness of Adaptive Servo Ventilation in the treatment of hypocapnic central sleep apnea of various etiologies.

Background: Central sleep apnea (CSA) occurs in clinical situations that induce hypocapnia and respiratory instability during sleep. This is true, not only in heart failure patients, but also in patients suffering from neurological diseases and idiopathic CSA. Adaptive Servo Ventilation (ASV) is frequently prescribed in France for the treatment of CSA, but only a few studies have evaluated ASV treatment with regards to long term effectiveness and compliance.

Choroidal blood flow regulation after posture change or isometric exercise in men with obstructive sleep apnea syndrome.

Purpose: Obstructive sleep apnea (OSA) syndrome generates hypertension, atherosclerosis, and endothelial and autonomic dysfunction, which may mutually interact with ocular vascular regulation. Exercise and posture changes can be used to manipulate blood pressure, ocular perfusion pressure (OPP), or both. It was hypothesized that choroidal vascular reactivity in response to isometric exercise and posture changes could be altered in OSA patients.

Effect of chronic intermittent hypoxia on exercise adaptations in healthy subjects.

Reduced exercise tolerance has been reported in obstructive sleep apnea syndrome (OSAS) patients, although the associated hypertension, obesity and/or metabolic disorder may underlie this reduction. Therefore, we evaluated the effects of chronic intermittent hypoxia (CIH) in 12 healthy subjects on exercise capacity, cardio-respiratory responses, and substrate oxidation during maximal and sub-maximal exercise. Subjects were exposed to 30 cycles of hypoxia-reoxygenation per hour for 14 nights.

Noninvasive ventilation in mild obesity hypoventilation syndrome: a randomized controlled trial.

Objective: Open studies suggest that treatment of obesity hypoventilation syndrome (OHS) by noninvasive ventilation (NIV) restores sleep quality and daytime vigilance and reduces cardiovascular morbidity. However, to our knowledge no randomized controlled trial (RCT) comparing NIV to conservative measures is available in the field. The goal of this study was to assess in patients with OHS, during an RCT, effects of 1-month NIV compared with lifestyle counseling on blood gas measurements, sleep quality, vigilance, and cardiovascular, metabolic, and inflammatory parameters.