Sleep
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Randomized Controlled Trial
A randomized, double crossover study to investigate the influence of saline infusion on sleep apnea severity in men.
Obstructive sleep apnea (OSA) is commoner in patients with fluid-retaining states than in those without fluid retention, in men than in women, and worsens with aging. In men, OSA severity is related to the amount of fluid shifting out of the legs overnight, but a cause-effect relationship is not established. Our objective was to test the hypothesis that mimicking fluid overload during sleep would increase severity of OSA more in older (≥ 40 years) than in younger men (< 40 years). ⋯ Older men are more susceptible to the adverse effects of intravenous fluid loading on obstructive sleep apnea severity than younger men. This may be due to age-related differences in the amount of fluid accumulating in the neck or upper airway collapsibility in response to intravenous fluid loading. These possibilities remain to be tested in future studies.
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Controlled Clinical Trial
Acute melatonin administration in humans impairs glucose tolerance in both the morning and evening.
To study the effect of melatonin administration on glucose metabolism in humans in the morning and evening. ⋯ Acute melatonin administration in humans impairs glucose tolerance in both the morning and evening. When administering melatonin, the proximity to meal timing may need to be considered, particularly in those at risk for glucose intolerance.
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Randomized Controlled Trial
Influence of cerebral blood flow on central sleep apnea at high altitude.
To further our understanding of central sleep apnea (CSA) at high altitude during acclimatization, we tested the hypothesis that pharmacologically altering cerebral blood flow (CBF) would alter the severity of CSA at high altitude. ⋯ Our findings indicate an important role for cerebral blood flow regulation in the pathophysiology of central sleep apnea at high altitude.
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Upper airway anatomy plays a major role in obstructive sleep apnea (OSA) pathogenesis. An inferiorly displaced hyoid as measured by the mandibular plane to hyoid distance (MPH) has been consistently associated with OSA. The hyoid is also a common landmark for pharyngeal length, upper airway volume, and tongue base. Tongue dimensions, pharyngeal length, and obesity are associated with OSA severity, although the link between these anatomical variables and pharyngeal collapsibility is less well known. We hypothesized that obesity as measured by body mass index (BMI), neck and waist circumferences, and variables associated with hyoid position (pharyngeal length, upper airway volume, and tongue dimensions) would be associated with passive pharyngeal critical closing pressure (Pcrit). ⋯ Pharyngeal critical closing pressure is associated with obesity and hyoid position. Tongue dimensions, pharyngeal length, and the mandibular plane to hyoid distance are associated with obesity variables. These findings provide novel insight into the potential factors mediating upper airway collapse in obstructive sleep apnea.
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To examine the combined impact of sleep disordered breathing (SDB) and metabolic syndrome (MetS) in endothelial dysfunction. ⋯ Sleep disordered breathing and concurrent metabolic syndrome are synergistically associated with worse endothelial function. Individuals with both of these conditions appear to be at a significantly higher risk for cardiovascular disease complications.