Sleep & breathing = Schlaf & Atmung
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Obstructive sleep apnea syndrome (OSAS) is considered to be associated with cardiovascular complications, and atherosclerosis could mediate this relationship. Cardiovascular risk factors of OSAS still need to be elucidated in elderly patients, since studies about the association between OSAS and cardiovascular diseases have been done mainly in middle-aged adults. To investigate whether endothelial dysfunction, as an early marker of atherosclerosis, and inflammatory responses in OSAS were affected by age, we studied flow-mediated dilatation (FMD) and C-reactive protein (CRP) in elderly and middle-aged patients with OSAS. ⋯ FMD was significantly lower in the elderly patients (p = 0.04), but no difference was observed between two age groups in body mass index (BMI), neck circumference, waist-to-hip ratio, apnea hypopnea index (AHI), serum CRP level, or NPSG findings related with nocturnal hypoxemia such as average O(2) saturation, percentage of time below 90% O(2) saturation, and oxygen desaturation index (ODI). From the results of stepwise multiple linear regression analysis, the lowest oxygen saturation was a significant determinant of FMD (beta = 0.25, p < 0.01, adjusted R (2) = 6%), and BMI (beta = 0.22, p < 0.05) and waist-to-hip ratio (beta = 0.21, p < 0.05) were significant variables to explain CRP (adjusted R (2) = 11%, p < 0.01) in the middle aged patients. In the elderly patients, no variable was significant for predicting FMD, but AHI was significant determinant of CRP (beta = 0.46, p < 0.01, adjusted R (2) = 19%, p < 0.01). In predicting cardiovascular risks of OSAS, both hypoxia and obesity should be considered in the middle-aged group, whereas nocturnal respiratory disturbances are important in the elderly group.
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Animal models have shown a quantal slowing of respiratory pattern when exposed to opioid agonist, in a pattern similar to that observed in central sleep apnea. We postulated that opioid-induced hypoventilation is more likely to be associated with sleep apnea rather than hypoventilation alone. Since we did not have a direct measure of hypoventilation we used hypoxemia as an indirect measure reasoning that significant hypoventilation would not occur in the absence of hypoxemia. ⋯ Patients on chronic opiate therapy for chronic pain have an extremely high prevalence of sleep apnea and nocturnal hypoxemia. Hypoxemia can occur during quiet wakefulness in patients on chronic opioid medications with and without sleep apnea. In patients on chronic opioid therapy, isolated nocturnal hypoxemia without coexisting sleep apnea or daytime hypoxemia is very uncommon.