Sleep & breathing = Schlaf & Atmung
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Obstructive sleep apnea (OSA) occurs in 2% of middle-aged women and 4% of middle-aged men in the general population and the prevalence is much higher in specific patient groups. Intermittent hypoxia (IH, oxygen desaturation and re-oxygenation) cycle, a major pathophysiologic character of OSA, and the physiological responses this evokes are thought to be responsible for its association with increased cardiovascular morbidity and mortality. Endothelial dysfunction, resulting from IH and as a key early event in atherosclerosis, was demonstrated repeatedly in patients with OSA and in animal models of IH, providing an important mechanistic link between the acute cyclical IH during sleep and the increased prevalence of chronic vascular diseases. ⋯ From this work, we conclude that IH from OSA may result in endothelial dysfunction, as a potential promoter of atherosclerosis, through nitric oxide unavailability, oxidative stress and inflammation, cell apoptosis, the crosstalk between endothelial cells and circulating inflammatory cells, microparticles, and damage repairing process. Though effective continuous positive airway pressure (CPAP) may specifically improve endothelial function, more controlled larger interventional trials that will include multiple centers and randomized allocation of CPAP therapy are needed to see if such changes are reversible before cause and effect can be implied finally, while further studies on cellular and animal level are also needed to elucidate molecular biologic/pathologic pathways.
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In the clinical practice of sleep medicine, the coexistence of common sleep disorders is not uncommon. Patients with sleep disordered breathing (SDB) may present with insomnia, and studies have shown that SDB is common among insomnia patients. Little is known about the pathophysiological mechanisms underlying this coexistence, and limited information is available regarding the impact of each disorder on the other. It is essential to consider the effect of each disorder on the other and to understand the clinical consequences anticipated when treating each disorder in isolation. The management plan should be directed toward both disorders in a systematic and evidence-based approach. Unfortunately, a consensus standard approach for the management of comorbid insomnia and SDB is not yet available. ⋯ Therefore, we have reviewed published studies that investigated insomnia in patients with different types of SBD; obstructive sleep apnea, central sleep apnea, and hypoventilation syndromes, as well as studies that assessed SBD in patients with insomnia. In addition, we reviewed the effects of SBD treatment modalities on insomnia and the effects of insomnia treatments on SBD.