Sleep
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Decrease of respiratory muscle capacities in neuromuscular disease can lead to chronic respiratory failure with permanent alveolar hypoventilation. Respiratory centers elaborate a strategy of breathing dedicated to prevent overt respiratory muscles fatigue. This strategy may worsen chronic hypercapnia. ⋯ The effects of atonia are amplified by a very low reactivity of respiratory centers. Nocturnal mechanical ventilation improves nocturnal hypoventilation and daytime arterial blood gases (ABG). Mechanism of improvement in ABG and how nocturnal hypoventilation and diurnal hypoventilation interact, are still a matter of debate.
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The cardiovascular sequelae best shown to be associated with OSA are systemic hypertension and acute vascular events. The cardiovascular sequelae, including acute myocardial infarction or nocturnal angina may be contributed to by arterial vasospasm or clot formation in the area of an atheroma. Thus far there are no data showing that treatment of OSA eliminates vascular sequelae, but much evidence shows that chronic CPAP therapy may lower elevated blood pressure in some patients. However, for a variety of reasons mentioned above, CPAP does not correct hypertension in all OSA patients.
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The mammalian circadian oscillator, located in the suprachiasmatic nuclei of the anterior hypothalamus, serves as the principal source of rhythmic temporal information for virtually all physiologic processes in the organism, including the alternating expression of sleep and wakefulness. Recent studies, in both animal models and human subjects, have demonstrated the important modulation of sleep and wakefulness mediated by the circadian clock. Independent of other factors, notably prior sleep-wake history, the circadian clock potentiates wakefulness (and alertness) at one phase of the diurnal cycle, while facilitating sleep and its attendant processes at the opposite phase. ⋯ This response can be prevented or overridden with extraordinary avoidance of sunlight or with provision of artificial light of sufficient duration and intensity to negate the sunlight signal, an approach shown to be effective in the treatment of shiftwork sleep disruption. Practical issues sharply limit the application of artificial lighting to all shiftwork settings, however, and the role for a pharmacological chronobiotic agent capable of accomplishing the same end is potentially very large (Copinschi et al., 1995; Jamieson et al., 1998). For example, the effects of zolpidem vs. placebo on sleep, daytime alertness, and fatigue in travelers who complain of jet lag was co
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Practice Guideline Guideline
Practice parameters for the evaluation of chronic insomnia. An American Academy of Sleep Medicine report. Standards of Practice Committee of the American Academy of Sleep Medicine.
Chronic insomnia is the most common sleep complaint which health care practitioners must confront. Most insomnia patients are not, however, seen by sleep physicians but rather by a variety of primary care physicians. There is little agreement concerning methods for effective assessment and subsequent differential diagnosis of this pervasive problem. ⋯ However, the complaint of insomnia does not preclude the appropriate use of these tests for diagnosis of specific sleep disorders such as obstructive sleep apnea, periodic limb movement disorder, and narcolepsy that may be present in patients with insomnia. There is insufficient evidence to suggest whether portable sleep studies, actigraphy, or other alternative assessment measures including static charge beds are effective in the evaluation of insomnia complaints. Instruments such as sleep logs, self-administered questionnaires, symptom checklist, or psychological screening tests may be of benefit to discriminate insomnia patients from normals, but these instruments have not been shown to differentiate subtypes of insomnia complaints.
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The time and resource intensive nature of the traditional two-night paradigm for diagnosing and titrating positive pressure therapy for Obstructive Sleep Apnea/Hypopnea (OSA/H) contributes to patient care cost and limitation of service availability. Although split night polysomography (PSG(SN)) algorithms can establish a diagnosis of OSA/H and establish a positive pressure prescription for many patients, there has been only limited evidence that this strategy does not impair acceptance and adherence to treatment. The objective of this study was to test the null hypothesis that PSG(SN) does not adversely impact acceptance and adherence to positive pressure therapy for OSA/H compared with a standard two-night PSG strategy (PSG(TN)). ⋯ In a population of predominantly moderate-to-severe OSA/H patients, PSG(SN) strategy does not adversely impact on adherence to positive pressure therapy over the first six weeks of treatment. Acceptance of therapy is comparable to that reported in the literature following PSG(TN).