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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Central sleep apnea is a disorder characterized by apneic episodes during sleep with no associated ventilatory effort. More commonly than not these apneas are seen in patients who also have obstructive and mixed events. Although patients with this disorder frequently complain of insomnia and depression, frank hypersomnolence is rarely encountered. As these complaints are common ones seen in numerous clinical situations, and since sleep studies are rarely conducted to investigate their etiology, the true incidence of central sleep apnea has not been determined. The etiology of central apnea remains unknown, although the association between these breathing events and a number of other disease processes has increased our understanding of the disorder. Central apneas during sleep commonly occur after hyperventilation with the associated hypocapnic alkalosis. This occurs at high altitude when hyperventilation is induced by hypoxia and at sea level when spontaneous nocturnal hyperventilation occurs. This suggests that PCO2 is the primary stimulus to ventilation during sleep and that loss of this drive, as occurs with hypocapnia, may produce dysrhythmic breathing. Patients with complete absence of ventilatory chemosensitivity such as occurs with Ondine's curse (central alveolar hypoventilation) or the obesity-hypoventilation syndrome may also have central apneas. For reasons that remain unexplained, central sleep apnea is commonly seen in patients with congestive heart failure, nasal obstruction, and certain neurologic disorders. However, in most patients with central sleep apnea no obvious cause or association can be found. The treatment of this disorder is not entirely satisfactory. If it is severe, mechanical ventilation during sleep can be provided by any one of a number of techniques. However, for the patient who simply complains of insomnia and is found to have a moderate number of central apneas, the treatment choices are limited. Acetazolamide has been shown to decrease central apneas during short-term use, but results have been variable with prolonged administration. Other ventilatory stimulants seem to have little efficacy. Interestingly, oxygen administration has been shown to reduce central apneas considerably in a number of studies, although the explanation for its success is unknown. Central sleep apnea therefore remains a relatively rare disorder whose etiology is not fully understood and whose treatment is not completely satisfactory.
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PMID:Central sleep apnea. 393 82

Four basic control mechanisms of breathing (brainstem respiratory centre, peripheral and central chemoreceptors, intero- and exteroceptive reflexes and suprapontine influences), as well as their sleep-related disorders are analysed. A decrease in central chemoreceptor sensitivity to CO2 and an increase in upper airway resistance during sleep result in hypoventilation and mild hypoxaemia already in physiological conditions. Compensatory increase in ventilatory effort with synchronous inhibition of pharyngeal dilators during sleep reduces the upper airway lumen manifesting with snoring, upper airway resistance syndrome, and OSA. The resulting hypoxaemia may cause marked cardiovascular, neuro-psychic, endocrine-metabolic and behavioural disorders. The augmented ventilatory effort and hypoxaemia evoke reflex dilation of airways and arousal from sleep, stimulating the sympatho-adrenal system, which provokes autoresuscitation by gasping preventing fatal asphyxia. Failure of this autoresuscitation mechanism seems to cause SIDS. Elimination of voluntary breathing by sleep either in Ondine's curse induced by lesions of respiratory centre, or in congenital central hypoventilation syndrome caused by insufficient central chemoreceptors result in respiratory failure and death. Nocturnal attacks of bronchial and cardiac asthma, lung oedema and other consequences of pulmonary congestion are also discussed. The pathomechanism of extreme daytime sleepiness, chronic fatigue, and disorders of memory, cognitive and other brain functions, are also analysed. Severe cardiovascular consequences of SAS may manifest acutely as angina pectoris, myocardial infarction. dysrhythmias, transient ischaemic attacks and even stroke or sudden cardiac death. OSAS may result also in development of hypertension, central obesity, diabetes mellitus, erectile dysfunction, depression, and various behavioural disorders.
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PMID:[Regulation of respiration and its sleep-related disorders]. 1244 39

Sleep is a biological mechanism essential to maintaining good health. A series of physiological changes takes place during sleep. From a ventilation point of view, during deep sleep, tidal volume increases, the inhalation and expiration phases become longer, and respiratory frequency slows, while the same volume/time ratio as in wakefulness is maintained. The concept of "sleep-related respiratory disorders" refers to a group of respiratory diseases that are aggravated during sleep. Some of these disorders are almost exclusively manifested during sleep, such as sleep apnea-hypopnea syndrome -undoubtedly the most frequent respiratory disease despite being underdiagnosed- and congenital central hypoventilation syndrome (also called Ondine's curse). However, this concept also encompasses other disorders that occur during the daytime since they worsen while patients are asleep, as seen in many obstructive or restrictive pulmonary diseases. Sleep disorders can be a manifestation of underlying diseases, some of which are highly prevalent such as obesity and gastroesophageal reflux. Likewise, abnormal sleep cycles may be a cause or a result of cognitive disorders and disturbances in children's learning processes.
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PMID:[Obstructive sleep-related respiratory disorders in children]. 2135 86