Pathophysiology of cardiovascular risk in sleep apnea syndrome (SAS)

Different pathophysiological mechanisms underlie the morbid associations observed between sleep apnea syndrome (SAS) and cardiovascular disease. Cardiovascular responses to apnea can be divided into acute cardiovascular modifications following each nocturnal respiratory event and chronic adaptations of the cardiovascular system. The same stimuli always trigger acute cardiovascular response: hypoxemia, hypercapnea, changes in the intra-thoracic pressure, micro-arousals. Each obstructive or central respiratory event is associated with a peak in blood pressure, changes in the heart rate, generally bradycardia at onset of apnea and tachycardia when respiration is renewed. Oxygen desaturation is the strongest stimulus explaining the observed acute cardiovascular responses. When these stimuli are repeated every night, the cardiovascular system adapts with a higher sympathetic tone and lower parasympathetic tone during the diurnal period. Baroreceptors also become less sensitive in apneic patients. Finally, endothelial function is altered in SAS patients with a desensitization of the alpha and beta-2 adrengeric receptors, altered NO-dependent vasodilatation, and hypersensitivity to vasoconstriction induced, for example, by angiotensin 2. The cardiovascular morbidity associated with SAS is currently thought to concern the development of diurnal hypertension (dose-effect response), left ventricular failure, higher risk of coronary or cerebral events. Very recently, epidemiological studies suggested that continuous positive pressure ventilation in SAS patients can reduce the cardiovascular risk.     

Predictors of uvulopalatopharyngoplasty success in the treatment of obstructive sleep apnea syndrome

ObjectiveUvulopalatopharyngoplasty (UPPP) has been described as an option for treating obstructive sleep apnea syndrome (OSAS), with variable success rates. The main purpose of our study was to correlate UPPP success to craniofacial bony structure and orofacial muscles function.MethodsClinical variables, including body mass index (BMI), age, and preoperative apnea-hypopnea index (AHI); cephalometric measurements of the craniofacial region and hyoid bone position; and muscle function variables including clinical protocol and tongue strength measures were evaluated in 54 patients who underwent UPPP in the last 7 years. The measurements were related to the success or failure of UPPP based on the results of preoperative and postoperative polysomnography (PSG).ResultsThe variables BMI, preoperative AHI, and cephalometric measurements showed no influence on surgical success. The clinical muscle protocol also was similar between groups. However, the muscle strength of the anterior portion of the tongue was significantly greater in the group that showed surgical success compared to those with surgical failure.ConclusionOSAS is a multifactorial disease and diagnostic symptom assessments should be individualized. In addition, special attention should be given to functional muscle alterations of the airways, as they might influence the evolution of the disease.     

Pattern of upper airway obstruction during sleep before and after uvulopalatopharyngoplasty in patients with obstructive sleep apnea

Objective: To investigate the pre-and postoperative pattern of upper airway obstruction in obstructive sleep apnea (OSA) patients treated by uvulopalatopharyngoplasty (UPPP).Background: The response rate to UPPP in unselected OSA patients is generally about 50%.Methods: Intraluminal pressure measurements during sleep were employed to analyze the pattern of upper airway obstruction before and after surgery.Results: Ten patients with mild to moderate OSA (respiratory disturbance index 19.7 (16.9–27.5) events/hr underwent a full night polysomnography before and 114 (6 1–138) days after UPPP. UPPP resulted in a significant improvement in subjective snoring and daytime sleepiness, but did not significantly alter the severity of sleep-disordered breathing. Preoperatively, the major site of obstruction was located at the oropharynx in nine patients, seven of them had additional minor obstruction sites outside the oropharynx. Complete relief of upper airway obstruction was only observed in those two patients with collapse confined to the oropharynx.Conclusions: In unselected OSA patients, UPPP improved subjective snoring and daytime sleepiness but did not result in a significant improvement in RDI or sleep architecture. Our results emphasize the need for a pre-operative investigation of the upper airway during sleep to select patients with collapse confined to the oropharynx.     

Plasma norepinephrine in sleep apnea syndrome

In 8 male patients suffering from sleep apnea syndrome, plasma norepinephrine (NE) levels were examined. At 22.00 and at 6.30 blood samples were obtained. In 3 cases, plasma NE levels displayed little changes between 22.00 and 6.30. In 2 cases, plasma NE levels at 6.30 increased 20% compared with those at 22.00. In 3 cases, plasma NE levels at 6.30 increased more than 40%. No significant correlation between apnea index and plasma NE levels was observed. Total time under 90% arterial oxygen saturation (SaO2) significantly correlated with the ratio of plasma NE levels at 6.30 to those at 22.00. In 2 cases of the 8 patients blood samples were drawn hourly (22.00-6.00) and at 6.30. In these 2 cases, when SaO2 decreased, plasma NE levels tended to increase. It is concluded that in sleep apnea syndrome plasma NE levels increased during sleep and did not correlate with apnea index but with oxygen desaturation.     

阿尔茨海默痴呆与睡眠呼吸暂停综合征

睡眠呼吸暂停(SA)是睡眠时呼吸气流反复中止>10 s的一种临床现象.美同流行病学调查显示,在30～60岁的人群中,男性患病率约为4%,女性为2%[1];我国的流行病学调查资料表明,阻塞性睡眠呼吸障碍在成人中的患病率为2.62%～4.12%[2].     

The eye in sleep apnea syndrome

Sleep apnea syndrome (SAS) is a disease characterized by recurrent complete or partial upper airway obstructions during sleep. The majority of patients with SAS demonstrate this obstruction either at the nasopharynx or the oropharynx. Risk factors for SAS include obesity, male gender, upper airway abnormalities, alcohol use, snoring, and neck girth of more than 17 in. in men or 16 in. in women. Reported ophthalmic findings in patients with SAS include floppy eyelid syndrome (FES), glaucoma, and non-arteritic anterior ischemic optic neuropathy (NAION).     

Effectiveness of mirtazapine in the treatment of sleep apnea/hypopnea syndrome (SAHS)

Several drugs have been described as possible treatments for Sleep Apnea/Hypopnea Syndrome (SAHS) but the data available does not support their use. In an animal model of central apnea the use of mirtazapine produced a significant reduction of apneas. We present a male patient, 82 years old, with excessive daytime sleepiness and loud snoring during at least 10 years. An overnight polysomnography (PSG) revealed an apnea/hypopnea index of 54.9 events per hour of sleep with a minimum pulse oximetric saturation (SaO(2)) of 78% and an arousal index of 40.4 per hour. A nasal CPAP titration in the second half of the night showed suppression of apneas with a CPAP level of 8 cmH(2)O. The patient refused to use the CPAP device and began with 15 mg of mirtazapine at bedtime. A second PSG performed after 3 months of mirtazapine showed a significant reduction in the apnea/hypopnea index (9.3 events per hour of sleep; 81% minimal oxygen saturation (SaO(2))). Clinically, the patient and his wife reported a clear reduction of excessive daytime sleepiness and an improvement in self-reported functioning and well-being without any important side effects. This successful case appears to be the first report with mirtazapine in human SAHS and supports the need for an appropriate clinical trial with this drug.     

Supine sleep and obstructive sleep apnea syndrome in Parkinson's disease

ObjectiveSupine sleep is associated with increased obstructive sleep apnea. People with Parkinson's disease (PD) complain about difficulties turning around in bed. The relationship between supine sleep and sleep-disordered breathing has never been explored in people with Parkinson's disease.MethodsFifteen consecutive people with PD with severe Obstructive Sleep Apnea Syndrome (OSAS) were compared to: (1) 15 age-matched, gender-matched, body mass index-matched and Unified Parkinson's Disease Rating Scale-III score-matched people with PD without sleep-disordered breathing; (2) 11 age-matched and gender-matched people with severe obstructive sleep apnea syndrome (OSAS) alone; and (3) 11 age-matched and gender-matched healthy controls. Outcomes were: number of position changes during the night and per hour of sleep, and the percentage of sleep time spent in supine.ResultsPeople with PD and severe OSAS spent most of their sleep time in the supine position (93 ± 11%); while people with PD without OSAS (61 ± 24%, p <0.001), people with isolated, severe OSAS (50 ± 28%, p <0.001), and the controls (40 ± 21, p <0.001) spent significantly less time on their back. People with PD and severe OSAS changed their position in bed per hour of sleep (0.4 ± 0.5) less frequently than those with PD without OSAS (1.1 ± 0.8, p = 0.002), those with isolated OSAS (1.2 ± 1.0, p = 0.006) and the controls (1.5 ± 0.5, p <0.001).ConclusionPD and severe OSAS are associated with a major reduction in the number of position changes and an increased supine sleep position during the night. For people with PD, alleviating the difficulties of turning around in bed might reduce the supine sleep position and improve sleep-disordered breathing.     

Methadone and sleep apnea syndrome]

BACKGROUND: Sleep apnea syndrome occurs when, during sleep, breathing stops for 10 seconds or longer, with an index of 5 times or more an hour. It is clinically characterized by loud snoring at night, continuous or interrupted by pauses followed by loud breathing. Sleep is fitful, broken by arousals, and yields little rest. There is daytime excessive sleepiness with repeated involuntary falling asleep, often unknown by the subject. CLINICAL DESCRIPTION: In this article, we describe an observation of central sleep apnea syndrome in a female patient receiving an opiate replacement therapy. METHOD: An analysis of the before and after methadone withdrawal polysomnograhic tracing was done for this patient. RESULTS: This diagnosis etiology and physiopathology are critically approached. Clinicians should be careful in treating induced sleep disorders in such patients. Conclusion: Prescribing benzodiazepines during an opiate withdrawal of the methadone type is not recommended when central apnea occurs.     

睡眠呼吸暂停综合征病人的记忆和情绪障碍

目的为探讨睡眠呼吸暂停综合征病人的记忆和情绪改变及其与血气和睡眠结构之间的关系。方法应用中国科学院心理研究所编制的（临床记忆量表）及抑郁、焦虑量表检测25例睡眠呼吸暂停综合征患者的记忆功能和情绪变化。结果睡眠呼吸暂停综合征病人的记忆功能显著差于鼾症病人组，并且存在着明显的情绪障碍。患者的记忆功能与血氧饱和度（SaO2）呈正相关，与睡眠呼吸紊乱指数（AHI）呈负相关；而抑郁症状与快速眼动睡眠（REM）时间里负相关。结论提示睡眠呼吸暂停综合征病人的低氧血症和睡眠结构紊乱是引起记忆功能和情绪障碍的主要原因。     

Baroreflex modulation during sleep and in obstructive sleep apnea syndrome

This review focuses on the complex integration between cardiovascular reflexes and central autonomic influences controlling physiological sleep-dependent changes in arterial blood pressure and heart rate. A brief introduction on the anatomic and functional organization of the arterial baroreflex and the methods available to assess its function in humans is followed by an analysis of the functional interaction between autonomic nervous system and sleep mechanisms at the highest levels of brain organization. An insight into these interactions is important to shed light on the physiopathology of the most frequent complications of obstructive sleep apnea syndrome, such as sustained arterial hypertension, and excessive daytime sleepiness.     

Clinical prediction of the sleep apnea syndrome

Polysomnography, the standard diagnostic test for people suspected of having sleep apnea, is a limited resource due to its expense. Decisions about which patients to refer to a sleep center and which require polysomnography can be made based on an estimate of the probability that they have sleep apnea. Clinical features that are associated with the severity of sleep apnea, as judged by the apnea-hypopnea index, can be combined together using statistical modeling into a clinical prediction rule, whose diagnostic performance can be summarized by its sensitivity and specificity or by likelihood ratios. To date, at least seven different sleep apnea clinical prediction rules have been developed, most incorporate anthropomorphic variables such as the body mass index, waist circumference, and/or neck circumference, and some type of abnormal respiration during sleep (snoring, apneas, choking and/or gasping) witnessed by a bed partner. In general these rules have reasonably high sensitivities but only intermediate specificities, thus they can be useful in excluding the diagnosis but do not usually raise the probability of sleep apnea high enough to warrant initiating therapy without at least some type of additional testing to confirm the diagnosis. In isolation the apnea-hypopnea index is not an optimal indicator of disease severity, thus ultimately clinical decisions about the need for polysomnography and/or the need for treatment must take into account other important clinical information such as symptom severity, quality of life, and the presence or absence of comorbid illness.     

Health care costs and the sleep apnea syndrome

This paper reviews some concepts on health economics from the authors personal perspective. It then examines the few papers published on health economics analysis applied to the field of sleep apnea syndrome, as well as the literature on the indirect (cost) consequences of sleep apnea syndrome. It appears that undiagnosed sleep apnea leads to a roughly two-fold increase in medical expenses in the years preceding the diagnosis and that treating the disease (once it is diagnosed) results in a decrease in these excess costs. It seems clear that sleep apnea increases the actual number of road traffic accidents, which will carry a definite, but unmeasured up to now, economic cost consequence. From the health economic point of view, the best diagnostic strategy is the one with the greater utility (i.e. polysomnography), although it could appear at first sight to be the more expensive one. From the patient's perspective, sleep apnea results in a given decrease in the possibilities to enjoy life, and its treatment is worth considering, especially if one takes into account that the actual treatment costs are not great. The global image of the health costs related to sleep apnea is still blurred, and further work is required to get the complete and clear picture of the economic consequences of this disease and of its treatment.