Sleep-disordered breathing and oxygen desaturation in obese patients

Fourteen morbidly obese subjects, referred to our institution for bypass surgery for obesity, were studied with regard to pulmonary function and respiratory patterns during sleep. The seven female patients experienced no episodes of desaturation or disordered breathing during sleep. Six of the seven male patients experienced desaturation or disordered breathing. The one who did not had hypogonadism, suggesting that testosterone may have a role in the regulation of breathing during sleep. The two patients with the most frequent episodes of apnea and lowest oxygen saturation had a clinical picture consistent with the pickwickian syndrome. This supports the relationship previously noted between the degree of hypoxia and the presence of hypersomnolence.     

Deleterious effects of sleep-disordered breathing on the heart and vascular system

Obstructive sleep apnea (OSA) is the most common form of sleep-disordered breathing, affecting 5-15% of the population. It is characterized by intermittent episodes of partial or complete obstruction of the upper airway during sleep that disrupts normal ventilation and sleep architecture, and is typically associated with excessive daytime sleepiness, snoring, and witnessed apneas. Patients with obstructive sleep apnea present risk to the general public safety by causing 8-fold increase in vehicle accidents, and they may themselves also suffer from the physiologic consequences of OSA; these include hypertension, coronary artery disease, stroke, congestive heart failure, pulmonary hypertension, and cardiac arrhythmias. Of these possible cardiovascular consequences, the association between OSA and hypertension has been found to be the most convincing. Although the exact mechanism has not been understood, there is some evidence that OSA is associated with frequent apneas causing mechanical effects on intrathoracic pressure, cardiac function, and intermittent hypoxemia, which may in turn cause endothelial dysfunction and increase in sympathetic drive. Therapy with continuous positive airway pressure has been demonstrated to improve cardiopulmonary hemodynamics in patients with OSA and may reverse the endothelial cell dysfunction. Despite the availability of diagnostic measures and effective treatment, many patients with sleep-disordered breathing remain undiagnosed. Therefore, OSA continues to be a significant health risk both for affected individuals and for the general public. Awareness and timely initiation of an effective treatment may prevent potential deleterious cardiovascular effects of OSA.     

Controversies in monitoring and testing for sleep-disordered breathing.

Despite significant advances in the understanding of the pathophysiology of the obstructive sleep apnea syndrome, the best index to classify the severity of sleep-disordered breathing has not been established. The use of new measurement techniques suggests that subtle changes in airflow not detected by conventional thermal sensing devices may signal events associated with significant sleep disruption. Recurrent increased respiratory efforts without discernable changes in airflow, which are currently reliably detectable only by invasive means, also may be important. However, it is still uncertain which events should be considered clinically significant, and the correlation of the frequency of various types of respiratory events with long term physiologic consequences is not clear. Outpatient screening with multichannel portable devices or pulse oximetry has important limitations. However, in combination with the clinical pretest probability of significant sleep-disordered breathing, such screening may correctly classify a large proportion of patients. Combining a partial night diagnostic sleep study with a therapeutic titration of continuous positive airway pressure seems to provide adequate information for appropriate management of many patients with obstructive sleep apnea and reduces time between presentation and initiation of treatment.     

Sleep quality and pulmonary function in the healthy elderly

Loss of sleep causes deterioration of pulmonary function and ventilatory responsiveness in normal humans and in patients with chronic obstructive pulmonary disease. To evaluate the effects of variations in sleep quality on breathing, we studied 48 healthy elderly volunteers (mean age, 70 years). Electroencephalographically derived indices of sleep quality were correlated with spirometric performance, MIP, MEP, and waking SaO2. We found significant correlations between several indices of sleep quality and the spirometric measurements in the group as a whole, and striking correlations between sleep quality and PFTs in those with sleep efficiency less than or equal to 70 percent. We conclude that sleep disturbance may be related to poor performance on PFTs. These results suggest that spirometry should be performed on well-rested patients. The results also point to sleep quality as a potentially important variable in the management of patients with pulmonary disease.     

The effect of human heart-lung transplantation upon breathing at rest and during sleep

We have assessed the contribution of intrathoracic pulmonary nerves to the control of breathing in humans. During relaxed wakefulness and during sleep the level, pattern and variability of breathing have been quantified in 8 healthy patients 1 month to 2 years after combined heart--lung transplantation. These data have been compared with similar data from both of 2 matched control groups; either healthy normal controls, or healthy patients after heart transplantation alone. We found no significant differences in the mean levels of respiratory variables between the 3 groups either during relaxed wakefulness or sleep. There were no significant differences between groups (other than would be expected by chance alone) either in the variability of breathing, or in the shapes of the frequency distributions of respiratory variables during these states. There were no respiratory disorders associated with sleep nor any disturbances in blood gases in any group. We conclude that in man breathing is remarkably normal, during relaxed wakefulness and during sleep, after chronic pulmonary denervation. When the ventilatory demands are minimal the human ventilation system functions normally in the absence of a control loop involving pulmonary proprioceptors and the medullary respiratory centres.     

Treatment of central sleep apnea in patients with heart failure: Now and future

Heart failure (HF) is known to be associated with sleep-disordered breathing (SDB). In addition to disturbing patients’ sleep, SDB is also associated with a deterioration in the cardiac function and an increased mortality and morbidity. Central sleep apnea (CSA), typically characterized by Cheyne-Stokes breathing (CSB), is increasingly found in patients with HF compared to the general population. An important pathogenetic factor of CSA seen in HF patients is an instability in the control of the respiratory system, characterized by both hypocapnia and increased chemosensitivity. Sympathetic overactivation, pulmonary congestion and increased chemosensitivity associated with HF stimulate the pulmonary vagal irritant receptor, resulting in chronic hyperventilation and hypocapnia. Additionally, the repetitive apnea and arousal cycles induce cyclic sympathetic activation, which may worsen the cardiac prognosis. Correcting CSB may improve both patient’s quality of life and HF syndrome itself. However, a treatment for HF in patients also experiencing CSA is yet to be found. In fact, conflicting results from numerous clinical studies investigating sleep apnea with HF guide to a troubling question, that is whether (or not) sleep apnea should be treated in patients with HF? This editorial attempts to both collect the current evidence about randomized control trials investigating CSA in patients with HF and highlight the effect of specific CSA treatments on cardiovascular endpoints.     

Breathing during wakefulness and sleep after human heart-lung transplantation

To study the effects of pulmonary denervation on breathing during sleep, sleep studies were conducted on seven heart-lung transplant recipients (H-LT) and a comparable number of sex-matched normal subjects of similar age. Four of the H-LT patients had a restrictive pattern on spirometry. The time since transplantation ranged from 45 to 1,102 days. There were no significant differences between the groups with respect to total sleep time or distribution of sleep stages. There were no significant differences between the H-LT recipients and normal subjects with respect to baseline awake oxyhemoglobin saturation (SaO2) or the nadirs of SaO2 during REM and non-REM sleep, the absolute number and frequency (number per hour of sleep) of apneas, hypopneas, desaturation events, both over the whole night of study or separately during non-REM and REM sleep. Across wakefulness and all sleep stages, the H-LT patients tended to have shorter total respiratory cycle times (Ttot) (p = 0.052) and more rapid breathing frequency (F) than the normal subjects. This was associated with significantly shorter inspiratory times (Tl) (p less than 0.001) and smaller duty cycles (Tl/Ttot) (p less than 0.005) in the H-LT recipients. During non-REM and REM sleep, F tended to be higher in the H-LT recipients with pulmonary restriction than in the nonrestricted patients. There were no significant differences between the H-LT recipients and the normal subjects with regard to the periodicity of breathing, either in terms of timing parameters or breath amplitude.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sleep and respiration: a postscript

The recent advances in our understanding of breathing in sleep include an evolution in the selection and surgical therapy of patients with the sleep apnea syndrome. Recent work suggests that shorter polysomnographic studies may be adequate for diagnostic purposes in many sleep apnea patients. It is now clear that central apnea may occur, paradoxically, in patients with either very blunted chemical drives to breathe or increased drives to breathe.     

Nasal and sinus inflammation in chronic obstructive pulmonary disease

Epidemiologic studies suggest that as many as 75% of patients with COPD have concomitant nasal symptoms and more than 1/3 of patients with sinusitis also have lower airway symptoms of asthma or COPD. Because the inflammatory response of the upper and lower airways are similar, and both sites have a similar exposure to allergens and irritants, it is not surprising that rhinitis or sinusitis would coexist with COPD. Possible mechanisms of combined upper and lower airway dysfunction include the so-called nasal-bronchial reflex, inflammation caused by smoking, mouth breathing caused by nasal obstruction, and pulmonary aspiration of nasal contents. Patients with chronic sinusitis commonly have nonspecific bronchial hyperresponsiveness, suggesting a neural reflex. Postnasal drainage of nasal inflammatory mediators during sleep also may increase lower airway responsiveness. Therapy of nasal and sinus disease is associated with improved pulmonary function in patients with COPD.     

Treatment of sleep disordered breathing in congestive heart failure

In patients with congestive heart failure, sleep disordered breathing occurs commonly and is associated with an increased mortality. In addition to central sleep apnea (Cheyne–Stokes respiration), obstructive sleep apnea is more prevalent in patients with congestive heart failure than in the general population. As a result, a number of treatments have been investigated, with varying results. While many therapies may improve the severity of sleep disordered breathing, only positive pressure ventilation has been shown to improve cardiac function. Newer forms of positive pressure ventilation, such as adaptive servo-ventilation, appear to be even more effective at correcting central sleep apnea. Whether any of these treatments have an effect on transplant-free survival is presently unknown and awaits further study.     

慢性阻塞性肺病与阻塞性睡眠呼吸暂停综合征关系研究

目的调查住院和门诊COPD患者中OSAS的患病率及OSAS患者中COPD的患病率,探讨COPD与OSAS之间的关系,分析重叠综合征患者睡眠呼吸紊乱的特点。方法对200例稳定期的COPD患者经问卷、爱波沃斯（ESS）评分及家庭血氧饱和度监测,对氧减饱和指数大于5或爱波沃斯（ESS）评分大于或等于10的患者进行多导生理记录仪睡眠呼吸监测（PSG）。结果门诊COPD患者中OSAS的患病率为2．5％,住院COPD患者中OSAS患病率为6．7％,OSAS患者中COPD的患病率为11．2％。重叠综合征患者与单纯OSAS患者在夜间平均氧饱和度、呼吸暂停指数、低通气指数等方面差异有显著性（P〈0．01）。结论COPD与OSAS两者之间没有必然联系,重叠综合征患者夜间呼吸紊乱模式以肺泡通气不足和肺泡低通气为主而非呼吸暂停,重叠综合征患者睡眠中低氧程度比单纯OSAS患者更严重。     

Schlafbezogene Atmungsst?rungen

Sleep related breathing disorders are common conditions and the management of patients with sleep apnea is an essential component of routine patient care. Daytime sleepiness is the leading symptom of sleep apnea but not mandatory. Especially patients with cardiac, pulmonary or metabolic comorbidities can benefit from treatment of sleep apnea and those patients should be considered for cardio-respiratory screening even with mild clinical symptoms. Continuous positive airway pressure therapy is still the most efficient treatment for sleep apnea and standard treatment for severe forms. With patient education, training and close follow-up a reasonably good compliance can be achieved in adequately selected patients. In mild forms of sleep apnea oral appliances may be efficient and in highly selected lean patients with anatomic risk factors upper airway surgery may be considered. Central sleep apnea, especially Cheyne-Stokes respiration, is highly prevalent in patients with severe cardiac insufficiency. If this disorder persists after cardiac treatment special ventilation modes like adaptive servo ventilation can be used.     

Sleep related breathing disorders

Sleep related breathing disorders are common conditions and the management of patients with sleep apnea is an essential component of routine patient care. Daytime sleepiness is the leading symptom of sleep apnea but not mandatory. Especially patients with cardiac, pulmonary or metabolic comorbidities can benefit from treatment of sleep apnea and those patients should be considered for cardio-respiratory screening even with mild clinical symptoms. Continuous positive airway pressure therapy is still the most efficient treatment for sleep apnea and standard treatment for severe forms. With patient education, training and close follow-up a reasonably good compliance can be achieved in adequately selected patients. In mild forms of sleep apnea oral appliances may be efficient and in highly selected lean patients with anatomic risk factors upper airway surgery may be considered. Central sleep apnea, especially Cheyne-Stokes respiration, is highly prevalent in patients with severe cardiac insufficiency. If this disorder persists after cardiac treatment special ventilation modes like adaptive servo ventilation can be used.     

Positive pressure ventilation in the management of acute and chronic cardiac failure: a systematic review and meta-analysis

Chronic heart failure (CHF) is a common condition and is associated with excess morbidity and mortality, in spite of the many advances in its treatment. Chronic stable heart failure is also associated with an increased incidence of sleep-related breathing disorders, such as central sleep apnoea (CSA) and Cheyne Stokes respiration (CSR). Continuous positive airways pressure (CPAP) has been shown to alleviate the symptoms of CHF, improve left ventricular function and oxygenation. To a certain extent, CPAP also abolishes sleep-related breathing disorders in patients with chronic heart failure. In patients with acute pulmonary oedema, the use of positive pressure ventilation improves cardiac haemodynamic indices, as well as symptoms and oxygenation, and is associated with a lower need for intubation. However, some studies have cast doubts about its safety and suggest a higher rate of myocardial infarction associated with its use. In our opinion, non-invasive positive pressure ventilation and CPAP offers an adjunctive mode of therapy in patients with acute pulmonary oedema and chronic heart failure, who may not be suitable for intubation and in those not responsive to conventional therapies. Non-invasive ventilation also helps to improve oxygenation in those patients with exhaustion and respiratory acidosis. Many trials are still ongoing and the results of these studies would throw more light on the present role of non-invasive ventilation in the management of CHF.     

合并睡眠呼吸暂停低通气综合征的老年慢性阻塞性肺病患者的临床特点分析

目的分析慢性阻塞性肺疾病（COPD）合并阻塞性睡眠呼吸暂停低通气综合征（OSAHS）,即重叠综合征患者睡眠呼吸紊乱的临床特点,比较门诊和住院COPD患者的呼吸紊乱情况。方法对Epworth嗜睡量表评分≥10,夜间氧减饱和指数ODI4（每小时血氧饱和度下降4％的次数）≥5的门诊及住院稳定期300例COPD患者进行多导睡眠图监测。结果住院COPD患者的呼吸紊乱程度更严重,住院与门诊COPD合并OSAHS患者在体重指数、血氧饱和度低于90％的时间占总记录时间的百分比、夜间平均血氧饱和度、夜间最低血氧饱和度、呼吸紊乱指数等方面差异显著。此外,住院COPD患者睡眠中心率增快。结论睡眠呼吸紊乱可以影响并加重COPD患者病情。     

Afternoon serum-melatonin in sleep disordered breathing

OBJECTIVES: To study afternoon serum-melatonin values in patients with sleep disordered breathing. Melatonin has a strong circadian rhythm with high values during the night-time and low values in the afternoon. Sleep disordered breathing may change the circadian rhythm of melatonin which may have diagnostic implications. SETTING: The Sleep Laboratory, The Department of Internal Medicine, Avesta Hospital, Sweden, and the Department of Anaesthesiology, Glostrup University Hospital, Copenhagen, Denmark. SUBJECTS: We examined 60 consecutive patients admitted for sleep disordered breathing and 10 healthy non snoring controls. The patients underwent a sleep apnoea screening test having a specificity of 100% for the obstructive sleep apnoea syndrome (OSAS) using a combination of static charge sensitive bed and oximetry. Obstructive sleep apnoea syndrome was found in 49 patients, eight patients had borderline sleep disordered breathing (BSDB) and three patients were excluded due to interfering disease. MAIN OUTCOME MEASURES: Patients and controls had an afternoon determination of serum-melatonin. The Epworth Sleepiness Scale was used to score day-time sleepiness. RESULTS: In comparison with normal controls patients suffering from OSAS had significantly higher serum-melatonin levels in the afternoon. However, as a diagnostic test for OSAS in patients with sleep disordered breathing serum-melatonin showed a low sensitivity but a high specificity. The results indicate that breathing disorders during sleep in general affect pineal function. CONCLUSIONS: Sleep disordered breathing seems to disturb pineal function. Determination of afternoon serum-melatonin alone or together with a scoring of daytime sleepiness does not identify OSAS-patients in a heterogeneous population of patients complaining of heavy snoring and excessive daytime sleepiness.     

Sleep in restrictive and neuromuscular respiratory disorders

Thoracic restrictive disorders (i.e., chest wall deformities or neuromuscular diseases), may predispose to sleep-disordered breathing, poor sleep quality, and nocturnal hypoventilation. These disorders intensify the effects of reductions in both respiratory center output and central chemosensitivity and increases in upper airway resistance that occur with the onset of sleep. Normally, rapid eye movement (REM) sleep suppresses the activity of nondiaphragmatic breathing muscles, further reducing ventilation. Diaphragmatic or upper airway muscle weakness and reduced chest wall compliance in patients with thoracic restrictive disorders enhance the severity of sleep-disordered breathing during REM sleep, worsening gas exchange abnormalities and sleep fragmentation and impairing daytime functioning. Although daytime respiratory function and nocturnal oxygen saturation are not well correlated, some markers may be useful for identifying patients with thoracic restriction at risk for sleep-disordered breathing. Although some patients may respond to continuous positive airway pressure (CPAP) alone, noninvasive positive pressure ventilation (NPPV) is a more important part of disease management for patients with restrictive thoracic disorders. This technique improves nocturnal ventilation and sleep quality but may also contribute to sleep fragmentation in some patients. If the patient is an unsuitable candidate for or fails NPPV, tracheostomy mechanical ventilation should be considered.     

Sleep disorders and sleep-related breathing disorders

Normal sleep consists of 4-5 sleep cycles including light-, deep- and rapid eye-movement sleep. Restoration of physical and psychological function are the main effects of sleep. In most cases, disturbances of normal sleep become clinically evident as problems of initiating and maintaining sleep and/or as increased daytime sleepiness. Approximately 10% of adults suffer from pronounced insomnia, a similar percentage from markedly increased daytime sleepiness. Sleep disorders cause high socio-economic costs due to increased accident risk, cardiovascular sequelae and sick leave. Most of the 88 distinct diagnoses summarized in the international classification of sleep disorders can be differentiated and managed according to patients history. In patients with severe daytime sleepiness - sleep disordered breathing being the most frequent cause - the diagnostic evaluation and treatment in the sleep laboratory is required. Effective therapeutic strategies are available for many sleep disorders. According to the underlying disorder, treatment includes a variety of measures like life style changes, differentiated medical treatment and the use of nasally applied positive pressure in patients suffering from sleep disordered breathing.     

Sleep-Related Breathing Disorders in Patients with Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic and usually fatal lung disease of unknown etiology. The aim of this study was to describe clinical and polysomnographic features of sleep-related breathing disorders (SRBD) and to identify predictors of obstructive sleep apnea (OSA) in IPF patients. Eight hundred fifty-seven patients with IPF were admitted to the Cleveland Clinic from 2001 to 2005. An all-night polysomnogram (PSG) was performed in 18 of them to investigate complaints suggestive of sleep-disordered breathing. OSA was confirmed in 11 of the 18 IPF patients with complaints suggestive of sleep apnea, while the remain 7 patients had a diagnosis of primary snoring or upper airway resistance syndrome (UARS). All patients showed a reduction in sleep efficiency, REM sleep, and slow wave sleep. The apnea-hypopnea index (AHI) was positively correlated with body mass index (p < 0.0001, r = 0.80). The REM AHI and overall AHI were negatively correlated with FEV₁ (p = 0.008, r = −0.59 and p = 0.04, r = −0.49, respectively) and FVC percentages (p = 0.03, r = −0.50 and p = 0.08, r = −0.42, respectively). Our study is the first describing SRBD in IPF patients. An increased BMI and a significant impairment in pulmonary function testing may be predictors of OSA in this population. In the absence of effective treatments for IPF, the diagnosis and treatment of comorbid SRBD may lead to improvements in quality of life.     

Insomnia complaints in patients evaluated for obstructive sleep apnea

Obstructive sleep apnea (OSA) and insomnia are among the most common sleep diagnoses encountered in the sleep clinic population, however little is known about potential interactions or associations between the two disorders. This retrospective, cross-sectional study was designed to determine the prevalence of insomnia complaints in patients undergoing evaluation for OSA and to ascertain which clinical and polysomnographic features are associated with insomnia. Of 255 consecutive patients who underwent polysomnography for clinically suspected OSA, 54.9% reported a complaint of insomnia: 33.4% reported difficulty initiating sleep, 38.8% difficulty maintaining sleep, and 31.4% early morning awakenings. Insomnia complaints were noted more commonly in patients without significant sleep-disordered breathing [apnea hypopnea index (AHI)<10; 81.5%] vs those with sleep-disordered breathing (AHI≥10; 51.8%); p=0.01. Clinical factors associated with insomnia included female gender, psychiatric diagnoses, chronic pain, the absence of regular alcohol use, restless leg symptoms, and reports of nocturnal kicking. Polysomnographic factors associated with insomnia included lower AHI and lower desaturation index (DI). In the subgroup of patients with significant sleep-disordered breathing (AHI≥10, n=228), there was no association between insomnia complaints and AHI or DI. These results suggest that insomnia is a common complaint in patients being evaluated for OSA, but it is not strongly associated with sleep-disordered breathing and may instead reflect other coexisting factors.