Atrial natriuretic peptide and catecholamines in obstructive sleep apnea syndrome.

Nocturnal polyuria with repeated micturitions during the night is a clinically evident feature of obstructive sleep apnea syndrome (OSAS). These effects are reversed by continuous positive airway pressure (CPAP). There is some evidence that atrial natriuretic peptide (ANP) and catecholaminergic activity may be implicated in the pathogenesis of these symptoms. We studied these biochemical parameters in six patients with severe OSAS during two nights: the first (basal) in their normal conditions and the second during CPAP treatment. CPAP treatment reversed apnea episodes in all our patients. A significant (p less than 0.035) reduction of nocturnal urine volume (from 902 +/- 297 to 447 +/- 130 ml; mean +/- SD), sodium excretion (from 150 +/- 33 to 89 +/- 35 mEq/12 h), noradrenaline excretion (from 95 +/- 101 to 52 +/- 16 micrograms/g creatinine), noradrenaline plasma concentrations (from 325 +/- 96 to 259 +/- 75 pg/ml), ANP plasma concentrations (from 35 +/- 20 to 19 +/- 5 pg/ml) was observed during the night under CPAP application. These data suggest that in OSAS patients the high ANP plasma concentration is responsible for the observed elevated diuresis and sodium excretion. These effects are rapidly reversible, as they are reversed during the first CPAP treated night.     

Rhythm of melatonin excretion in obstructive sleep apnea syndrome

Melatonin is a pineal hormone that regulates sleep and wake status. Melatonin concentrations in blood serum were measured using radioisotope method in 33 males (age 48 +/- 10) with obstructive sleep apnea syndrome. The following melatonin concentrations were measured: 54 +/- 72 pg/ml (9 p.m.) 424 +/- 838 pg/ml (2 a.m.) and 307 +/- 534 pg/ml (6 a.m.). In patients with high peak melatonin concentration (> 200 pg/ml) as compared with the patients with low peak melatonin concentration (< 200 pg/ml) there were higher index of respiratory disorders during sleep (53 +/- 18 vs 38 +/- 20, p < 0.05) and lower minimal SaO2 during sleep apnea (52 +/- 17% vs 70 +/- 10%, p < 0.05); they were also more tired in the morning and were more sleepy during the day (Epworth sleepiness scale 17 +/- 6 vs 11 +/- 6, p < 0.01). In 66% of patients peak melatonin concentration was observed at 2 a.m. In 24% of patients peak melatonin secretion was prolonged to early morning hours. CONCLUSIONS: In most of patients there is peak melatonin excretion at 2 a.m. Patients with high apnea and hypopnea index and daytime sleepiness have high peak melatonin concentrations.     

CPAP治疗阻塞型睡眠呼吸暂停综合征前后患者血清IL-6和TNF-α的动态变化

目的：通过研究阻塞型睡眠呼吸暂停综合征（OSAS）患者血浆白细胞介素-6（IL-6）和肿瘤坏死因子-α（TNF-α）的水平及经持续气道正压通气（CPAP）治疗前后的变化,探讨IL-6和TNF-α在OSAS患者发病机制及病理生理中的作用。方法：①选择我院OSAS患者60例及正常人30例,详细询问病史,对所有观察对象于晨起采集静脉血标本,采用放射免疫分析集中检测血浆IL-6、TNF-α水平。比较OSAS组与对照组间血浆IL-6、TNF-α水平的差异;分析OSAS患者血浆IL-6、TNF-α水平与睡眠呼吸暂停低通气指数（AHI）和最低血氧饱和度的相关性。②OSAS组患者进行CPAP治疗并随访,3个月后复查上述各项指标,比较OSAS患者经CPAP治疗前后血浆IL-6、TNF-α水平等指标变化。结果：OSAS组患者血浆IL-6和TNF-α水平分别为（25.92±4.48）pg/ml,（11.27±2.60）pg/ml。较对照组升高（13.21±1.97）pg/ml,（5.83±0.99）pg/ml差异有统计学意义。②OSAS患者血浆IL-6和TNF-α水平与其AHI均呈正相关,相关系数分别为0.456（P〈0.05）,0.464（P〈0.05）。OSAS患者血浆IL-6和TNF-α水平与其最低血氧饱和度均呈负相关,相关系数分别为-0.495（P〈0.05）,-0.483（P〈0.05）。③OSAS患者进行CPAP治疗并随访,3个月后回访20例,再次测定血浆IL-6、TNF-α水平,分别为（15.37±1.78）pg/ml,（6.79±0.87）pg/ml较治疗前减低,差异有统计学意义。结论：CPAP治疗能有效地降低OSAS患者的血浆IL-6及TNF-α水平。     

N-terminal pro-brain natriuretic peptide for detection of cardiovascular stress in patients with obstructive sleep apnea syndrome

Patients with obstructive sleep apnea syndrome (OSAS) have an elevated incidence of cardiovascular events that may be related to an increased ventricular load and hypoxemia caused by apneas and hypopneas. N-terminal pro-brain natriuretic peptide (NTproBNP) appears to be an excellent marker of myocardial stretch and could serve as an indicator of subclinical cardiac stress, thereby identifying a patient population at risk for cardiac effects from OSAS. Adult patients presenting with suspected OSAS and scheduled for nocturnal polysomnography were recruited. Patients with heart or renal failure or severe lung disease were excluded. NTproBNP was measured the evening before and the morning after sleep. Blood pressure (BP) was monitored intermittently throughout the night. Fifteen male and 15 female subjects with a mean +/- SD body mass index of 38.2 +/- 9.8 were studied. Mean Apnea-Hypopnea Index (AHI) was 38.4 +/- 26, with 17 subjects having severe OSAS (AHI > 30). No subject had a significant rise in BP. NTproBNP values overnight decreased in 19 patients and rose in 11 (mean change 3.8 +/- 33 pg mL(-1)), but only one patient had an abnormal morning value. Three patients had an abnormal NTproBNP value prior to sleep, but their levels decreased with sleep. No correlations were detected between the evening baseline or postsleep NTproBNP levels and OSAS. Monitoring pre- and postsleep NTproBNP levels revealed no association with the occurrence or degree of OSAS, making it unlikely that NTproBNP could serve as a marker of cardiac stress in OSAS patients with stable BP and without overt heart failure.     

Obstructive sleep apnea can be provocative for right-to-left shunting through a patent foramen ovale

STUDY OBJECTIVES: Under particular conditions, a patent foramen ovale (PFO) can potentially give rise to ischemic stroke by means of paradoxical embolization, due to right-to-left shunt. Our study aimed to evaluate the presence of right-to-left shunt in patients with obstructive sleep apnea syndrome (OSAS) and diagnosed PFO during sleep. DESIGN AND SETTING: Assessment of provocative-only PFO and concomitant OSAS. Evaluation of right-to-left shunting during sleep by means of transcranial doppler with contrast medium injected in the cubital vein. PARTICIPANTS: 10 consecutive patients affected by PFO detectable only under Valsalva maneuver during wakefulness and affected by OSAS (mean age 52.8 +/- 10.7 years). INTERVENTIONS: Patients underwent transcranial doppler with injection of agitated saline solution mixed with air during normal breathing and during periods of apnea/hypopnea in nocturnal sleep. MEASUREMENTS AND RESULTS: Right-to-left shunt was present in 9 patients out of 10 and appeared during obstructive apneas longer than 17 seconds. In 1 out of 10 patients, only hypopneas occurred and no right-to-left shunt could be shown. The number of microembolic signals detected during periods of nocturnal apnea was positively correlated with the number detected during Valsalva maneuver in wakefulness (p<0.0001). CONCLUSIONS: In the nocturnal sleep period, right-to-left shunt can occur during single obstructive apneas in patients with OSAS and concomitant presence of PFO. This can be a risk factor for cerebrovascular diseases. This risk could probably increase proportionally to the respiratory disturbance index of these patients.     

Proton magnetic resonance spectroscopy study of brain metabolism in obstructive sleep apnoea syndrome before and after continuous positive airway pressure treatment

STUDY OBJECTIVES: Obstructive sleep apnoea syndrome (OSAS) causes sleep related oxygen desaturation, excessive daytime sleepiness (EDS), and cognitive impairment. The role of hypoxic brain damage, sleep fragmentation, and the associated comorbidities (hypertension, vascular disorders) in the pathogenesis of cognitive deficits remains controversial. The aim of this study was to evaluate the cerebral metabolism of OSAS patients in vivo before and after CPAP treatment. DESIGN AND PATIENTS: Fourteen OSAS patients without cardiovascular or cerebrovascular impairment underwent the same protocol before and after 6 months of CPAP including: overnight videopolysomnography (VPSG), Multiple Sleep Latency Test (MSLT), and within the next 2 days neuropsychological and 1H-MRS evaluations. Single voxel 1H-MRS was performed in the parietal-occipital cortex, and absolute concentrations of N-acetyl-aspartate (NAA), creatine, and choline were measured, acquiring spectra at multiple echo-times and using water as internal standard. Ten matched controls were also studied. RESULTS: OSAS patients had a mean RDI of 58/hr, a mean arousal index of 57/hr, and a mean nadir SpO2 of 71%. Before CPAP, all patients showed a normal global cognitive functioning, with only a small number of pathological tasks in working memory and attention tests in a minority of patients. CPAP therapy was effective in resolving sleep apnoea and normalizing sleep structure, and improving EDS and neuropsychological alterations. Before CPAP treatment cortical [NAA] in OSAS (11.86 mM +/- 0.80, mean +/- SD) was significantly lower than in controls (12.85 +/- 0.93; P = 0.01) and positively correlated with minimum SpO2 during sleep (r = 0.69; P = 0.006) and MSLT scores (r = 0.62; P = 0.01). Cortical [NAA] reduction persisted after therapy (11.94 +/- 1.33; P = 0.87 versus pre-CPAP). CONCLUSIONS: OSAS patients have cortical metabolic changes consistent with neuronal loss even in the absence of vascular comorbidities. Metabolic changes persisted after CPAP in the absence of EDS, nocturnal arousals, and major cognitive deficits, likely related to hypoxic damage prior to CPAP treatment.     

Sleep apnea, proteinuria, and nephrotic syndrome

Renal abnormalities in patients with obstructive sleep apnea syndrome (OSAS) have not been previously described. Medical records of patients who had been evaluated for possible sleep apnea syndrome and had had complete polysomnograms and urinalyses were reviewed to determine the frequency of proteinuria. High-grade proteinuria (greater than or equal to 3+ on urinalysis) was found in 6 of the 34 patients with obstructive sleep apnea, but in none of 34 patients in a control group matched for sex, age, and weight. In three patients, proteinuria was in the nephrotic range (3.5 g/24 h). The weight (mean +/- SD) of the patients with obstructive sleep apnea (112.7 +/- 35.3 kg) was not significantly different from the control group (109.2 +/- 30.3 kg). Microscopic examination of renal tissue in one patient with OSAS showed minimal changes. In four patients who were followed for 3 years, proteinuria improved after therapy for sleep apnea syndrome. We suggest that proteinuria may not be uncommon in patients with severe obstructive sleep apnea syndrome and may be reversible with correction of the sleep apnea syndrome.     

Treatment with continuous positive airway pressure may affect blood glucose levels in nondiabetic patients with obstructive sleep apnea syndrome

STUDY OBJECTIVES: Obstructive sleep apnea syndrome (OSAS) is often associated with impaired glucose metabolism. Data on the effects of OSAS treatment with continuous positive airway pressure (CPAP) on blood glucose and insulin resistance are conflicting. The study aimed at assessing the immediate effect of CPAP on glucose control measured with a continuous glucose monitoring system (CGMS). PARTICIPANTS AND MEASUREMENTS: Nine non-diabetes subjects with OSAS (mean age 53.0 +/- 8.0 years; body mass index 34.8 +/- 5.3 kg/m2) underwent 2 overnight polysomnographic examinations: a diagnostic study and one with CPAP treatment. Continuous glucose monitoring system (CGMS) was applied overnight on both occasions. Glucose metabolism was assessed with a 75-g oral glucose tolerance test, plasma insulin and homeostatic model assessment of insulin resistance (HOMA-IR) index. RESULTS: The mean (+/- SD) apnoea-hypopnea index (AHI) at diagnostic polysomnography was 54.3 +/- 29.3 (range 16-81). Fasting plasma insulin levels in patients with OSAS was 84.3 +/- 43.4 pM at baseline, and the HOMA-IR was 3.6 +/- 2.2. CPAP treatment in the subjects with OSAS resulted in a significant reduction in the AHI to 4.5 +/- 7.1. All of the major saturation parameters improved significantly on CPAP. CGMS showed mean glucose values significantly higher during the CPAP night than during the diagnostic night: 80 +/- 11 mg/dL versus 63 +/- 7 mg/dL (P < .01). Fasting insulin and HOMA-IR measured after the CPAP night tended to be higher than at baseline (98.4 +/- 51.0 pmol vs 84.3 +/- 43.4 pmol and 3.9 pmol +/- 2.6 vs 3.6 +/- 2.2 pmol, respectively, P > .05). CONCLUSION: CPAP treatment in nondiabetic obese patients with OSAS may have an immediate elevating effect on blood glucose.     

Atrial natriuretic peptide levels and pulmonary artery pressure awake, at exercise and asleep in obstructive sleep apnoea syndrome

Elevated nocturnal plasma atrial natriuretic peptide (ANP) levels were found in patients with obstructive sleep apnoea (OSA). The purpose of our study was to examine the secretion of ANP during the night and to measure changes in oxygen saturation, pulmonary artery pressure and intrathoracic pressure swings in patients with OSA. Moreover, we analysed the secretion of ANP and the pulmonary artery pressure in different behavioural states, e.g. awake, at exercise and asleep. Consecutive apnoeas in non-rapid eye movement (NREM) sleep at the beginning, middle and end of the sleep study were analysed in six patients with obstructive sleep apnoea. In addition, we measured the plasma levels of ANP. The apnoea duration was significantly longer (P< 0.05) at the middle of the sleep study than at the beginning or end. Correspondingly, the end-apnoeic oxygen saturation and end-apnoeic oesophageal pressure were both significantly lower (P< 0.05) in the middle of the sleep study than at the beginning or end. No significant differences were found in the end-apnoeic systolic transmural pulmonary artery pressure (P(PATM)) and the levels of ANP. Evaluation of the ANP levels during different behavioural states revealed that the asleep levels were slightly, but not significantly, higher than the awake levels (0.235+/-0.088 vs. 0.207+/-0.057 nmol/L). However, the highest levels were found during exercise (0.334+/-0.170 nmol/L) with a significant difference compared with the awake and asleep levels. These data suggest that volume effects may be a potent factor in liberating ANP during exercise, but the role of OSA in ANP secretion when asleep is questionable.     

Correlation between the severity of obstructive sleep apnea and heart rate variability indices

The risk of cardiovascular disease is known to be increased in obstructive sleep apnea syndrome (OSAS). Its mechanism can be explained by the observation that the sympathetic tone increases due to repetitive apneas accompanied by hypoxias and arousals during sleep. Heart rate variability (HRV) representing cardiac autonomic function is mediated by respiratory sinus arrhythmia, baroreflex-related fluctuation, and thermoregulation-related fluctuation. We evaluated the heart rate variability of OSAS patients during night to assess their relationship with the severity of the symptoms. We studied overnight polysomnographies of 59 male untreated OSAS patients with moderate to severe symptoms (mean age 45.4+/- 11.7 yr, apnea-hypopnea index [AHI]=43.2+/-23.4 events per hour, and AHI >15). Moderate (mean age 47.1+/-9.4 yr, AHI=15-30, n=22) and severe (mean age 44.5 +/-12.9 yr, AHI >30, n=37) OSAS patients were compared for the indices derived from time and frequency domain analysis of HRV, AHI, oxygen desaturation event index (ODI), arousal index (ArI), and sleep parameters. As a result, the severe OSAS group showed higher mean powers of total frequency (TF) (p=0.012), very low frequency (VLF) (p= 0.038), and low frequency (LF) (p=0.002) than the moderate OSAS group. The LF/HF ratio (p=0.005) was higher in the severe group compared to that of the moderate group. On the time domain analysis, the HRV triangular index (p=0.026) of severe OSAS group was significantly higher. AHI was correlated best with the LF/HF ratio (r(p))=0.610, p<0.001) of all the HRV indices. According to the results, the frequency domain indices tended to reveal the difference between the groups better than time domain indices. Especially the LF/HF ratio was thought to be the most useful parameter to estimate the degree of AHI in OSAS patients.     

Serum Cardiotrophin-1 and IL-6 Levels in Patients with Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea syndrome (OSAS) is associated with increased rates of cardiovascular diseases (CVD). Basic mechanisms involved in the increased cardiovascular risk of OSAS remain unclear. Inflammation has been shown to potentially play a critical role in this association. The aim of the present study was to investigate the level of cardiotrophin-1 (CT-1) in patients with OSAS. Forty-eight newly diagnosed OSAS patients and 37 nonapneic controls were enrolled in this study. Demographic data, cigarette smoking status, previous history of chronic diseases including CVD and metabolic diseases and drugs, and habits were obtained by a standardized questionnaire. All patients underwent polysomnographic evaluation. The mean age was 48.3?±?12.3 (24–74) years in OSAS group. Median apnea–hypopnea index was 23.6 (6–91.8) and median body mass index was 30.4 (24.2–49.4) in the OSAS group. Plasma CT-1 levels in OSAS and control groups, respectively, were 12.03?±?1.08 and 11.85?±?1.18 pg/ml. There was no significant difference in the plasma levels of CT-1 and IL-6 between the OSAS group and the controls.     

Lateral sleeping position reduces severity of central sleep apnea / Cheyne-Stokes respiration

INTRODUCTION: The influence of sleeping position on obstructive sleep apnea severity is well established. However, in central sleep apnea with Cheyne Stokes respiration (CSA-CSR) in which respiratory-control instability plays a major pathophysiologic role, the effect of position is less clear. STUDY OBJECTIVES: To examine the influence of position on CSA-CSR severity as well as central and mixed apnea frequency. METHODS: Polysomnograms with digitized video surveillance of 20 consecutive patients with heart failure and CSA-CSR were analyzed for total apnea-hypopnea index, mean event duration, and mean oxygen desaturation according to sleep stage and position. Position effects on mixed and central apnea index, mean apnea duration, and mean desaturation were also examined in non-rapid eye movement sleep. RESULTS: Data are presented as mean +/- SEM unless otherwise indicated. Group age was 59.9 +/- 2.3 years, and total apnea-hypopnea index was 26.4 +/- 3.0 events per hour. Compared with supine position, lateral position reduced the apnea-hypopnea index in all sleep stages (Stage 1, 54.7 +/- 4.2 events per hour vs 27.2 +/- 4.1 events per hour [p < .001]; Stage 2, 43.3 +/- 6.1 events per hour vs 14.4 +/- 3.6 events per hour [p < .001]; slow-wave sleep, 15.9 +/- 6.4 events per hour vs 5.4 +/- 2.9 events per hour [p < .01]; rapid eye movement sleep, 38.0 +/- 7.3 events per hour vs 11.0 +/- 3.0 events per hour [p < .001]). Lateral position attenuated apnea and hypopnea associated desaturation (supine 4.7% +/- 0.3%, lateral 3.0% +/- 0.4%; p < .001) with no difference in event duration (supine 25.7 +/- 2.8 seconds, lateral 26.9 +/- 3.4 seconds; p = .921). Mixed apneas were longer than central (29.1 +/- 2.1 seconds and 19.3 +/- 1.1 seconds; p < .001) and produced greater desaturation (6.1% +/- 0.5% and 4.5% +/- 0.5%, p = .003). Lateral position decreased desaturation independent of apnea type (supine 5.4% +/- 0.5%, lateral 3.9% < or = 0.4%; p = .003). CONCLUSIONS: Lateral position attenuates severity of CSA-CSR. This effect is independent of postural effects on the upper airway and is likely to be due to changes in pulmonary oxygen stores. Further studies are required to investigate mechanisms involved.     

The therapeutic effect of theophylline on sustained attention in patients with obstructive sleep apnea

Summary Question of the Study Patients with obstructive sleep apnea syndrome (OSAS) often suffer from daytime sleepiness and reduced alertness which frequently cannot be normalized despite of nCPAP therapy. Therefore additional treatment options for residual deficits is urgently needed. The objective of this study was to prove the efficacy of Theophylline on a component of attention (tracking) in patients with untreated obstructive sleep apnea syndrome (OSAS). Patients and Methods Theophylline or placebo was given two times in the morning (8:00 and 12:00 a. m.) in randomized order on two consecutive days. During the afternoon, 39 OSAS patients performed a randomised cross-over driving simulation test with the aid of "Carsim", a newly developed driving simulator, prior to undergoing CPAP- therapy. The program "Carsim" simulates a road with curves on a screen, the simulated vehicle should be kept on the right lane by moving the steering wheel. Results Under the effect of Theophylline (the serum level under placebo at the beginning of the measurement was 2.1 µg/ml ± 1.6 µg/ml and under Theopylline 11.2  µg/ml ± 2.8  µg/ml), the duration of track deviations measured by the driving simulator improved significantly from 49.3 ± 99.5 s to 13.6 ± 18.0 s.   Conclusions Theophylline may improve alertness in patients with sleep fragmentation and reduced sustained attention.     

Tongue-muscle training by intraoral electrical neurostimulation in patients with obstructive sleep apnea

STUDY OBJECTIVES: To investigate the efficacy of tongue-muscle training by electrical neurostimulation of the upper-airway muscles as an alternative therapy option for obstructive sleep apnea syndrome. DESIGN: A randomized, placebo-controlled, double-blind study. SETTING: Department of pneumology and sleep laboratory, University of Witten/Herdecke, Germany. PATIENTS: 67 patients with an apnea-hypopnea index of 10 to 40 per hour were randomly assigned to 2 groups: a treatment group of 33 patients (mean age, 50.8 +/- 12.1 years; mean body mass index, 29.1 +/- 4.4 kg/m2) and a placebo group of 34 patients (mean age, 53.3 +/- 11.3 years; mean body mass index, 28.9 +/- 4.9 kg/m2). Fifty-seven patients completed the study. INTERVENTIONS: Tongue-muscle training during the daytime for 20 minutes twice a day for 8 weeks. MEASUREMENTS AND RESULTS: Treatment efficacy was examined by polysomnography. Snoring, but not apnea-hypopnea index, improved with stimulation (snoring baseline, 63.9 +/- 23.1 epochs per hour; stimulation training, 47.5 +/- 31.2; P < .05) but not with placebo training (snoring baseline, 62.4 +/- 26.1 epochs per hour; placebo, 62.1 +/- 23.8; NS.). CONCLUSIONS: Although tongue-muscle training cannot generally be recommended for the treatment of sleep apnea, the method has proven to be effective in the treatment of snoring.     

Comparison of answers to a sleep questionnaire of middle-age adults in Warsaw

In 1997 we evaluated answers to a sleep questionnaire in a representative sample of 1186 persons of adult population of Warsaw. In the year 2000 we sent the same questionnaire to all persons who participated in the 1997 investigations. 676 (57%) subjects responded. There were 53% males and 47% females in the studied group. Their mean age was 56.6 +/- 8 years. There was no difference in age and sex between responders and non-responders. The standardized questionnaire contained questions assessing the following items: snoring, excessive daytime sleepiness, apnoeas observed by the sleep partner, sleep time and sleep latency. During a 3-year follow-up mean sleep time on working days did not change and remained 7.1 +/- 1.1 h. However, the subjects slept significantly shorter time at weekends, 8.1 +/- 1.3 and 7.9 +/- 1.3 h respectively (p < 0.001). There was a decrease in percentage of snorers from 81% to 75% and increase in BMI from 27 +/- 4.5 to 29 +/- 5 kg/m2. The daytime sleepiness was reduced from 7.9 +/- 4.5 to 6.4 +/- 3.9 points (p < 0.001).     

No evidence of enhanced oxidant production in blood obtained from patients with obstructive sleep apnea

Background

Obstructive sleep apnea syndrome (OSAS) is a recognized risk factor for cardiovascular morbidity and mortality, perhaps due to causative exacerbations of systemic oxidative stress. Putative oxidative stress related to numerous episodes of intermittent hypoxia, may be an oxidants chief driving force in OSAS patients.

Methods

We assessed the resting and n-formyl-methionyl-leucyl-phenylalanine (fMLP)- induced whole blood chemiluminescence (as a measure of oxidant production by polymorphonuclear leukocytes and monocytes), ferric reducing ability of plasma (FRAP) and H₂O₂ generation in the whole blood of 27 untreated OSAS patients, 22 subjects after a night of CPAP therapy and 11 controls without OSAS. All of them were matched to age, BMI (body mass index) and smoking habits. All parameters were measured before and after polysomnography-controlled sleep, individual results were obtained as a mean from duplicated experiments.

Results

No significant differences were distinguished between evening and morning blood chemiluminescence, H₂O₂ activity and FRAP within and between all three study groups. For instance patients with untreated OSAS had similar morning and evening resting whole blood chemiluminescence (2.3 +/- 2.2 vs. 2.4 +/- 2.2 [aU·10^-4 phagocytes]), total light emission after stimulation with fMLP (1790 +/- 1371 vs. 1939 +/- 1532 [aU·s·10^-4 phagocytes]), as well as FRAP after 3 min. plasma incubation (602 +/- 202 vs. 671 +/- 221 [uM]). Although, in the subgroup of 11 patients with severe OSAS (apnea/hypopnea index 58 +/- 18/h and oxygen desaturation index 55 +/- 19/h), the morning vs. evening resting chemiluminescence and total light emission after stimulation with fMLP observed a propensity to elevate 2.5 +/- 2.7 vs. 1.9 +/- 1.8 [aU·10^-4 phagocytes] and 1778 +/- 1442 vs. 1503 +/- 1391 [aU·s·10^-4 phagocytes], respectively, these did not attain statistical significance (p > 0.05).

Conclusion

Our investigation exposed no evidence in the overproduction of oxidants via circulating phagocytes, once considered a culprit in the oxidative stress of OSAS patients.     

OSAS合并原发性高血压患者血浆内皮素-1与颈动脉内膜中层厚度的变化

目的观察阻塞性睡眠呼吸暂停综合征（obstructive sleep apnea syndrome,OSAS）及OSAS合并原发性高血压（essential hypertension,EH）患者血浆内皮素-1（Endothelin-1,ET-1）、颈动脉内膜中层厚度（carotid artery intima—media thickness,IMT）的变化及相互关系。方法选择OSAS合并EH患者组50例,OSAS患者组40例及健康对照组30例,采用ELISA法测定其血浆ET-1浓度,及利用颈动脉超声检测IMT。结果OSAS合并EH组的血浆ET-1浓度均高于单纯OSAS组及对照组即（124．66±18．90）pg／mL、（54．53±10．82）pg／mL,（45．07±6．45）pg／mL,差异有统计学意义（P〈0．01）;而单纯OSAS组的血浆ET-1浓度亦高于对照组,即（54．53±10．82）pg／mL对（45．07±6．45）pg／mL,差异有统计学意义（P〈0．05）;OSAS合并心血管病组的IMT明显高于单纯OSAS组及对照组,即（1．03±0．11）mm对（0．93±0．06）mm,（0．88±0．07mm,差异有统计学意义（P〈0．01）。结论OSAS患者存在内皮功能损害,OSAS合并EH者内皮功能紊乱更严重,同时伴IMT增厚。     

Changes in the QT interval during obstructive sleep apnea

Abnormalities of ventricular repolarization are associated with life-threatening ventricular arrhythmias. The effects of obstructive sleep apnea on the QT interval were evaluated in 12 male patients with obstructive sleep apnea syndrome (OSAS) who had no evidence of underlying cardiac, pulmonary or central nervous system disease. Seventy episodes of OSAS during nonrapid eye movement (NREM) sleep were randomly selected for analysis of RR and QT intervals. Differences in the QT interval, corrected QT interval (QTc) and RR interval just before the onset of apnea, at the end of apnea and during the postapnea hyperventilation period were compared. As expected, the RR interval prolonged considerably during OSAS (1,499 +/- 128 msec) compared to quiet sleep (1,019 +/- 131 msec, p less than 0.002) and decreased during the postapnea hyperventilation period (969 +/- 152 msec, p less than 0.002). The QT interval was prolonged at the onset of apnea (482 +/- 34 msec) compared to the active awake state (421 +/- 10 msec, p less than 0.01). Further prolongation of the QT interval was observed during OSAS (528 +/- 64 msec, p less than 0.002). The QT interval shortened abruptly during the postapnea hyperventilation period (435 +/- 34 msec, p less than 0.002). The QTc was also prolonged during the onset of apnea (482 +/- 34 msec) and shortened significantly during apnea (435 +/- 34 msec, p less than 0.002) and during the postapnea hyperventilation period (423 +/- 39 msec). Significant variations of the RR interval, QT and QTc intervals were not observed during episodes of NREM sleep after initiation of effective therapy in six patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inhibitory motor control in apneic and insomniac patients: a stop task study

The aim of this study was to assess with a stop task the inhibitory motor control efficiency--a major component of executive control functions--in patients suffering from sleep disorders. Twenty-two patients with untreated obstructive sleep apnea syndrome (OSAS) (mean age 46 +/- 9 years; mean apnea-hypopnea index, AHI = 30 +/- 20) and 13 patients with psychophysiological insomnia (mean age 47 +/- 12 years) were compared with individually matched healthy controls. Sleep disturbances in the patient populations were clinically and polysomnographically diagnosed. The stop task has a frequent visual 'Go' stimulus to set up a response tendency and a less frequent auditory 'Stop' signal to withhold the planned or prepotent response. The stop signal reaction time (SSRT) reflects the time to internally suppress the ongoing response. SSRT was slower for the apneic patients than for their respective controls (248 +/- 107 versus 171 +/- 115 ms, anova, P < 0.05) but not for the insomniac patients compared with their controls (235 +/- 112 versus 194 +/- 109 ms, NS). Moreover, in apneic patients, slower SSRT was associated with lower nocturnal oxygen saturation (r = -0.477, P < 0.05). By contrast, neither apneics nor insomniacs differed from their matched controls for reaction times on Go trials. To conclude, unlike insomniacs, OSAS patients present an impaired inhibitory motor control, an executive function which is required in many common everyday life situations. Inhibitory motor control relies on the integrity of the inferior prefrontal cortex, which could be affected by nocturnal oxyhemoglobin desaturation in apneic patients.     

Effects of nasal O2 on sleep-related disordered breathing in ambulatory patients with stable heart failure

OBJECTIVE: The purpose of this study was 1) to determine the effects of nasal O2 on periodic breathing, arterial oxyhemoglobin desaturation and nocturnal ventricular arrhythmias in patients with heart failure and 2) determine the characteristics of patients whose periodic breathing will be reversed by O2 administration; our hypothesis was that patients with more severe periodic breathing and desaturation, will respond more favorably to oxygen. DESIGN: Prospective study. SETTING: Referral sleep laboratory of a Department of Veterans Affairs Medical Center. PARTICIPANTS: 36 ambulatory male patients with heart failure whose initial polysomnograms showed periodic breathing with fifteen or more episodes of apnea (A) and hypopnea (H) per hour (AH index, AHI) were treated with nasal O2 during the subsequent full night polysomnography. INTERVENTIONS: Oxygen. MEASUREMENTS AND RESULTS: Arterial blood gases and hydrogen ion concentrations were measured, and cardiac radionuclide ventriculography, Holter monitoring, and polysomnography were done. The studies were scored blindly. Treatment with O2 resulted in a significant reduction in AHI (49+/-19 vs 29+/-29, means+/-SD), central apnea index (28+/-23 vs 13+/-18 per hour), and the percent of total sleep time below an arterial oxyhemoglobin saturation of 90% (23+/-21% vs 0.8+/-2.3%). In spite of virtual normalization of saturation with O2 therapy, the number of ventricular arrhythmias during sleep did not change significantly. In 39% of the patients (14 out of 36), O2 therapy resulted in reversal of central sleep apnea (defined by a reduction in AHI to less than 15/hr). In this group, the AHI decreased by 78% which was significantly (p=0.0001) more than improved (22%) in AHI of the remaining patients (n=22). The main differences between baseline characteristics of the two groups was a significantly higher mean PaCO2 in patients who did respond fully to O2 (39.3+/-5.4 vs 36.1+/-4.2 mm Hg, p=0.03). In both groups, however, O2 administration resulted in significant and similar improvement in arterial oxyhemoglobin saturation (saturation <90%, percent total sleep time 0.1+/-0.3% vs 1+/-3%). CONCLUSION: In patients with stable heart failure, administration of nasal O2 significantly improves periodic breathing and virtually eliminates clinically significant arterial oxyhemoglobin desaturation. The beneficial effects of O2, however, may be modulated by the level of arterial PCO2. Acute O2 therapy has important benefits on sleep apnea and nocturnal arterial oxyhemoglobin desaturation in heart failure patients. Long term benefits of O2 therapy in heart failure and sleep apnea need to be determined.