• Sleep Medicine and Psychophysiology
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• v.2 no.1
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• pp.55-64
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• 1995

During sleep, relatively major respiratory physiological changes occur in healthy subjects. The contributions and interactions of voluntary and metabolic breathing control systems during waking and sleep are quite different Alterations of ventilatory control occur in chemosensitivity, response to mechanical loads, and stability of ventilation. The activities of intercostal muscles and muscles involved in regulating upper airway size are decreased during sleep. These respiratory physiological changes during sleep compromise the nocturnal ventilatory function, and sleep is an important physiological cause of the nocturnal alveolar hypoventilation. There are several causes of chronic alveolar hypoventilation including cardiopulmonary, neuromuscular diseases. Obstructive sleep apnea syndrome (OSAS) is an important cause of nocturnal hypoventilation and hypoxia. Coexistent cardiopulmonary or neuromuscular disease in patients with OSAS contributes to the development of diurnal alveolar hypoventilation, diurnal hypoxia and hypercapnia. The existing data indicates that nocturnal recurrent hypoxia and fragmentation of sleep in patients with OSAS contributes to the development of systemic hypertension and cardiac bradytachyarrhythmia, and diurnal pulmonary hypertension and cor pulmonale in patients with OSAS is usually present in patients with coexisting cardiac or pulmonary disease. Recent studies reported that untreated patients with OSAS had high long-term mortality rates, cardiovascular complications of OSAS had a major effect on mortality, and effective management of OSAS significantly decreased mortality.

• Tuberculosis and Respiratory Diseases
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• v.45 no.1
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• pp.153-168
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• 1998

Background: The existing data indicate that obstructive sleep apnea syndrome contributes to the development of cardiovascular dysfunction such as systemic hypertension and cardiac arrhythmias, and the cardiovascular dysfunction has a major effect on high long-term mortality rate in obstructive sleep apnea syndrome patients. To a large extent the various studies have helped to clarify the pathophysiology of obstructive sleep apnea, but many basic questions still remain unanswered. Methods: In this study, the influence of obstructive sleep apnea on systemic blood pressure, cardiac rhythm and urinary catecholamines concentration was evaluated. Over-night polysomnography, 24-hour ambulatory blood pressure and ECG monitoring, and measurement of urinary catecholamines, norepinephrine (UNE) and epinephrine (UEP), during waking and sleep were undertaken in obstructive sleep apnea syndrome patients group (OSAS, n=29) and control group (Control, n=25). Results: 1) In OSAS and Control, UNE and UEP concentrations during sleep were significantly lower than during waking (P<0.01). In UNE concentrations during sleep, OSAS showed higher levels compare to Control (P<0.05). 2) In OSAS, there was a increasing tendency of the number of non-dipper of nocturnal blood pressure compare to Control (P=0.089). 3) In both group (n=54), mean systolic blood pressure during waking and sleep showed significant correlation with polysomnographic data including apnea index (AI), apnea-hypopnea index (AHI), arterial oxygen saturation nadir ($SaO_2$ nadir) and degree of oxygen desaturation (DOD). And UNE concentrations during sleep were correlated with AI, AHI, $SaO_2$ nadir, DOD and mean diastolic blood pressure during sleep. 4) In OSAS with AI>20 (n==14), there was a significant difference of heart rates before, during and after apneic events (P<0.01), and these changes of heart rates were correlated with the duration of apnea (P<0.01). The difference of heart rates between apneic and postapneic period (${\Delta}HR$) was significantly correlated with the difference of arterial oxygen saturation between before and after apneic event (${\Delta}SaO_2$) (r=0.223, P<0.001). 5) There was no significant difference in the incidence of cardiac arrhythmias between OSAS and Control In Control, the incidence of ventricular ectopy during sleep was significantly lower than during waking. But in OSAS, there was no difference between during waking and sleep. Conclusion : These results suggested that recurrent hypoxia and arousals from sleep in patients with obstructive sleep apnea syndrome may increase sympathetic nervous system activity, and recurrent hypoxia and increased sympathetic nervous system activity could contribute to the development of cardiovascular dysfunction including the changes of systemic blood pressure and cardiac function.

• Sleep Medicine and Psychophysiology
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• v.7 no.1
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• pp.27-33
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• 2000

Objectives: The sensitivity and accuracy of thermistor airflow signal has been debated. The purposes of this study were to compare apnea-hypopnea index(AHI) detected from a conventional thermistor signal and a nasal pressure transducer of airflow(NPT), to evaluate the value of NPT for the diagnosis of upper airway resistance syndrome(UARS), and to measure airway pressure fluctuations which produced respiratory arousals in UARS by naso-oro-esophageal manometer catheter. The subjects were 30 patients with obstructive sleep apnea syndrome [mild(540), 10), and 6 UARS patients. Airway resistance arousal in this study was defined as arousals which were not associated with apnea or hypopnea of thermistor signal, but showed significant decrease of nasal airflow pressure just before arousal and a prompt recovery of nasal airflow pressure after arousal. The airway pressure fluctuations were measured during 260 airway resistance arousals observed in 10 patients with OSAS, 2 with UARS. Results: Mean AHIs of patients with OSAS were 33.4 by thermistor and 48.4 by NPT. The AHIs of mild, moderate and severe OSAS groups were 10.2, 32.1, 65.4 respectively by thermistor and 23.1, 45.9, 76.4 by NPT. The mean AHI of patients with UARS was 3.2 by thermistor and 10.8 by NPT. The mean AHI of patients with nonspecific arousals was 2.7 by thermistor and 4.4 by NPT. The mean airway pressure changes during respiratory arousals of different groups were $8.7\;cmH_2O$ in mild OSAS, $11.4\;cmH_2O$ in moderate OSAS, $24.7\;cmH_2O$ in severe OSAS and $6.6\;cmH_2O$ in UARS. Conclusion: The nasal pressure transducer of airflow was more sensitive and accurate for assessing respiratory disturbances of patients with OSAS and was extremely helpful for the diagnosis of UARS without esophageal pressure monitoring. From the results, we would like to propose carefully the NPT diagnostic criteria for sleep disordered breathing as follows: NPT-AHI 5-15 $\rightarrow$ UARS, 15-35 $\rightarrow$ mild OSAS, 35-55 $\rightarrow$ moderate OSAS and >55 $\rightarrow$ severe OSAS.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.201-209
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• 2014

Obstructive sleep apnea syndrome(OSAS) is a respiratory disease caused by partial or complete obstruction of the upper airway during sleep. In this paper, we proposed the optical flow method to analyze the upper airway dynamic changes during respiration for children with OSAS and control subjects. We compared the absolute value of difference between inspiration and expiration for airway area analysis method and optical flow method for 5 children with OSAS and 6 control subjects. From the statistical analysis, airway area analysis method and optical flow method are statistically significant at the 0.1 (p value is 0.0977) and 0.01 (p value is 0.0011) significance level respectively. From this simulations, the optical flow method could provide more accurate information to diagnose the OSAS patients than the traditional airway area analysis method.

• Sleep Medicine and Psychophysiology
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• v.4 no.2
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• pp.129-139
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• 1997

The data collected to date indicate that sleep-related breathing disorders, including sleep-disordered breathing(sleep apnea) and underlying respiratory system diseases, are one of the important risk factors for cardiovascular dysfunction. Sleep-disordered breathing(sleep apnea) is now recognized as one of the leading causes of systemic hypertension, cardiac arrhythmias, coronary heart disease, pulmonary hypertension, right heart failure, and stroke. Sleep may exert a profound effect on breathing in patients with underlying respiratory system disease including bronchopumonary diseases, chest wall abnormalities, central alveolar hypoventilation syndromes or respiratory neuromuscular disorders. Chronic hypoxia and hypercapnia in these patients may accelerate the development of long term cardiovascular complications such as cardiac arrhythmias, pulmonary hypertension, and right heart failure(cor pulmonale). Several recent studies reported that sleep-related breathing disorders are associated with long-term cardiovascular morbidity and mortality. Careful assessment of respiratory and cardiovascular function in these patients is critical. Aggressive and highly effective treatment of sleep-related breathing disorders using tracheostomy, mechanical ventilation, nasal continuous positive airway pressure therapy(nCPAP), intercurrent oxygen therapy or other interventions can reduce the prevalence of cardiovascular dysfunction and the long-term mortality.

• Sleep Medicine and Psychophysiology
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• v.2 no.2
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• pp.156-164
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• 1995

Objectives : Patients with obstructive sleep apnea syndrome(OSAS) often complain of nocturnal enuresis. There are a few reports that OSAS patients have altered renal function, and there are some evidences that the increased release of atrial natriuretic peptide(ANP) may be involved in the pathogenesis of nocturnal urinary symptoms of OSAS patients. In this study, we measured plasma ANP concentrations during waking and sleep in OSAS patients and normal controls to investigate whether there were differences of ANP concentrations between OSAS patients and normal subjects. Methods : 27 patients with OSAS and 10 normal subjects were studied. All subjects underwent a full-night polysomnographic study. Venous blood samples were separately drawn during waking and sleep. Plasma ANP concentrations were measured using radioimmunoassay. Results : In OSAS patients, ANP concentrations during sleep($122.9\;{\pm}\;29.9pg/ml$) were significantly higher than ANP concentrations during waking($60.2\;{\pm}\;5.8pg/ml$)(p < 0.05). However, in normal subjects, there was no significant difference between ANP concentrations during waking($59.2\;{\pm}\;5.7pg/ml$) and sleep($69.6\;{\pm}\;3.0pg/ml$)(p > 0.05). There was no significant difference of ANP concentrations during waking between OSAS patients($60.2\;{\pm}\;5.8pg/ml$) and normal controls($59.2\;{\pm}\;5.7pg/ml$)(p > 0.05), and also there was no significant difference during sleep between OSAS patients($122.9\;{\pm}\;29.9pg/ml$) and normal subjects($69.6\;{\pm}\;3.0pg/ml$)(p > 0.05). Plasma ANP concentrations during sleep showed significant positive correlations with apnea index(r = 0.3846, p < 0.05) and respiratory disturbance index(r = 0.3939, p < 0.05) in OSAS patients. Conclusion : These data suggest that, in OSAS patients, plasma ANP concentrations during sleep are significantly higher than plasma ANP concentrations during waking, and there is a positive correlation between the plasma ANP concentration during sleep and the severity of sleep apnea.

• Tuberculosis and Respiratory Diseases
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• v.45 no.2
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• pp.404-415
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• 1998

Background: Sleep apnea syndrome, which occurs in 1~4 % of the adult population, frequently has different cardiovascular complications such as hypertension, ischemic heart disease, cardiac arrythmia as well as sleep-wake disorder such as excessive daytime hypersomnolence or insomnia. Mortality and vascular morbidity are reported to be significantly higher in sleep apnea syndrome patients than in normal population. According to the recent studies, autonomic dysfunction as well as hypoxemia, hypercapneic acidosis, and increased respiratory effort, may playa role in the high prevalence of cardiovascular complications in patients with sleep apnea syndrome. However the cause and mechanism of autonomic neuropathy in patients with sleep apnea syndrome are not well understood. We studied the existence of autonomic neuropathy in patients with sleep apnea syndrome and factors which influence the pathogenesis of autonomic neuropathy. Method: We used the cardiovascular autonomic neuropathy(CAN) test as a method for evaluation of autonomic neuropathy. The subjects of this study were 20 patients who diagnosed sleep apnea syndrome by polysomnography and 15 persons who were normal by polysomnography. Results: Body mass index and resting systolic blood pressure were higher in sleep apnea group than control group. Apnea index(Al), respiratory disturbance index(RDI) and snoring time percentage were significantly higher in sleep apnea group compared with control group. But there were no significant differences in saturation of oxygen and sleep efficiency in two groups. In the cardiac autonomic neuropathy test, the valsalva ratio was significantly low in sleep apnea group compared with control group but other tests had no differences between two groups. The CAN scores and corrected QT(QTc) interval were calculated significantly higher in sleep apnea group, but there were no significant correlations between CAN scores and QTc interval. There were no significant data of polysomnography to correlate to the CAN score. It meant that the autonomic neuropathy in patients with sleep apnea was affected by other multiple factors. Conclusion: The cardiovascular autonomic neuropathy test was a useful method for the evaluation of autonomic neuropathy in patients with sleep apnea syndrome and abnormalities of cardiovascular autonomic neuropathy were observed in patients with sleep apnea syndrome. However, we failed to define the factors that influence the pathogenesis of autonomic neuropathy of sleep apnea syndrome. This study warrants futher investigations in order to define the pathogenesis of autonomic neuropathy in patients with sleep apnea syndrome.

• Sleep Medicine and Psychophysiology
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• v.11 no.1
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• pp.50-54
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• 2004

The obstructive sleep apnea syndrome can occur due to various etiologies in children. In otherwise healthy children, adenotonsillar hypertrophy is the leading cause of childhood obstuctive sleep apnea. Obstructive sleep apnea caused by adenotonsillar hypertrophy can lead to a variety of symptoms and sequelae such as behavioral disturbance, enuresis, failure to thrive, developmental delay, cor pulmonale, and hypertension. So if obstructive sleep apnea is clinically suspected, proper treatment should be administered to the patient after diagnostic examinations. More than 80% improvement is seen in symptoms of obstructive sleep apnea caused by adenotonsillar hypertrophy in children after tonsillectomy and adenoidectomy. However, when it is impossible to treat the patient using surgical methods or residual symptoms remained after tonsillectomy and adenoidectomy, additional treatments such as weight control, sleep position change, and continuous positive airway pressure (CPAP), should be considered. This paper reports a case using weight control and Auto-PAP to control mild sleep apnea and snoring, which in long-term follow-up were not resolved after tonsillectomy and adenoidectomy for severe obstructive sleep apnea.

• Sleep Medicine and Psychophysiology
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• v.18 no.2
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• pp.76-81
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• 2011

Objectives: This study aims to analyze the association between the severity of sleep apnea, sleep and mood related scales, and activity during sleep in obstructive sleep apnea syndrome (OSAS) patients. Methods: 176 drug-free male patients confirmed as OSAS (average age=$43{\pm}11$ years) were selected through nocturnal polysomnography (NPSG). OSAS was diagnosed with apnea-hypopnea index (AHI) >5, mean AHI was $39.6{\pm}26.0$. Sleep related scales were Stanford Sleepiness Scale (SSS), Epworth Sleepiness Scale (ESS), Pittsburg Sleep Quality Index (PSQI) and Morningness-Eveningness Scale (MES). Mood related scales were Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), State-Trait Anxiety Inventory (STAI) I, II and Profile of Mood States (POMS). NPSG was performed overnight with both wrist actigraphy (WATG). Parameters produced from WATG were total activity score, mean activity score and fragmentation index. We analyzed the correlation between each scale, AHI scored from NPSG and activity score analyzed from WATG. Results: ESS showed significant positive correlation with PSQI, BDI, BAI and STAI I, II, respectively (p<0.01). SSS showed significant positive correlation with PSQI and BAI (p<0.05, p<0.01). BAI showed significant positive correlation with total activity score, mean activity score and fragmentation index (p<0.05, p<0.01, p<0.05).Total activity score showed significant positive correlation with ESS and BAI, respectively (p<0.05). Fragmentation index showed significant positive correlation with ESS, PSQI and BAI (p<0.05, p<0.01, p<0.05). AHI, indicator of sleep apnea is showed no significant correlation with each sleep and mood related scale. Conclusion: The degree of daytime sleepiness tends to be associated with night sleep satisfaction, depression and anxiety, and the activity during sleep rather than the severity of sleep apnea.

• Sleep Medicine and Psychophysiology
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• v.12 no.1
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• pp.68-71
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• 2005

We report a case of obstructive sleep apnea syndrome, which occurred primarily during the REM sleep stage. A 55-year-old female patient who complained of chronic insomnia on the initial visit turned out to have obstructive sleep apnea syndrome of a mild degree (respiratory disturbance index (RDI) of 13.8/hour, %time spent below 90% of SaO2=5.0%) on nocturnal polysomnography. Interestingly, apnea episodes and desaturations mainly occurred during REM sleep stage. And RDI and destaturations during REM sleep stage were found to be severe enough to classify as a severe degree of obstructive sleep apnea syndrome. These findings suggest that severe obstructive sleep apnea syndrome might be masked under the symptom of chronic insomnia and that apneas can be predominantly localized within REM sleep epochs. In terms of treatment, "REM sleep-dependent" apneas may call for different methods of treatment, especially REM sleep-specific pharmacological intervention.