• Sleep Medicine and Psychophysiology
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• v.17 no.1
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• pp.41-49
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• 2010

Unlike the case of adult obstructive sleep apnea syndrome (OSAS), there was no consistent finding on the changes of sleep architecture in childhood OSAS. Further understanding of the sleep electroencephalogram (EEG) should be needed. Non-linear analysis of EEG is particularly useful in giving us a new perspective and in understanding the brain system. The objective of the current study is to compare the sleep architecture and the scaling exponent (${\alpha}$) from detrended fluctuation analysis (DFA) on sleep EEG between OSAS and normal children. Fifteen normal children (8 boys/7 girls, 6.0${\pm}4.3$2.2 years old) and twelve OSAS children (10 boys/2 girls, 6.4${\pm}4.3$3.4 years old) were studied with polysomnography (PSG). Sleep-related variables and OSAS severity indices were obtained. Scaling exponent of DFA were calculated from the EEG channels (C3/A2, C4/A1, O1/A2, and O2/A1), and compared between normal and OSAS children. No difference in sleep architecture was found between OSAS and normal controls except stage 1 sleep (%) and REM sleep latency (min). Stage 1 sleep (%) was significantly higher and REM latency was longer in OSAS group (9.3${\pm}4.3$4.3%, 181.5${\pm}4.3$59.9 min) than in controls (5.6${\pm}4.3$2.8%, 133.5${\pm}4.3$42.0 min). Scaling exponent (${\alpha}$) showed that sleep EEG of OSAS children also followed the 'longrange temporal correlation' characteristics. Value of ${\alpha}$ increased as sleep stages increased from stage 1 to stage 4. Value of ${\alpha}$ from C3/A2, C4/A1, O1/A2, O2/A1 were significantly lower in OSAS than in control (1.36${\pm}4.3$0.05 vs. 1.41${\pm}4.3$0.04, 1.37${\pm}4.3$0.04 vs. 1.41${\pm}4.3$0.04, 1.37${\pm}4.3$0.05 vs. 1.41${\pm}4.3$0.05, and 1.36${\pm}4.3$0.07 vs. 1.41${\pm}4.3$0.05, p<0.05). Higher stage 1 sleep (%) in OSAS children was consistent finding with OSAS adults. Lower $'{\alpha}'$ in OSAS children suggests decrease of self-organized criticality or the decreased piling-up energy of brain system during sleep in OSAS children.

• 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.

• Tuberculosis and Respiratory Diseases
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• v.56 no.4
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• pp.364-373
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• 2004

Background : Obstructive sleep apnea is a contributory factor of hypertension, arrhythmia, ischemic heart disease and other cardiovascular diseases. However, the pathophysiology underlying this relationship is unclear. Recent reports have shown that the soluble intercellular adhesion molecule-1(sICAM-1) and vascular endothelial growth factor(VEGF) are involved in the initiation and progression of atherosclerosis, and some reports state that increased levels of these cytokines are found in patients with obstructive sleep apnea. In this study, the levels of sICAM-1 and VEGF were measured in patients with obstructive sleep apnea in order to determine if obstructive sleep apnea is involved in the pathophysiology of cardiovascular diseases. Methods : Thirty-seven patients were chosen amongst a population who visited the Sleep Disorders Clinic of St. Paul's Hospital in Seoul, Korea for a diagnosis of obstructive sleep apnea and who had subsequently undergone an overnight polysomnography at the clinic. The sera from these patients were retrieved after an overnight polysomnography session and the samples were kept at $-70^{\circ}C$. The cytokine levels were determined with ELISA and the relationships between the serum levels of sICAM-1 and VEGF along with polysomnography parameters were analyzed. Results : No statistically significant correlation was observed between the sICAM-1 levels and the apnea-hypopnea index(r=0.27, P>0.05). Positive correlations were found between the apnea-hypopnea index and serum VEGF levels (r=0.50, P<0.01), the apnea index and the serum sICAM-1 levels (r=0.31, P<0.01), and the apnea index and the serum VEGF levels (r=0.45, P<0.01). Conclusions : Obstructive apnea or hypopnea leads to an increase in the sICAM-1 and VEGF levels. Such an increase in the cytokine levels most likely leads to the higher incidence of cardiovascular diseases observed in patients with obstructive sleep apnea.

• Korean Journal of Clinical Laboratory Science
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• v.51 no.1
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• pp.119-123
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• 2019

Obstructive sleep apnea (OSA) is a sleep disorder with no breathing symptoms due to repetitive upper airway resistance. OSA is a disease that can have significant effects on the cerebral cardiovascular system. Active treatment is needed to prevent these complications. The use of continuous positive airway pressure (CPAP), the standard therapy of OSA, has comparative therapeutic effects. On the other hand, there is no comparison report of the polysomnography (PSG) results before and after CPAP therapy without using a mask. This paper reports a patient who was diagnosed as OSA and used CPAP every night for more than 2 years. The patient showed a decrease in the apnea-hypopnea index from 64.7/h to 12.9/h. In addition, other sleep-related indicators improved significantly. The daily use of CPAP as a treatment for OSA for more than 2 years may improve the PSG results. Constant follow up of PSG will be needed to adjust the appropriate CPAP pressure to patients because there might be a change in the Apnea-Hypopnea Index and other sleep-related indicators for constant CPAP users for at least 2 years.

• Tuberculosis and Respiratory Diseases
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• v.49 no.6
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• pp.715-723
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• 2000

Background : Obstructive sleep apnea syndrome (OSAS) affects systemic blood pressure and cardiac function. The development of cardiovascular dysfunction including the changes of systemic blood pressure and cardiac rhythm, suggests that recurrent hypoxia and arousals from sleep may increase a sympathetic nervous system activity. Continuous positive airway pressure (CPAP) therapy has been found to be an effective treatment of OSAS. However, only a few studies have investigated the cardiovascular and sympathetic effects of CPAP therapy. We evaluated influences of nasal CPAP therapy on the cardiovascular system and the sympathetic activity in patients with OSAS. Methods : Thirteen patients with OSAS underwent CPAP therapy and were monitored using polysomnography, blood pressure, heart rate, presence of arrhythmia and the concentration of plasma catecholamines, before and with CPAP therapy. Results: The apnea-hypopnea index (AHI) was significant1y decreased (p<0.01) and the lowest arterial oxygen saturation level was elevated significantly after applying CPAP (p<0.01). Systolic blood pressure tended to decrease after CPAP but without statistical significance. Heart rates during sleep were not significantly different after CPAP. However, the frequency and number of types of arrhythmia decreased and sinus bradytachyarrhythmia disappeared after CPAP. Although there was no significant difference in the level of plasma epinephrine concentration, plasma norepinephrine concentration significantly decreased after CPAP (p<0.05). Conclusion : CPAP therapy decreased the apnea-hypopnea index, hypoxic episodes and plasma norepinephrine concentration. In addition, it decreased the incidence of arrhythmia and tended to decrease the systemic blood pressure. These results indicate that CPAP may play an important role in the prevention of cardiovascular complications in patients with OSAS.

• Tuberculosis and Respiratory Diseases
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• v.47 no.2
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• pp.218-230
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• 1999

Background: Craniofacial anatomic abnormalities related to structural narrowing of the upper airway have been reported in patients with obstructive sleep apnea syndrome. In this study, we evaluated the craniofacial anatomic characteristics of Korean patients with obstructive sleep apnea syndrome, and the role of cephalometric analysis in the prediction of abnormal breathing during sleep. Methods: Thirty-nine patients with obstructive sleep apnea syndrome(OSAS), 39 simple snorers(simple snorers) and 20 controls(control) had cephalometric analysis using the technique of Riley et al, and underwent standardized polysomnographic recordings. Different variables, including sex, body mass index, cephalometric and polysomnographic data, were statistically analyzed. Results: Pm-UPW and V-LPW distances were significantly shorter in OSAS when compared with simple snorers or control. PAS in simple snorers was shorter than in control. ANS-Gn distance in OSAS was significantly longer than in control. PNS-P distance in OSAS or simple snorers was significantly longer than in control. MP-H distance in OSAS was significantly longer than in simple snorers or control and MP-H distance in simple snorers was also longer than in control. NL/Pm-P angle in OSAS was lesser than in control. MP-H distance in OSAS or in the combined groups of OSAS and simple snorers was significantly correlated with apneahypopnea index(AHI). PNS-P distance in the combined groups of OSAS and simple snorers was correlated with AHI. In male of all subjects, body mass index was significantly correlated with PNS-P or MP-H distance. Conclusion: Cephalometric analysis can be useful tool in determining the craniofacial anatomic abnormalities in patients with obstructive sleep apnea syndrome. Cephalometric parameters, especially MP-H distance, can be useful for predicting frequency of narrowing or obstruction of upper airway during sleep.

• Sleep Medicine and Psychophysiology
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• v.18 no.2
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• pp.87-94
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• 2011

Objective: OSAS (obstructive sleep apnea syndrome) is a common disorder and its consequences are often serious. It is important to detect the disorder early in the course for proper treatment. This study is to grasp the snoring clinic visitors' knowledge level of OSAS. Method: One hundred and seventy-nine visitors at the of snoring clinic of Seoul National University Hospital were surveyed by questionnaire about reasons of visit and knowledge of treatment methods of snoring and OSAS, diagnostic method, OSAS-related symptoms, and complications. Results: Most of the respondents (89.4%) "have already heard about OSAS" and the major sources of information was the mass media (58.1%) such as television and radio. More than half (60.3%) were aware that snoring is closely related to OSAS. More than half (59.8%) recognized that a nocturnal polysomnograpy was necessary for proper diagnosis. Two thirds (67%) of the respondents noted surgery as a treatment for snoring. More than half (55.9%) answered that they would follow the doctor's advice on the treatment choice. Only 12.3% of respondents "have heard about nCPAP". No one chose nCPAP (nasal continuous positive airway pressure) as a treatment for either snoring or OSAS. About one third (34.6%) of the respondents were aware that OSAS is related to hypertension. Only 12.8% noted that OSAS is related to diabetes mellitus. Conclusion: Visitors at the snoring clinic were found to have substantially limited knowledge of health risks and proper treatments of OSAS. We suggest that it is crucially important to educate patients and offer easy-to-understand information on snoring and OSAS. We predict that provision of educaiton and information to patients and general public will faciliate the diagnosis and treatment of snoring and OSAS and reduce the related disorders such as hypertension, stroke, and diabetes mellitus.

• Tuberculosis and Respiratory Diseases
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• v.47 no.6
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• pp.824-835
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• 1999

Background: Sleep-related breathing disorders are commonly found in patients with chronic renal failure and particularly, sleep apnea may have an influence on the long-term mortality rates in these patients. Maintenance hemodialysis is the mainstay of medical measures for correcting the metabolic derangements of chronic renal failure but it is uncertain whether it may alleviate sleep disorders including sleep apnea. Methods: Forty seven patients on maintenance hemodialysis were surveyed with the sleep questionnaire about their clinical symptoms related to sleep disorders. Among them, 15 patients underwent the polysomnography and their blood levels of urea nitrogen, creatinine, electrolytes and the arterial blood gases in the nights before and following hemodialysis were measured. Results: Forty(85.1%) of the 47 patients complained of the symptoms associated with sleep-wake cycle disturbances, 55.3% experienced snoring and 27.7% reported witnessed apneas. The duration of REM sleep increased significantly in the nights after hemodialysis compared to the nights without hemodialysis(p<0.05) and the percentage of total sleep time comprising NREM sleep decreased significantly in the nights following hemodialysis compared to the nights before hemodialysis(p<0.05). The percentage of total sleep time consisting of the stage 1 and 2 NREM sleep showed the trend for a decrease in the nights after hemodialysis(p=0.051), while the percentage of total sleep time comprising the stage 3 and 4 NREM sleep did not change between nights. The obstructive sleep apnea was more predominant type than the central one in both nights and there were no differences in the apnea index and the apnea-hypopnea index between the nights. The decrease in the blood level of urea nitrogen, creatinine, potassium and phosphorus was observed after hemodialysis(p<0.05), but the differences of parameters measured during polysomnography between the nights did not correlate with the changes of biochemical factors obtained on the two nights. Arterial blood gas analysis showed that pH was significantly greater in the nights after hemodialysis than in the nights before hemodialysis(p<0.05), but there were no correlations between the parameters examined during polysomnography and the parameters of arterial blood gas analysis(p<0.05). Conclusion: These results suggest that chronic renal failure is an important systemic disorder which is strongly associated with sleep disorders. Maintenance hemodialysis, although it is a widely accepted measure to treat chronic renal failure, did not significantly modulate the sleep architecture and the severity of sleep apnea. Thus, taking the patients with chronic renal failure into account, it is advisable to try not only to find a substantial way for correcting metabolic derangements but also to consider the institution of more effective treatments for sleep disorders.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.3
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• pp.255-261
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• 2016

The purpose of this study was to investigate the relationship between excessive daytime sleepiness (EDS) and blood pressure (BP) in patients with obstructive sleep apnea-hypopnea (OSAH). Patients were classified into four groups based on their severity of polysomnographic data: the snoring group (n=108)-characterized by Apnea-Hypopnea Index (AHI<5); the mild OSA group (n=186)-AHI $5{\leq}AHI$<15; the moderate OSA group (n=179)- AHI $15{\leq}AHI$<30; and the severe OSA group (n=233)-$AHI{\geq}30$. On the same night of polysomnography (PSG), BP levels were measured before sleeping (bedtime BP) and immediately after waking up on the following morning (morning BP). EDS was recognized as ESS (epworth sleepiness scale)${\geq}9$. The differences and correlations between BP and PSG parameters in the EDS and non-EDS groups of OSAH patients were analyzed. MAP was positively correlated with BMI, AHI, and total arousal (r=0.099, r=0.142, r=0.135, p<0.01, p<0.01, p<0.01), while negatively correlated with mean $SaO_2$ (r=-0.258, p<0.01). The EDS group had overall younger population ($47.2{\pm}11.3$ vs $50.3{\pm}11.4$, p=0.023), higher DBP (both bedtime and morning, $83.1{\pm}9.7$ vs $81.4{\pm}8.8$ and $86.4{\pm}9.2$ vs $83.6{\pm}9.7$)(p=0.031, p=0.047), and higher SBP (both bedtime and morning, $126.7{\pm}11.2$ vs $123.4{\pm}12.4$, $128.9{\pm}12.4$ vs $125.3{\pm}12.9$)(p=0.021, p=0.021) than compared with the non-EDS group. In hypertensive OSAH patients, patients with EDS were also younger and had higher total arousal number, as well as higher morning and bedtime DBP and SBP than compared with the non-EDS group (p<0.005, p=0.008, p<0.001 and p<0.001). EDS in OSAHS patients is a special phenotype characterized by younger age, higher DBP, more severe desaturation, and hypertension.

• Tuberculosis and Respiratory Diseases
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• v.40 no.5
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• pp.501-508
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• 1993

Background: Sleep apnea syndrome is a common disorder which is estimated to affect about 1~4% of adult male population. And if untreated, sleep apnea can cause significant sequelae, such as hypertension, nocturnal cardiac arrhythmia, daytime hypersomnolence, and cognitive impairment. Various kinds of treatment for obstructive sleep apnea (OSA) have been developed. Among them nasal CPAP, first introduced by Sullivan et al in 1981, has received widespread interest and acclaim as a treatment of OSA, and is currently recommended as first-line treatment for OSA. We evaluated the effect of nasal CPAP in OSA and the side effects of nasal CPAP hindering patients from using nasal CPAP. Methods: We performed sleep studies in 20 OSA patients at 2 consecutive nights; baseline night at first day and CPAP night at second day. We compared apnea index, lowest oxygen concentration during apnea, maximal apnea time, and total apnea duration per total sleep time before and after CPAP. We also evaluated the side effects of CPAP with inquiry to the patients. Results: 1) Apnea index was significantly decreased after CPAP in 17 out of 20 OSA patients (85%) and increased in 3 patients (15%). 2) Average apnea index was significantly decreased after CPAP ($34.1{\pm}18.9/h{\rightarrow}15.4{\pm}10.3/h$, p<0.01). 3) Total apnea duration per total sleep time was also significantly decreased after CPAP ($28.5{\pm}16.0%{\rightarrow}11.9{\pm}9.3%$, p<0.05). 4) The lowest oxygen satuation and maximal apnea time were not significantly changed after CPAP. 5) The most frequent side effect of nasal CPAP was mask discomfort (80%), and the next was drying of nasal passages (65%). Conclusion: Nasal CPAP is an effective treatment for OSA. Futher studies should be concentrated on long term follow up of nasal CPAP for its therapeutic effects and the study of methods to enhance patients' compliance.