• Proceedings of the Korean Society of Computer Information Conference
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• 2014.01a
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• pp.393-394
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• 2014

폐쇄성 수면 무호흡증으로 인한 수면 중 잦은 각성은 수면의 질을 떨어뜨릴 뿐 아니라 졸음, 피로, 집중력 저하와 같은 주간 증상을 유발하게 되어 삶의 질을 떨어뜨리고 고혈압이나 부정맥 등과 같은 심각한 심폐질환 을 유발할 수 있다. 그러나 코골이와 달리 수면 무호흡증은 본인이나 타인에 의한 정확한 관측이나 진단이 어려워 전문병원에 입원하여 수면다원검사를 통하여 진단해야 하는 번거로움이 있다. 본 논문에서는 정밀하고 응답속도가 빠른 온습도 센서를 이용하여 호흡주기를 측정함으로서 폐쇄성 수면 무호흡증을 진단하고 경보를 발생하는 휴대형 수면 무호흡 측정기의 설계 및 구현 기법을 제안하였다.

• 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.

• Sleep Medicine and Psychophysiology
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• v.9 no.1
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• pp.34-40
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• 2002

Objectives: The gold standard for diagnosing obstructive sleep apnea syndrome (OSAS) is nocturnal polysomnography (NPSG). This is rather expensive and somewhat inconvenient, however, and consequently simpler and cheaper alternatives to NPSG have been proposed. Oximetry is appealing because of its widespread availability and ease of application. In this study, we have evaluated whether oximetry alone can be used to diagnose or screen OSAS. The diagnostic performance of an analysis algorithm using arterial oxygen saturation ($SaO_2$) base on 'dip index', mean of $SaO_2$, and CT90 (the percentage of time spent at $SaO_2$<90%) was compared with that of NPSG. Methods: Fifty-six patients referred for NPSG to the Division of Sleep Studies at Seoul National University Hospital, were randomly selected. For each patient, NPSG with oximetry was carried out. We obtained three variables from the oximetry data such as the dip index most linearly correlated with respiratory disturbance index (RDI) from NPSG, mean $SaO_2$, and CT90 with diagnosis from NPSG. In each case, sensitivity, specificity and positive and negative predictive values of oximetry data were calculated. Results: Thirty-nine patients out of fifty-six patients were diagnosed as OSAS with NPSG. Mean RDI was 17.5, mean $SaO_2$ was 94.9%, and mean CT90 was 5.1%. The dip index [4%-4sec] was most linearly correlated with RDI (r=0.861). With dip index [4%-4sec]${\geq}2$ as diagnostic criteria, we obtained sensitivity of 0.95, specificity of 0.71, positive predictive value of 0.88, and negative predictive value of 0.86. Using mean $SaO_2{\leq}97%$, we obtained sensitivity of 0.95, specificity of 0.41, positive predictive value of 0.79, and negative predictive value of 0.78. Using $CT90{\geq}5%$, we obtained sensitivity of 0.28, specificity of 1.00, positive predictive value of 1.00, and negative predictive value of 0.38. Conclusions: The dip index [4%-4sec] and mean $SaO_2{\leq}97%$ obtained from nocturnal oximetry data are helpful in diagnosis of OSAS. CT90${\leq}$5% can be also used in excluding OSAS.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.315-318
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• 2002

본 논문은 도플러 레이다의 원리를 이용하여 인체 호흡수 측정기술에 관하여 기술하였다. 주파수 1.59㎓ 대역의 전자파를 이용한 인체 호흡수 측정의 역사적 배경과 함께 자세한 측정원리 및 방법을 제시하였다. 인체의 흉곽 운동에 의해 반사된 신호의 도플러 주파수 차이만큼의 변이량을 오실로스코프 상에서 단위시간 당 호흡수를 나타내었다. 헤테로다인 방식의 시스템으로 측정하였으며, 폴디드 슬롯 안테나를 자체 제작하여 사용하였다. 이와 같은 인체 호흡수 측정기는 생명체 탐지 장치나 수면 무호흡증 측정기로 사용될 수 있으며 동작 감지 레벨을 높이면 그 적용 범위는 더욱더 늘어날 것으로 예상된다.

• Sleep Medicine and Psychophysiology
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• v.9 no.1
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• pp.24-33
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• 2002

Objectives: Nasal continuous positive airway pressure (CPAP) corrected elevated blood pressure (BP) in some studies of obstructive sleep apnea syndrome (OSAS) but not in others. Such inconsistent results in previous studies might be due to differences in factors influencing the effects of CPAP on BP. The factors referred to include BP monitoring techniques, the characteristics of subjects, and method of CPAP application. Therefore, we evaluated the effects of one night CPAP application on BP and heart rate (HR) reactivity using non-invasive beat-to-beat BP measurement in normotensive and hypertensive subjects with OSAS. Methods: Finger arterial BP and oxygen saturation monitoring with nocturnal polysomnography were performed on 10 OSAS patients (mean age $52.2{\pm}12.4\;years$; 9 males, 1 female; respiratory disturbance index (RDI)>5) for one baseline night and another CPAP night. Beat-to-beat measurement of BP and HR was done with finger arterial BP monitor ($Finapres^{(R)}$) and mean arterial oxygen saturation ($SaO_2$) was also measured at 2-second intervals for both nights. We compared the mean values of cardiovascular and respiratory variables between baseline and CPAP nights using Wilcoxon signed ranks test. Delta ($\Delta$) BP, defined as the subtracted value of CPAP night BP from baseline night BP, was correlated with age, body mass index (BMI), baseline night values of BP, BP variability, HR, HR variability, mean $SaO_2$ and respiratory disturbance index (RDI), and CPAP night values of TWT% (total wake time%) and CPAP pressure, using Spearman's correlation. Results: 1) Although increase of mean $SaO_2$ (p<.01) and decrease of RDI (p<.01) were observed on the CPAP night, there were no significant differences in other variables between two nights. 2) However, delta BP tended to increase or decease depending on BP values of the baseline night and age. Delta systolic BP and baseline systolic BP showed a significant positive correlation (p<.01), but delta diastolic BP and baseline diastolic BP did not show a significant correlation except for a positive correlation in wake stage (p<.01). Delta diastolic BP and age showed a significant negative correlation (p<.05) during all stages except for REM stage, but delta systolic BP and age did not. 3) Delta systolic and diastolic BPs did not significantly correlate with other factors, such as BMI, baseline night values of BP variability, HR, HR variability, mean SaO2 and RDI, and CPAP night values of TWT% and CPAP pressure, except for a positive correlation of delta diastolic pressure and TWT% of CPAP night (p<.01). Conclusions: We observed that systolic BP and diastolic BP tended to decrease, increase or remain still in accordance with the systolic BP level of baseline night and aging. We suggest that BP reactivity by CPAP be dealt with as a complex phenomenon rather than a simple undifferentiated BP decrease.