• Journal of Oral Medicine and Pain
• /
• v.41 no.4
• /
• pp.180-187
• /
• 2016

Purpose: The aims of this study were to evaluate the differences of clinical and polysomnographic features between rapid eye movement (REM)-related obstructive sleep apnea (OSA) and not-REM-related OSA, and to suggest the pathogenesis according to the REM dependency of OSA. Methods: One hundred ninety consecutive patients diagnosed with OSA were evaluated clinical features and performed full night polysomnography. The patients were divided into REM-related (REM apnea-hypopnea index [AHI] at least two times higher than their non-REM AHI) and not-REM-related (a REM AHI less than two times higher than their non-REM AHI) OSA groups and evaluated the differences in age, body mass index (BMI), neck circumference, Ep-worth Sleepiness Scale score, and parameters of polysomnography. Results: REM-related patients were younger and showed higher sleep efficacy, low percentage of light sleep stage (stage 1 sleep), and low rate of positional OSA. Age was significantly associated with REM dependency of OSA and REM AHI were significant correlated with BMI, neck circumference, percentage of sleep in supine position, and percentage time of snoring. Conclusions: Our results showed that REM-related OSA patients showed less severe polysomnographic parameters than not-REM-related patients. However, significant risk factors were differed depending on the REM dependency and OSA severity, and the clinical features correlated with REM AHI and non-REM AHI were also showed differently. We suggest that the occurrence of OSA according to the REM dependency can be based on different mechanisms.

• Sleep Medicine and Psychophysiology
• /
• v.15 no.1
• /
• pp.25-32
• /
• 2008

Objectives: A few studies have compared REM sleep-dependent obstructive sleep apnea syndrome (REM-OSA) with sleep stage non-dependent apnea syndrome (SND-OSA). Despite that REM-OSA might be more common in women than men, no studies have examined the probable characteristics of women patients with obstructive sleep apnea syndrome (OSAS). This study aimed at finding out the characteristics of REM-OSA in women by comparing it with SND-OSA. Methods: Fifty-three subjects diagnosed as OSAS (AHI>5 ; AHI : apnea-hypopnea index) with nocturnal polysomnography at the Center for Sleep and Chronobiology of the Seoul National University Hospital between October 2004 and February 2006 were studied. Of them, 44 subjects with OSAS severity of mild (52 and AHI-NR<15 (AHI-R : AHI during REM sleep, AHI-NR : AHI during non-REM sleep). We compared REM-OSA group with SND-OSA as well as the criteria-determined REM-OSA cases with the visually-determined ones. Results: Among 44 subjects, 28 persons (63.6%) turned out to have REM-OSA by our criteria and 24 persons (54.5%) by visual determination. Statistically significant differences (p<0.05) were found between REM-OSA and SND-OSA groups in AHI, hypopnea index, total sleep time, total wake time, sleep efficiency index, percents of stage 1, 2 and REM sleep, and REM latency. Percent of stage REM sleep (%REM) turned out to have influence on AHI ratio (AHI-R/AHI-NR) (B=0.537, p=0.002). REM-OSA was likely to be diagnosed in milder severity of OSAS (${\chi}^2=13.117$, p<0.001) and those with higher %REM (${\chi}^2=11.325$, p=0.001). There was no significant difference between the criteria-determined and the visually-determined cases of REM-OSA. Conclusion: We suggest that REM-OSA and SND-OSA patients be differentiated in terms of pathophysiology and treatment strategies. Visual determination of REM-OSA might be useful as the screening procedure of REM-OSA. Further studies on women with OSAS and REM-OSA need to be done.

• Journal of Oral Medicine and Pain
• /
• v.41 no.1
• /
• pp.7-15
• /
• 2016

Purpose: Mandibular advancement device (MAD) is widely recognized as an important treatment option for obstructive sleep apnea (OSA) and is readily accepted than any other treatment options owing to its simplicity and ambulatory nature. At this time, there are a multitude of MAD designs and their efficacies may be influenced by adjustment and retention mechanism. The MAD with the anterior connector (anteriorly adjustable mandibular advancement device, AAMAD) was newly developed in the Department of Oral Medicine, Dankook University Dental Hospital (Cheonan, Korea) and was prescribed for the OSA patients including snoring patients. Thus, this study was aimed to objectively investigate the effectiveness of the AAMAD on the OSA patients using the self-applied portable device (ApneaLink), and evaluate the treatment outcomes among patients with various severity of OSA level. Methods: Results of the treatment of fourteen patients (13 male, 1 female) with the AAMAD were retrospectively analyzed. Each patient underwent home sleep test before treatment and were divided into two groups, i.e., those with mild (apnea-hypopnea index [AHI] ${\geq}5$ and <15) to moderate OSA (AHI ${\geq}15$ and <30) and severe OSA (AHI ${\geq}30$). After treatment, home sleep test was conducted again and treatment outcomes were compared between mild to moderate and severe OSA patients. Results: Of all patients, 78.6% showed more than 50% AHI reduction. We found a significant reduction (85.3%) of AHI in the severe OSA patients. Patients with mild to moderate OSA showed the reduced AHI (56.1%). Conclusions: We concluded that AAMAD is an effective oral appliance for the majority of OSA patients.

• Journal of Biomedical Engineering Research
• /
• v.35 no.4
• /
• pp.95-98
• /
• 2014

The baroreflex is one kind of homeostatic mechanisms to regulate acute blood pressure (BP) changes by controlling heartbeat interval (HBI). To quantify the effect of baroreflex, we suggested a new approach of analyzing Granger causality between systolic BP (SBP) and HBI. The index defined as baroreflex effectiveness (BRE) was generated by the hypothesis that more effectual baroreflex would be related to more effective Granger causal influence of SBP on HBI. Six obstructive sleep apnea (OSA) patients (apnea-hypopnea index, AHI ${\geq}5$ events/hr) and six normal subjects participated in the study. Their SBP and HBI during nocturnal sleep were obtained from a non-invasive continuous BP measurement device. While the BRE ($mean{\pm}SD$) of normal subjects was $47.0{\pm}4.0%$, OSA patients exhibited the BRE of $34.0{\pm}3.8%$. The impaired baroreflex function of OSA patients can be explained by the physiological mechanism associated with recurrent hypoxic episodes during sleep. Thus, the significantly lower BRE in OSA patients verified the availability of Granger causality analysis to evaluate baroreflex during sleep. Furthermore, the range of BRE obtained from normal subjects was not overlapped with that obtained from OSA patients. It suggests the potential of BRE as a new helpful tool for diagnosing OSA.

• Journal of Sleep Medicine
• /
• v.15 no.2
• /
• pp.48-54
• /
• 2018

Objectives: The aim of this study was to develop a predicting model for the optimal continuous positive airway pressure (CPAP) for obstructive sleep apnea (OSA) patient with obesity by using a machine learning. Methods: We retrospectively investigated the medical records of 162 OSA patients who had obesity [body mass index (BMI) ≥ 25] and undertaken successful CPAP titration study. We divided the data to a training set (90%) and a test set (10%), randomly. We made a random forest model and a least absolute shrinkage and selection operator (lasso) regression model to predict the optimal pressure by using the training set, and then applied our models and previous reported equations to the test set. To compare the fitness of each models, we used a correlation coefficient (CC) and a mean absolute error (MAE). Results: The random forest model showed the best performance {CC 0.78 [95% confidence interval (CI) 0.43-0.93], MAE 1.20}. The lasso regression model also showed the improved result [CC 0.78 (95% CI 0.42-0.93), MAE 1.26] compared to the Hoffstein equation [CC 0.68 (95% CI 0.23-0.89), MAE 1.34] and the Choi's equation [CC 0.72 (95% CI 0.30-0.90), MAE 1.40]. Conclusions: Our random forest model and lasso model ($26.213+0.084{\times}BMI+0.004{\times}$apnea-hypopnea index+$0.004{\times}oxygen$ desaturation index-$0.215{\times}mean$ oxygen saturation) showed the improved performance compared to the previous reported equations. The further study for other subgroup or phenotype of OSA is required.

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
• /
• v.61 no.11
• /
• pp.593-599
• /
• 2018

Background and Objectives Respiratory scoring guidelines for children and adults have been used for evaluating adolescents both in the 2007 and 2012 American Academy of Sleep Medicine (AASM) scoring manuals. We compared the scoring methods of polysomnography used in these scoring manuals, where pediatric and adult scoring rules were adopted for the diagnosis of sleep apnea in adolescents. Subjects and Method 106 Korean subjects aged between 13 and 18 years were enrolled. All subjects underwent overnight polysomnography in a sleep laboratory. Data were scored according to both pediatric and adult guidelines in the 2007 and 2012 AASM scoring manuals. Results Both pediatric and adult apnea hypopnea index (AHI) using the 2012 method were significantly higher than those using the 2007 method. The difference in AHI compared between pediatric and adult scores with the 2012 AASM scoring system was markedly decreased from that with the 2007 method. There was a significant discordance in sleep apnea diagnosis between pediatric and adult scoring rules in the 2012 method. Conclusion Both pediatric and adult rules were used for the diagnosis of adolescent sleep apnea in the 2012 method. However, there was significant discordance in the diagnosis between pediatric and adult scoring guidelines in the 2012 AASM manual, probably due to different cut-off values of AHI for the diagnosis of sleep apnea in pediatric (${\geq}1$) and adult (${\geq}5$) patients. Further studies are needed to determine a more reasonable cut-off value for the diagnosis of sleep apnea in adolescents.

• Sleep Medicine and Psychophysiology
• /
• v.18 no.2
• /
• pp.82-86
• /
• 2011

Objectives: The Berlin Questionnaire (BQ) has been used to help identify patients at high risk of having sleep apnea in primary care. But it has not been validated in a sleep clinic for Korean patients. The aim of this study is to evaluate the usefulness of the BQ as a screening tool for obstructive sleep apnea (OSA) for Korean patients in a sleep clinic. Methods: The BQ was prospectively applied to 121 subjects with OSA suspicion who visited to our sleep clinic. All subjects performed overnight polysomnography. OSA was defined as an apnea-hypopnea index (AHI) ${\geq}5$. We investigated the sensitivity, specificity, positive and negative predictive values of the BQ according to severity by AHI. Results: In 121 subjects, 73.6% were males, with a mean age of $48.8{\pm}13.0$ years. Twenty-five (20.6%) patients did not have OSA (AHI<5), 30 (25%) patients had mild OSA ($AHI{\geq}5$ and <15), 26 (21.4%) had moderate ($AHI{\geq}15$ and <30), and 40 (33%) had severe OSA ($AHI{\geq}30$). The BQ identified 69.4% of the patients as being at high risk for having OSA. The sensitivity and specificity of the BQ were 71.9% and 40%, for $AHI{\geq}5$, 75.8% and 38.2% for $AHI{\geq}15$, 77.5% and 34.6% for $AHI{\geq}30$, respectively. The positive and negative predictive values of the BQ were 82.1% and 27.0% for $AHI{\geq}5$, respectively. Positive and negative likelihood ratios were 1.2 and 0.7, and the overall diagnostic accuracy of the BQ was 65.3%, using an AHI cut-off of 5. Conclusion: Due to modest sensitivity and low specificity, the BQ does not seem to be an appropriate tool for identifying patients with obstructive sleep apnea in a sleep clinic population.

• Healthcare Informatics Research
• /
• v.24 no.4
• /
• pp.346-358
• /
• 2018

Objectives: The association between obstructive sleep apnea (OSA) and mortality or serious cardiovascular events over a long period of time is not clearly understood. The aim of this observational study was to estimate the clinical effectiveness of continuous positive airway pressure (CPAP) treatment on an outcome variable combining mortality, acute myocardial infarction (AMI), and cerebrovascular insult (CVI) during a follow-up period of 15.5 years ($186{\pm}58$ months). Methods: The data set consisted of 978 patients with an apnea-hypopnea index (AHI) ${\geq}5.0$. One-third had used CPAP treatment. For the first time, a data-driven causal Bayesian network (DDBN) and a hypothesis-driven causal Bayesian network (HDBN) were used to investigate the effectiveness of CPAP. Results: In the DDBN, coronary heart disease (CHD), congestive heart failure (CHF), and diuretic use were directly associated with the outcome variable. Sleep apnea parameters and CPAP treatment had no direct association with the outcome variable. In the HDBN, CPAP treatment showed an average improvement of 5.3 percentage points in the outcome. The greatest improvement was seen in patients aged ${\leq}55$ years. The effect of CPAP treatment was weaker in older patients (>55 years) and in patients with CHD. In CHF patients, CPAP treatment was associated with an increased risk of mortality, AMI, or CVI. Conclusions: The effectiveness of CPAP is modest in younger patients. Long-term effectiveness is limited in older patients and in patients with heart disease (CHD or CHF).

• Journal of Rhinology
• /
• v.25 no.2
• /
• pp.80-85
• /
• 2018

Background and Objectives: Obesity is one of the most important risk factors for obstructive sleep apnea (OSA). There is limited evidence regarding the obesity-related anthropometric characteristics of Korean patients. Materials and Method: Medical records of 984 patients referred to 3 tertiary referral hospitals for habitual snoring or sleep apnea were analyzed. We defined OSA as apnea-hypopnea index (AHI) ${\geq}5$ and analyzed data to determine the anthropometric characteristics of patients with OSA such as neck circumference (NC), waist circumference (WC), hip circumference (HC), and waist to hip ratio (WHR). Results: A total of 952 patients (719 men) were included in the analysis. The main findings were: 1) BMI, WC, NC, HC, and WHR were greater among patients with OSA than among controls (AHI <5); 2) for both sexes, the proportion of patients with an OSA diagnosis increased with age; it increased steeply for women aged >50 years; 3) WC and WHR were most strongly correlated with AHI for men and women, respectively. Conclusion: OSA is associated with anthropometric characteristics, although different patterns were observed between men and women. OSA was more strongly associated with NC or WC among men and with WHR among women.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.35 no.3
• /
• pp.161-166
• /
• 2013

Purpose: This study was intended to perform a cephalometric comparison between the patients with and without obstructive sleep apnea (OSA). The factors influencing the OSA in the lateral cephalogram were also investigated. Methods: Fifty patients who had visited the Sleep Disorder Clinic at the Ajou University Hospital and evaluated with the polysomnograph (PSG) and cephalogram, were included in the study. The patients had the apnea-hypopnea episode over 5 times per hour (apnea-hypopnea index $[AHI]{\geq}5$) were diagnosed as OSA after the overnight PSG. To evaluate the hard and soft tissue profiles, the cephalometric radiograms were taken at the maximal intercuspation. The correlation between the patient's age, height, weight, body mass index (BMI) and AHI was inspected in the OSA and control group. The difference between the OSA and control group was evaluated (Mann-Whitney U Test). The cephalometric influencing factors to OSA were analyzed (Pearson's correlation coefficient) statistically using SPSS statistics. Results: The OSA Group had a significantly higher BMI than the control group. The mean lower facial height (ANS-Me) was longer in the OSA group; however, statistically significant difference was not detected in the anteroposterior craniofacial measurements. The distance between mandibular plane and hyoid bone of the OSA group was significantly longer than that of the control group. The hyoid position (MP-Hyoid) had a positive correlation between AHI (P<0.001). However, the measurements of oropharyngeal airway were not different between the two groups. The hypothesis, that the antero-posteriorly narrow oropharyngeal airway may aggravate the airway resistance and give rise to a higher AHI, was rejected in the study. Conclusion: We suggest that the lateral cephalogram may be utilized as a useful method to evaluate OSA. The patients with a lower hyoid position can be expected to have higher risks of OSA. However, a comprehensive intraoral inspection, including the soft palate and tonsilar hypertrophy, is emphasized, as the lateral cepahlogram cannot visualize the oropharyngeal status completely.