Detection of sleep disordered breathing severity using acoustic biomarker and machine learning techniques

Purpose Breathing sounds during sleep are altered and characterized by various acoustic specificities in patients with sleep disordered breathing (SDB). This study aimed to identify acoustic biomarkers indicative of the severity of SDB by analyzing the breathing sounds collected from a large number of subjects during entire overnight sleep. Methods The participants were patients who presented at a sleep center with snoring or cessation of breathing during sleep. They were subjected to full-night polysomnography (PSG) during which the breathing sound was recorded using a microphone. Then, audio features were extracted and a group of features differing significantly between different SDB severity groups was selected as a potential acoustic biomarker. To assess the validity of the acoustic biomarker, classification tasks were performed using several machine learning techniques. Based on the apnea–hypopnea index of the subjects, four-group classification and binary classification were performed. Results Using tenfold cross validation, we achieved an accuracy of 88.3% in the four-group classification and an accuracy of 92.5% in the binary classification. Experimental evaluation demonstrated that the models trained on the proposed acoustic biomarkers can be used to estimate the severity of SDB. Conclusions Acoustic biomarkers may be useful to accurately predict the severity of SDB based on the patients breathing sounds during sleep, without conducting attended full-night PSG. This study implies that any device with a microphone, such as a smartphone, could be potentially utilized outside specialized facilities as a screening tool for detecting SDB.The work was partly supported by the SNUBH Grant #06-2014-157 and the Bio and Medical Technology Development Program of the National Research Foundation (NRF) funded by the Korean government, Ministry of Science, ICT & Future Planning (MSIP) (NRF-2015M3A9D7066972, NRF-2015M3A9D7066980)

Lifestyle Modification in Patients with Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a disorder in which the upper respiratory tract is closed repeatedly during sleep. Treatment of OSA includes continuous positive airway pressure (CPAP), intraoral devices, and upper respiratory tract surgery, among which CPAP is known as the most effective treatment method. However, even in the case of CPAP, adherence rates during long-term follow-up are lowered considerably due to inconvenience of wearing, and low adherence rates limit its therapeutic effect. Therefore, studies have been carried out to confirm the effect of lifestyle modification which corrects modifiable risk factors of OSA, such as obesity. The aim of this study was to examine the effects of weight loss and aerobic exercise to improve the severity of OSA, and to examine the effect of drinking and smoking on OSA. In consideration of the difficulty of modifying one’s lifestyle through traditional individual counseling, we propose the use of smart devices in the management of patients’ lifestyles

Cortical Magnetic Resonance Imaging Findings in Patients With Posttraumatic Olfactory Dysfunction: Comparison According to the Interval Between Trauma and Evaluation

ObjectivesPatients with smell loss after craniocerebral trauma are known to have some brain abnormalities, but there was no study to analyze the findings according to the time interval between injury and evaluation. We aimed to identify whether the time interval may influence on the findings in the brain.MethodsMedical records of 19 patients with posttraumatic olfactory dysfunction were reviewed. All of them underwent a magnetic resonance imaging and olfactory function tests. The patients were divided into early (n=10) and delayed (n=9) groups according to the time interval.ResultsMagnetic resonance imaging was taken at a mean time of 2.2 and 59.6 months after trauma in the early and delayed groups, respectively. Abnormal findings in the brain were found in 6 and 8 patients in the early and delayed groups, respectively. The olfactory bulb and orbitofrontal cortex were commonly affected olfactory pathways in both groups. In the early group, the abnormalities were brain tissue defect, hemorrhage, and focal edema whereas tissue defect was the only finding in the delayed group. In the early group, 5 of 6 patients with severe olfactory dysfunction showed brain abnormality while 1 of 4 patients with mild dysfunction had abnormality. In the delayed group, all the patients had severe dysfunction and 8 of 9 patients showed brain abnormality.ConclusionMost patients with traumatic olfactory dysfunction had abnormality in the brain, and brain abnormality might be different according to the timing of evaluation. Furthermore, there might be an association between the severity of olfactory dysfunction and radiological abnormalities

Associations Between Systemic Inflammatory Markers Based on Blood Cells and Polysomnographic Factors in Obstructive Sleep Apnea

Objectives. Systemic inflammation plays a key role in the pathogenesis of obstructive sleep apnea (OSA); however, easy-to-use methods to evaluate the severity of systemic inflammation have yet to be developed. This study investigated the association between systemic inflammation markers that could be derived from the complete blood count (CBC) profile and sleep parameters in a large number of patients with OSA. Methods. Patients who visited our hospital’s Otorhinolaryngology Sleep Clinic between January 2017 and April 2022 underwent polysomnography and routine laboratory tests, including a CBC. Associations between three systemic inflammatory markers—the systemic immune-inflammation index (SII), neutrophil-lymphocyte ratio (NLR), and platelet-lymphocyte ratio (PLR)—and polysomnographic and demographic factors including age, sex, body mass index, the apnea-hypopnea index (AHI), the hypopnea index (HI), lowest oxygen saturation (%), the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale, and percentages of non-rapid eye movement (REM) sleep stage 3, REM sleep, and snoring time were analyzed. The inflammation markers were compared among OSA subgroups, and associations were also analyzed in subgroups with different OSA severities. Results. In total, 1,102 patients (968 men and 134 women) were included, and their mean AHI was 33.0±24.3. PSQI was significantly associated with SII (P=0.027). No independent significant factors were identified for the NLR or PLR. Within the simple snoring and mild OSA subgroups, no significant association was found between sleep parameters and the SII. In the severe OSA subgroup, the AHI (P=0.004) and PSQI (P=0.012) were independently associated with the SII. Conclusion. Our study analyzed systemic inflammatory markers based on the CBC, a simple, relatively cost-effective test, and showed that the AHI and SII were significantly correlated only in the severe OSA subgroup

Relationship Between Snoring Intensity and Severity of Obstructive Sleep Apnea

ObjectivesThe aim of this study was to determine the relationship between the intensity of snoring and severity of sleep apnea using Watch-PAT (peripheral arterial tone) 100.MethodsA total of 404 patients (338 males and 66 females) who underwent home-based portable sleep study using Watch-PAT 100 for obstructive sleep apnea (OSA) from January 2009 through December 2011 were included in this study. Subjects were divided into 4 groups; no OSA (PAT apnea hypopnea index [pAHI]<5/hour), mild OSA (5≤pAHI<15/hour), moderate OSA (15≤pAHI<30/hour), or severe OSA groups (pAHI≥30/hour). Mean snoring intensity and percent sleep time with snoring intensity greater than 40, 50, and 60 dB were measured by Watch-PAT 100. Correlations of these parameters with apnea hypopnea index (AHI), respiratory disturbance index (RDI), and oxygen desaturation index were assessed.ResultsThe mean age and body mass index were 46.5±14.8 years and 24.7±3.4 kg/m2, respectively. Mean AHI and RDI were 16.5±15.3/hour and 20.8±14.3/hour, respectively. The mean snoring intensity in the no, mild, moderate, and severe OSA groups was 44.0±2.7, 45.4±6.0, 47.7±5.0, and 50.5±5.6 dB, respectively (P<0.001). There was a positive correlation between snoring intensity and pAHI or PAT RDI (pRDI) (r=0.391 and r=0.385, respectively, both P<0.001). There was also a positive correlation between percent sleep time with the snoring intensity greater than 50 dB and pAHI or pRDI (r=0.423 and r=0.411, respectively, both P<0.001).ConclusionThis study revealed that the intensity of snoring increased with the severity of sleep apnea, which suggests that the loudness of snoring might be an indicator of the severity of OSA

Non-association between low vitamin d levels and aeroallergen-positivity evaluated using multiple allergen simultaneous test in Korean adults

Background Studies on the association between vitamin D levels and allergen sensitization have reported conflicting results. We aimed to evaluate the association between low vitamin D levels and sensitization to 59 aeroallergens in Korean adults. Methods We retrospectively reviewed serum 25-hydroxyvitamin D (25[OH]D) measurements of participants (n = 57,467) in a healthcare center between May 2003 and June 2020. Serum 25(OH)D levels were categorized as follows: severe deficiency (< 10 ng/mL), deficiency (10 to < 20 ng/mL), insufficiency (20 to < 30 ng/mL), and sufficiency (≥ 30 ng/mL). Among all subjects, 1277 simultaneously underwent the multiple allergen simultaneous test. Multiple linear and logistic regression analyses were used to estimate coefficients and odds ratios (ORs) with 95% confidence interval (CI) for the association between serum vitamin D deficiency and aeroallergen sensitization after adjustment for potential confounders. Subgroup analyses were conducted for the types of aeroallergen (house dust mites, pollens, animal dander, foods, cockroach, and fungus). Results Vitamin D deficiency, defined as serum 25(OH)D level < 20 ng/mL, was noted in 56.4% of participants. There were significant differences in serum 25(OH)D levels according to sex, age, season, and bone mineral density (all P < 0.001). In multiple linear regression analyses, serum 25(OH)D levels were significantly lower in young subjects (adjusted coefficient [95% CI], 0.188 [0.101, 0.275]) and during winter (− 4.114 [− 6.528, − 1.699]). However, no significant association was observed between serum 25(OH)D levels and allergen sensitization (adjusted coefficients [95% CI], − 0.211 [− 1.989, 1.567], P = 0.816). In multivariate logistic regression analyses, male sex, young age, and winter season were significant risk factors for vitamin D deficiency. However, allergen sensitization showed no significant association with 25(OD)D levels after adjusting for confounders (adjusted OR [95% CI], 1.037 [0.642, 1.674] in insufficiency; 0.910 [0.573, 1.445] in deficiency; 0.869 [0.298, 2.539] in severe deficiency groups, P for trend = 0.334). There were consistent findings across subgroups regarding type of aeroallergen sensitized. Conclusion Vitamin D deficiency was prevalent but was not significantly associated with aeroallergen sensitization in Korean adults. To the best of our knowledge, this is the first large-scale study to evaluate the association between vitamin D deficiency and sensitization to 59 different aeroallergens.This research was funded by National Research Foundation (NRF) of Korea, Grant Number (NRF-2020-R1G1A1005390 by Jee Hye Wee). The funding organization did not contribute to the design or conduct of this study, preparation, review, approval, or decision to submit this manuscript for publication

Charge states and magnetic ordering in LaMnO3/SrTiO3 superlattices

We investigated the magnetic and optical properties of [(LaMnO3)n/(SrTiO3)8]20 (n = 1, 2, and 8) superlattices grown by pulsed laser deposition. We found a weak ferromagnetic and semiconducting state developed in all superlattices. An analysis of the optical conductivity showed that the LaMnO3 layers in the superlattices were slightly doped. The amount of doping was almost identical regardless of the LaMnO3 layer thickness up to eight unit cells, suggesting that the effect is not limited to the interface. On the other hand, the magnetic ordering became less stable as the LaMnO3 layer thickness decreased, probably due to a dimensional effect.Comment: 17 pages including 4 figures, accepted for publication in Phys. Rev.

Prediction of Obstructive Sleep Apnea Based on Respiratory Sounds Recorded Between Sleep Onset and Sleep Offset

Objectives To develop a simple algorithm for prescreening of obstructive sleep apnea (OSA) on the basis of respiratorysounds recorded during polysomnography during all sleep stages between sleep onset and offset. Methods Patients who underwent attended, in-laboratory, full-night polysomnography were included. For all patients, audiorecordings were performed with an air-conduction microphone during polysomnography. Analyses included allsleep stages (i.e., N1, N2, N3, rapid eye movement, and waking). After noise reduction preprocessing, data were segmentedinto 5-s windows and sound features were extracted. Prediction models were established and validated with10-fold cross-validation by using simple logistic regression. Binary classifications were separately conducted for threedifferent threshold criteria at apnea hypopnea index (AHI) of 5, 15, or 30. Prediction model characteristics, includingaccuracy, sensitivity, specificity, positive predictive value (precision), negative predictive value, and area under thecurve (AUC) of the receiver operating characteristic were computed. Results A total of 116 subjects were included; their mean age, body mass index, and AHI were 50.4 years, 25.5 kg/m2, and23.0/hr, respectively. A total of 508 sound features were extracted from respiratory sounds recorded throughoutsleep. Accuracies of binary classifiers at AHIs of 5, 15, and 30 were 82.7%, 84.4%, and 85.3%, respectively. Predictionperformances for the classifiers at AHIs of 5, 15, and 30 were AUC, 0.83, 0.901, and 0.91; sensitivity, 87.5%,81.6%, and 60%; and specificity, 67.8%, 87.5%, and 94.1%. Respective precision values of the classifiers were89.5%, 87.5%, and 78.2% for AHIs of 5, 15, and 30. Conclusion This study showed that our binary classifier predicted patients with AHI of ≥15 with sensitivity and specificityof >80% by using respiratory sounds during sleep. Since our prediction model included all sleep stage data, algorithmsbased on respiratory sounds may have a high value for prescreening OSA with mobile devices

Clinical Characteristics of Allergic Rhinitis According to Allergic Rhinitis and Its Impact on Asthma Guidelines

ObjectivesThe Allergic rhinitis and its impact on asthma (ARIA) guidelines were suggested for use to classify allergic rhinitis (AR). However, few studies have been performed in Asians. The objective of this study is to identify the clinical characteristics of AR in Korean patients according to the ARIA guidelines.MethodsFor the study, 610 patients who had been diagnosed with allergic rhinitis at Seoul National University Bundang Hospital and 545 patients who had been diagnosed with allergic rhinitis at 3 local clinics were included. All the patients were categorized into 4 groups, such as the mild intermittent, mild persistent, moderate-severe intermittent and moderate-severe persistent groups. The patients were given a questionnaire on allergic rhinitis-related symptoms and they underwent blood tests, including the blood eosinophil count and the serum total IgE level.ResultsThe most prevalent type was the moderate-severe persistent group (34.7%), and the moderate-severe intermittent group (17.1%) was the rarest. There were significant differences among the 4 groups for olfaction (P<0.001), self-awareness of rhinitis (P=0.013), a previous history of AR (P<0.001), self-awareness of asthma (P=0.001) and allergic conjunctivitis (P<0.001). On the allergy laboratory tests, there was a significant difference between the groups for the eosinophi count (P=0.004). The number of blood eosinophil was more in the persistent groups than in the intermittent groups.ConclusionAccording to the ARIA guidelines, the moderate-severe persistent group was the most prevalent for Korean patients. Blood eosinophilia and olfactory dysfunction were the most severe in the moderate-severe persistent group