Nocturnal change of circulating intercellular adhesion molecule 1 levels in children with snoring

Hypoxia promotes adherence of leukocytes to endothelial cells by inducing expression of adhesion molecules like intercellular adhesion molecule 1 (ICAM-1). Increased serum levels of circulating ICAM-1 (cICAM-1) have been reported in adults with sleep apnea and associated hypoxemia. This investigation assessed the hypothesis that the overnight change of cICAM-1 levels in children with snoring is correlated with the severity of obstructive sleep-disordered breathing. Evening and morning serum levels of cICAM-1 were measured in children with snoring referred for polysomnography. Twenty-five children with an apnea–hypopnea index greater than or equal to 5 episodes/h (5.5 ± 1.8 years), 30 subjects with an index less than 5 and greater than 1 (6.3 ± 2 years), and 19 children with an index less than or equal to 1 (7.1 ± 3 years) were recruited. Overnight change in cICAM-1 (log-transformed ratio of morning-to-evening levels) was similar in subjects with an apnea–hypopnea index greater than or equal to 5 episodes/h compared to those with an index less than 5 and greater than 1 or to children with an index less than or equal to 1 (−0.001 ± 0.08 vs −0.03 ± 0.09 vs −0.06 ± 0.1; p > 0.05). When multiple regression analysis was applied, apnea–hypopnea index, respiratory arousal index, and oxygen saturation of hemoglobin nadir were not significant predictors of overnight change in cICAM-1 levels. Thus, in children with snoring, overnight change in cICAM-1 levels is not related to severity of obstructive sleep-disordered breathing.     

Obstructive sleep apnea and history of asthma in snoring children

Asthma has been identified as a possible risk factor for Obstructive Sleep Apnea (OSA) in children. It is not known whether parent-reported asthma increases the likelihood of the diagnosis of OSA in snoring children. We hypothesized that snoring children with asthma are more likely to have OSA than snoring children without asthma. This study is a 1-year retrospective review of polysomnogram and questionnaire data collected on 236 patients referred to the University of Maryland Pediatric Sleep laboratory for evaluation of snoring. Of the 236 patients, 58% (137/236) were boys, and 79% (173/219 reporting race) were African-American (AA). The age at referral was 7.2 ± 3.7 years (mean ± S.D.). Mean body mass index (BMI) percentile was 73.4 ± 32.3%, with 43.2% (54/125) >95th percentile. A history of asthma was reported by 31.4% (74/236); no subject was symptomatic on the night of the study. We found no increased risk for polysomnographically diagnosed OSA for asthmatics. To the contrary, by logistic regression analysis, a parent/guardian report of asthma decreased the odds of having OSA by 34% (p = 0.027), controlling for individual and socioeconomic factors and assessment results. Polysomnographic (PSG) differences between asthmatic and non-asthmatic children were found in only the arousal index (11.0 vs.9.3 ± 6.5/h, p = 0.099) and total sleep time (337.1 ± 64.3 vs. 347 ± 65.2 min, p = 0.1) In a referral-based group of predominantly AA inner-city snoring children, asymptomatic asthma decreased the likelihood of OSA.     

Hypoxemia and obesity modulate plasma C-reactive protein and interleukin-6 levels in sleep-disordered breathing

C-reactive protein (CRP) and interleukin-6 (IL-6) are pro-inflammatory proteins and important risk factors for atherosclerosis. Plasma CRP levels in snoring children may or may not be elevated. Since obesity is prevalent among snoring children and is associated with elevated CRP levels, we aimed to investigate the relative contributions of sleep-disordered breathing (SDB) and obesity to the inflammatory processes in snoring children in this prospective study. Two hundred forty-four children (mean age 8.9 ± 3.4 years) underwent polysomnographic evaluation. CRP was measured the following morning, and plasma IL-6 levels from 111 randomly selected children were also examined. Plasma CRP and IL-6 levels were elevated in children with SDB. Log plasma CRP levels were higher in the moderate-severe SDB group (apnea/hypopnea index, AHI ≥ 5) compared to the mild SDB group (AHI ≥ 1 and <5; p < 0.0001) or the control group (AHI < 1; p = 0.0001). Log plasma CRP levels correlated with AHI, arousal index, relative BMI, and SpO₂ nadir (r = 0.30, p < 0.0001; r = 0.21, p = 0.002; r = 0.39, p < 0.0001, r = −0.36, p < 0.0001, respectively). Log plasma CRP levels were lower in children with SpO₂ nadir ≥90 (p < 0.0001). Sub-analysis of the 116 non-obese children in the cohort revealed similar findings. Log plasma IL-6 levels were increased in children with moderate–severe SDB compared to controls (p = 0.03) and correlated with AHI (r = 0.28, p = 0.003) and SpO₂ nadir (r = −0.24, p = 0.02). Children with SDB display significant severity-dependent increases in plasma CRP and IL-6 levels independent of obesity.     

Modified Epworth Sleepiness Scale in Chinese children with obstructive sleep apnea: a retrospective study

Background and objective  The purpose of this study is to assess whether Chinese children with high apnea–hypopnea index (AHI) are sleepier by a modified Epworth Sleepiness Scale (ESS). Materials and methods  Records were retrospectively reviewed. We included children who were between 3 and 12 years old, admitted for overnight polysomnogram because of suspected obstructive sleep apnea syndrome (OSAS). A modified ESS was used to assess excessive daytime sleepiness (EDS) of the children. Results  One hundred ninety-two Chinese children were included. Children with high AHI, defined as AHI > 5.0, were sleepier than children with AHI less than or equal to 5. After adjustment by age, gender, and obesity, children with high AHI remained significantly sleepier. Modified ESS was significantly correlated with AHI (rho = 0.124, 95% CI = 0.004–0.281). Modified ESS score of >8 was the best cutoff point with the sensitivity and specificity of 0.29 and 0.91, respectively. The odds ratio of children with modified ESS > 10 having high AHI was 4.231 (95%CI = 1.248 to 14.338) and children with modified ESS > 8 had the highest odds ratio, 4.295(95%CI = 1.66 to 11.1), of having high AHI. Conclusion   Chinese children with high AHI appear to be sleepier than children with low AHI. Children with suspected OSAS and high modified ESS, i.e., ESS > 8, had significantly higher odds ratio of having high AHI. Increased sleepiness is a specific but not a sensitive symptom in snoring children with high AHI. Screening for EDS in snoring children may help us identify those with high AHI and prioritize the management of those children. All authors worked and the study was carried out in Kwong Wah Hospital in Hong Kong. There was no conflict of interest and no specific source of funding for the study.     

Mandibular advancement splint titration in obstructive sleep apnoea

Introduction  Mandibular advancement splints (MAS) allowing self-adjustment may be better tolerated, but the optimum titration protocol needs systematic study. Aim  The aims of the study are to assess the effectiveness of a titratable MAS device in consecutive patients with body mass index (BMI) < 35 kg/m² and obstructive sleep apnoea [OSA, apnoea–hypopnoea index (AHI) 10–40/h] and compare two methods of adjustment [self-adjustment or adjustment after polysomnographic (PSG) feedback]. Materials and methods  Twenty-eight patients (24 M, mean age 49 years, mean BMI 27.6 kg/m²) with symptomatic (Epworth Sleepiness score > 8/24, snoring, choking or poor sleep quality) OSA (mean AHI 25.7/h, range 10–46/h) had a MAS set at 70% maximal protrusion and were randomised to subjective self-adjustment for 6 weeks (n = 16) or objective adjustment (n = 12; fixed position for 3 weeks, then PSG based feedback at 3 weeks with self-adjustment instructions). Primary outcome variable (AHI) and OSA symptoms were compared by t tests and chi-squared tests at baseline and after 6 weeks. Resolution of apnoea was defined as AHI < 5/h; improvement was defined as AHI decreased by >50% but still >5/h. Results  The groups had similar baseline demographics, OSA severity and occlusal type. MAS therapy improved or resolved OSA in 20 out of 28 (71%) and was reportedly used nightly by 91% of the objective group and 63% of the subjective group (p = 0.04). MAS were used all night by 75% of the objective group and 69% of the subjective group (p > 0.05). MAS adjustment following PSG feedback did not lower AHI further from 3 weeks (baseline 26.5 ± 12.0/h, 3 weeks 15.3 ± 13.5/h p = 0.01, 6 weeks 11.7 ± 10.0/h, p = 0.11). The overall improvement was similar to that achieved with subjective adjustment (baseline AHI 25.4 ± 7.4/h, 6 weeks 14.3 ± 10.7/h, p = 0.0002). Symptomatic benefit was reported by both groups. Conclusion  In selected patients, titratable MAS improved or resolved OSA in the majority of patients and was well tolerated. PSG-based feedback at 3 weeks allowed objective confirmation of efficacy and increased device use but did not result in greater improvement in AHI or symptoms. Neither titration method was significantly superior for us to provide firm endorsement. However, we recommend a follow-up sleep study to confirm MAS efficacy.     

Automated detection of sleep disordered breathing using a nasal pressure monitoring device

To assess the accuracy of a single channel portable monitoring device (RUSleeping™ RTS, Respironics, Murrysville, PA) that measures nasal pressure (a surrogate for airflow) to detect sleep disordered breathing (SDB). Twenty-five adult patients referred to a community sleep laboratory with suspected obstructive sleep apnea (OSA) participated in this investigation. The portable monitoring device was used in the sleep laboratory to acquire data concurrently with a standard multi-channel polysomnogram (PSG) to assess SDB. Respiratory events were scored manually on the PSG using standard criteria for clinical research to quantify an apnea–hypopnea index (AHI) based on events during sleep. The portable monitoring device automatically calculated an unedited respiratory event index (REI) based on recording time. These data were then compared using the Pearson product–moment correlation coefficient, Bland–Altman analysis, receiver operating characteristic (ROC) curves, and likelihood ratios. All 25 subjects completed the study. Mean age of subjects was 42.4 ± 12.9 years and mean body mass index was 31.0 ± 7.4 kg m⁻². There was good agreement between the REI and the AHI (R = 0.77, p < 0.001, mean difference 2.6 events per hour [2 SD: 39.8] using a Bland–Altman plot). The area under the ROC curve for detecting SDB (PSG AHI greater than or equal to five events per hour) with the REI was 0.94 (95% CI 0.84–1.0). For an REI >11.9 events per hour, the sensitivity was 0.89 (95% CI 0.65–0.99) and the specificity was 0.86 (95% CI 0.42–1.0) with a likelihood ratio of 6.2 for a positive test (LR+) and 0.13 for a negative test (LR−). Similar results were observed for detecting moderate–severe SDB (PSG AHI ≥ 15 events h⁻¹) using REI >15.2 events h⁻¹. In a population of subjects with suspected OSA, this portable monitoring device can automatically quantify an REI that compares well to the AHI scored manually on a concurrent PSG. Such a device may prove useful to assess SDB in high risk populations with self-administered testing in ambulatory settings such as the home. This study was performed at the Sleep Center of Greater Pittsburgh Sleep Laboratory.     

The prevalence and significance of periodic leg movements during sleep in patients with congestive heart failure

Purpose  The aim of this study was to evaluate (1) the prevalence of periodic leg movements during sleep (PLMs) in a consecutive sample of congestive heart failure (CHF) outpatients; (2) the presence of correlation between PLMs, subjective daytime sleepiness, and sleep architecture; and (3) the heart rate response to PLMs in CHF. Materials and methods  Seventy-nine [50 men, age 59 ± 11 years, body mass index (BMI) 26 ± 5 kg/m²] consecutive adult stable outpatients with CHF [left ventricular ejection fraction (LVEF) 36 ± 6%] were prospectively evaluated. The patients underwent assessment of echocardiography, sleepiness (Epworth Scale), and overnight in-lab polysomnography. Results  Fifteen patients (19%) had PLM index >5. These subjects were similar in sex distribution, BMI, subjective somnolence, LVEF, and apnea–hypopnea index (AHI), but were significantly older than subjects without PLMs. Sleep architecture was similar in subjects with and without PLMs. There was a small but significant elevation of heart rate after PLMs (80.1 ± 9.4 vs. 81.5 ± 9.2; p < 0.001). The cardiac acceleration was also present in absence of electroencephalogram activation. Conclusion  The prevalence of PLMs in consecutive sample of adult CHF outpatients was 19%. There were no differences in subjective daytime sleepiness, sleep architecture, AHI, and severity of CHF in subjects with and without PLMs. PLMs caused a small but statistically significant cardiac acceleration.     

Sleep-related breathing in children with mucopolysaccharidosis

Summary   Background: The mucopolysaccharidoses (MPSs), a group of genetic lysosomal storage disorders, are associated with significant morbidity. Secondarily to specific associated anatomical abnormalities, MPS is associated with sleep disordered breathing (SDB), specifically obstructive sleep apnoea (OSA) that may confer additional morbidity. Few studies have examined SDB in children with MPS using full polysomnography (PSG) and thus the exact prevalence and severity of SDB is unknown. Further, successful treatments for SDB in this population have not been explored. Objectives: This study evaluated both SDB and the efficacy of treatments offered to children with MPS using PSG data. Patients and methods: A retrospective chart review was conducted on all children with MPS and a history of suspected OSA who were referred to the Hospital for Sick Children, Toronto. Both baseline and follow up treatment PSG data were analysed. PSG data recorded included obstructive apnoea-hypopnoea index (OAHI) and central apnoea index (CAI). Results: Fourteen patients (10 male) underwent a baseline PSG. Three of 14 children on ERT were excluded from the main analyses. The median (range) baseline parameters of the population (n = 11) were recorded. The age was 5.2 years (0.8–17.8) and the body mass index (BMI) was 19.9 (13.7–22.2). The OAHI was 6.6 (0.0–54.8); the CAI was 0.6 (0.0–2.6). Seven of 11 (64%) had evidence for OSA and 3/7 children were classified as having severe OSA (OAHI > 10). Of these, 5/7 children underwent treatment for OSA with 3/5 children showing a significant reduction in their OAHI. Further, the 2 patients on ERT therapy with OSA were also both successfully treated. Conclusions: Children with MPS have a high prevalence of significant OSA and thus should be carefully screened for OSA using full polysomnography and treated accordingly. Competing interests: None declared     

Obstructive sleep-disordered breathing and plasma levels of vascular endothelial growth factor in children

Vascular endothelial growth factor (VEGF) may be one of the pathophysiologic links in the association between obstructive sleep apnea-hypopnea and cardiovascular disease. Morning serum VEGF levels are increased in children with obstructive sleep apnea. However, release of VEGF by platelets and leukocytes during blood clotting may affect its concentration in serum. In the present study, VEGF levels were measured in children with and without habitual snoring using plasma specimens. Evening and morning plasma VEGF concentrations were determined in: (i) 20 children with habitual snoring and apnea-hypopnea index (AHI)5 episodes/h (median age 5; range 1.9-13 years); (ii) 55 children with snoring and AHI<5 episodes/h (median age 6; 2-13 years); and (iii) 25 controls without snoring (median age 6.5; 3-13 years). No differences were identified between the three study groups regarding evening [median 2.5 (range 2.5-174.5) versus 22.5 (2.5-159.4) versus 26.8 (2.5-108) pg/mL; P>0.05] and morning VEGF levels [median 7.7 (range 2.5-120.5) versus 25.1 (2.5-198.4) versus 48.4 (2.5-147.7) pg/mL; P>0.05]. AHI and % sleep time with oxygen saturation of hemoglobin less than 90% were not significant predictors of log-transformed morning VEGF concentrations (P>0.05). In summary, both evening and morning plasma VEGF levels were similar in children with obstructive sleep-disordered breathing of variable severity and in controls without snoring. VEGF may not play an important pathophysiologic role in all cases of obstructive sleep-disordered breathing in childhood.     

A community study of sleep-disordered breathing in middle-aged Chinese men in Hong Kong

BACKGROUND: Sleep-disordered breathing (SDB) in Asian populations is being increasingly recognized. This study investigated the prevalence of SDB in Chinese middle-aged office-based male workers in Hong Kong. METHODS: Sleep questionnaires were distributed to 1,542 men (age range, 30 to 60 years), and 784 questionnaires were returned. Subsequently, full polysomnographic (PSG) examinations were conducted in 153 questionnaire respondents. Subjects with an apnea-hypopnea index (AHI) > or =5 were recalled for clinical assessment. RESULTS: Questionnaire respondents were similar in age and body mass index (BMI) to the general community in the target age range and gender. Habitual snoring was reported by 23% of this cohort and was associated with excessive daytime sleepiness (EDS), hypertension, witnessed abnormal breathing pattern, BMI, and leg movements during sleep. Allowing for subject bias in undergoing PSG, the estimated prevalence of SDB and obstructive sleep apnea syndrome (OSAS) (defined as SDB in the presence of EDS) at various AHI cutoff threshold values was 8.8% and 4.1% (AHI > or =5), 6.3% and 3.2% (AHI > or =10), and 5.3% and 3.1% (AHI > or =15). Multiple stepwise logistic regression analysis identified BMI, habitual snoring, time taken to fall asleep, and age as predictors of SDB at AHI > or =5. Analysis of anthropometric parameters indicated that the relative risk of OSAS attributable to obesity was less than in white subjects. CONCLUSION: This community-based study of sleep apnea among middle-aged men in Hong Kong using full PSG demonstrated an estimated prevalence of OSAS (AHI > or =5 and EDS) at 4.1%. Increasing BMI and age were associated with SDB, although factors other than adiposity may also have an important pathogenic role in OSA in Chinese subjects.     

Predictors of sleep-disordered breathing in community-dwelling adults: the Sleep Heart Health Study

BACKGROUND: Sleep-disordered breathing (SDB) is common, but largely undiagnosed in the general population. Information on demographic patterns of SDB occurrence and its predictive factors in the general population is needed to target high-risk groups that may benefit from diagnosis. METHODS: The sample comprised 5615 community-dwelling men and women aged between 40 and 98 years who were enrolled in the Sleep Heart Health Study. Data were collected by questionnaire, clinical examinations, and in-home polysomnography. Sleep-disordered breathing status was based on the average number of apnea and hypopnea episodes per hour of sleep (apnea-hypopnea index [AHI]). We used multiple logistic regression modeling to estimate cross-sectional associations of selected participant characteristics with SDB defined by an AHI of 15 or greater. RESULTS: Male sex, age, body mass index, neck girth, snoring, and repeated breathing pause frequency were independent, significant correlates of an AHI of 15 or greater. People reporting habitual snoring, loud snoring, and frequent breathing pauses were 3 to 4 times more likely to have an AHI of 15 or greater vs an AHI less than 15, but there were weaker associations for other factors with an AHI of 15 or greater. The odds ratios (95% confidence interval) for an AHI of 15 or greater vs an AHI less than 15 were 1.6 and 1.5, respectively, for 1-SD increments in body mass index and neck girth. As age increased, the magnitude of associations for SDB and body habitus, snoring, and breathing pauses decreased. CONCLUSIONS: A significant proportion of occult SDB in the general population would be missed if screening or case finding were based solely on increased body habitus or male sex. Breathing pauses and obesity may be particularly insensitive for identifying SDB in older people. A better understanding of predictive factors for SDB, particularly in older adults, is needed.     

老年心血管疾病患者阻塞性睡眠呼吸暂停综合征的评价

目的 评价老年心血管疾病患者阻塞性睡眠呼吸暂停综合征(OSAS)的患病情况和特点,为临床决策提供参考. 方法 采用便携式睡眠监测仪对入住在老年心内科的患者,进行睡眠呼吸监测,了解其阻塞性睡眠呼吸暂停(OSA)的患病情况. 结果 共监测了317例老年心血管疾病患者的夜间睡眠呼吸紊乱情况,得出符合OSA[睡眠呼吸紊乱指数(AHI)≥5]的有281例,占88.6%;符合阻塞性睡眠呼吸暂停综合征(OSAS)[AHI≥5,Epworth量表(ESS)≥9分]的有47例,占14.8%.多元回归分析结果 提示,以OSA严重程度作为因变量,对它影响有显著性意义的是最低血氧饱和度和血氧饱和度下降指数(简称氧减指数),而年龄、习惯性打鼾、嗜睡评分、体质指数(BMI)、血氧饱和度平均值和低于90%的时间对其影响无显著性意义. 结论 老年心血管疾病患者中OSAS具有高的患病率,而且无白天嗜睡症状的OSA的老年人患病率更高.对睡眠呼吸暂停严重程度的独立预测因子是最低血氧饱和度氧减指数,而老年人的年龄、BMI、是否经常打鼾、是否白天嗜睡与OSA的严重程度关系不密切.     

Tissue specificity of insulin resistance in humans: fat in the liver rather than muscle is associated with features of the metabolic syndrome

Aims/hypothesis The aim of this study was to investigate whether intrahepatic and intramyocellular fat are related to insulin resistance in these respective tissues or to the metabolic syndrome. Methods Hepatic (insulin 1.8 pmol kg⁻¹ min⁻¹ combined with [3-³H]glucose) and muscle (insulin 6.0 pmol kg⁻¹ min⁻¹) insulin sensitivity were measured on separate occasions in 45 non-diabetic men (age 42 ± 1 years, BMI 26.2 ± 0.6 kg/m²) using the euglycaemic–hyperinsulinaemic clamp. Liver fat and intramyocellular lipid (IMCL) were measured by proton magnetic resonance spectroscopy and body composition by magnetic resonance imaging. We also determined fasting serum insulin and adiponectin concentrations, components of the metabolic syndrome and maximal oxygen consumption. Results In participants with high [median 12.0% (interquartile range 5.7–18.5%)] vs low [2.0% (1.0–2.0%)] liver fat, fasting serum triacylglycerols (1.6 ± 0.2 vs 1.0 ± 0.1 mmol/l, p = 0.002) and fasting serum insulin (55 ± 4 vs 32 ± 2 pmol/l, p < 0.0001) were increased and serum HDL-cholesterol (1.26 ± 0.1 vs 1.48 ± 0.1 mmol/l, p = 0.02) and fasting serum adiponectin (9.5 ± 1.2 vs 12.2 ± 1.2 μg/ml, p = 0.05) decreased. In participants with high [19.5% (16.0–26.0%)] vs low [5.0% (2.3–7.5%)] IMCL, these parameters were comparable. Liver fat was higher in participants with [10.5% (3.0–18.0%)] than in those without [2.0% (1.5–6.0%), p = 0.010] the metabolic syndrome, even independently of obesity, while IMCL was comparable. Insulin suppression of glucose rate of appearance and serum NEFA was significantly impaired in the high liver fat group. Conclusions/interpretation Fat accumulation in the liver rather than in skeletal muscle is associated with features of the metabolic syndrome, i.e. increased fasting serum triacylglycerols and decreased fasting serum HDL-cholesterol, as well as with hyperinsulinaemia and low adiponectin.     

Chronic Sleep Complaints in Premenopausal Women and Their Association with Sleep-Disordered Breathing

Background  In clinical practice, we have found that premenopausal women have delayed diagnosis of sleep-disordered breathing (SDB). Methods  During a 4-year period, we systematically collected the clinical and polysomnographic variables for all women referred for sleep complaints using preestablished questionnaires, scales, clinical grid, polygraphic montage, and scoring criteria. The variables collected on premenopausal SDB women were analyzed and compared to those of postmenopausal women within 5 years of menopause. Results  Of 977 women, 316 were premenopausal with SDB. Complaints of chronic insomnia and sleepwalking were the most common reasons for referral, had been present for a mean of 6.4 ± 5.4 years, and had lead to unsuccessful symptomatic treatment. The normal-weight premenopausal SDB group had anatomically small upper airways, while those with body mass index (BMI) ≥ 25 kg/m² complained more frequently of snoring and daytime sleepiness and their clinical presentation was closer to those of the postmenopausal SDB comparison group. Premenopausal women often had a low apnea-hypopnea index (AHI), but there was a discrepancy between the low AHI and the amount of continuous positive airway pressure (CPAP) needed to control the SDB, and there was a need for higher pressures in overweight premenopausal SDB women (mean 9.1 ± 1.9 and 10.1 ± 2.6 cmH₂O). Conclusion  Normal-weight premenopausal SDB women often present with atypical sleep complaints of chronic insomnia and parasomnias. Clinical attention paid to craniofacial features and use of specific scales such as Mallampati help with the suspicion of the presence of SDB, and a low AHI is unrelated to the positive clinical impact of nasal CPAP treatment.     

N-terminal pro-B-type natriuretic peptide and functional capacity in patients with obstructive sleep apnea

The obstructive sleep apnea syndrome (OSAS) is associated with cardiovascular abnormalities including left ventricular hypertrophy, left ventricular diastolic dysfunction, and endothelial dysfunction. The present study evaluated whether N-terminal pro-B-type natriuretic peptide (NT-proBNP) and peak oxygen consumption (peak VO₂), both integral markers of cardiovascular function, are related to OSAS severity. In addition, we tested whether NT-proBNP levels depend on body composition in OSAS patients, similar to what has been reported in patients without OSAS. Eighty-nine patients with untreated OSAS underwent NT-proBNP measurement, dual X-ray absorptiometry, and cardiopulmonary exercise testing. In a representative subgroup (n = 32), transthoracic echocardiography was performed. The severity of OSAS was classified based on apnea–hypopnea index (AHI) values as mild (AHI 5–15 h⁻¹), moderate (AHI 15–30 h⁻¹), and severe (AHI >30 h⁻¹). OSAS was mild in 19 (21%), moderate in 21 (24%), and severe in 49 (55%) patients. NT-proBNP levels did not differ among patients with mild [30 (10–57)], moderate [37 (14–55)], and severe [24 (13–49) pg/ml; p = 0.8] OSAS and were not related to body mass index (r = 0.07; p = 0.5), percent lean body mass (r = −0.17; p = 0.1), and percent fat mass (r = 0.18; p = 0.1). Percent predicted peak VO₂ was on average normal and did not differ among patients with mild (115 ± 26), moderate (112 ± 23), and severe OSAS (106 ± 29%; p = 0.4). Body weight-indexed peak VO₂ did not differ among patients with mild (31.9 ± 10.3), moderate (32.1 ± 7.9), and severe OSAS (30.0 ± 9.9 ml kg⁻¹ min⁻¹; p = 0.6) either. Lower NT-proBNP (β = −0.2; p = 0.02) was independently but weakly associated with higher body weight-indexed peak VO₂. In the echocardiography subgroup, NT-proBNP was not significantly related to left ventricular mass index (r = 0.26; p = 0.2). In conclusion, NT-proBNP and peak VO₂ are not related to OSAS severity, and NT-proBNP poorly reflects left ventricular hypertrophy in OSAS. The lack of a relationship between NT-proBNP and OSAS severity is not due to a significant influence of body composition on NT-proBNP. There is an association between higher NT-proBNP and lower peak VO₂, indicating that NT-proBNP is a marker of cardiorespiratory fitness in patients with OSAS. However, the association is too weak to be clinically useful.     

Insulin and obstructive sleep apnea in obese Chinese children

OBJECTIVE: In adults, obstructive sleep apnea (OSA) is associated with insulin resistance and dyslipidemia. We aimed to establish correlation between OSA, serum lipid profile, and insulin levels in obese snoring children. METHODS: Consecutive obese children with habitual snoring were recruited. They underwent physical examination, overnight polysomnography (PSG), and metabolic studies. OSA was diagnosed if apnea hypopnea index (AHI) > 1.0, and cases were considered to have moderate to severe OSA if AHI > 10. RESULTS: Ninety-four obese subjects with habitual snoring were studied. Seventy-three subjects were male and the median age of the studied group was 12.0 years (IQR 9.7-13.9). None of the subjects had active cardiopulmonary disease, and the BMI values of our subjects were >95th percentile using local reference charts. Sixty subjects had OSA, 47 being mild, and 13 being moderate to severe OSA. Multiple logistic regression analysis revealed that saturation nadir and insulin levels were significantly associated with OSA. CONCLUSION: OSA is prevalent among obese children with habitual snoring and insulin is independently associated with the condition. Its role in the cardiovascular complications of childhood sleep apnea is worthy of further exploration.     

CPAP compliance in patients with obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is characterized by repeated cessations of breathing during sleep. Major symptoms of this disease are excessive daytime sleepiness, snoring, and witnessed apnea. Most of the patients are treated with CPAP. In this study, we aimed to evaluate the factors affecting adherence to the CPAP treatment. Seventy-one patients were enrolled to this study. Patients were divided into three groups according to CPAP usage. Group I consisted of patients who had never used CPAP, group II consisted of patients who had used CPAP occasionally, and group-III patients had used CPAP treatment regularly. Group-III patients had higher apnea–hypopnea index (AHI) than groups I and II (respectively, 56.6 ± 27.7, 26.3 ± 7.5, and 32.3 ± 7.06; p < 0.000 for both). Oxygen desaturation index was significantly higher in group-III patients comparing to groups I and II (44.6 ± 22.3, 15.9 ± 8.3, and 25.6 ± 9.5; p < 0.000 for all). Our findings have shown that only very severe patients use the CPAP device regularly (mean AHI 56.6 ± 27.7). Compliance to CPAP treatment seemed to be poor in patients with moderate to severe, AHI about 30, OSAS. Considering the well-established benefits of CPAP treatment in patients with true indications, patients should be encouraged to use CPAP regularly, and complications of OSAS should be keynoted.     

Radiofrequency surgery of the tongue base in the treatment of snoring—a pilot study

In a previously published study, a significant reduction of snoring was reported after treatment with radiofrequency surgery of the tongue base in patients suffering from obstructive sleep apnea syndrome. The aim of this study was to investigate the efficacy of radiofrequency surgery of the tongue base in the treatment of primary snoring. Twenty patients suffering from primary snoring (AHI < 10/h, body mass index < 32 kg/m²) and an isolated hypertrophic tongue base at clinical examination were enrolled in this clinical trial. The patients underwent bipolar radiofrequency surgery of the tongue base under local anaesthesia. Pre- and post-operative body weight, daytime sleepiness (Epworth sleepiness scale) and snoring scores (visual analogue scales) were evaluated by the patients and their bed partners, respectively. Postoperative follow-up data was collected 6–8 weeks after treatment. A statistically significant reduction of the preoperative snoring levels from 7.5 ± 2.4 to 6.1 ± 2.8 was seen after treatment (p < 0.001). Body weight and daytime sleepiness remained unaffected. Only 3 out of 20 patients were satisfied with the result as defined by VAS < 3. Despite statistically significant reduction of the subjective snoring scores after radiofrequency of the tongue base, only minimal clinical improvement was achieved. Only 3 out of 20 patients were satisfied with the results. With regard to the clearly beneficial effect seen in patients with obstructive sleep apnea, this result indicates different pathophysiological principles in the generation of snoring.     

Efficacy and patient satisfaction with autoadjusting CPAP with variable expiratory pressure vs standard CPAP: a two-night randomized crossover trial

Expiratory pressure relief (C-Flex) technology monitors the patient’s airflow during expiration and reduces the pressure in response to the patient. Increased comfort levels associated with C-Flex therapy have potential to improve patient adherence to therapy. The purpose of this study was to assess the combination of autoadjusting CPAP (APAP) and C-Flex in terms of (1) treatment efficacy, and (2) patient preference when compared to standard CPAP. Fifteen patients who had previously undergone formal CPAP titration polysomnography were treated with either one night of the APAP with C-Flex or one night of conventional CPAP, in a crossover trial. Patient satisfaction levels were recorded using visual analog scales (VAS) on the morning after the study. Mean patient age was 50 ± 12 years, body mass index (BMI) was 36 ± 6 kg/m², baseline AHI was 53 ± 31 events/h, and CPAP Pressure was 11 ± 2 cm/H₂O. APAP with C-Flex was as effective as CPAP, with no differences detected in sleep latency (17 ± 5 vs 12.3 ± 3 min, p = 0.4), or respiratory indices (AHI of 4.2 ± 2 vs 2.4 ± 0.7 events/h, p = 0.1). VAS scores (scale 0–10) indicated a trend towards increased patient satisfaction while using APAP with C-Flex (7.9 vs 7.2, p = 0.07). 10 patients expressed a preference for APAP with C-Flex (VAS, 0 to10) over standard CPAP (total positive score of 68, mean score of 4.8 ± 4.3). One patient expressed no preference. Four patients expressed a preference for CPAP (total positive score of 13, mean score of 0.9 ± 1.9) (APAP with C-Flex vs standard CPAP, p < 0.01 paired t test). APAP with C-Flex eliminates sleep disordered breathing as effectively as standard CPAP. Patients indicated a preference for APAP with C-Flex suggesting a possible advantage in terms of patient adherence for this mode of treatment.     

Risk factors associated with habitual snoring and sleep-disordered breathing in a multi-ethnic Asian population: a population-based study

INTRODUCTION: There is scant data on the risk factors of sleep-disordered breathing (SDB) in the general population in Asian countries. METHODS: Cross-sectional survey of a random population sample of 2298 adults aged 20-75 years, stratified by gender, ethnicity (Chinese, Malay and Indian) and age. An interviewer-administered questionnaire was used to elicit responses to questions on daytime somnolence and nocturnal events. Three categories of SDB were defined for analysis: habitual snoring; apnoeic snoring (SDB I); and apnoeic snoring or snoring with diurnal hypersomnia (SDB II). RESULTS: Snoring was reported by 201 persons (6.8%), SDB-I in 44 (1.9%) and SDB-II in 112 (4.9%) in the sample. The adjusted odds ratio (95% C.I.) of association with snoring were: male gender, 3.79 (2.69-5.33); older age (>60 years old), 2.15 (1.41-3.29); Indian versus Chinese, 1.54 (1.05-2.25); family history, 2.21 (1.56-3.12); obesity (BMI>30), 2.64 (1.62-4.30); neck circumference (>40 cm), 2.57 (1.59-4.11); and cigarette smoking, 2.05 (1.21-3.45). The risk factors for SDB were similar to that of snoring. CONCLUSION: Population risk factors associated with habitual snoring and SDB in Singapore are largely similar to those reported in other populations. Differential risks underscore the importance of ethnicity in determining the burden of SDB.