Frequency of moderate-to-severe obstructive sleep apnea syndrome among children with snoring and blood pressure in the hypertensive range.

BACKGROUND: It is recommended that children with hypertension and loud snoring should be referred for polysomnography. We aimed to compare the frequency of moderate-to-severe obstructive sleep apnea syndrome (OSAS) among snorers with and without hypertension. Thus, it was hypothesized that systolic or diastolic hypertension among children with snoring is a risk factor for moderate-to-severe OSAS. METHODS: Data of children with snoring and adenotonsillar hypertrophy and/or obesity referred for polysomnography were retrospectively analyzed. Blood pressure (BP) was measured three times in the morning after polysomnography and percentiles were calculated for the average of the second and third measurement. Association of systolic or diastolic hypertension with moderate-to severe OSAS (apnea-hypopnea index-AHI > 5 episodes/h) adjusted for age and obesity was assessed by logistic regression. RESULTS: Data of 646 children with snoring (median age, 6.5 years; 3-14.9 years; 25.7% obese) were analyzed. Prevalence of systolic or diastolic hypertension was 14.1% and 16.1%, respectively and frequency of AHI > 5 episodes/h was 18.3%. Systolic hypertension was a significant predictor of moderate-to-severe OSAS (OR 1.87; 95% CI 1.10 to 3.17; P = 0.02) after adjustment for age and obesity, but diastolic hypertension was not (OR, 0.96; 0.55 to 1.67; P > 0.05). Odds of AHI > 5 episodes/h prior to considering systolic hypertension was 0.25 and after considering its presence, increased to 0.46 (Bayes' theorem), or for every three children with systolic hypertension and snoring tested, one had AHI > 5 episodes/h. CONCLUSIONS: In the context of systolic hypertension and snoring, referral for polysomnography to rule out moderate-to-severe OSAS is a clinically productive practice.

Serum leukotriene B4 levels, tonsillar hypertrophy and sleep-disordered breathing in childhood.

OBJECTIVES: In children with snoring, increased production of leukotriene B4 (LTB4) may promote tonsillar hypertrophy and sleep-disordered breathing (SDB) or conversely SDB may enhance LTB4 synthesis. We explored whether: i) high LTB4 serum levels predict tonsillar hypertrophy; and ii) SDB severity correlates with LTB4 serum concentration. METHODS: Normal-weight children with SDB or controls underwent polysomnography and measurement of LTB4 serum concentration. Tonsillar hypertrophy was the main outcome measure and high LTB4 serum level (>75 t h percentile value in controls) was the primary explanatory variable. Odds ratio (OR) and the corresponding 95% confidence intervals (CI) for tonsillar hypertrophy in children with versus without high LTB4 level were calculated. The control subgroup and subgroups of subjects with increasing SDB severity were compared regarding LTB4 concentration by Kruskal-Wallis test. Spearman's correlation co-efficient was applied to assess the association of LTB4 concentration with SDB severity. RESULTS: A total of 104 children with SDB and mean obstructive apnea-hypopnea index-AHI of 4.8 ±â€¯5.3 episodes/h (primary snoring: n = 19; mild SDB: n = 49; moderate/severe SDB: n = 36) and 13 controls (no snoring; AHI: 0.4 ±â€¯0.2 episodes/h) were recruited. The four study subgroups were similar regarding LTB4 serum concentration (P = 0.64). High LTB4 (>170.3 pg/mL) was a significant predictor of tonsillar hypertrophy after adjustment for age and gender (OR 3.0 [1.2-7.2]; P = 0.01). There was no association between AHI or desaturation index and LTB4 serum concentration (r = -0.08; P = 0.37 and r = -0.1; P = 0.30, respectively). CONCLUSION: No association was identified between SDB severity and LTB4 levels, but high LTB4 concentration predicted tonsillar hypertrophy.

ERS statement on obstructive sleep disordered breathing in 1- to 23-month-old children.

The present statement was produced by a European Respiratory Society Task Force to summarise the evidence and current practice on the diagnosis and management of obstructive sleep disordered breathing (SDB) in children aged 1-23 months. A systematic literature search was completed and 159 articles were summarised to answer clinically relevant questions. SDB is suspected when symptoms or abnormalities related to upper airway obstruction are identified. Morbidity (pulmonary hypertension, growth delay, behavioural problems) and coexisting conditions (feeding difficulties, recurrent otitis media) may be present. SDB severity is measured objectively, preferably by polysomnography, or alternatively polygraphy or nocturnal oximetry. Children with apparent upper airway obstruction during wakefulness, those with abnormal sleep study in combination with SDB symptoms (e.g. snoring) and/or conditions predisposing to SDB (e.g. mandibular hypoplasia) as well as children with SDB and complex conditions (e.g. Down syndrome, Prader-Willi syndrome) will benefit from treatment. Adenotonsillectomy and continuous positive airway pressure are the most frequently used treatment measures along with interventions targeting specific conditions (e.g. supraglottoplasty for laryngomalacia or nasopharyngeal airway for mandibular hypoplasia). Hence, obstructive SDB in children aged 1-23 months is a multifactorial disorder that requires objective assessment and treatment of all underlying abnormalities that contribute to upper airway obstruction during sleep.

Obstructive sleep disordered breathing in 2- to 18-year-old children: diagnosis and management.

This document summarises the conclusions of a European Respiratory Society Task Force on the diagnosis and management of obstructive sleep disordered breathing (SDB) in childhood and refers to children aged 2-18 years. Prospective cohort studies describing the natural history of SDB or randomised, double-blind, placebo-controlled trials regarding its management are scarce. Selected evidence (362 articles) can be consolidated into seven management steps. SDB is suspected when symptoms or abnormalities related to upper airway obstruction are present (step 1). Central nervous or cardiovascular system morbidity, growth failure or enuresis and predictors of SDB persistence in the long-term are recognised (steps 2 and 3), and SDB severity is determined objectively preferably using polysomnography (step 4). Children with an apnoea-hypopnoea index (AHI) >5 episodes·h(-1), those with an AHI of 1-5 episodes·h(-1) and the presence of morbidity or factors predicting SDB persistence, and children with complex conditions (e.g. Down syndrome and Prader-Willi syndrome) all appear to benefit from treatment (step 5). Treatment interventions are usually implemented in a stepwise fashion addressing all abnormalities that predispose to SDB (step 6) with re-evaluation after each intervention to detect residual disease and to determine the need for additional treatment (step 7).

Infants with viral bronchiolitis demonstrate two distinct patterns of nocturnal oxyhaemoglobin desaturation.

AIM: This study aimed to demonstrate that viral bronchiolitis is associated with intermittent oxygen saturation of haemoglobin (SpO2 ) drops (≥3%) and low basal SpO2 between episodes of haemoglobin desaturation. METHODS: Infants with bronchiolitis underwent pulse oximetry during the first night following hospital admission and a subgroup of them underwent repeat oximetry before hospital discharge. Oximetry was also performed in infants with partial upper airway obstruction (UAO) and without lung disease and in control participants without UAO or lung disease. RESULTS: We enrolled 53 infants: 21 with bronchiolitis, 11 with UAO and 21 healthy controls. Participants with bronchiolitis had lower basal SpO2 (median 93.7% [10th-90th percentiles: 91.1-96.8]) than the subjects with UAO (96.9% [95.3-98.1]; p < 0.01) or the controls (98.7% [96.9-99.3]; p < 0.01). The bronchiolitis group was not different from the UAO group regarding the desaturation index (23.3 episodes/hour [10.3-46.6] and 15.5 episodes/hour [5.4-36.4], respectively; p = 0.08), but differed significantly from the controls (3.1 episodes/hour [0.3-5.5]; p < 0.01). The basal SpO2 and desaturation index improved in 10 subjects with bronchiolitis who had follow-up oximetry before discharge, but these indices remained abnormal when compared to values in the control group. CONCLUSION: Bronchiolitis was characterised by low nocturnal basal SpO2 and intermittent SpO2 drops.

Nocturnal enuresis is associated with moderate-to-severe obstructive sleep apnea in children with snoring.

BACKGROUND: Conflicting data suggest that prevalence of monosymptomatic primary nocturnal enuresis (NE) increases with increasing severity of obstructive sleep apnea (OSA) in childhood and especially in girls. We hypothesized that NE is associated with increased risk of moderate-to-severe OSA (obstructive apnea-hypopnea index (AHI) >5 episodes/hour) among children with snoring. METHODS: Data of children (≥5 y old) with snoring who were referred for polysomnography over 12 y were reviewed. RESULTS: Data of 525 children with mean age (±SD) 7.5 (± 2.2) y and median obstructive AHI (10th-90th percentiles) 1.9 (0.4-7.3) episodes/hour were analyzed. Three hundred and fifty-five children (67.6%) had NE and 87 (16.6%) had moderate-to-severe OSA. There was no interaction between NE and gender regarding the association with moderate-to-severe OSA (P > 0.05). NE was associated significantly with presence of moderate-to-severe OSA after adjustment for tonsillar hypertrophy, obesity, gender, and age (adjusted odds ratio = 1.92 (1.08-3.43); P = 0.03). Presence of NE had high sensitivity (78.2%) and low positive predictive value (19.2%) for detecting moderate-to-severe OSA and low specificity (34.5%) and high negative predictive value (88.8%) for ruling it out. CONCLUSION: Children with snoring and without NE referred for polysomnography are less likely to have moderate-to-severe OSA compared to those with NE.

Atopy does not affect the frequency of adenotonsillar hypertrophy and sleep apnoea in children who snore.

AIM: Viral respiratory infections and atopy have been implicated in the pathogenesis of adenotonsillar hypertrophy and obstructive sleep apnoea (OSA), but the role of atopy is controversial. We aimed to test our hypothesis that atopy, expressed as physician-diagnosed eczema, was associated with adenotonsillar hypertrophy and OSA among children who snored. METHODS: Data on children who snored and were referred for polysomnography were reviewed. The primary outcome measures were adenotonsillar hypertrophy and OSA. RESULTS: We analysed data on 855 children with a mean age (±standard deviation) of 6.3 (±2.5) years and median obstructive apnoea-hypopnea index of 2.1 episodes per hour. Of the 855 subjects, 133 (15.6%) had physician-diagnosed eczema, 591 (69.1%) had adenoidal hypertrophy, 605 (70.8%) had tonsillar hypertrophy, 219 (25.6%) were obese and 470 (55%) had OSA. Eczema was not related to adenoidal or tonsillar hypertrophy after adjustment for gender and age, with odds ratios (OR) of 1.00 (95% confidence interval 0.67-1.49; p = 0.98) and 0.88 (95% confidence interval 0.59-1.32; p = 0.54), respectively. Similarly, eczema did not affect OSA frequency after adjustment for adenoidal and tonsillar hypertrophy, obesity, gender and age, with an adjusted OR of 0.82 (0.56-1.21; p = 0.32). CONCLUSIONS: Atopy was not related to adenotonsillar hypertrophy or OSA in children who snore.

Validation of the Greek OSD-6 quality of life questionnaire in children undergoing polysomnography.

OBJECTIVE: OSD-6 is a disease specific questionnaire for pediatric obstructive sleep apnea (OSA). The aims of this study were to validate OSD-6 in Greek language and correlate OSD-6 with polysomnography results. STUDY DESIGN: Prospective study. SETTING: Tertiary referral center. SUBJECTS AND METHODS: OSD-6 questionnaire was translated to Greek and back to English. A prospective study was conducted on children undergoing overnight polysomnography due to snoring and disrupted sleep. Test-retest evaluation was carried out. Internal consistency and test-retest reliability were evaluated. Validity was assessed by exploring correlations between OSD-6 scores and apnea-hypopnea index (AHI), and by comparing total scores of OSA and non-OSA groups. Responsiveness was assessed by comparing preoperative to postoperative total scores in OSA children who underwent adenotonsillectomy. RESULTS: Test-retest evaluation of 91 subjects showed good internal consistency (Cronbach's alpha 0.860 for test and 0.873 for retest) and reliability (Pearson's correlation coefficients between test and retest scores: 0.751-0.546; p<0.01). Total and domains' OSD-6 scores and AHI were significantly correlated (Spearman's correlation coefficients: 0.277-0.630; p<0.01), while children with OSA had higher total OSD-6 score than those without OSA (median (interquartile range): 16 (11) vs. 10 (7), respectively; p<0.01), indicating good validity. Postoperative OSD-6 scores were significantly lower than preoperative (2.84 ± 3.21 vs. 15.42 ± 6.48, respectively; p<0.001), suggesting good responsiveness. CONCLUSION: The Greek version of the OSD-6 questionnaire proved to be a valid instrument with satisfactory internal consistency, reliability, validity and responsiveness. Furthermore, in our study OSD-6 was significantly correlated to polysomnography results.

Parental history of adenotonsillectomy is associated with obstructive sleep apnea severity in children with snoring.

OBJECTIVE: To test the hypothesis that history of adenoidectomy and/or tonsillectomy (AT) in at least 1 of the parents during childhood, is a risk factor for moderate-to-severe obstructive sleep apnea (OSA) (apnea-hypopnea index [AHI] >5 episodes/hour) in the offspring with snoring. STUDY DESIGN: Data of children with snoring who were referred for polysomnography over 12 years by primary care physicians were reviewed. RESULTS: Data of 798 children without history of prior AT, neuromuscular, or genetic disorders or craniofacial abnormalities were analyzed. Of these children, 69.3% had tonsillar hypertrophy, 25.8% were obese, 26.8% had at least 1 parent with history of AT, and 22.1% had AHI >5 episodes/hour. Parental history of AT was significantly associated with moderate-to-severe OSA (logit model including sex, tonsillar hypertrophy, obesity, and physician-diagnosed wheezing; OR [95% CI], 1.70 [1.18-2.46]; P < .01). When significant variables from the logit model (tonsillar hypertrophy, obesity, parental history of AT) were considered independently or in combination, tonsillar hypertrophy combined with history of AT in at least 1 of the parents had high specificity (84.4%) and the highest positive likelihood ratio (1.78) for identifying children with AHI >5 episodes/hour. CONCLUSIONS: Among children with snoring who are referred for polysomnography by primary care physicians, those with tonsillar hypertrophy and parental history of AT have increased risk of moderate-to-severe OSA and represent 1 of the subgroups that should be prioritized for a sleep study in settings with limited resources.

Variants in C-reactive protein and IL-6 genes and susceptibility to obstructive sleep apnea in children: a candidate-gene association study in European American and Southeast European populations.

BACKGROUND: Preliminary evidence indicates that variants of the C-reactive protein (CRP) and IL-6 genes might be associated with the presence of obstructive sleep apnea (OSA) in childhood. Thus a candidate-gene association study was conducted to investigate the association of four variants of the CRP gene (1444C/T, -717T/C, 1861C/T, and 1919A/T) and two variants of the IL-6 gene (-174G/C and 597G/A) with OSA in a cohort of European American and Greek children. METHODS: The genetic risk effects were estimated based on the odds ratio (OR) of the allele contrast and the generalized odds ratio (ORG), which is a model-free approach. The mode of inheritance was assessed using the degree of dominance index. The impact of haplotypes was also examined. RESULTS: In the American population, the allele contrast and the model-free approach produced significant ORs for the CRP 1444C/T variant (OR, 3.82 [95% confidence interval {CI}, 1.91-7.63] and ORG, 4.37 [95% CI, 1.96-9.76]), respectively, and the mode of inheritance was recessiveness of allele T. Significance was also shown for the CRP 1919A/T variant (OR, 2.45 [95% CI, 1.23-4.85] and ORG, 2.76 [95% CI, 1.26-6.03]) with the mode of inheritance being nondominance of allele T. For the IL-6-174G/C variant, there was an indication of recessiveness of allele C. Finally, the IL-6-174C/IL-6 597A haplotype was associated with OSA. In the Greek population, no association was detected for any variant or haplotype. CONCLUSIONS: Genetic variation in the IL-6/CRP pathway was associated with increased risk for OSA in European American children and may account for the higher CRP levels in the context of pediatric OSA compared to Greek children.

Obstructive sleep apnea, excessive daytime sleepiness, and morning plasma TNF-α levels in Greek children.

BACKGROUND: Obstructive sleep apnea (OSA) has been associated with increased frequency of excessive daytime sleepiness (EDS). Increased plasma TNF-α levels may mediate this association in adults, but conflicting results have been reported in children. We hypothesized that: (i) the higher the OSA severity in childhood, the higher the frequency of EDS and morning plasma TNF-α levels; and (ii) high TNF-α levels predict presence of EDS. METHODS: Children without and with snoring underwent polysomnography. EDS was determined by parental response to specific questions, and plasma TNF-α levels were measured. RESULTS: Children with moderate-to-severe OSA (n = 24; 5.7 ± 2 years; apnea-hypopnea index [AHI] 11.5 ± 5.1/h), but not participants with mild OSA (n = 22; 6 ± 2.5 years; AHI 2.1 ± 1/h) were at significantly higher risk for EDS than controls (n = 22; 6.8 ± 2.1 years; AHI 0.5 ± 0.3/h) (OR [95% CI] adjusted for age, gender, and obesity: 9.2 [1.7-50.2] and 3.8 [0.7-21.8], respectively). The 3 groups did not differ regarding TNF-α concentration (0.63 ± 0.2 vs 0.65 ± 0.18 vs 0.63 ± 0.17 pg/mL; P > 0.05). TNF-α levels were associated significantly with body mass index z-score (P < 0.05) and not with polysomnography indices (P > 0.05). Subjects with high TNF-α levels (> 0.57 pg/mL) were not at higher risk for EDS than participants with low levels (OR [95% CI] adjusted for age, gender, and obesity: 1.7 [0.5-5.7]). CONCLUSIONS: Increasing severity of OSA is associated with increasing frequency of EDS, but not with elevated plasma TNF-α concentration. High TNF-α levels cannot be used as predictor for the presence of EDS in children with sleep apnea.

Low morning serum cortisol levels in children with tonsillar hypertrophy and moderate-to-severe OSA.

BACKGROUND: Hypertrophic tonsillar tissue in children with obstructive sleep apnea (OSA) has enhanced expression of glucocorticoid receptors, which may reflect low endogenous cortisol levels. We have evaluated the effect of the interaction between tonsillar hypertrophy and OSA severity on morning serum cortisol levels. METHODS: Children with and without snoring underwent polysomnography, tonsillar size grading, and measurement of morning serum cortisol. RESULTS: Seventy children (2-13 years old) were recruited: 30 with moderate-to-severe OSA (apnea-hypopnea index [AHI] > 5 episodes/h), 26 with mild OSA (AHI > 1 and ≤ 5), and 14 controls (no snoring; AHI ≤ 1). Tonsillar hypertrophy was present in 56.7%, 53.8%, and 42.9% of participants in each group, respectively. Application of a general linear model demonstrated a significant effect of the interaction between severity of OSA and tonsillar hypertrophy on cortisol levels (P = 0.04), after adjustment for obesity, gender, and age. Among children with tonsillar hypertrophy, subjects with moderate-to-severe OSA (n = 17; AHI 14.7 ± 10.6), mild OSA (n = 14; AHI 2.3 ± 1.2), and control participants (n = 6; AHI 0.7 ± 0.2) were significantly different regarding cortisol levels (P = 0.02). Subjects with moderate-to-severe OSA had lower cortisol (16.9 ± 8.7 mcg/dL) than those with mild OSA (23.3 ± 4.2; P = 0.01) and those without OSA (controls) (23.6 ± 5.3 mcg/dL; P = 0.04). In contrast, children with normal-size tonsils and moderate-to-severe OSA, mild OSA, and controls did not differ in cortisol levels. CONCLUSIONS: Children with moderate-to-severe obstructive sleep apnea and the phenotype of hypertrophic tonsils have reduced morning serum cortisol levels and potentially decreased glucocorticoid inhibitory effects on tonsillar growth.

Low-grade albuminuria in children with obstructive sleep apnea.

Small urinary protein loss (low-grade albuminuria or microalbuminuria) may reflect altered permeability of the glomerular filtration barrier. In the present study, it was hypothesized that children with obstructive sleep apnea have an increased risk of microalbuminuria compared with control subjects without sleep-disordered breathing. Albumin-to-creatinine ratio was measured in morning spot urine specimens collected from consecutive children with or without snoring who were referred for polysomnography. Three groups were studied: (i) control subjects (no snoring, apnea-hypopnea index < 1 episode h(-1) ; n = 31); (ii) mild obstructive sleep apnea (snoring, apnea-hypopnea index = 1-5 episodes h(-1) ; n = 71); and (iii) moderate-to-severe obstructive sleep apnea (snoring, apnea-hypopnea index > 5 episodes∙h(-1) ; n = 27). Indications for polysomnography in control subjects included nightmares, somnambulism and morning headaches. An albumin-to-creatinine ratio > median value in the control group (1.85 mg of albumin per g of creatinine) was defined as elevated. Logistic regression analysis revealed that children with moderate-to-severe obstructive sleep apnea, but not those with mild obstructive sleep apnea, had increased risk of elevated albumin-to-creatinine ratio relative to controls (reference) after adjustment for age, gender and presence of obesity: odds ratio 3.8 (95% confidence interval 1.1-12.6); P = 0.04 and 1.5 (0.6-3.7); P > 0.05, respectively. Oxygen desaturation of hemoglobin and respiratory arousal indices were significant predictors of albumin-to-creatinine ratio (r = 0.31, P = 0.01; and r = 0.43, P < 0.01, respectively). In conclusion, children with moderate-to-severe obstructive sleep apnea are at significantly higher risk of increased low-grade excretion of albumin in the morning urine as compared with control subjects without obstructive sleep apnea. These findings may reflect altered permeability of the glomerular filtration barrier related to nocturnal hypoxemia and sympathetic activation which are induced by obstructive sleep apnea.

Oxidative stress and inflammatory markers in the exhaled breath condensate of children with OSA.

INTRODUCTION: Obstructive sleep apnea (OSA) in children has been associated with systemic inflammation and oxidative stress. Limited evidence indicates that pediatric OSA is associated with oxidative stress and inflammation in the airway. OBJECTIVE: The objective of this study is to assess the hypothesis that levels of oxidative stress and inflammatory markers in the exhaled breath condensate (EBC) of children with OSA are higher than those of control subjects. METHODS: Participants were children with OSA and control subjects who underwent overnight polysomnography. Morning levels of hydrogen peroxide (H(2)O(2)) and sum of nitrite and nitrate (NO(x)) in EBC of participants were measured. RESULTS: Twelve subjects with moderate-to-severe OSA (mean age ± standard deviation: 6.3 ± 1.7 years; apnea-hypopnea index--AHI, 13.6 ± 10.1 episodes/h), 22 subjects with mild OSA (6.7 ± 2.1 years; AHI, 2.8 ± 1 episodes/h) and 16 control participants (7.7 ± 2.4 years; AHI, 0.6 ± 0.3 episodes/h) were recruited. Children with moderate-to severe OSA had higher log-transformed H(2)O(2) concentrations in EBC compared to subjects with mild OSA, or to control participants: 0.4 ± 1.1 versus -0.9 ± 1.3 (p = 0.015), or versus -1.2 ± 1.2 (p = 0.003), respectively. AHI and % sleep time with oxygen saturation of hemoglobin <95% were significant predictors of log-transformed H(2)O(2) after adjustment by age and body mass index z score (p < 0.05). No significant differences were demonstrated between the three study groups in terms of EBC NO(x) levels. CONCLUSIONS: Children with moderate-to-severe OSA have increased H(2)O(2) levels in morning EBC, an indirect index of altered redox status in the respiratory tract.

Effects of adenotonsillectomy on R-R interval and brain natriuretic peptide levels in children with sleep apnea: a preliminary report.

OBJECTIVES: Obstructive sleep apnea is associated with decreased R-R interval length and overall R-R interval variability in the electrocardiogram along with increased morning brain natriuretic peptide (BNP) blood levels. These findings indicate enhanced sympathetic tone and cardiac strain. In this study, it was hypothesized that adenotonsillectomy (AT) in children with sleep apnea is accompanied by improvement in polysomnography indices, increase in length and variability of R-R interval, and reduction in BNP levels. METHODS: Polysomnography and measurements of morning BNP levels were performed before and 4-6months after AT. Mean and standard deviation of R-R interval were calculated from polysomnography electrocardiogram recordings. RESULTS: Twenty-one children were studied. Apnea-hypopnea index and log-transformed BNP levels decreased postoperatively from 8.4±7.6 episodes/h and 2.2±0.7, to 1.8±1.4 episodes/h and 1.9±0.3, respectively (p<0.05). Mean R-R interval increased from 703.2±137.4ms (Stage 2), 699.3±135.8ms (Stage 3), 707.4±128.9ms (Stage 4) and 660.5±140.1ms (Stage REM), to 773.5±122.7ms (Stage 2), 765.7±73.7ms (Stage 3), 771.2±71.6ms (Stage 4), and 738.6±81.7ms (Stage REM), respectively (p<0.05 for comparisons pre- vs. post-operatively). Standard deviation of R-R in Stage 2 increased from 88.5±29.6 to 122.7±67ms (p=0.045). CONCLUSIONS: Increase in nocturnal length of R-R interval and decrease in BNP levels after AT for sleep apnea may reflect postoperative reduction in sympathetic tone and cardiac strain.

Effects of obstructive sleep apnea severity on serum lipid levels in Greek children with snoring.

BACKGROUND: Although obstructive sleep apnea (OSA) is related to dyslipidemia in adults, limited data are available regarding its effects on serum lipids during childhood. Aim of this study was to assess the potential relationships between severity of OSA and cholesterol or triglyceride levels in a cohort of Greek children. METHODS: Data from children with snoring who underwent polysomnography and complete serum lipids measurements during a specified study period were analyzed retrospectively. RESULTS: Overall, obese children (n = 261) had lower HDL cholesterol levels than non-obese subjects (n = 113) (49.6 ± 10.5 vs. 53.9 ± 11.4 mg/dL; p = 0.001) and higher triglyceride concentrations (69.8 ± 32.2 vs. 63.2 ± 27 mg/dL; p = 0.041). Non-obese subjects with moderate-to-severe OSA did not differ in triglycerides, total, and LDL cholesterol concentrations but had lower HDL cholesterol, when compared to non-obese children with primary snoring/mild OSA (50.4 ± 13.1 vs. 54.9 ± 10.7 mg/dL; p = 0.008). The risk for having low HDL cholesterol (≤40 mg/dL) was threefold higher in non-obese subjects with moderate-to-severe OSA than in those with primary snoring/mild OSA, even after adjustment for age and gender [OR = 3.44 (95% CI 1.44 to 8.24; p = 0.006)]. Concentrations of serum lipids in obese children were not associated with severity of OSA. HDL cholesterol was 48.5 ± 8.7 mg/dL in subjects with moderate-to-severe OSA and 50.0 ± 11.1 mg/dL in children with primary snoring/mild OSA (p = 0.519). CONCLUSIONS: HDL cholesterol levels are inversely related to severity of OSA in non-obese children with snoring.

Correlation of urinary excretion of sodium with severity of sleep-disordered breathing in children: a preliminary study.

BACKGROUND: Nocturnal urinary sodium excretion is related to blood pressure (BP) levels. Elevated BP and increased nocturnal natriuresis have been demonstrated in adults with sleep apnea. Although evidence indicates increased BP in children with obstructive sleep-disordered breathing (SDB), it is unknown whether these children have also enhanced urinary sodium excretion. OBJECTIVE: To evaluate the effects of SDB and morning BP on urinary sodium excretion. METHODS: Consecutive children with snoring (n = 95) underwent polysomnography and morning BP measurement. Fractional excretion of sodium (FE(Na)) was the primary outcome measure and was calculated using sodium and creatinine concentrations in early morning serum and urine specimens. RESULTS: Subjects with moderate-to-severe SDB had similar log-transformed FE(Na) to that of children with mild SDB and higher than children with primary snoring: -0.13 ± 0.53 versus -0.28 ± 0.41 versus -0.61 ± 0.65 (P = 0.657 and P = 0.003). Obstructive apnea-hypopnea index was significantly related to FE(Na) after adjustment for age, gender and body mass index z-score (P = 0.002). Children with moderate-to-severe SDB had similar systolic BP z-scores to those of subjects with mild SDB and higher than participants with primary snoring: 0.7 ± 1.2 versus 0.1 ± 1.0 versus -0.02 ± 1.0 (P = 0.074 and P = 0.046). In addition, participants with diastolic BP z-scores in the upper quartile of measured values had higher FE(Na) than subjects with z-scores in the lower quartiles: -0.08 ± 0.39 versus -0.41 ± 0.57 (P = 0.007). CONCLUSIONS: Morning natriuresis is related to severity of SDB in children and this association may be mediated in part by elevated BP.

Adiposity and low-grade systemic inflammation modulate matrix metalloproteinase-9 levels in Greek children with sleep apnea.

BACKGROUND: Matrix metalloproteinase-9 (MMP-9) plasma levels correlate with C-reactive protein (CRP) concentrations and they are both increased in adults with obstructive sleep apnea (OSA). No studies have evaluated MMP-9 levels in children with sleep apnea and CRP is not consistently elevated in pediatric OSA. The aim of this investigation was to evaluate the association of severity of OSA, adiposity, and CRP with MMP-9 plasma levels in Greek children. METHODS: Consecutive children with snoring who underwent polysomnography and were found to have OSA (obstructive apnea-hypopnea index-OAHI > or = 1 episode/hr) were recruited. Subjects without OSA (OAHI < 1 episode/hr) were included for comparison. Morning plasma MMP-9 and CRP were measured. RESULTS: Twenty-nine children with moderate-to-severe OSA (age 5.4 +/- 1.5 years; OAHI 13.9 +/- 13.0 episodes/hr), 55 participants with mild OSA (6.4 +/- 2.6 years; OAHI 2.4 +/- 1.1 episodes/hr) and 22 subjects without OSA (6.8 +/- 2.6 years; OAHI 0.6 +/- 0.2 episodes/hr) were studied. Children with moderate-to-severe OSA were similar to those with mild OSA or without OSA regarding ln-transformed MMP-9 values (5.87 +/- 0.60 vs. 5.84 +/- 0.55 vs. 5.80 +/- 0.46; P > 0.05) and CRP concentrations (0.22 +/- 0.29 mg/dl vs. 0.21 +/- 0.36 vs. 0.13 +/- 0.16 mg/dl; P > 0.05). In multiple linear regression, body mass index (P = 0.027) and CRP levels (P = 0.008), but not OAHI or SpO(2) nadir (P > 0.05), were significantly related to MMP-9 values. CONCLUSIONS: Adiposity and systemic inflammation unrelated to OSA severity, modulate MMP-9 levels in Greek children.

Serum nitrite and nitrate levels in children with obstructive sleep-disordered breathing.

BACKGROUND: Diminished nitric oxide (NO) levels have been reported in adults with obstructive sleep apnea but no data are available for children with obstructive sleep-disordered breathing (SDB). OBJECTIVES: To assess levels of serum NO metabolites in children with SDB and to explore the effects of NO metabolites, SDB and their interaction on blood pressure. METHODS: Morning nitrite, the sum of nitrite and nitrate (NO(x)), and the average of evening and morning blood pressure were assessed in children with SDB referred for polysomnography and in controls without SDB. RESULTS: Forty-three children with SDB (age: 5.8+/-2.1 years) had moderate-to-severe nocturnal hypoxemia (SpO(2) nadir: 85.6+/-4%), 54 subjects (6.6+/-2.7 years) had mild hypoxemia (SpO(2) nadir: 91.4+/-1.3%) and 20 subjects were controls free of SDB (6.7+/-3.7 years). Subjects with moderate-to-severe hypoxemia had significantly lower ln-transformed NO metabolites (1.4+/-0.7, nitrites; 2.6+/-0.5, NO(x)) compared to those with mild hypoxemia (1.9+/-0.8, nitrites; 3+/-0.6, NO(x)) and controls (2.2+/-0.7, nitrite; 3+/-0.6, NO(x); p<0.05). The effects of NO metabolites and SDB or their interaction on blood pressure were not significant (p>0.05). CONCLUSIONS: Moderate-to-severe hypoxemia accompanying SDB is associated with reduced concentrations of morning serum NO metabolites, but NO levels do not seem to affect blood pressure.