N Schrauwen

University of Antwerp, Antwerpen, Flanders, Belgium

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Publications (12)37.8 Total impact

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    ABSTRACT: The aim of this retrospective study was to investigate if sleep-disordered breathing (SDB) was an independent predictor of suspected fatty liver disease in a clinical sample of overweight children and adolescents. Consecutive overweight and obese children attending a pediatric obesity clinic underwent polysomnography, fasting blood sample, and abdominal ultrasound. The respiratory disturbance index, percentage of total sleep time with SO2 < 90%, and SaO2nadir were associated with higher alanine amino-transferases (ALT) independent of abdominal obesity. Multiple logistic regression selected waist circumference (odds ratio = 1.05; p = 0.05) and SaO2nadir (odds ratio = 0.87; p = 0.03) as predictors of suggestive fatty liver disease, defined as ALT > 40 U/L and/or hyperechoic liver on abdominal ultrasound. This study supports the association between the severity of SDB and suspected fatty liver disease in a clinical sample of overweight children and adolescents. We recommend more research on the influence of SDB on the development of fatty liver disease and on the effect of treating sleep apnea on liver function parameters.
    Sleep And Breathing 11/2008; 13(2):207-10. · 2.26 Impact Factor
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    ABSTRACT: To assess whether sleep-disordered breathing (SDB) in overweight children and adolescents has an additional effect on the spectrum of urinary albumin to protein loss, as markers of early kidney dysfunction. Prospective study in a clinical sample of overweight children and adolescents. Each subject underwent anthropometry, blood sampling, oral glucose tolerance test and polysomnography. From a 24-hour urine collection, albumin excretion rate and total urinary protein to creatinine ratio (UPCR) were calculated. 94 nondiabetic subjects were included (mean age = 11.0 +/- 2.5, 42 boys). Average BMI z-score was 2.25 +/- 0.47 (26 overweight subjects and 68 obese subjects). There was no difference in albumin excretion rate or UPCR between subjects with and without SDB. None of the SDB parameters correlated with the transformed albumin excretion rate or UPCR. Albumin excretion rate significantly correlated with fasting insulin and C-peptide and with post-challenge glucose, insulin and C-peptide levels, while UPCR correlated with fasting and post-challenge C-peptide levels. Multiple regression indicated that post-challenge glucose levels were the most important predictors of albumin excretion rate. Insulin resistance, and not SDB, was associated with increased levels of albuminuria, indicating early renal dysfunction, in this clinical sample of overweight children and adolescents.
    Hormone Research 10/2008; 70(4):224-9. · 2.48 Impact Factor
  • Journal of Paediatrics and Child Health 10/2008; 44(9):529-30. · 1.25 Impact Factor
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    ABSTRACT: To investigate the relationship between obstructive sleep apnea syndrome (OSAS) and exhaled nitric oxide (eNO) in overweight children and adolescents without asthma or atopy and to assess whether obesity per se is associated with increased airway inflammation. Consecutive overweight subjects without symptoms of asthma or allergy were recruited at a pediatric obesity clinic. A normal-weight control group without OSAS and asthma or allergy was also recruited. All subjects underwent polysomnography and two measurements of eNO (afternoon and morning after polysomnography). Controlling for age, the mean (+/- SD) afternoon eNO concentration was significantly higher in the snoring group (14.1 +/- 1.1 parts per billion [ppb]) compared with the normal-weight group (10.1 +/- 0.8 ppb; p = 0.03) and with the overweight group with normal polysomnography findings (8.9 +/- 0.8 ppb; p = 0.007). The afternoon eNO concentration was also different between the OSAS group (11.9 +/- 1.0 ppb) and the overweight group with normal polysomnography findings (p = 0.03). Morning eNO values were higher in the OSAS group (12.3 +/- 1.1 ppb) than in the normal weight group (9.9 +/- 0.8 ppb; p = 0.047) and in the overweight control group (9.7 +/- 0.7 ppb; p = 0.02). BMI z score was not significantly correlated with afternoon eNO concentration or with morning eNO concentration. This study illustrates that both habitual snoring and OSAS are associated with increased airway inflammation in overweight children as assessed by higher eNO levels. Furthermore, it was demonstrated that childhood obesity in the absence of sleep-disordered breathing is not associated with increased airway inflammation.
    Chest 09/2008; 134(6):1169-75. · 7.13 Impact Factor
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    ABSTRACT: To assess if the severity of sleep-disordered breathing (SDB) and mainly intermittent hypoxia is associated with increased peripheral leukocytes in overweight children and adolescents, controlling for adiposity and obesity-related metabolic abnormalities. Consecutive subjects were recruited at a pediatric obesity clinic. All subjects underwent polysomnography and a fasting blood sample. In total, 95 subjects were included ( =11.1+/-2.6, 43 boys, body mass index, =2.3+/-0.5, 29 subjects were overweight and 66 obese). Total white blood cell count increased significantly by worsening of intermittent hypoxia. Total white blood cell count was correlated with the maximal degree of desaturation, independent of puberty, HOMA and HDL-cholesterol. Neutrophil levels were associated with the degree of desaturation, while controlling for puberty and HOMA. This study supports the hypothesis of an independent interaction between intermittent hypoxia and nocturnal desaturation during sleep, and increased white blood cell and neutrophil levels in overweight and obese children and adolescents. This finding may contribute to the mechanisms linking SDB with increased cardiovascular morbidity.
    International journal of pediatric obesity: IJPO: an official journal of the International Association for the Study of Obesity 07/2008; 3(4):234-9. · 2.00 Impact Factor
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    Archives of Disease in Childhood 02/2008; 93(1):89-90. · 3.05 Impact Factor
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    ABSTRACT: Sleep-disordered breathing (SDB) in childhood obesity is associated with hyperinsulinemia, dyslipidemia and inflammation and by these mechanisms, SDB could contribute to development of non-alcoholic fatty liver disease. We, therefore, investigated if SDB was an independent predictor of suspected fatty liver disease in a clinical sample of overweight and obese children and adolescents. Retrospective case study of consecutive overweight or obese children and adolescents attending a paediatric obesity clinic. Suggestive fatty liver disease was defined as a serum alanine aminotransferase >40 U·L–1 and/or a hyperechoic liver on abdominal ultrasound. Subjects with suggestive fatty liver disease presented with higher waist circumference, more circulating peripheral leukocytes and a lower % of total sleep time with SaO2 95% than their peers with a normal liver evaluation. Multiple logistic regression (stepwise forward) selected waist circumference (odds ratio = 1.05; 95% confidence interval = 1.00–1.10; p = 0.06) and SaO2nadir (odds ratio = 0.87; 95% confidence interval = 0.76–0.99; p = 0.03) as predictors of suggestive fatty liver disease. This study suggests an association between the severity of SDB and suspected fatty liver disease in a clinical sample of overweight and obese children and adolescents. We strongly recommend more and carefully designed research on the influence of SDB on the development of fatty liver disease and on the effect of treating sleep apnoea on liver function parameters.
    European Respiratory Review. 01/2008;
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    ABSTRACT: To assess whether sleep-disordered breathing (SDB) is a risk factor of the metabolic syndrome (MS) in children and adolescents who are overweight and to examine whether the severity of SDB was independently associated with glucose intolerance, insulin resistance, and/or dyslipidemia. Consecutive subjects who were overweight or obese underwent polysomnography, fasting blood sample, and oral glucose tolerance test (for calculation of area under the curve [AUC]). SDB was defined as a respiratory disturbance index > or = 2. MS was present when > or = 3 of these factors were present: waist circumference > or = 90th percentile; fasting glucose level > or = 110 mg/dL; triglyceride level > or = 110 mg/dL; high-density lipoprotein cholesterol level < or = 40 mg/dL; blood pressure > or = 90th percentile. A total of 104 subjects were included in the study (44% boys; 58% prepubertal; mean age, 11.1 +/- 2.6 years; 69% obese). Mean SaO2 (odds ratio, 0.54) and SaO2nadir (odds ratio, 0.89) were independent, significant predictors of the presence of MS. Multiple regression showed significant associations between SaO2nadir and high-density lipoprotein cholesterol level, mean SaO2 and both AUC glucose and triglyceride levels, and between the percentage of total sleep time with SaO2 > or = 95% and cholesterol level, while controlling for adiposity and sex, puberty, or both. This study supports the hypothesis of an interaction between SDB and metabolic abnormalities, independent of estimates of body fat distribution, in children and adolescents who are overweight and obese.
    The Journal of pediatrics 07/2007; 150(6):608-12. · 4.02 Impact Factor
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    ABSTRACT: The aim of this study was to determine whether the severity of sleep-disordered breathing (SDB) was associated with increased levels of uric acid (UA), both in serum and in urine, as a marker of tissue hypoxia, in a sample of overweight and obese subjects, irrespective of indexes of adiposity. Consecutive subjects underwent polysomnography, fasting blood sampling, and 24-h urine collection. Outcome parameters were serum UA, UA excretion ([24-h urinary UA x serum creatinine]/urine creatinine) and urinary UA/creatinine ratio. A total of 93 subjects were included (44% boys; mean [+/- SD] age = 11.1 +/- 2.5; 73% obese). A fasting measurement of serum UA levels was available for 62 patients. The respiratory disturbance index was a significant covariate (beta = 0.09 +/- 0.03; p = 0.01) in the regression model for serum UA, controlling for sex (beta = 0.32 +/- 0.29; p = 0.3), puberty (beta = 0.87 +/- 0.34; p = 0.01), and waist circumference (beta = 0.04 +/- 0.01; p = 0.005). The percentage of total sleep time with arterial oxygen saturation < or = 89% (beta = 0.94 +/- 0.45; p = 0.04) was also significantly associated with serum UA level, controlling for sex (beta = 0.22 +/- 0.30; p = 0.5), puberty (beta = 0.83 +/- 0.35; p = 0.02), and waist circumference (beta = 0.04 +/- 0.02; p = 0.02). None of the SDB variables correlated with UA excretion or with urinary UA/creatinine ratio. This study in overweight children and adolescents demonstrated a relationship between the severity of sleep apnea and increased levels of serum UA, independent of abdominal adiposity. In view of the known associations between UA and cardiovascular risk, this finding may contribute to the mechanisms linking SDB with cardiovascular morbidity.
    Chest 07/2007; 132(1):76-80. · 7.13 Impact Factor
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    ABSTRACT: To determine the prevalence of sleep-disordered breathing (SDB) in a clinical sample of overweight and obese children and adolescents, and to examine the contribution of fat distribution. Consecutive subjects without chronic lung disease, neuromuscular disease, laryngomalacia, or any genetic or craniofacial syndrome were recruited. All underwent measurements of neck and waist circumference, waist-to-hip ratio, % fat mass and polysomnography. Obstructive apnoea index > or =1 or obstructive apnoea-hypopnoea index (OAHI) > or =2, further classified as mild (2< or =OAHI<5) or moderate-to-severe (OAHI> or =5), were used as diagnostic criteria for obstructive sleep apnoea (OSA). Central sleep apnoea was diagnosed when central apnoeas/hypopnoeas > or =10 s were present accompanied by >1 age-specific bradytachycardia and/or >1 desaturation <89%. Subjects with desaturation < or =85% after central events of any duration were also diagnosed with central sleep apnoea. Primary snoring was diagnosed when: snoring was detected by microphone and normal obstructive indices and saturation. 27 overweight and 64 obese subjects were included (40 boys; mean (standard deviation (SD)) age 11.2 (2.6) years). Among the obese children, 53% were normal, 11% had primary snoring, 11% had mild OSA, 8% had moderate-to-severe OSA and 17% had central sleep apnoea. Half of the patients with central sleep apnoea had desaturation <85%. Only enlarged tonsils were predictive of moderate-to-severe OSA. On the other hand, higher levels of abdominal obesity and fat mass were associated with central sleep apnoea. SDB is very common in this clinical sample of overweight children. OSA is not associated with abdominal obesity. On the contrary, higher levels of abdominal obesity and fat mass are associated with central sleep apnoea.
    Archives of Disease in Childhood 04/2007; 92(3):205-8. · 3.05 Impact Factor
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    ABSTRACT: Only a limited number of studies, designed to establish normal values for sleep-related respiratory variables in children, have been reported, and all are non-European. The aim of this study was to expand the knowledge on normative data in children. Subjects ranging from 6 to 16 years were recruited and underwent full polysomnography. Only subjects without sleep disordered breathing or other sleep problems as assessed by clinical history were included. Sixty subjects were studied ( = 11.7 +/- 2.6 years; 28 boys; = 118.8 +/- 30.6%). was 0.85 +/- 1.06 (range: 0.0-5.5). was 0.06 +/- 0.16 (range: 0.0-0.9); 11 patients had a total of 31 obstructive apneas. Only five obstructive hypopneas were detected with = 0.08 +/- 0.17 (range: 0.0-0.9). was 1.98 +/- 1.39 (range: 0.1-7.2). was 97.0 +/- 0.6% (range: 96.0-98.0); was 91.8 +/- 2.7% (range: 82.0-96.0); <% of total sleep time with SaO2 >or= 95%> was 98.7 +/- 2.1% (range: 90.8-100.0); was 0.8 +/- 0.9 (range: 0.0-4.9) and was 6.1 +/- 1.8 (range: 2.7-10.9). Snoring was detected in 15 patients (4 overweight subjects), with no difference in patient characteristics and sleep-related respiratory variables between snorers and non-snorers. Subjects in the overweight group (n = 22) had a lower SaO2nadir (90.8 +/- 2.7 vs. 92.4 +/- 2.6; P = 0.01) and a higher ODI (1.3 +/- 1.3 vs. 0.4 +/- 0.4; P = 0.0002) than their normal weight peers. Our data are in agreement with other non-European studies, designed to establish normal values in children.
    Pediatric Pulmonology 03/2007; 42(2):159-67. · 2.38 Impact Factor
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    ABSTRACT: To assess the presence of a first night effect (FNE) in children and adolescents and to examine if a single night polysomnography (PSG) is sufficient for diagnosing obstructive sleep apnoea syndrome (OSAS). Prospective case study of 70 patients (group 1: 2-6 years, n = 22; group 2: 7-12 years, n = 32; group 3: 13-17 years, n = 16) referred for OSAS. Diagnostic criteria for OSAS: one or more of the following: (1) obstructive apnoea index (OAI) > or =1; (2) obstructive apnoea hypopnoea index (oAHI) > or =2; (3) SaO2 < or =89% in association with obstruction. In all age groups, but mainly in the oldest children, REMS increased during the second night, mainly at the expense of stage 2 sleep. The first night PSG correctly identified OSAS in 86%, 91%, and 100% of the children for groups 1, 2, and 3 respectively. This represents 9% false negatives for OSAS when only the first night PSG was used. All cases missed had mild OSAS, except for one with oAHI >5 on night 2. There were also seven patients with OSAS on night 1 but with a normal PSG on night 2: all had oAHI <5. There is a FNE in children and adolescents. A single night PSG is sufficient for diagnosing OSAS, but in cases with a suggestive history and examination and with a negative first night, a second night study might be advisable.
    Archives of Disease in Childhood 03/2006; 91(3):233-7. · 3.05 Impact Factor