title: Sleep disordered breathing and autonomic function in overweight and obese children and adolescents.
abstract: Obstructive sleep apnoea (OSA), common in children with obesity, is associated with cardiovascular morbidity. Autonomic dysfunction has been suggested to be a key player in the development of these complications. We investigated the relationship between obesity, OSA and sympathetic activity in children. 191 children with obesity were included and distributed into two groups: 131 controls and 60 with OSA. Beat-to-beat RR interval data were extracted from polysomnography for heart rate variability analysis. Urinary free cortisol levels were determined. Urinary free cortisol did not differ between groups and was not associated with OSA, independent of the level of obesity. Differences in heart rate variability measures were found: mean RR interval decreased with OSA, while low/high-frequency band ratio and mean heart rate increased with OSA. Heart rate variability measures correlated with OSA, independent of obesity parameters and age: oxygen desaturation index correlated with mean heart rate (r=0.19, p=0.009) and mean RR interval (r= -0.18, p=0.02), while high-frequency bands and low/high-frequency band ratio correlated with arterial oxygen saturation measured by pulse oximetry (SpO2) (r= -0.20, p=0.008 and r= -0.16, p=0.04) andSpO2nadir (r=0.23, p=0.003 and r= -0.19, p=0.02). These results suggest that sympathetic heart activity is increased in children with obesity and OSA. Measures of hypoxia were related to increased sympathetic tone, suggesting that intermittent hypoxia is involved in autonomic dysfunction.
authors.affiliation: Laboratory of Experimental Medicine and Pediatrics, University of Antwerp, Antwerp, Belgium; Dept of Paediatrics, Antwerp University Hospital, Edegem, Belgium.
authors.forename: Annelies
authors.initials: A
authors.lastname: Van Eyck
authors.affiliation: Laboratory of Experimental Medicine and Pediatrics, University of Antwerp, Antwerp, Belgium; Dept of Paediatrics, Antwerp University Hospital, Edegem, Belgium.
authors.forename: Kim
authors.initials: K
authors.lastname: Van Hoorenbeeck
authors.affiliation: Laboratory of Experimental Medicine and Pediatrics, University of Antwerp, Antwerp, Belgium.
authors.forename: Benedicte Y
authors.initials: BY
authors.lastname: De Winter
authors.affiliation: Laboratory of Experimental Medicine and Pediatrics, University of Antwerp, Antwerp, Belgium; Dept of Endocrinology, Diabetology and Metabolism, Antwerp University Hospital, Edegem, Belgium.
authors.forename: Luc
authors.initials: L
authors.lastname: Van Gaal
authors.affiliation: Laboratory of Experimental Medicine and Pediatrics, University of Antwerp, Antwerp, Belgium; Dept of Pulmonology, Antwerp University Hospital, Edegem, Belgium.
authors.forename: Wilfried
authors.initials: W
authors.lastname: De Backer
authors.affiliation: Laboratory of Experimental Medicine and Pediatrics, University of Antwerp, Antwerp, Belgium; Dept of Paediatrics, Antwerp University Hospital, Edegem, Belgium.
authors.forename: Stijn L
authors.initials: SL
authors.lastname: Verhulst