title: Delayed brachial artery dilation response and increased resting blood flow velocity in young children with mild sleep-disordered breathing.
abstract: OBJECTIVE
  This study aimed to evaluate whether the vascular dysfunction perceived in adults with sleep-disordered breathing (SDB) was also evident in children with snoring referred for evaluation of clinically suspected SDB.
  
  
  OBJECTIVE
  This study compared flow-mediated dilatation (FMD), measured at the brachial artery, at rest and during hyperaemic stress between children who snore [n = 23; mean standard deviation (SD) age = 7.51 (1.3) years] and healthy, non-snoring children [n = 11; age = 8.0 (1.3) years].
  
  
  METHODS
  Children with suspected obstructive sleep apnoea (OSA) and healthy non-snoring controls underwent overnight polysomnography (PSG). Using standard techniques, non-invasive FMD and brachial arterial blood flow velocity during rest and hyperaemia were subsequently measured by ultrasound imaging
  
  
  METHODS
  Resting and hyperaemic velocity time integral (area under the curve of mean systolic velocity × ejection time), maximal dilation response (highest percentage difference from baseline diameter) and the time taken to reach maximal dilation were calculated.
  
  
  RESULTS
  Children awaiting adenotonsillectomy compared to healthy non-snoring control children had higher velocity time integrals at rest (14 ± 3 m vs. 20 ± 8 m, p < 0.01) and during hyperaemic stress (56 ± 6m vs. 63 ± 13m, p < 0.01) despite having only mild SDB on polysomnographic assessment. Lower nadir oxygen saturation values during non-rapid eye movement sleep were negatively associated with higher resting (r = -0.58, p <0.001) and hyperaemic (r = -0.36, p < 0.05) velocity time integrals. Maximal FMD dilatation response was not significantly different between snoring and non-snoring groups, but the estimated time to reach maximal dilation was significantly delayed in children who snored (60.7 ± 28.4 vs. 39.2 ± 13.2 s, p < 0.05).
  
  
  CONCLUSIONS
  Children with mild SDB showed increased blood flow velocity at rest and during hyperaemic stress suggesting altered cardiovascular and haemodynamic function. The delay in time to maximal vessel dilatation in children who snored also suggests possible reduced vascular compliance in response to hyperaemic sheer stress. Mild SDB appears to alter the peripheral vascular response in young children. The long-term vascular implications of these changes in the growing child are unknown and warrant further investigation.
authors.affiliation: Robinson's Institute, School of Paediatrics and Reproductive Health, University of Adelaide, Australia. Electronic address: anna.kontos@adelaide.edu.au.
authors.forename: Anna
authors.initials: A
authors.lastname: Kontos
authors.affiliation: Research Branch, University of Adelaide, Australia.
authors.forename: Cameron
authors.initials: C
authors.lastname: van den Heuvel
authors.affiliation: Department of Respiratory and Sleep Medicine, Women's and Children's Hospital, Adelaide, Australia.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Pamula
authors.affiliation: Robinson's Institute, School of Paediatrics and Reproductive Health, University of Adelaide, Australia; Department of Respiratory and Sleep Medicine, Women's and Children's Hospital, Adelaide, Australia.
authors.forename: James
authors.initials: J
authors.lastname: Martin
authors.affiliation: School of Psychology, Social Work and Social Policy, University of South Australia, Australia.
authors.forename: Kurt
authors.initials: K
authors.lastname: Lushington
authors.affiliation: School of Electrical and Electronic Engineering, University of Adelaide, Adelaide, Australia.
authors.forename: Mathias
authors.initials: M
authors.lastname: Baumert
authors.affiliation: School of Medicine, University of Adelaide, Australia.
authors.forename: Scott
authors.initials: S
authors.lastname: Willoughby
authors.affiliation: Department of Medical Imaging, Women's and Children's Hospital, Adelaide, Australia.
authors.forename: Roger
authors.initials: R
authors.lastname: Gent
authors.affiliation: Robinson's Institute, School of Paediatrics and Reproductive Health, University of Adelaide, Australia.
authors.forename: Jenny
authors.initials: J
authors.lastname: Couper
authors.affiliation: Robinson's Institute, School of Paediatrics and Reproductive Health, University of Adelaide, Australia; Department of Respiratory and Sleep Medicine, Women's and Children's Hospital, Adelaide, Australia.
authors.forename: Declan
authors.initials: D
authors.lastname: Kennedy
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology*; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D002648:Child; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000209:etiology; D008297:Male; D017286:Polysomnography; D012146:Rest / Q000502:physiology; D012891:Sleep Apnea Syndromes / Q000503:physiopathology*; D012913:Snoring / Q000150:complications / Q000503:physiopathology*; D014463:Ultrasonography; D014664:Vasodilation
keywords: Blood flow velocity; Cardiovascular; Flow-mediated dilatation; Paediatric; Sleep apnoea