title: Improved long-term autonomic function following resolution of sleep-disordered breathing in preschool-aged children.
abstract: OBJECTIVE
  Sleep-disordered breathing (SDB) prevalence peaks in preschool children and is associated with deficits in cardiovascular functioning during sleep. No long-term studies have investigated the effects of SDB resolution in mitigating these outcomes. We hypothesized that following 3 years, normalization of alterations to heart rate (HR), pulse transit time (PTT), heart rate variability (HRV), and urinary catecholamines identified at the initial diagnosis would be associated with resolution of SDB.
  
  
  METHODS
  Forty-five children with SDB and 28 non-snoring controls underwent polysomnography at baseline (3-5 years) and follow-up (6-9 years). Children were classified into control, resolved, and unresolved SDB. Resolution was defined as an obstructive apnea-hypopnea index (OAHI) ≤1 event/h, no snoring on polysomnography (PSG), or indicated by parents. PTT is an inverse surrogate measure of blood pressure change. HRV was assessed using power spectral analysis.
  
  
  RESULTS
  There was no change in PTT or HR between studies for any group. Our HRV data suggest reduced parasympathetic activity in children whose SDB resolved and increased parasympathetic activity in children whose SDB remained the same or worsened at follow-up. We identified a significant correlation between low frequency power and urinary dopamine and adrenaline levels at follow-up in the unresolved group, suggesting increased sympathetic activity in children with unresolved SDB.
  
  
  CONCLUSIONS
  Our findings suggest an association between resolution of SDB and normalization of HRV in the long term in these preschool children and an augmented sympathetic activity in the children with residual SDB. This highlights the autonomic impact of SDB in young children and the importance of detection and treatment.
authors.affiliation: The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia. lisa.walter@monash.edu.|Department of Paediatrics, Monash University, Melbourne, Australia. lisa.walter@monash.edu.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Walter
authors.affiliation: The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia.|Department of Paediatrics, Monash University, Melbourne, Australia.
authors.forename: Sarah N
authors.initials: SN
authors.lastname: Biggs
authors.affiliation: The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia.
authors.forename: Lauren C
authors.initials: LC
authors.lastname: Nisbet
authors.affiliation: The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia.
authors.forename: Aidan J
authors.initials: AJ
authors.lastname: Weichard
authors.affiliation: The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia.
authors.forename: Samantha L
authors.initials: SL
authors.lastname: Hollis
authors.affiliation: The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia.|Department of Paediatrics, Monash University, Melbourne, Australia.|Melbourne Children's Sleep Centre, Monash Children's Hospital, Melbourne, Australia.
authors.forename: Margot J
authors.initials: MJ
authors.lastname: Davey
authors.affiliation: Clinical Sciences Research, Murdoch Children's Research Institute, Melbourne, Australia.
authors.forename: Vicki
authors.initials: V
authors.lastname: Anderson
authors.affiliation: The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia.|Department of Paediatrics, Monash University, Melbourne, Australia.|Melbourne Children's Sleep Centre, Monash Children's Hospital, Melbourne, Australia.
authors.forename: Gillian M
authors.initials: GM
authors.lastname: Nixon
authors.affiliation: The Ritchie Centre, Hudson Institute of Medical Research, Melbourne, Australia.|Department of Paediatrics, Monash University, Melbourne, Australia.
authors.forename: Rosemary S C
authors.initials: RS
authors.lastname: Horne
mesh_terms: D001341:Autonomic Nervous System / Q000503:physiopathology*; D001794:Blood Pressure / Q000502:physiology; D002675:Child, Preschool; D004298:Dopamine / Q000652:urine; D004562:Electrocardiography; D004837:Epinephrine / Q000652:urine; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D063177:Pulse Wave Analysis; D012815:Signal Processing, Computer-Assisted; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology* / Q000628:therapy*; D016896:Treatment Outcome
chemical_list: D004298:Dopamine; D004837:Epinephrine
keywords: Autonomic nervous system; Obstructive sleep apnea; Pediatrics; Power spectral analysis