title: Poincaré plot width, morning urine norepinephrine levels, and autonomic imbalance in children with obstructive sleep apnea.
abstract: BACKGROUND
  Obstructive sleep apnea (OSA) in childhood is accompanied by sympathetic overflow unopposed by the parasympathetic tone. Complex methods like power spectral analysis of heart rate variability have been applied to study this imbalance. In this report, width of Poincaré scattergram of the R-R interval (parasympathetic tone) and morning urine norepinephrine concentration (sympathetic activity) were used to assess autonomic imbalance.
  
  
  METHODS
  Poincaré plot was obtained from the electrocardiographic channel of nocturnal polysomnography and its width was measured, and norepinephrine-to-creatinine concentration ratio was calculated in morning urine specimen.
  
  
  RESULTS
  Twenty children with obstructive sleep apnea and moderate-to-severe nocturnal hypoxemia (oxygen saturation of hemoglobin [SpO(2)] nadir <90%), 24 subjects with mild hypoxemia (SpO(2) nadir ≥90%), and 11 control subjects were recruited. Children with obstructive sleep apnea and moderate-to-severe hypoxemia had significantly narrower Poincaré plot width (318.7 ± 139.3 ms) and higher ln-transformed urine norepinephrine-to-creatinine ratio (4.5 ± 0.6) than control subjects (484.2 ± 104.4 ms and 3.8 ± 0.4, respectively; P < 0.05). Ln-transformed urine norepinephrine levels were inversely related to Poincaré plot width (P = 0.02).
  
  
  CONCLUSIONS
  Subjects with obstructive sleep apnea and moderate-to-severe nocturnal hypoxemia have enhanced sympathetic activity and reduced parasympathetic drive. Poincaré plot width and urine norepinephrine levels are simple measures of autonomic imbalance in pediatric obstructive sleep apnea.
authors: Pediatric Pulmonology Unit and Sleep Disorders Laboratory, First Department of Pediatrics, University of Athens School of Medicine and Aghia Sophia Children's Hospital, Athens, Greece.
authors: Konstantinos
authors: K
authors: Chaidas
authors: Pediatric Pulmonology Unit and Sleep Disorders Laboratory, First Department of Pediatrics, University of Athens School of Medicine and Aghia Sophia Children's Hospital, Athens, Greece.
authors: Marina
authors: M
authors: Tsaoussoglou
authors: Pediatric Pulmonology Unit and Sleep Disorders Laboratory, First Department of Pediatrics, University of Athens School of Medicine and Aghia Sophia Children's Hospital, Athens, Greece.
authors: Emmanouel
authors: E
authors: Theodorou
authors: Pediatric Pulmonology Unit and Sleep Disorders Laboratory, First Department of Pediatrics, University of Athens School of Medicine and Aghia Sophia Children's Hospital, Athens, Greece.
authors: Loukia
authors: L
authors: Lianou
authors: Pediatric Pulmonology Unit and Sleep Disorders Laboratory, First Department of Pediatrics, University of Athens School of Medicine and Aghia Sophia Children's Hospital, Athens, Greece.
authors: George
authors: G
authors: Chrousos
authors: Pediatric Pulmonology Unit and Sleep Disorders Laboratory, First Department of Pediatrics, University of Athens School of Medicine and Aghia Sophia Children's Hospital, Athens, Greece. Electronic address: kaditia@hotmail.com.
authors: Athanasios G
authors: AG
authors: Kaditis
mesh_terms: D001342:Autonomic Nervous System Diseases / Q000209:etiology* / Q000503:physiopathology / Q000652:urine; D002648:Child; D002675:Child, Preschool; D004562:Electrocardiography; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D000860:Hypoxia / Q000150:complications*; D009638:Norepinephrine / Q000652:urine*; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000150:complications*
chemical_list: D009638:Norepinephrine
keywords: Poincaré plot; sleep apnea; sleep-disordered breathing; sympathetic tone; urine norepinephrine