title: Cerebral Blood Flow Response to Hypercapnia in Children with Obstructive Sleep Apnea Syndrome.
abstract: OBJECTIVE
  Children with obstructive sleep apnea syndrome (OSAS) often experience periods of hypercapnia during sleep, a potent stimulator of cerebral blood flow (CBF). Considering this hypercapnia exposure during sleep, it is possible that children with OSAS have abnormal CBF responses to hypercapnia even during wakefulness. Therefore, we hypothesized that children with OSAS have blunted CBF response to hypercapnia during wakefulness, compared to snorers and controls.
  
  
  METHODS
  CBF changes during hypercapnic ventilatory response (HCVR) were tested in children with OSAS, snorers, and healthy controls using diffuse correlation spectroscopy (DCS). Peak CBF changes with respect to pre-hypercapnic baseline were measured for each group. The study was conducted at an academic pediatric sleep center.
  
  
  RESULTS
  Twelve children with OSAS (aged 10.1 ± 2.5 [mean ± standard deviation] y, obstructive apnea hypopnea index [AHI] = 9.4 [5.1-15.4] [median, interquartile range] events/hour), eight snorers (11 ± 3 y, 0.5 [0-1.3] events/hour), and 10 controls (11.4 ± 2.6 y, 0.3 [0.2-0.4] events/hour) were studied. The fractional CBF change during hypercapnia, normalized to the change in end-tidal carbon dioxide, was significantly higher in controls (9 ± 1.8 %/mmHg) compared to OSAS (7.1 ± 1.5, P = 0.023) and snorers (6.7 ± 1.9, P = 0.025).
  
  
  CONCLUSIONS
  Children with OSAS and snorers have blunted CBF response to hypercapnia during wakefulness compared to controls. Noninvasive DCS blood flow measurements of hypercapnic reactivity offer insights into physiopathology of OSAS in children, which could lead to further understanding about the central nervous system complications of OSAS.
authors.affiliation: Division of Neurology, Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.|Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA.
authors.forename: David R
authors.initials: DR
authors.lastname: Busch
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Lynch
authors.affiliation: Division of Neurology, Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.
authors.forename: Madeline E
authors.initials: ME
authors.lastname: Winters
authors.affiliation: Temple University School of Medicine, Philadelphia, PA.
authors.forename: Ann L
authors.initials: AL
authors.lastname: McCarthy
authors.affiliation: Division of Neurology, Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.
authors.forename: John J
authors.initials: JJ
authors.lastname: Newland
authors.affiliation: Department of Biomedical Engineering, University of Pennsylvania, Philadelphia, PA.
authors.forename: Tiffany
authors.initials: T
authors.lastname: Ko
authors.affiliation: The Sleep Center, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.
authors.forename: Mary Anne
authors.initials: MA
authors.lastname: Cornaglia
authors.affiliation: Clinical and Translational Research Center, Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.
authors.forename: Jerilynn
authors.initials: J
authors.lastname: Radcliffe
authors.affiliation: The Sleep Center, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: McDonough
authors.affiliation: The Sleep Center, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.
authors.forename: John
authors.initials: J
authors.lastname: Samuel
authors.affiliation: The Sleep Center, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.
authors.forename: Edward
authors.initials: E
authors.lastname: Matthews
authors.affiliation: Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, PA.
authors.forename: Rui
authors.initials: R
authors.lastname: Xiao
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA.
authors.forename: Arjun G
authors.initials: AG
authors.lastname: Yodh
authors.affiliation: The Sleep Center, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.
authors.forename: Carole L
authors.initials: CL
authors.lastname: Marcus
authors.affiliation: Division of Neurology, Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Licht
authors.affiliation: The Sleep Center, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.
authors.forename: Ignacio E
authors.initials: IE
authors.lastname: Tapia
mesh_terms: D000293:Adolescent; D002245:Carbon Dioxide / Q000097:blood; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002648:Child; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000097:blood / Q000150:complications* / Q000503:physiopathology*; D008297:Male; D017286:Polysomnography; D012890:Sleep; D020181:Sleep Apnea, Obstructive / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D012913:Snoring / Q000097:blood / Q000150:complications / Q000503:physiopathology; D014851:Wakefulness
chemical_list: D002245:Carbon Dioxide
keywords: cerebral blood flow; child; humans; hypercapnia; obstructive; sleep apnea