title: Quantitative study on cerebral blood volume determined by a near-infrared spectroscopy during postural change in children.
abstract: OBJECTIVE
  To investigate changes in cerebral blood volume during standing in healthy children with or without abnormal cardiovascular responses.
  
  
  METHODS
  We studied 53 children (age, 10-15 years). Cerebral oxygenated haemoglobin (oxy-Hb) and deoxygenated Hb (deoxy-Hb) were non-invasively and continuously measured using near-infrared spectroscopy (NIRS) (NIRO 300, Hamamatsu Photomedics, Shizuoka, Japan) during active standing. Beat-to-beat arterial pressure was monitored by Portapres.
  
  
  RESULTS
  Of 49 children with complete data acquisition, 33 had a normal cardiovascular response to the test (Group I) and 16 showed an abnormal response (Group II); nine with instantaneous orthostatic hypotension, three with postural tachycardia syndrome, three with neutrally mediated syncope and one with delayed orthostatic hypotension. At the onset of standing, Group II showed a significantly larger fall of oxy-Hb than Group I did (-2.9 +/- 2.8 micromol/L vs. -6.4 +/- 7.2 micromol/L, respectively, p < 0.05). During min 1 to 7 of standing, with one exception, changes in oxy-Hb were normally distributed over the level of -4 micromol/L in Group I. Group II also showed a significantly marked decrease in oxy-Hb compared to Group I. Decreases in oxy-Hb were not correlated with blood pressure changes.
  
  
  CONCLUSIONS
  This study shows that precise change in cerebral blood volume caused by orthostatic stress can be determined by NIRS in children in a quantitative manner of NIRS. Children with abnormal circulatory responses to standing showed a significant reduction of oxy-Hb compared with normal counterparts, suggesting impairment of cerebral autoregulation in these children.
authors.affiliation: Department of Pediatrics, Osaka Medical College, Osaka, Japan. y.t.kim@vesta.ocn.ne.jp
authors.forename: Yasuko Taeja
authors.initials: YT
authors.lastname: Kim
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Tanaka
authors.forename: Ryuzo
authors.initials: R
authors.lastname: Takaya
authors.forename: Mitsugu
authors.initials: M
authors.lastname: Kajiura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tamai
authors.forename: Mikio
authors.initials: M
authors.lastname: Arita
mesh_terms: D000293:Adolescent; D001810:Blood Volume; D002560:Cerebrovascular Circulation; D002648:Child; D004244:Dizziness / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D010108:Oxyhemoglobins / Q000378:metabolism*; D011187:Posture / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared
chemical_list: D010108:Oxyhemoglobins