title: Impact of acute hypobaric hypoxia on blood flow distribution in brain.
abstract: OBJECTIVE
  Acute hypobaric hypoxia is well known to alter brain circulation and to cause neuropsychological impairment. However, very few studies have examined the regional changes occurring in the brain during acute exposure to extreme hypoxic conditions.
  
  
  METHODS
  Regional cerebral blood flow (rCBF) response to hypoxia was investigated in six healthy subjects exposed to either normobaric normoxia or hypobaric hypoxia with ambient pressure/inspired oxygen pressure of 101/21 kPa and 50/11 kPa respectively. After 40 min at the desired pressure they were injected (99m)Tc-HMPAO and subsequently underwent single photon emission computed tomography. Regional cerebral blood flow distribution changes in the whole brain were assessed by Statistical Parametric Mapping, a well established voxel-based analysis method.
  
  
  RESULTS
  Hypobaric hypoxia increased rCBF distribution in sensorymotor and prefrontal cortices and in central structures. PCO(2) correlated positively and SatO(2) negatively with rCBF in several temporal, parahippocampal, parietal and central structures.
  
  
  CONCLUSIONS
  These findings underscore the specific sensitivity of the frontal lobe to acute hypobaric hypoxia and of limbic and central structures to blood gas changes emphasizing the involvement of these brain areas in acute hypoxia.
authors.affiliation: Institute of Cognitive Sciences and Technologies, CNR, Rome & Padua, Italy. marco.pagani@istc.cnr.it
authors.forename: M
authors.initials: M
authors.lastname: Pagani
authors.forename: D
authors.initials: D
authors.lastname: Salmaso
authors.forename: G Gr
authors.initials: GG
authors.lastname: Sidiras
authors.forename: C
authors.initials: C
authors.lastname: Jonsson
authors.forename: H
authors.initials: H
authors.lastname: Jacobsson
authors.forename: S A
authors.initials: SA
authors.lastname: Larsson
authors.forename: F
authors.initials: F
authors.lastname: Lind
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology / Q000098:blood supply / Q000000981:diagnostic imaging; D001931:Brain Mapping / Q000379:methods; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D012039:Regional Blood Flow / Q000502:physiology*; D019690:Technetium Tc 99m Exametazime / Q000378:metabolism; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods
chemical_list: D019690:Technetium Tc 99m Exametazime