title: Arteriovenous transit time as a measure for microvascular perfusion in cerebral ischemia and reperfusion.
abstract: OBJECTIVE
  The aim of this study was to measure microvascular perfusion (MVP) on the brain surface in global ischemia and reperfusion by means of intravital fluorescence microscopy.
  
  
  METHODS
  Global ischemia was induced in gerbils for 15 minutes with 3 hours of reperfusion. The passage of a rhodamine bolus (25 mul intravenously) from an arteriole to a venule was analyzed by intravital fluorescence microscopy through a cranial window. After the changes of fluorescence intensities in an arteriole and venule, the arteriovenous transit time and the MVP were calculated using the integral difference method. Additionally, regional cerebral blood flow was assessed by laser Doppler flowmetry and vessel diameters and blood pressure were recorded.
  
  
  RESULTS
  The baseline mean MVP was 2.21 +/- 0.89 sec(-1) in the control group, remaining stable throughout observation in sham operated animals. In ischemic animals, the MVP was 2.11 +/- 0.47 sec(-1) at baseline, showing a significant decrease during ischemia to 0.07 +/- 0.16 sec(-1) (3%; P < 0.01). There was postischemic maximum hyperperfusion of 2.72 +/- 0.40 sec(-1) (134 +/- 11%; P < 0.05) at 15.4 +/- 6.9 minutes and hypoperfusion of 1.63 +/- 0.57 sec(-1) (77 +/- 13%; P = 0.19) at 36.6 +/- 16.4 minutes. There was a strong, significant correlation between MVP and regional cerebral blood flow (R = 0.82; P < 0.0001).
  
  
  CONCLUSIONS
  MVP on the brain surface can be calculated from the transit time of a dye bolus from an arteriole to a venule. MVP shows a high correlation to regional cerebral blood flow. The assessment of MVP allows one to easily and repeatedly quantify perfusion changes of the microvascular network on the brain surface.
authors.affiliation: Department of Neurosurgery, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany. J.Beck@em.uni-frankfurt.de
authors.forename: Jürgen
authors.initials: J
authors.lastname: Beck
authors.forename: Walter
authors.initials: W
authors.lastname: Stummer
authors.forename: Jens
authors.initials: J
authors.lastname: Lehmberg
authors.forename: Alexander
authors.initials: A
authors.lastname: Baethmann
authors.forename: Eberhard
authors.initials: E
authors.lastname: Uhl
mesh_terms: D000818:Animals; D001776:Blood Circulation Time / Q000379:methods*; D001794:Blood Pressure / Q000502:physiology; D002545:Brain Ischemia / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005849:Gerbillinae; D008297:Male; D008833:Microcirculation / Q000502:physiology; D015424:Reperfusion / Q000379:methods*; D014894:Weights and Measures