title: Transcranial Doppler blood flow velocity versus 133Xe clearance cerebral blood flow during mild hypothermic cardiopulmonary bypass.
abstract: OBJECTIVE
  Transcranial doppler (TCD) is used during cardiopulmonary bypass (CPB) to assess cerebral emboli and to estimate cerebral perfusion. We sought to compare TCD middle cerebral artery blood flow velocity (Vmca) to 133Xe clearance cerebral blood flow (CBF) measurements during mild hypothermic CPB thus determining its utility in cerebral perfusion assessment.
  
  
  METHODS
  Thirty-four patients undergoing mild hypothermic CPB (35 degrees C) were studied and had comparisons of Vmca and 133Xe CBF at three time intervals, 10, 30 and 60 min after the institution of CPB. Linear regression analysis was performed on data from each of the 3 intervals as well as for pooled data from all 3 periods.
  
  
  RESULTS
  The correlation coefficients for the 3 time periods were, r = 0.32 (p = 0.12), r = 0.32 (p = 0.11), r = 0.48 (p = (0.02), respectively. The pooled data correlation had a coefficient of 0.34 (p = 0.003).
  
  
  CONCLUSIONS
  These findings suggest that TCD Vmca is a relatively poor correlate of CBF during mild hypothermic CPB.
authors.affiliation: Department of Anesthesiology, Duke Heart Center, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: H P
authors.initials: HP
authors.lastname: Grocott
authors.forename: D W
authors.initials: DW
authors.lastname: Amory
authors.forename: E
authors.initials: E
authors.lastname: Lowry
authors.forename: N D
authors.initials: ND
authors.lastname: Croughwell
authors.forename: M F
authors.initials: MF
authors.lastname: Newman
mesh_terms: D000704:Analysis of Variance; D001783:Blood Flow Velocity / Q000502:physiology; D002315:Cardiopulmonary Bypass; D002536:Cerebral Arteries / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation / Q000502:physiology*; D001026:Coronary Artery Bypass; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods*; D002542:Intracranial Embolism and Thrombosis / Q000000981:diagnostic imaging; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D013997:Time Factors; D017585:Ultrasonography, Doppler, Transcranial; D014980:Xenon Radioisotopes
chemical_list: D019275:Radiopharmaceuticals; D014980:Xenon Radioisotopes