title: Systemic blood pressure and cerebral blood flow velocity during carotid surgery.
abstract: BACKGROUND
  To evaluate the effect of mean arterial blood pressure (MAP) on cerebral perfusion during carotid surgery, we investigated blood flow velocity in the middle cerebral (Vs,mca) using transcranial Doppler ultrasonography (TCD).
  
  
  METHODS
  During carotid crossclamping, treatment included either phenylephrine-induced hypertension without shunting (Group XC; n = 11) or insertion of a shunt (Group S; n = 12).
  
  
  RESULTS
  Increasing MAP in Group XC before crossclamping (81 + /-13 mmHg to 107 +/- 12 mmHg) caused an increase of Vs,mca (59 +/- 17 cm/s to 75 +/- 20 cm/s; p < 0.001). During crossclamping without a shunt, Vs,mca was not dependent on MAP, and was reduced (mean 47 +/- 24 cm/s) in relation to preclamp values. In Group S, Vs,mca was always dependent on MAP and the preclamp velocity was maintained (before shunt: 75 +/- 26 cm/sec; during shunt: 79 +/- 30 cm/sec).
  
  
  CONCLUSIONS
  Although we found an impaired cerebral autoregulation, Vs,mca was independent of MAP during carotid crossclamping. Thus, TCD measurements have to be interpreted with caution during crossclamping, and the effect of induced hypertension has to be confirmed with more invasive measures of cerebral blood flow.
authors.affiliation: Department of Cardiothoracic and Vascular Anesthesia and Intensive Care, University Hospital, Vienna, Austria. Georg.Grubhofer@univie.ac.at
authors.forename: G
authors.initials: G
authors.lastname: Grubhofer
authors.forename: A
authors.initials: A
authors.lastname: Lassnigg
authors.forename: T
authors.initials: T
authors.lastname: Pernerstorfer
authors.forename: O
authors.initials: O
authors.lastname: Ipsiroglu
authors.forename: M
authors.initials: M
authors.lastname: Czerny
authors.forename: P
authors.initials: P
authors.lastname: Polterauer
authors.forename: M
authors.initials: M
authors.lastname: Hiesmayr
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002560:Cerebrovascular Circulation; D016894:Endarterectomy, Carotid; D005260:Female; D006801:Humans; D007430:Intraoperative Care; D008297:Male; D011446:Prospective Studies