title: The effects of nicardipine on dynamic cerebral autoregulation in patients anesthetized with propofol and fentanyl.
abstract: We investigated the effects of nicardipine on dynamic cerebral pressure autoregulation in 13 normal adult patients undergoing gynecologic or orthopedic surgery. Anesthesia was induced and maintained with propofol and fentanyl. Hypotension to a mean arterial pressure of 60-65 mm Hg was induced and maintained with a continuous infusion of nicardipine. Time-averaged mean blood flow velocity in the right middle cerebral artery was measured continuously by using transcranial Doppler ultrasonography. The cerebral autoregulatory responses were activated by releasing thigh cuffs. The actual blood flow velocity in the right middle cerebral artery response to acute change in mean arterial pressure was fitted to 1 of 10 computer-generated curves to determine the dynamic rate of cerebral autoregulation (dRoR), and the best fitting curve was used. The autoregulation test was repeated until two values of dRoR were obtained at baseline and during induced hypotension. Nicardipine significantly reduced dRoR values of 13.1% +/- 3.6%/s at baseline to 8.3% +/- 2.6%/s during hypotension (P: < 0.01). During deliberate hypotension induced by nicardipine, the cerebral dynamic autoregulatory response is impaired in normal adult patients.
  
  
  CONCLUSIONS
  During deliberate hypotension induced by nicardipine, the cerebral dynamic autoregulatory response is impaired in normal adult patients.
authors.affiliation: Departments of Emergency and Critical Care Medicine and Anesthesiology, Niigata University School of Medicine, Japan. endoh@med.niigata-u.ac.jp
authors.forename: H
authors.initials: H
authors.lastname: Endoh
authors.forename: T
authors.initials: T
authors.lastname: Honda
authors.forename: N
authors.initials: N
authors.lastname: Komura
authors.forename: C
authors.initials: C
authors.lastname: Shibue
authors.forename: I
authors.initials: I
authors.lastname: Watanabe
authors.forename: K
authors.initials: K
authors.lastname: Shimoji
mesh_terms: D000759:Adjuvants, Anesthesia; D000368:Aged; D000771:Anesthesia, Intravenous; D018686:Anesthetics, Intravenous; D001794:Blood Pressure / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D005260:Female; D005283:Fentanyl; D006706:Homeostasis / Q000187:drug effects*; D006801:Humans; D007023:Hypotension, Controlled; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000187:drug effects; D009529:Nicardipine / Q000494:pharmacology*; D015742:Propofol
chemical_list: D000759:Adjuvants, Anesthesia; D018686:Anesthetics, Intravenous; D002121:Calcium Channel Blockers; D009529:Nicardipine; D005283:Fentanyl; D015742:Propofol