title: Dynamic and static cerebral autoregulation during isoflurane, desflurane, and propofol anesthesia.
abstract: BACKGROUND
  Although inhalation anesthetic agents are thought to impair cerebral autoregulation more than intravenous agents, there are few controlled studies in humans.
  
  
  METHODS
  In the first group (n = 24), dynamic autoregulation was assessed from the response of middle cerebral artery blood flow velocity (Vmca) to a transient step decrease in mean arterial blood pressure (MABP). The transient hypotension was induced by rapid deflation of thigh cuffs after inflation for 3 min. In the second group (n = 18), static autoregulation was studied by observing Vmca in response to a phenylephrine-induced increase in MABP. All patients were studied during fentanyl (3 micrograms.kg-1.h-1)/nitrous oxide (70%) anesthesia, followed by, in a randomized manner, isoflurane, desflurane, or propofol in a low dose (0.5 MAC or 100 micrograms.kg-1.min-1) and a high dose (1.5 MAC or 200 micrograms.kg-1.min-1). The dynamic rate of regulation (dROR) was assessed from the rate of change in cerebrovascular resistance (MABP/Vmca) with the blood pressure decreases using computer modeling, whereas the static rate of regulation (sROR) was assessed from the change in Vmca with the change in MABP.
  
  
  RESULTS
  Low-dose isoflurane delayed (dROR decreased) but did not reduce the autoregulatory response (sROR intact). Low-dose desflurane decreased both dROR and sROR. During 1.5 MAC isoflurane or desflurane, autoregulation was ablated (both dROR and sROR impaired). Neither dROR nor sROR changed with low- or high-dose propofol.
  
  
  CONCLUSIONS
  At 1.5 MAC, isoflurane and desflurane impaired autoregulation whereas propofol (200 micrograms.kg-1.min-1) preserved it.
authors.affiliation: Departments of Anesthesiology and Neurological Surgery, University of Washington, Seattle, USA.
authors.forename: S
authors.initials: S
authors.lastname: Strebel
authors.forename: A M
authors.initials: AM
authors.lastname: Lam
authors.forename: B
authors.initials: B
authors.lastname: Matta
authors.forename: T S
authors.initials: TS
authors.lastname: Mayberg
authors.forename: R
authors.initials: R
authors.lastname: Aaslid
authors.forename: D W
authors.initials: DW
authors.lastname: Newell
mesh_terms: D000328:Adult; D000758:Anesthesia; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000187:drug effects* / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000187:drug effects; D000077335:Desflurane; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects*; D006801:Humans; D007530:Isoflurane / Q000031:analogs & derivatives* / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D015742:Propofol / Q000494:pharmacology*
chemical_list: D018685:Anesthetics, Inhalation; D000077335:Desflurane; D007530:Isoflurane; D015742:Propofol