title: [Effect of propofol on visual evoked potentials during neurosurgery].
abstract: BACKGROUND
  Evoked potentials are used to monitor the central nervous system during neurosurgery and it is well known that they are affected by the depth of anesthesia. Many studies on the evoked potential like somatosensory evoked potential (SEP) and auditory brain stem response (ABR) are reported, but studies on visual evoked potential (VEP) are few. We investigated the influence of the propofol concentration on VEP in neurosurgical patients.
  
  
  METHODS
  Seven patients scheduled for neurosurgery, three with cranial aneurysm and four with brain tumor, were studied. Anesthesia was maintained with intravenous propofol using target controlled infusion (TCI). We measured the change of amplitude and latency of VEP at three propofol concentrations (effect site concentrations of 1.5, 2.0 and 3.0 microg x ml(-1)), and also evaluated bispectral index (BIS) at each propofol concentration.
  
  
  RESULTS
  Amplitude of VEP at 3.0 microg x ml(-1) propofol concentration decreased significantly compared with the amplitude at 1.5 microg x ml(-1) concentration. No significant change was observed with the latency of VEP. The value of BIS at 3.0 microg x ml(-1) propofol concentration also decreased significantly compared with 2.0 microg x ml(-1) concentration.
  
  
  CONCLUSIONS
  Amplitude of VEP is strongly affected by the concentration of propofol. Caution should be taken in evaluating VEP in patients undergoing propofol anesthesia.
authors.affiliation: Department of Anesthesia, Chugoku Rosai General Hospital, Kure.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Hamaguchi
authors.forename: Itsuo
authors.initials: I
authors.lastname: Nakagawa
authors.forename: Shozo
authors.initials: S
authors.lastname: Hidaka
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Uesugi
authors.forename: Takashi
authors.initials: T
authors.lastname: Kubo
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kato
mesh_terms: D000368:Aged; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D005074:Evoked Potentials, Visual / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D019635:Neurosurgical Procedures; D015742:Propofol / Q000494:pharmacology*
chemical_list: D018686:Anesthetics, Intravenous; D015742:Propofol