title: Noxious stimuli do not modify myogenic motor evoked potentials by electrical stimulation during anesthesia with propofol-based anesthesia.
abstract: OBJECTIVE
  To investigate whether motor evoked potentials (MEP) to transcranial electrical stimulation under constant blood propofol concentration are affected by the arousing effect of surgical noxious stimuli.
  
  
  METHODS
  Twenty patients who underwent elective spinal surgery were studied. Patients were anesthetized with 50% nitrous oxide in oxygen, fentanyl, and propofol to maintain the bispectral index (BIS) score around 50. MEP in response to a multipulse transcranial electrical stimulation at stimulus sites of C3-C4 were recorded over the right abductor pollicis brevis muscle. Changes of peak-to-peak amplitude and onset latency of MEP, BIS score before and after surgical stimuli were evaluated. Propofol plasma concentration was measured at the same time points.
  
  
  RESULTS
  Both MEP amplitude and latency did not change significantly after surgical stimuli although BIS increased significantly (48 +/- 6 to 58 +/- 5; P < 0.05). Plasma propofol concentration was maintained at the same level between the two measurement points (3.3 +/- 0.7 to 3.3 +/- 0.7 micro g*mL(-1)). There was no relation between BIS change and changes of MEP amplitude and latency, and propofol plasma concentration.
  
  
  CONCLUSIONS
  MEP to the transcranial electrical stimulation under a constant and clinically appropriate blood propofol concentration are not affected by surgical noxious stimuli.
authors.affiliation: Department of Anesthesiology and Neurosurgery, Nara Medical University, Japan. sinoue@vapop.ucsd.edu
authors.forename: Satoki
authors.initials: S
authors.lastname: Inoue
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kawaguchi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takahashi
authors.forename: Meiko
authors.initials: M
authors.lastname: Kakimoto
authors.forename: Takanori
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Katsuyasu
authors.initials: K
authors.lastname: Kitaguchi
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Furuya
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Morimoto
authors.forename: Toshisuke
authors.initials: T
authors.lastname: Sakaki
mesh_terms: D000768:Anesthesia, General; D018686:Anesthetics, Intravenous / Q000097:blood / Q000627:therapeutic use*; D001921:Brain / Q000502:physiology; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation; D015742:Propofol / Q000097:blood / Q000627:therapeutic use*; D013131:Spine / Q000601:surgery*; D013514:Surgical Procedures, Operative
chemical_list: D018686:Anesthetics, Intravenous; D015742:Propofol