title: Influence of the descending thoracic aortic cross clamping on bispectral index value and plasma propofol concentration in humans.
abstract: BACKGROUND
  In this study, the authors investigated changes in Bispectral Index (BIS) values and plasma propofol concentrations (Cp) after aortic cross clamping in the descending thoracic aortic aneurysm repair surgery during propofol anesthesia.
  
  
  METHODS
  Prospectively, in 10 patients undergoing thoracic aortic surgery during total intravenous anesthesia with propofol, BIS values were recorded during cross clamping of the descending thoracic aorta. In this study, the rate of propofol infusion was controlled to keep the BIS value between 30 and 60 throughout surgery. Simultaneously, Cp values in the blood samples taken from the right radial artery (area proximal to cross clamping) and the left femoral artery (area distal to cross clamping) were measured.
  
  
  RESULTS
  Approximately 15 min after initiating aortic cross clamping, BIS values in all cases started to decrease abruptly. Cp values of samples taken from the radial artery after cross clamping of the aorta were significantly (P < 0.05) increased compared with pre-cross clamp values (1.8 +/- 0.4 microg/ml), and the mean Cp after aortic cross clamping varied between 3.0 and 5.3 microg/ml. In addition, there were significant differences in the Cp values between radial arterial and femoral arterial blood samples throughout aortic cross clamping. Cp values in samples from the radial artery were approximately two to seven times higher than those from the femoral artery.
  
  
  CONCLUSIONS
  This study showed that Cp values increased and BIS values decreased rapidly after aortic cross clamping in thoracic aortic aneurysm repair surgery during propofol anesthesia. These findings suggested that all anesthesiologists should control the infusion rate carefully, taking the abrupt changes in its pharmacokinetics into consideration, especially during cross clamping of the descending thoracic aorta.
authors.affiliation: Department of Anesthesiology, Faculty of Medicine, University of the Ryukyus, Uehara, Okinawa, Japan. mnb-shk@ryukyu.ne.jp
authors.forename: Manabu
authors.initials: M
authors.lastname: Kakinohana
authors.forename: Seiya
authors.initials: S
authors.lastname: Nakamura
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Fuchigami
authors.forename: Yuji
authors.initials: Y
authors.lastname: Miyata
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Sugahara
mesh_terms: D000328:Adult; D000368:Aged; D000771:Anesthesia, Intravenous; D018686:Anesthetics, Intravenous / Q000097:blood; D001013:Aorta, Thoracic / Q000502:physiology*; D017545:Aortic Aneurysm, Thoracic / Q000601:surgery; D003250:Constriction; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015742:Propofol / Q000097:blood; D011446:Prospective Studies; D014656:Vascular Surgical Procedures
chemical_list: D018686:Anesthetics, Intravenous; D015742:Propofol