title: Individual indicators of appropriate hypnotic level during propofol anesthesia: highest alpha power and effect-site concentrations of propofol at loss of response.
abstract: BACKGROUND
  Electroencephalogram (EEG) waveforms vary widely among individuals, this decreases the usefulness of BIS™ monitors for assessing the effects of propofol. Practically, anesthesia is only seen as too deep when evidence of burst-suppression is seen. We designed an experiment to help towards better assessment of individual anesthetic needs. First, to mark the Ce (effect-site concentration) of propofol at loss of response to calling name and gently shaking shoulders (LOR), we defined Ce-LOR. To mark the transient power increase in the alpha range (9-14 Hz), common to all patients, when propofol concentration gradually increases, we defined Ce-alpha as the highest recorded alpha power for Ce. We also defined Ce-OBS as the Ce of propofol at initial observation of burst-suppression. Then we tried to predict Ce-LOR and Ce-alpha from Ce-OBS, vice versa, and considered the significance of these parameters.
  
  
  METHODS
  We enrolled 26 female patients (age 33-65) who were undergoing scheduled mastectomy. During anesthesia, we recorded all raw EEG packets as well as EEG-derived parameters on a computer from BIS-XP™ monitor. Propofol was infused using a TCI pump. Target concentration was adjusted so that Ce of propofol was gradually increased.
  
  
  RESULTS
  We obtained the following regression equation; Ce-alpha or Ce-OBS = Ce-LOR × 0.87 + 1.06 + dummy × 0.83 (for Ce-alpha dummy = 0, and for Ce-OBS = 1; adjusted r = 0.90, p < 2.2e-16) by ANCOVA. At Ce-alpha, BIS was 50.2 ± 7.7.
  
  
  CONCLUSIONS
  Ce-alpha and Ce-OBS could be estimated from Ce-LOR. Based on Ce-LOR it is possible to manage the hypnotic level of individual patients.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita City, 565-0871, Osaka, Japan.
authors.forename: Hongling
authors.initials: H
authors.lastname: Kang
authors.affiliation: Department of Anesthesiology, Faculty of Medicine, Al-Minia University, Al-Minia, Egypt.
authors.forename: Hassan Mamdouh Hassan
authors.initials: HMH
authors.lastname: Mohamed
authors.affiliation: Surgical Center, Osaka University Hospital, 2-15 Yamadaoka, Suita City, 565-0871, Osaka, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Takashina
authors.affiliation: Department of Anesthesilogy, Surgical Center, Osaka General Medical Center, 3-1-56 Bandai-higashi, Sumiyoshi-ku, Osaka, 558-8558, Japan.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Mori
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita City, 565-0871, Osaka, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Fujino
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita City, 565-0871, Osaka, Japan. hagihira@anes.med.osaka-u.ac.jp.|Department of Anesthesilogy, Surgical Center, Osaka General Medical Center, 3-1-56 Bandai-higashi, Sumiyoshi-ku, Osaka, 558-8558, Japan. hagihira@anes.med.osaka-u.ac.jp.
authors.forename: Satoshi
authors.identifier: http://orcid.org/0000-0002-3127-8588
authors.initials: S
authors.lastname: Hagihira
mesh_terms: D000328:Adult; D000368:Aged; D000771:Anesthesia, Intravenous; D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D004569:Electroencephalography / Q000187:drug effects; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage*; D008875:Middle Aged; D008991:Monitoring, Physiologic; D015742:Propofol / Q000008:administration & dosage* / Q000494:pharmacology
chemical_list: D018686:Anesthetics, Intravenous; D006993:Hypnotics and Sedatives; D015742:Propofol
keywords: Electroencephalogram; Inter-individual variation; Pharmacodynamics; Propofol