title: C50 for propofol-remifentanil target-controlled infusion and bispectral index at loss of consciousness and response to painful stimulus in Chinese patients: a multicenter clinical trial.
abstract: BACKGROUND
  In this study, we evaluated the predicted blood and effect-site C(50) for propofol and remifentanil target-controlled infusion and the Bispectral Index (BIS) values at loss of consciousness (LOC) and response to a standard noxious painful stimulus in Chinese patients. We hypothesized that these values would be different from previously published data on Caucasians.
  
  
  METHODS
  Five medical centers enrolled 405 ASA physical status I and II unpremedicated Chinese patients (97 men, 308 women) aged 18-65 yr. Propofol was initially given to a predicted blood concentration of 1.2 microg/mL and thereafter increased by 0.3 microg/mL every 30 s until Observer's Assessment of Alertness and Sedation score was 1. The propofol was kept constant, and remifentanil was given to provide a predict blood concentration of 2.0 ng/mL, and then increased by 0.3 ng/mL every 30 s until loss of response to a tetanic stimulus. BIS (version 3.22, BIS Quattro sensor) was also recorded.
  
  
  RESULTS
  The propofol effect-site C(50) at LOC was 2.2 (2.2-2.3) microg/mL. The remifentanil effect-site C(50) at loss of response to painful stimulus was 3.3 ng/mL. Fifty percent of patients lost consciousness at a BIS value of 58, and 95% had lost consciousness at BIS values <40. The BIS value at C(50) at loss of response to painful stimulus was 65.4, which was higher than that at LOS (P < 0.001).
  
  
  CONCLUSIONS
  The predicted blood and effect-site concentrations of propofol and BIS values at LOC were lower than those in previously published studies of Caucasian populations.
authors.affiliation: Beijing Chaoyang Hospital, Capital Medical University, Beijing, People's Republic of China.
authors.forename: Zhipeng
authors.initials: Z
authors.lastname: Xu
authors.forename: Fang
authors.initials: F
authors.lastname: Liu
authors.forename: Yun
authors.initials: Y
authors.lastname: Yue
authors.forename: Tiehu
authors.initials: T
authors.lastname: Ye
authors.forename: Bingxi
authors.initials: B
authors.lastname: Zhang
authors.forename: Mingzhang
authors.initials: M
authors.lastname: Zuo
authors.forename: Mingjun
authors.initials: M
authors.lastname: Xu
authors.forename: Rongrong
authors.initials: R
authors.lastname: Hao
authors.forename: Yuan
authors.initials: Y
authors.lastname: Xu
authors.forename: Ning
authors.initials: N
authors.lastname: Yang
authors.forename: Xiangming
authors.initials: X
authors.lastname: Che
mesh_terms: D000293:Adolescent; D000328:Adult; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D001794:Blood Pressure / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography / Q000187:drug effects*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D010100:Oxygen / Q000097:blood; D010147:Pain Measurement / Q000187:drug effects*; D010880:Piperidines / Q000008:administration & dosage; D015742:Propofol / Q000008:administration & dosage; D011446:Prospective Studies; D000077208:Remifentanil; D012129:Respiratory Function Tests; D014474:Unconsciousness / Q000139:chemically induced* / Q000523:psychology; D055815:Young Adult
chemical_list: D018686:Anesthetics, Intravenous; D010880:Piperidines; D000077208:Remifentanil; D010100:Oxygen; D015742:Propofol