title: Optimal propofol plasma concentration during upper gastrointestinal endoscopy in young, middle-aged, and elderly patients.
abstract: BACKGROUND
  Suitable propofol plasma concentrations during gastroscopy have not been determined for suppressing somatic and hemodynamic responses in different age groups.
  
  
  METHODS
  Propofol sedation at target plasma concentrations from 0.5 to 4.0 microgram/ml were performed randomly in three groups of patients (23 per group) who were undergoing elective outpatient gastroscopy: ages 17-49 yr (group 1), 50-69 yr (group 2), and 70-89 yr (group 3). Plasma propofol concentration in which 50% of patients do not respond to these different stimuli were determined by logistic regression: verbal command (Cp50ls), somatic response to gastroscopy (Cp50endo), and gag response to gastroscopy (Cp50gag). Hemodynamic responses were also investigated in the different age groups.
  
  
  RESULTS
  Cp50ls concentrations were 2.23 microgram/ml (group 1), 1.75 microgram/ml (group 2), and 1.40 microgram/ml (group 3). The Cp50endo values in groups 1 and 2 were 2.87 and 2.34 microgram/ml, respectively, which were significantly higher than their respective Cp50ls values. Cp50endo value in group 3 was 1.64 microgram/ml, which was close to its Cp50ls value. Because of a high degree of interpatient variability, Cp50gag could not be defined. Systolic blood pressure response decreased with increasing propofol concentrations.
  
  
  CONCLUSIONS
  The authors determined the propofol concentration necessary for gastroscopy and showed that increasing age reduces it. Propofol concentration that suppresses somatic response induces loss of consciousness in almost all young patients.
authors.affiliation: Departments of Anesthesiology and Intensive Care and Endoscopic and Photodynamic Medicine, Hamamatsu University School of Medicine, and the Center for Digestive Disease, Hamamatsu South Hospital, Hamamatsu, Japan. tkazama@hama-med.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Kazama
authors.forename: K
authors.initials: K
authors.lastname: Takeuchi
authors.forename: K
authors.initials: K
authors.lastname: Ikeda
authors.forename: T
authors.initials: T
authors.lastname: Ikeda
authors.forename: M
authors.initials: M
authors.lastname: Kikura
authors.forename: T
authors.initials: T
authors.lastname: Iida
authors.forename: S
authors.initials: S
authors.lastname: Suzuki
authors.forename: H
authors.initials: H
authors.lastname: Hanai
authors.forename: S
authors.initials: S
authors.lastname: Sato
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D018686:Anesthetics, Intravenous / Q000097:blood*; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D005773:Gastroscopy / Q000009:adverse effects; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D015742:Propofol / Q000008:administration & dosage / Q000097:blood*
chemical_list: D018686:Anesthetics, Intravenous; D015742:Propofol