title: Online breath analysis of propofol during anesthesia: clinical application of membrane inlet-ion mobility spectrometry.
abstract: BACKGROUND
  Breath analysis of propofol is a potential noninvasive method for approximating the plasma propofol concentration. There have been various reported techniques for measuring the exhaled propofol concentration at steady state; however, the propofol concentration undergoes marked changes during clinical anesthesia. Therefore, this study investigated the use of membrane inlet-ion mobility spectrometry (MI-IMS) to monitor exhaled propofol discontinuously and continuously during propofol anesthesia.
  
  
  METHODS
  The study included 19 patients of American Society of Anesthesiologists physical status I or II. In experiment I (discontinuous study), breath and blood samples were collected discontinuously, with stable target propofol concentrations of 2.8 μg/ml, 3.2 μg/ml, 3.5 μg/ml, and 3.8 μg/ml. In experiment II (continuous study), propofol concentration was maintained at 3.5 μg/ml after induction, and exhaled breath was collected continuously every 3 min during propofol infusion. Relationships of the exhaled propofol concentration with the plasma propofol concentration, measured by high-performance liquid chromatography and the continuously measured bispectral (BIS) index were investigated.
  
  
  RESULTS
  Comparison of the exhaled and plasma propofol concentrations revealed a bias ± precision of 2.1% ± 14.6% (95% limits of agreement: - 26.5-30.7%) in experiment I and - 10.4% ± 13.2 (- 36.3-15.4%) in experiment II. In both experiments, exhaled propofol concentrations measured by MI-IMS were consistent with, the propofol effect represented by the BIS index.
  
  
  CONCLUSIONS
  MI-IMS may be a suitable method to predict plasma propofol concentration online during propofol anesthesia. Monitoring exhaled propofol may improve the safety of propofol anesthesia.
authors.affiliation: Department of Anesthesiology, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: Y
authors.initials: Y
authors.lastname: Gong
authors.forename: C
authors.initials: C
authors.lastname: Wang
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: Q
authors.initials: Q
authors.lastname: Zhou
authors.forename: D
authors.initials: D
authors.lastname: Wang
authors.forename: L
authors.initials: L
authors.lastname: Guo
authors.forename: X
authors.initials: X
authors.lastname: Pi
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: S
authors.initials: S
authors.lastname: Luo
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.forename: E
authors.initials: E
authors.lastname: Li
mesh_terms: D018686:Anesthetics, Intravenous / Q000378:metabolism*; D001944:Breath Tests / Q000295:instrumentation* / Q000379:methods*; D005260:Female; D006801:Humans; D020407:Internet; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods; D015742:Propofol / Q000378:metabolism*; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D018686:Anesthetics, Intravenous; D015742:Propofol