title: Gas chromatograph-surface acoustic wave for quick real-time assessment of blood/exhaled gas ratio of propofol in humans.
abstract: BACKGROUND
  Although pilot studies have reported that exhaled propofol concentrations can reflect intraoperative plasma propofol concentrations in an individual, the blood/exhaled partial pressure ratio RBE varies between patients, and the relevant factors have not yet been clearly addressed. No efficient method has been reported for the quick evaluation of RBE and its association with inter-individual variables.
  
  
  METHODS
  We proposed a novel method that uses a surface acoustic wave (SAW) sensor combined with a fast gas chromatograph (GC) to simultaneously detect propofol concentrations in blood and exhaled gas in 28 patients who were receiving propofol i.v. A two-compartment pharmacokinetic (PK) model was established to simulate propofol concentrations in exhaled gas and blood after a bolus injection. Simulated propofol concentrations for exhaled gas and blood were used in a linear regression model to evaluate RBE.
  
  
  RESULTS
  The fast GC-SAW system showed reliability and efficiency for simultaneous quantitative determination of propofol in blood (correlation coefficient R(2)=0.994, P<0.01) and exhaled gas (R(2)=0.991, P<0.01). The evaluation of RBE takes <50 min for a patient. The distribution of RBE in 28 patients showed inter-individual differences in RBE (median 1.27; inter-quartile range 1.07-1.59).
  
  
  CONCLUSIONS
  Fast GC-SAW, which analyses samples in seconds, can perform both rapid monitoring of exhaled propofol concentrations and fast analysis of blood propofol concentrations. The proposed method allows early determination of the coefficient RBE in individuals. Further studies are required to quantify the distribution of RBE in a larger cohort and assess the effect of other potential factors.
  
  
  BACKGROUND
  ChiCTR-ONC-13003291.
authors.affiliation: Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education of China, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: X
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education of China, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: X L
authors.initials: XL
authors.lastname: Zhang
authors.affiliation: Department of Anaesthesia, The Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, Zhejiang 310009, China.
authors.forename: L
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Anaesthesia, The Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, Zhejiang 310009, China Department of Anaesthesia, The First People Hospital of Hangzhou, Hangzhou, Zhejiang, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Anaesthesia, The Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, Zhejiang 310009, China.
authors.forename: M Y
authors.initials: MY
authors.lastname: Piao
authors.affiliation: Department of Anaesthesia, The Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, Zhejiang 310009, China.
authors.forename: F J
authors.initials: FJ
authors.lastname: Zhang
authors.affiliation: Department of Anaesthesia, The Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, Zhejiang 310009, China.
authors.forename: W D
authors.initials: WD
authors.lastname: Wu
authors.affiliation: Department of Anaesthesia, The Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, Zhejiang 310009, China.
authors.forename: Y B
authors.initials: YB
authors.lastname: Zhong
authors.affiliation: Department of Anaesthesia, The Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, Zhejiang 310009, China.
authors.forename: K
authors.initials: K
authors.lastname: Sun
authors.affiliation: Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education of China, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: Y C
authors.initials: YC
authors.lastname: Zou
authors.affiliation: Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education of China, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education of China, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: D
authors.initials: D
authors.lastname: Wang
authors.affiliation: Department of Biomedical Engineering, Key Laboratory of Biomedical Engineering of Ministry of Education of China, Zhejiang University, Hangzhou, Zhejiang, China.
authors.forename: P
authors.initials: P
authors.lastname: Wang
authors.affiliation: Department of Anaesthesia, The Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, Zhejiang 310009, China yanminnina@hotmail.com.
authors.forename: M
authors.initials: M
authors.lastname: Yan
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D018686:Anesthetics, Intravenous / Q000032:analysis* / Q000097:blood / Q000493:pharmacokinetics*; D001944:Breath Tests; D002138:Calibration; D002849:Chromatography, Gas / Q000295:instrumentation / Q000379:methods*; D005260:Female; D005740:Gases / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D015742:Propofol / Q000032:analysis* / Q000097:blood / Q000493:pharmacokinetics*; D015203:Reproducibility of Results
chemical_list: D018686:Anesthetics, Intravenous; D005740:Gases; D015742:Propofol
keywords: anaesthetics i.v., propofol; chromatography, gas; monitoring; surface acoustic wave sensor