title: Establishing the relationship between FGF/MV and FI/FD, and determining the saturation state of sevoflurane anaesthesia during the induction phase and factors affecting nonrespiratory tract ejection volume.
abstract: OBJECTIVE
  To investigate (i) the relationship between the ratio of fresh gas flow to min volume (FGF/MV) and the ratio of the fraction of inspired sevoflurane to the delivered concentration of sevoflurane (FI/FD); (ii) to establish the saturation state of sevoflurane anaesthesia and factors affecting the volume of ejected sevoflurane through the nonrespiratory tract route (nVERT) during the saturation state.
  
  
  METHODS
  Two studies were undertaken in patients with cancer, scheduled to undergo surgery. All patients received tracheal intubation and inhaled sevoflurane. In study 1, anaesthesia parameters were fixed, the initial FD of sevoflurane was 2.2% vol and the FGF/MV was set to 0.2, 0.3, 0.4 and 1.0 in groups A, B, C and D, respectively. In study 2, FGF = MV and the initial FD of sevoflurane was 2.2% vol, but the tidal volume (TV) was set to 6, 8 or 10 ml/kg in groups I, II and III, respectively.
  
  
  RESULTS
  Study 1 (n = 60) showed a positive relationship between FI/FD and FGF/MV. In study 2 (n = 60), when TV was fixed, nVERT increased during the saturation state as FD increased; when FD was fixed, nVERT remained stable, despite increased TV.
  
  
  CONCLUSIONS
  FI/FD is positively associated with FGF/MV; nVERT is affected by FD but not TV.
authors.affiliation: Department of Anaesthesiology, Cancer Hospital, Shanghai Medical College, Fudan University, Shanghai, China. chzhygg@yahoo.com.cn
authors.forename: Zhi-Yang
authors.initials: ZY
authors.lastname: Chen
mesh_terms: D000328:Adult; D000769:Anesthesia, Inhalation / Q000379:methods*; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000601:surgery; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal; D007700:Kinetics; D008297:Male; D008738:Methyl Ethers / Q000494:pharmacology*; D008875:Middle Aged; D000077149:Sevoflurane; D013964:Thyroid Neoplasms / Q000188:drug therapy / Q000601:surgery; D013990:Tidal Volume / Q000187:drug effects*
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane
keywords: Sevoflurane; fresh gas flow; inhalation anaesthesia; minute volume