title: 1-1-12 one-step wash-in scheme for desflurane-nitrous oxide low-flow anesthesia: rapid and predictable induction.
abstract: BACKGROUND
  We propose a 1-1-12 wash-in scheme for desflurane-nitrous oxide (N2O) low-flow anesthesia. The objective of our study was to determine the time to achieve alveolar concentration of desflurane (FAD) at 1, 2, 3, 4, 5, and 6%.
  
  
  METHODS
  We enrolled 106 patients scheduled for elective surgery under general anesthesia. After induction and intubation, wash-in was started with a fresh gas flow (FGF) of N2O : O2 1 : 1 L min(-1) and vaporizer concentration of desflurane (FD) of 12%. Ventilation was controlled to maintain PACO2 at 30-35 mmHg.
  
  
  RESULTS
  The FAD rose rapidly from 0 to 4% in 2 min in a linear manner in 0.5 min increments. An FAD of 6% was achieved in 4 min in a linear fashion from FAD of 4% but in 1 min increments. An FAD of 1 to 6% occurred at 0.6, 1, 1.5, 2, 3, and 4 min. Heart rate during wash-in showed a statistically, albeit not clinically, significant pattern of increase. By contrast, blood pressure slightly decreased during this period.
  
  
  CONCLUSIONS
  We developed a 1-1-12 wash-in scheme using a FGF of N2O : O2 1 : 1 L min(-1) and FD of 12% for desflurane-nitrous oxide low-flow anesthesia. A respective FAD of 1, 2, 3, 4, 5, and 6% can be expected at 0.6, 1, 1.5, 2, 3, and 4 min.
authors.affiliation: Department of Anesthesiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Thepakorn
authors.identifier: 0000-0002-8401-1510
authors.initials: T
authors.lastname: Sathitkarnmanee
authors.affiliation: Department of Anesthesiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Sirirat
authors.identifier: 0000-0001-9434-4792
authors.initials: S
authors.lastname: Tribuddharat
authors.affiliation: Department of Anesthesiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Chakthip
authors.initials: C
authors.lastname: Suttinarakorn
authors.affiliation: Department of Anesthesiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Duangthida
authors.initials: D
authors.lastname: Nonlhaopol
authors.affiliation: Department of Anesthesiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Maneerat
authors.initials: M
authors.lastname: Thananun
authors.affiliation: Department of Anesthesiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Wilawan
authors.initials: W
authors.lastname: Somdee
authors.affiliation: Department of Anesthesiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Sunchai
authors.initials: S
authors.lastname: Theerapongpakdee
mesh_terms: D000328:Adult; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D001794:Blood Pressure / Q000187:drug effects; D000077335:Desflurane; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007530:Isoflurane / Q000008:administration & dosage / Q000031:analogs & derivatives*; D008297:Male; D008875:Middle Aged; D009609:Nitrous Oxide / Q000008:administration & dosage*
chemical_list: D018685:Anesthetics, Inhalation; D000077335:Desflurane; D007530:Isoflurane; D009609:Nitrous Oxide