title: The optimal bolus dose of alfentanil for tracheal intubation during sevoflurane induction without neuromuscular blockade in day-case anaesthesia.
abstract: BACKGROUND
  The purpose of this study was to determine the optimal bolus dose of alfentanil required to provide successful intubating conditions following inhalation induction of anaesthesia using 5% sevoflurane and 60% nitrous oxide without neuromuscular blockade in adult day-case anaesthesia.
  
  
  METHODS
  Twenty-four adults, aged 18-60 years, undergoing general anaesthesia for short ambulatory surgery were enroled into the study. After vital capacity induction, with sevoflurane 5% and 60% nitrous oxide in oxygen, pre-determined dose of alfentanil was injected over 30 s. The dose of alfentanil was determined by modified Dixon's up-and-down method (2 microg/kg as a step size). Ninety seconds after the end of bolus administration of alfentanil, the trachea was intubated. Systolic blood pressure, heart rate and SpO2 were recorded at anaesthetic induction, before, 1 min and 3 min after intubation.
  
  
  RESULTS
  The bolus dose of alfentanil for successful tracheal intubation was 10.7+/-2.1 microg/kg in 50% of patients during inhalation induction. From probit analysis, 50% effective dose (ED(50)) and ED(95) values (95% confidence limits) of alfentanil were 10.7 microg/kg (8.0-12.9 microg/kg) and 14.9 microg/kg (12.9-31.1 microg/kg), respectively.
  
  
  CONCLUSIONS
  Using the modified Dixon's up-and-down method, the bolus dose of alfentanil for successful tracheal intubation was 10.7+/-2.1 microg/kg in 50% of adult patients during inhalation induction using 5% sevoflurane and 60% nitrous oxide in oxygen without neuromuscular blocking agent in day-case anaesthesia.
authors.affiliation: Department of Anaesthesiology and Pain Medicine, Gachon University of Medicine and Science, Gil Medical Center, Incheon, Korea.
authors.forename: J Y
authors.initials: JY
authors.lastname: Kim
authors.forename: Y L
authors.initials: YL
authors.lastname: Kwak
authors.forename: K C
authors.initials: KC
authors.lastname: Lee
authors.forename: Y J
authors.initials: YJ
authors.lastname: Chang
authors.forename: H J
authors.initials: HJ
authors.lastname: Kwak
mesh_terms: D000293:Adolescent; D000328:Adult; D015760:Alfentanil / Q000008:administration & dosage* / Q000494:pharmacology; D000556:Ambulatory Surgical Procedures; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000009:adverse effects* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004569:Electroencephalography / Q000187:drug effects; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007275:Injections, Intravenous; D007442:Intubation, Intratracheal; D008297:Male; D008738:Methyl Ethers / Q000008:administration & dosage / Q000009:adverse effects* / Q000494:pharmacology; D008875:Middle Aged; D009294:Narcotics / Q000008:administration & dosage* / Q000494:pharmacology; D019148:Neuromuscular Blockade; D009609:Nitrous Oxide / Q000008:administration & dosage; D000077149:Sevoflurane
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D009294:Narcotics; D015760:Alfentanil; D000077149:Sevoflurane; D009609:Nitrous Oxide