title: Can remifentanil replace nitrous oxide during anesthesia for ambulatory orthopedic surgery with desflurane and fentanyl?
abstract: BACKGROUND
  The administration of nitrous oxide (N2O) may be associated with side effects and toxicities. Remifentanil shares characteristics with N2O, including MAC-reducing and antinociceptive effects and a rapid decrease in clinical effect when discontinued. We compared the outcome after ambulatory orthopedic surgery with desflurane and fentanyl supplemented with clinically equivalent doses of either N2O or remifentanil.
  
  
  METHODS
  Seventy patients undergoing ambulatory orthopedic surgery were studied. Thirty-five received 66% N2O and 35 received remifentanil 0.085 microg x kg(-1) x min(-1) in addition to desflurane, titrated to a bispectral index (BIS) value of 50, and a fentanyl infusion. The principle outcome measure was time to awakening to verbal stimulation. Secondary outcome measures included neuropsychological testing, time to orientation, hemodynamic values, pain and nausea visual analog scores, discharge times, and satisfaction scores. The average end-tidal desflurane concentration and fentanyl effect-site concentration were determined.
  
  
  RESULTS
  The median time (interquartile range) to awakening to verbal stimulation, 3.0 min (3.0-5.0 min) in the remifentanil group and 4.6 min (3.0-8.1 min) in the N2O group was not significantly different. Median time to orientation was significantly faster in the remifentanil group: 6.0 min (5.0-8.5 min) compared with 8.0 min (5.0-12.8 min) for the N2O group. There was no difference between groups in desflurane or fentanyl administration, neuropsychological testing, or any other outcome measure.
  
  
  CONCLUSIONS
  This study demonstrates that a remifentanil infusion of 0.085 microg x kg(-1) x min(-1) may be substituted for 66% N2O during desflurane/fentanyl anesthesia without any clinically significant change in outcome.
authors.affiliation: Department of Anesthesiology, St. Vincent Catholic Medical Centers, St. Vincent's Manhattan, New York, USA. dmathews@svcmcny.org
authors.forename: Donald M
authors.initials: DM
authors.lastname: Mathews
authors.forename: Vijay
authors.initials: V
authors.lastname: Gaba
authors.forename: Bledi
authors.initials: B
authors.lastname: Zaku
authors.forename: George G
authors.initials: GG
authors.lastname: Neuman
mesh_terms: D000328:Adult; D000556:Ambulatory Surgical Procedures; D000700:Analgesics / Q000627:therapeutic use; D019162:Anesthetics, Combined / Q000009:adverse effects*; D018685:Anesthetics, Inhalation / Q000009:adverse effects*; D018686:Anesthetics, Intravenous / Q000009:adverse effects*; D000077335:Desflurane; D005260:Female; D005283:Fentanyl; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007530:Isoflurane / Q000009:adverse effects / Q000031:analogs & derivatives*; D007902:Length of Stay; D008297:Male; D009048:Motor Skills / Q000187:drug effects; D009609:Nitrous Oxide / Q000009:adverse effects*; D009949:Orientation / Q000187:drug effects; D019637:Orthopedic Procedures; D010149:Postoperative Pain / Q000517:prevention & control; D017060:Patient Satisfaction; D010880:Piperidines / Q000009:adverse effects*; D020250:Postoperative Nausea and Vomiting / Q000139:chemically induced; D000077208:Remifentanil; D013997:Time Factors; D016896:Treatment Outcome; D014851:Wakefulness / Q000187:drug effects
chemical_list: D000700:Analgesics; D019162:Anesthetics, Combined; D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D010880:Piperidines; D000077335:Desflurane; D007530:Isoflurane; D009609:Nitrous Oxide; D000077208:Remifentanil; D005283:Fentanyl