title: Effect of a target-controlled infusion of remifentanil in combination with desflurane during the "maintenance" phase of general anesthesia.
abstract: BACKGROUND
  The goal of this study was to determine the optimal target-controlled concentration of remifentanil combined with desflurane, by using a more widely and decreasing end-tidal concentration of desflurane.
  
  
  METHODS
  Ninety ASA I patients, who underwent general anesthesia for elective orthopedic or extremity surgeries, were registered and randomly allocated to receive either a target-controlled concentration of 1 ng/ml (group R1), 2 ng/ml (group R2) remifentanil, or desflurane only without remifentanil infusion (group D). Mean arterial pressure (MAP) and heart rate (HR) were recorded at 5-min intervals from after a 10-15 min period of surgical incision to before a 10-min period prior to the end of an operation. End-tidal concentration of desflurane was increased or decreased in proportion to the changes in MAP and HR. If the value of bispectral index (BIS) was from 60-62 for more than 2 min or systolic blood pressure would fall below 90 mmHg, the patient was excluded from the study to prevent a risk of "explicit awareness" and shock.
  
  
  RESULTS
  The end-tidal desflurane concentration was lower in the group receiving 1 ng/ml (5.2 ± 0.5 vol%; P < 0.001) and 2 ng/ml remifenanil (4.4 ± 0.5 vol%; P < 0.001) compared to patients in group D (7.9 ± 0.5 vol%).
  
  
  CONCLUSIONS
  We recommend the use of 2 ng/ml or less remifentanil combined with desflurane for decreasing concentrations of desflurane without significant side effects, during the "maintenance" phase, and not during the induction phase of general anesthesia.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea.
authors.forename: Myoung-Keun
authors.initials: MK
authors.lastname: Shin
authors.forename: Haeng Seon
authors.initials: HS
authors.lastname: Shim
authors.forename: Geun Young
authors.initials: GY
authors.lastname: Yang
authors.forename: Woo Sung
authors.initials: WS
authors.lastname: Sung