title: Predicted EC₅₀ and EC₉₅ of Remifentanil for Smooth Removal of a Laryngeal Mask Airway Under Propofol Anesthesia.
abstract: OBJECTIVE
  The purpose of this study was to determine the effect-site concentration (Ce) of remifentanil in 50% of patients (EC₅₀) and 95% of patients (EC₉₅) for smooth laryngeal mask airway (LMA) removal in adults under propofol and remifentanil anesthesia.
  
  
  METHODS
  Twenty-five patients of ASA physical status I-II and ages 18-60 years who were to undergo minor gynecological or orthopedic surgery were assessed in this study. Anesthesia was induced and maintained with propofol and remifentanil target-controlled infusion (TCI). Remifentanil was maintained at a predetermined Ce during the emergence period. The modified Dixon's up-and-down method was used to determine the remifentanil concentration, starting from 1.0 ng/mL (step size of 0.2 ng/mL). Successful removal of the LMA was regarded as absence of coughing/gagging, clenched teeth, gross purposeful movements, breath holding, laryngospasm, or desaturation to SpO₂<90%.
  
  
  RESULTS
  The mean±SD Ce of remifentanil for smooth LMA removal after propofol anesthesia was 0.83±0.16 ng/mL. Using isotonic regression with a bootstrapping approach, the estimated EC₅₀ and EC₉₅ of remifentanil Ce were 0.91 ng/mL [95% confidence interval (CI), 0.77-1.07 ng/mL] and 1.35 ng/mL (95% CI, 1.16-1.38 ng/mL), respectively.
  
  
  CONCLUSIONS
  Our results showed that remifentanil TCI at an established Ce is a reliable technique for achieving safe and smooth emergence without coughing, laryngospasm, or other airway reflexes.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Yoo
authors.affiliation: Department of Anesthesiology and Pain Medicine, Gachon University, Gil Medical Center, Incheon, Korea.
authors.forename: Hyun Jeong
authors.initials: HJ
authors.lastname: Kwak
authors.affiliation: Department of Anesthesiology and Pain Medicine, Gachon University, Gil Medical Center, Incheon, Korea.
authors.forename: Kyung Cheon
authors.initials: KC
authors.lastname: Lee
authors.affiliation: Department of Anesthesiology and Pain Medicine, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Go Wun
authors.initials: GW
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Ajou University School of Medicine, Suwon, Korea. kjyeop@ajou.ac.kr.
authors.forename: Jong Yeop
authors.initials: JY
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D003371:Cough / Q000517:prevention & control; D020878:Device Removal; D004305:Dose-Response Relationship, Drug; D005260:Female; D013509:Gynecologic Surgical Procedures; D006801:Humans; D017214:Laryngeal Masks; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures; D010880:Piperidines / Q000008:administration & dosage*; D015742:Propofol / Q000008:administration & dosage*; D000077208:Remifentanil; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000701:Analgesics, Opioid; D018685:Anesthetics, Inhalation; D010880:Piperidines; D000077208:Remifentanil; D015742:Propofol
keywords: Laryngeal mask airway; device removal; effect-site concentration; general anesthesia; remifentanil; target-controlled infusion