title: Sex-related differences in the effect-site concentration of remifentanil for preventing QTc interval prolongation following intubation in elderly patients with a normal QTc interval.
abstract: BACKGROUND
  Female sex and age more than 65 years are common risk factors for the development of torsades de pointes in association with heart rate-corrected QT (QTc) interval prolongation, which can be induced by tracheal intubation during general anaesthesia. However, the administration of remifentanil can prevent intubation-induced QTc interval prolongation. We compared sex-related differences in the effect-site concentration (Ce) of remifentanil for preventing QTc interval prolongation among elderly patients.
  
  
  METHODS
  Twenty-two female and 22 male patients older than 65 years were enrolled. Anaesthesia was induced with remifentanil and propofol using a target-controlled infusion. The Ce of remifentanil for maintaining a QTc interval prolongation <15 ms following intubation was determined for each sex using the isotonic regression method and a bootstrapping approach following Dixon's up-and-down method.
  
  
  RESULTS
  The Ce of remifentanil for preventing QTc interval prolongation following intubation in 50 % of the population (EC50) and 95 % of the population (EC95) were significantly lower in females than in males. Isotonic regression revealed that the EC50 (83 % confidence interval) of remifentanil was 3.50 (2.95-4.08) ng/mL in females and 4.38 (4.08-4.63) ng/mL in males. The EC95 (95 % confidence interval) of remifentanil was 4.43 (4.25-4.48) ng/mL in females and 4.94 (4.78-4.98) ng/mL in males.
  
  
  CONCLUSIONS
  Target-controlled infusion of remifentanil is effective in attenuating QTc interval prolongation after intubation among elderly patients and the Ce of remifentanil is lower in females than in males.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Severance Hospital, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 120-752, Republic of Korea.
authors.forename: S Y
authors.initials: SY
authors.lastname: Kim
authors.forename: M K
authors.initials: MK
authors.lastname: Song
authors.forename: M-S
authors.initials: MS
authors.lastname: Kim
authors.forename: E H
authors.initials: EH
authors.lastname: Kim
authors.forename: D W
authors.initials: DW
authors.lastname: Han
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000768:Anesthesia, General / Q000009:adverse effects; D018686:Anesthetics, Intravenous / Q000008:administration & dosage* / Q000494:pharmacology; D001145:Arrhythmias, Cardiac / Q000517:prevention & control*; D004334:Drug Administration Schedule; D005260:Female; D006299:Health Services for the Aged; D006329:Heart Conduction System / Q000187:drug effects; D006801:Humans; D020128:Inhibitory Concentration 50; D007442:Intubation, Intratracheal / Q000009:adverse effects; D008297:Male; D010880:Piperidines / Q000008:administration & dosage* / Q000494:pharmacology; D011183:Postoperative Complications / Q000517:prevention & control*; D015742:Propofol / Q000008:administration & dosage; D000077208:Remifentanil; D012737:Sex Factors
chemical_list: D018686:Anesthetics, Intravenous; D010880:Piperidines; D000077208:Remifentanil; D015742:Propofol