title: Prospective evaluation of the time to peak effect of propofol to target the effect site in children.
abstract: BACKGROUND
  The plasma-effect site equilibration rate constant (k(e0)) of propofol has been determined in children with the use of the time to maximum effect (t(peak)), however, it has not been validated. The objective was to measure the t(peak;) of propofol with two depths of anesthesia monitors in children and to evaluate these measurements with a target-controlled infusion (TCI) system.
  
  
  METHODS
  Unpremedicated, ASA I children from 3 to 11 years were studied. In Part 1, children were monitored simultaneously with the bispectral index (BIS) and the A-Line ARX-index (AAI) from the Alaris A-Line auditory-evoked potential monitor/2. The t(peak) after a bolus dose of propofol was measured. In Part 2, the t(peak) measured was used to target the effect site with a TCI system. The median (MD) and the absolute median (MDA) difference between the predicted time of peak concentration at the effect site (Ce) and the measured time of peak effect in the index of depth of anesthesia (t(error)) was used to evaluate the performance of the system.
  
  
  RESULTS
  The BIS recordings were of a better quality than the AAI. The mean +/- standard deviation t(peak) was 65 +/- 14 s with the BIS (n=25) and 201 +/- 74 s with the AAI (n=10)(P<0.001). Validation was only performed with the BIS monitor in 40 children, yielding an MD t(error) of -9.5 s and an MDA t(error) of 10.0 s.
  
  
  CONCLUSIONS
  The small delay between the evolution of Ce of propofol and the observed effect suggests that this can be a useful model to target the effect site in children.
authors.affiliation: Departamento de Anestesiología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: H R
authors.initials: HR
authors.lastname: Muñoz
authors.forename: P J
authors.initials: PJ
authors.lastname: León
authors.forename: R S
authors.initials: RS
authors.lastname: Fuentes
authors.forename: G C
authors.initials: GC
authors.lastname: Echevarría
authors.forename: L I
authors.initials: LI
authors.lastname: Cortínez
mesh_terms: D000771:Anesthesia, Intravenous; D018686:Anesthetics, Intravenous / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography / Q000187:drug effects; D005072:Evoked Potentials, Auditory / Q000187:drug effects; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D016343:Monitoring, Intraoperative; D015742:Propofol / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000494:pharmacology*; D011446:Prospective Studies
chemical_list: D018686:Anesthetics, Intravenous; D015742:Propofol