title: The predictive performance of a pharmacokinetic model for manually adjusted infusion of liquid sevofluorane for use with the Anesthetic-Conserving Device (AnaConDa): a clinical study.
abstract: BACKGROUND
  The Anesthetic-Conserving Device (AnaConDa) can be used to administer inhaled anesthetics using an intensive care unit (ICU) ventilator. We evaluated the predictive performance of a simple manually adjusted pump infusion scheme, for infusion of liquid sevoflurane to the AnaConDa.
  
  
  METHODS
  We studied 50 ICU patients who received sevoflurane via the AnaConDa. They were randomly divided into three groups. A 6-h infusion of liquid anesthetic was adjusted according to the infusion scheme to a target end-tidal sevoflurane concentration of 1% (Group 1%, n = 15) and 1.5% (Group 1.5%, n = 15). The initial rate was adjusted to reach the target concentration in 10 min and then the infusion was reduced to the first hour maintenance rate and readjusted once each hour afterwards. The actual concentrations were measured in the breathing circuit and compared with the target values. In the third group (n = 20) we used the model to increase and decrease the target concentration (+/-0.3%) for 3 h and evaluated the actual change in concentration achieved. The ability of the infusion scheme to provide the target concentration was quantified by calculating the performance error (PE). Infusion scheme performance was evaluated in terms of accuracy (median absolute PE, MDAPE) and bias (median PE, MDPE).
  
  
  RESULTS
  Performance parameters (mean +/- SD, %) were for 1%, 1.5%, increase of concentration by 0.3% and decrease of concentration by 0.3% groups, respectively: MDAPE 5.3 +/- 5.5, 2.6 +/- 4.0, 5.0 +/- 5.6, 5.5 +/- 5.4; MDPE -5.3 +/- 5.5, -2.3 +/- 4.1, -0.1 +/- 7.1, 0.2 +/- 5.4. No significant differences were found between means of all performance parameters when the 1% and 1.5% groups were compared.
  
  
  CONCLUSIONS
  There is an excellent 6-h predictive performance of a simplified pharmacokinetic model for manually adjusted infusion of liquid sevoflurane when using the AnaConDa to deliver sevoflurane to ICU patients.
authors: Anesthesiology and Intensive Care Department, Hospital Clínico Universitario de Valencia, Avenida Blasco Ibáñez, 17. 46010 Valencia, Spain. fjbelda@uv.es
authors: Javier F
authors: JF
authors: Belda
authors: Marina
authors: M
authors: Soro
authors: Rafael
authors: R
authors: Badenes
authors: Andreas
authors: A
authors: Meiser
authors: María Luisa
authors: ML
authors: García
authors: Gerardo
authors: G
authors: Aguilar
authors: Francisco J
authors: FJ
authors: Martí
mesh_terms: D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000493:pharmacokinetics*; D001794:Blood Pressure; D003201:Computers; D006801:Humans; D007262:Infusions, Intravenous; D007362:Intensive Care Units; D007700:Kinetics; D008657:Metabolic Clearance Rate; D008738:Methyl Ethers / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008954:Models, Biological; D011184:Postoperative Period; D012121:Respiration, Artificial / Q000295:instrumentation / Q000379:methods; D000077149:Sevoflurane; D014018:Tissue Distribution
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane