title: Target-controlled infusion of propofol and remifentanil in cardiac anaesthesia: influence of age on predicted effect-site concentrations.
abstract: BACKGROUND
  Propofol-anaesthesia administrated via target-controlled infusion (TCI) has been proposed for cardiac surgery. Age-related changes in pharmacology explain why propofol dose requirement is reduced in elderly patients. However, the Marsh pharmacokinetic model incorporated in the Diprifusor propofol device does not take age into account as a covariable. In the absence of depth of anaesthesia monitoring, this limitation could cause adverse cardiovascular effects resulting from propofol overdose in older patients. We assessed the influence of age on effect-site propofol concentrations predicted by the Diprifusor and titrated to the bispectral index score (BIS) during cardiac anaesthesia.
  
  
  METHODS
  Forty-five patients received propofol by Diprifusor and remifentanil by software including Minto model. Propofol and remifentanil effect-site concentrations were adapted to BIS (40-60) and haemodynamic profile, respectively. The influence of age on effect-site concentrations was assessed by dividing patients into two groups: young (<65 yr) and elderly (> or =65 yr).
  
  
  RESULTS
  For a similar depth of anaesthesia, effect-site propofol concentrations were significantly lower in elderly patients at the different stages of cardiac surgery. The mean dose of propofol required to perform tracheal intubation was significantly lower in elderly patients. However, the overall doses of propofol were comparable in both groups. Neither effect-site remifentanil concentrations nor overall doses of remifentanil were significantly different between the two groups.
  
  
  CONCLUSIONS
  In cardiac anaesthesia, target concentrations of propofol must be reduced in elderly patients. Although this probably contributes to improving intraoperative haemodynamic stability, the absence of decrease in overall dose requirement of propofol suggests that this adjustment is relatively moderate.
authors.affiliation: Institute of Cardiology, Department of Anaesthesia and Intensive Care, Pitié-Salpêtrière University Hospital, Paris, France. alexandre.ouattara@psl.ap-hop-paris.fr
authors.forename: A
authors.initials: A
authors.lastname: Ouattara
authors.forename: G
authors.initials: G
authors.lastname: Boccara
authors.forename: S
authors.initials: S
authors.lastname: Lemaire
authors.forename: U
authors.initials: U
authors.lastname: Köckler
authors.forename: M
authors.initials: M
authors.lastname: Landi
authors.forename: E
authors.initials: E
authors.lastname: Vaissier
authors.forename: P
authors.initials: P
authors.lastname: Léger
authors.forename: P
authors.initials: P
authors.lastname: Coriat
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D019162:Anesthetics, Combined / Q000008:administration & dosage*; D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D006348:Cardiac Surgical Procedures; D004334:Drug Administration Schedule; D016503:Drug Delivery Systems; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D010880:Piperidines / Q000008:administration & dosage*; D015742:Propofol / Q000008:administration & dosage*; D011446:Prospective Studies; D000077208:Remifentanil
chemical_list: D019162:Anesthetics, Combined; D018686:Anesthetics, Intravenous; D010880:Piperidines; D000077208:Remifentanil; D015742:Propofol