Remifentanil, alfentanil and fentanyl all reduced the incidence of withdrawal movement when administered 90 s before the injection of rocuronium compared with saline. Remifentanil was the most effective, followed by alfentanil. Fentanyl was less effective but significantly different from the saline in reducing withdrawal movement in children.

this study demonstrated that inhalation induction with sevoflurane can prevent the withdrawal movement induced by rocuronium in children, and IT(50) and IT(95) for the prevention of movement was 1.7 and 2.3 min, respectively.

SummaryThis study compared the predicted effect-site concentration of propofol at loss and recovery of consciousness when using target-controlled infusion devices with the same pharmacokinetic model (Marsh) but a different plasma effect-site equilibration rate constant (k e0 ), the Diprifusor TM (k e0 0.26 min À1) and Base Primea TM (k e0 1.21 min À1). We studied 60 female patients undergoing minor gynaecological surgery under general anaesthesia. Although the total dose of propofol and time until loss of consciousness were comparable, the effect-site concentration at loss of consciousness was significantly lower with the Diprifusor than with the Base Primea (1.2 (0.3) lg.ml À1 vs 4.5 (0.9) lg.ml À1, respectively, p < 0.001). The effect-site concentration at recovery of consciousness was significantly higher with the Diprifusor than with the Base Primea (1.8 (0.4) lg.ml À1 vs 1.5 (0.2) lg.ml À1, respectively, p = 0.01). In conclusion, the effect-site concentration of propofol differs depending on the k e0 , despite the use of the same pharmacokinetic model. Therefore, the k e0 should be considered when predicting loss and recovery of consciousness based on the effect-site concentration of propofol. Target-controlled infusion (TCI) systems control the infusion rate of intravenous drugs according to predetermined pharmacokinetic profiles targeting plasma or effect-site concentration of the drug. After intravenous administration, the plasma concentration of a drug gradually equilibrates with its effect-site concentration. The rate of equilibration between plasma and effect-site concentration depends on the rate of transfer of the drug from the plasma to the effect-site [1]. The time course of equilibration between plasma and effect-site concentrations can be mathematically described by a first-order rate constant, known as the plasma effect-site equilibration rate constant (k e0 ), which can be used to estimate effect-site concentration [2].There are currently several commercial TCI devices designed for the infusion of propofol, such as the Diprifusor TM (AstraZeneca, Macclesfield, UK) and Base Primea TM (Fresenius-Vial, Br ezins, France). The 1232

Background:The aim of this study was to investigate the optimal exhaled sevoflurane concentration that produces adequate endotracheal intubation conditions when sevoflurane is combined with the different bolus doses of remifentanil used in clinical practice.Methods:The patients were randomized to 3 groups (groups 1.0, 1.5, and 2.0), receiving remifentanil bolus doses of 1.0, 1.5, and 2.0 μg/kg, respectively. For each group, the concentration of sevoflurane used for each consecutive patient was increased or decreased using the “up-and-down” method based on the success or failure to achieve adequate conditions for intubation in the previous patient. The remifentanil bolus dose was administered 90 s before intubation and after the target sevoflurane concentration was achieved.Results:In groups 1.0, 1.5, and 2.0, the effective concentration in 50% (EC50) of the sevoflurane concentration required to perform successful intubation was 3.0, 2.0, and 1.29 vol% and the effective concentration in 95% was 3.45, 2.91, and 1.89 vol%, respectively. When sevoflurane was administered for the induction, the increase in heart rate (HR) of group 1.0 was the highest among the groups. The highest number of adverse events occurred in group 2.0, including vocal cord rigidity, hypotension, and bradycardia.Discussion:The EC50 of the sevoflurane concentration was 3.0, 2.0, and 1.29 vol% when it was combined with a bolus dose of remifentanil of 1.0, 1.5, and 2.0 μg/kg, respectively. Of the 3 different bolus doses of remifentanil, the dose of 1.5 μg/kg was least associated with changes in the HR/mean blood pressure during intubation without increasing adverse effects.