Abstract

Background: The Schnider pharmacokinetic (PK) model ́s overall perfor- mance has been evaluated following a bolus and perfusion(1).Our aim is to analyze the performance of the model in long stable ascending and descend- ing steps of TCI infusion. methods: After approval of Ethics Committee of Clinica Alemana and written informed consent, 14 healthy volunteers were enrolled. An effect site pro- pofol TCI using Schnider’s model was administered in plateaus of 0.5 ug/ml and 7 minutes each, up to two levels above loss consciousness (LOC) fol- lowed by declines of equal magnitude and duration to Ccal 0.5ug/ml. Venous blood samples were taken at the end of each step to measure propofol by ration of surger y (P=0,963) and surgery (P=0.569), whole hospital stay (P=0.840), total fentanyl (P=0.377), fentanyl/kg (P=0.728), intraoperative blood loss (P=0.931), first drink intake (P=0.817), upstanding (P=0.676) and food intake (P=0.956) after the sur- gery. There was some difference in total rocuronium (P=0.043), but not for rocuronium/kg (P=0.368). Extubation time (2 min vs. 4 min, P<0.001) and time of discharge to the ward (3 min vs. 9 min, P<0.001) were shorter in S group. Unpaired t- test for normally distributed glucose values showed sig- HPLC. Var vel ́s(2) method Population median PE (MDPE) was calculated for each step as a measure of bias, and the absolute median (MDAPE) as a measure of inaccuracy between measured and predicted values. Interindividual variability was determined by calculating wobble (the median absolute deviation from Results: 203 blood samples were analyzed; the overall performance of the model was MDPE 0.5%, MDAPE 26%. Divergence was 19.24% h-1 and wob- ble 4%. Steps up 0-1μg/mL shows a mDPE -36%, mDAPE 39 and step down 1-0μg/mL, mDPE 35%, mDAPE 55% (figure 1). Conclusion: Overall performance for each step are within accepted values. At low concentrations (i.e: less than 1 μg/ml) the model overpredicts during induction and underpredicts at recovery. Variability on induction is smaller in relation to the variability of recovery. References: 1. Br J Anaesth 2009; 102: 626-32