PHARMACOKINETIC MODEL-DRIVEN INFUSION OF FENTANYL IN CHILDREN

Background: This study determined the accuracy of previously defined a dult fentanyl pharmacokinetics in children having surgery; from this p opulation, the pharmacokinetics of fentanyl were characterized in chil dren when administered via a computerized assisted continuous-infusion device. Methods: Twenty children between the ages of 2.7 and 11 y sch eduled to undergo elective noncardiac surgery were studied. After indu ction, anesthesia was maintained with 60% nitrous oxide in oxygen supp lemented with fentanyl (n = 10) or fentanyl plus isoflurane (n = 10), Fentanyl was administered via computerized assisted continuous-infusio n to target concentrations determined by clinical requirements, Plasma fentanyl concentrations were measured and used to evaluate the perfor mance of the fentanyl pharmacokinetics and then to determine a new set of pharmacokinetic parameters and the variance in the context-sensiti ve half-times simulated for these patients. Results: The original adul t fentanyl pharmacokinetics resulted in a positive bias (10.4%), indic ating that measured concentrations were mostly greater than predicted. A tno-compartment model with age and weight as covariates provided th e optimal pharmacokinetic parameters. These resulted in a residual per formance error of -1.1% and a median absolute performance error of 17. 4%, The context-sensitive times determined from this pediatric populat ion mere considerably shorter than the context-sensitive times previou sly published for adults. Conclusions: The pharmacokinetics of fentany l administered by computerized assisted continuous-infusion differ bet ween adults and children. The newly derived parameters are probably mo re suitable to determine infusion schemes of up to 4 h in children bet ween the ages of 2 and 11 y.