Estimation of the Plasma Effect Site Equilibration Rate Constant (ke0) of Propofol in Children Using the Time to Peak Effect

Hernán R. Muñoz, Luis I. Cortínez, Mauricio E. Ibacache, Fernando R. Altermatt
2004 Anesthesiology  
Targeting the effect site concentration may offer advantages over the traditional forms of administrating intravenous anesthetics. Because the lack of the plasma effect site equilibration rate constant (k e0 ) for propofol in children precludes the use of this technique in this population, the authors estimated the value of k e0 for propofol in children using the time to peak effect (t peak ) method and two pharmacokinetic models of propofol for children. Methods: The t peak after a submaximal
more » ... after a submaximal bolus dose of propofol was measured by means of the Alaris A-Line auditory evoked potential monitor (Danmeter A/S, Odense, Denmark) in 25 children (aged 3-11 yr) and 25 adults (aged 35-48 yr). Using t peak and two previously validated sets of pharmacokinetic parameters for propofol in children, Kataria's and that used in the Paedfusor (Graseby Medical Ltd., Hertfordshire, United Kingdom), the k e0 was estimated according to a method recently published. Results: The mean t peak was 80 ؎ 20 s in adults and 132 ؎ 49 s in children (P < 0.001). The median k e0 in children was 0.41 min ؊1 with the model of Kataria and 0.91 min ؊1 with the Paedfusor model (P < 0.01). The corresponding t 1/2 k e0 values, in minutes, were 1.7 and 0.8, respectively (P < 0.01). Conclusions: Children have a significantly longer t peak of propofol than adults. The values of k e0 of propofol calculated for children depend on the pharmacokinetic model used and also can only be used with the appropriate set of pharmacokinetic parameters to target effect site in this population.
doi:10.1097/00000542-200412000-00005 pmid:15564932 fatcat:kyi4qtcesnednjer7uofd53fci