Although targeting the effect site concentration may offer advantages over the traditional forms of administering intravenous anesthetics, it is not applicable for sufentanil in children because its plasma effect site equilibration rate constant (ke0) is not known yet. We estimated ke0 of sufentanil in children using the time to peak effect (tpeak) method.
Materials and Methods:

Under general anesthesia, sufentanil tpeak was measured after administration of a submaximal bolus dose by means of the decrease in heart rate, blood pressure and calculated approximate entropy (ApEn) of electroencephalogram in 105 children (age range: 3–11 years). ke0 was estimated using tpeak and known sufentanil pharmacokinetic parameters in normal children.
Results:

The mean tpeaks were measured as 44 ± 22 s and 227 ± 91 s by heart rate and by mean blood pressure respectively. The estimated ke0 were 5.16/min and 0.49/min by heart rate and blood pressure respectively. tpeak could not be measured using the ApEn, thus ke0 could not be calculated by ApEn in children.