Fig. 7.
Influence of variations in blood-effect-site equilibration half-life, t½ke0 (A and B), and potency parameter, C50 (C and D), on the shape of the utility functions (UFs). Continuous lines are the data estimated from the current study (UF in time domain are constructed for a 3.5 μg/kg of fentanyl injection). (A and B) Dashed line is the UF with analgesia’s t½ke0 × 2, the dotted line is the UF with analgesia’s t½ke0 × 0.5 (note that in the concentration domain, changes in t½ke0 do not affect the shape of the UF). (C and D) x-x- are the UFs with a lower potency for analgesia (C25 × 2), o-o- are the UFs with a higher potency for analgesia (C25 × 0.5). P(A) = probability for analgesia; P(R) = probability for respiratory depression.