Fig. 3.
Fentanyl concentrations and outcome variable of intradermal electrical stimulation. All values are represented as mean ± SE. Fentanyl concentrations were calculated by the iTIVA app (Shafer Model); P values from 4.5 to 6.5 h are based on the mixed-effects model; P values for 0 to 2 h are based on the area under the curve and a paired Wilcoxon Mann–Whitney U test. NRS = numeric rating scale.