Fig. 2.
Exemplary illustration of VPEP (A) and CHEP (B) at level I (lined), level II (dotted), and level III (dashed): decreasing P1-N2 amplitudes of VPEP and CHEP are shown under remifentanil administration (average all data from a single volunteer for VPEP and CHEP). CHEP = contact heat–evoked potential; VPEP = visceral pain–evoked potential; I = baseline without any drug application; II = drug concentration level II (here: remifentanil 0.05 μg·kg−1·min−1); III = drug concentration level III (here: remifentanil 0.15 μg·kg−1·min−1).
