Fig. 3. Time course of calculated S  (+)-ketamine plasma concentrations (broken line) caused by infusion rates shown as area under the curve (male subject; age, 30 yr; weight, 75 kg) (A ). Infusion of S  (+)-ketamine resulted in a significant increase in oxygen saturation (Spo²), mean arterial pressure (MAP), and heart rate (HR) (P < 0.05, analysis of variance) (B ). Pain ratings (C ) as well as areas of pin-prick hyperalgesia (D ) and touch-evoked allodynia (E ) were significant reduced by S  (+)-ketamine (P < 0.001, analysis of variance). The flare reaction, determined via  laser Doppler imaging, was not affected by the medication (nonsignificant, analysis of variance) (F ). Data are expressed as mean ± SEM (n = 12); *P < 0.05, planned comparisons corrected with the Bonferroni procedure. NRS = numeric rating scale.