Figure 3. The effect of intravenous lidocaine, at three different plasma concentrations, on von Frey hair thresholds of the volar aspect of the left forearm. After measuring thresholds at the 3-micro gram/ml targeted plasma level, intradermal capsaicin was administered on the volar aspect of the left forearm, and von Frey hair thresholds were repeated for sensation (CAP-T) and pain (CAP-P).