Fig. 4. Duration of postoperative sensory block. Sensitivity analysis comparing the efficacy of clonidine added to intermediate-acting and long-acting local anesthetics in patients receiving an axillary plexus block. Duration of sensory block was tested using pinprick. Meta-analyses were performed using a fixed effect model, except *random effects model ( P for heterogeneity < 0.1). Symbols and horizontal lines are mean differences (single trials) or WMDs (combined data) with 95% CIs. CI = confidence interval; LA = local anesthetic; n/a = not applicable (no relevant data available); WMD = weighted mean difference.